JP3538917B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an operating mechanism for a friction element which is fastened by supplying a fastening pressure from a released state of a friction element and released by supplying a release pressure in the fastened state. To a shift control device for an automatic transmission.

[0002]

2. Description of the Related Art An automatic transmission mounted on a vehicle is adapted to automatically shift an engine rotation input via a torque converter mainly using a throttle opening and a vehicle speed as parameters. In general, two sets of planetary gear sets are used as a gear train of an automatic transmission, and each component (sun gear, planetary gear, and ring gear) of the planetary gear set is appropriately connected or connected via friction elements such as a clutch and a brake. By being fixed, a desired gear ratio can be obtained. Further, the friction element is engaged and released by hydraulic pressure supplied from the control valve unit according to the shift speed.

As described above, the friction element has a brake, which is used to fix the components of the planetary gear set to the housing. By the way, there are a clutch type and a band type brake, and the band type brake is adapted to be fastened and released via a band servo as an operation mechanism.

In the band servo, a fastening chamber is provided on one side of a servo piston having a different pressure receiving area, and a release chamber is provided on the other side.
When no hydraulic pressure is supplied to the fastening chamber and the release chamber, the band brake is released by the urging force of the spring, and the hydraulic pressure (fastening pressure) is supplied to the fastening chamber to fasten the band brake. When the hydraulic pressure (release pressure) is supplied to the release chamber, the servo piston moves due to the pressure receiving area difference and the band brake is released. The hydraulic fluid in the fastening chamber and the release chamber is normally discharged through an orifice.

By the way, in the band brake having the band servo having such a configuration, even when the hydraulic pressure is not supplied to both the fastening chamber and the release chamber, the working oil remains in each chamber. When the band brake is fastened by supplying the fastening pressure to the servo piston, a large movement resistance is generated in the servo piston due to the remaining oil pressure in the release chamber.
In particular, when the operating oil temperature is low and cold, the viscosity of the operating oil is high, so that the discharge of the remaining oil pressure becomes slow, and the movement resistance of the servo piston further increases. For this reason, the engagement timing of the band brake is greatly changed depending on the magnitude of the remaining hydraulic pressure and the operating oil temperature that affects the viscosity, causing an engagement shock and delaying the engagement timing, causing an engine air blow. Would.

Therefore, conventionally, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent Application Publication (F16H 5/12), a switching valve for releasing the release chamber to the atmosphere when the fastening pressure is supplied is provided, and the discharge of the hydraulic oil remaining in the release chamber is limited to the orifice by the switching valve. There are things that are done smoothly without being done.

[0007]

However, in such a conventional shift control device for an automatic transmission, the fastening pressure of the band servo is used as the pilot pressure for switching the switching valve. During the generation, the switching valve is kept in a state of releasing the release chamber to the atmosphere. That is, while the band brake is engaged, the remaining hydraulic pressure in the release chamber is entirely drained by the atmosphere release portion. For this reason, the next time the release pressure is supplied to the release chamber and the band brake is released, the release pressure must be supplied to the release chamber from the beginning. Will occur.

In addition, it is disclosed that the switching valve is electrically released to the atmosphere instead of the switching valve. In this case, the timing for supplying the engagement pressure is obtained from a shift signal. For this reason, after reading the shift timing from the shift map, it is necessary to make a determination based on the shift flag, and the control is complicated because it is necessary to refer to the map. Further, even in this case, since the prohibition timing of the release to the atmosphere is not controlled, various problems that the residual pressure in the release chamber is unnecessarily discharged and the subsequent release timing is delayed as in the case of the switching valve. was there.

In view of the foregoing, the present invention has been made in consideration of the above-described conventional problems, and reduces the influence of the viscosity of hydraulic oil, smoothly engages and disengages a friction element, suppresses the occurrence of a shift shock, and provides simple control. SUMMARY OF THE INVENTION It is an object of the present invention to provide a shift control device for an automatic transmission which can achieve this.

[0010]

According to a first aspect of the present invention, in order to achieve the above object, a fastening is performed by supplying a fastening pressure from a released state of the friction element, and the releasing pressure is supplied in the fastened state. In a shift control device for an automatic transmission having an operation mechanism of a friction element released by being operated, a drain is provided in a supply passage of the release pressure, and the drain is opened when the fastening pressure is supplied to the operation mechanism. An opening / closing means for discharging the remaining release pressure is provided, and an actual shift start point at which the turbine rotation of the fluid coupling for transmitting the engine rotation to the automatic transmission changes from rising to falling is detected. The opening / closing means in the open state is closed by a signal.

Further, according to the second configuration of the present invention, the fastening is performed by supplying the fastening pressure from the released state of the friction element,
In a shift control device for an automatic transmission having an operation mechanism of a friction element that is released by the release pressure being supplied in the engaged state, a throttle unit is provided in each of the release pressure supply passage and the engagement pressure supply passage. A drain is provided on the downstream side of the throttle means in the release pressure supply passage, and a bypass passage is provided in the supply path of the fastening pressure to bypass the throttle means, and the drain and the bypass passage are respectively provided in the drain and the bypass passage. Providing opening / closing means, while opening the drain opening / closing means at the time of shifting to supply the fastening pressure and fastening the friction element, opening the bypass passage opening / closing means at the time of shifting to release the friction element by discharging the fastening pressure, Release of the friction element during cold is achieved by discharging the fastening pressure and the release pressure.

Further, it is desirable that the opening time of the bypass passage is controlled by a timer.

Further, it is desirable that the opening and closing means for the drain and the opening and closing means for the bypass passage are linked and integrated so that the drain and the bypass passage are opened synchronously.

[0014]

In the transmission control apparatus for an automatic transmission according to the first configuration of the present invention having the above configuration, the opening and closing of the drain provided in the release pressure supply passage when the engagement pressure is supplied to the operating mechanism. By opening the means, the release pressure is discharged from this drain and the fastening pressure is smoothly introduced into the operating mechanism, and the fastening operation of the friction element is performed quickly, preventing the engine from blowing. can do. At this time, in the present invention, the opening / closing means in the open state is closed by the detection signal of the actual shift start point at which the turbine rotation changes from rising to falling, so that the friction element is actually engaged at the actual shift start point. It is possible to prevent the release pressure from being unnecessarily discharged from the drain after the shift to. That is, the release pressure can be left in the operating mechanism in the state of the supply of the fastening pressure, and when the state of supply of the fastening pressure changes to the state of the supply of the release pressure, the supply of the release pressure to the operating mechanism is quickly performed. Therefore, the friction element can be released smoothly, and the drag phenomenon can be eliminated. Further, the timing for closing the drain can be directly controlled by the detection signal of the actual shift start point, so that the closing operation of the opening / closing means can be quickly and easily controlled.

In the second configuration of the present invention, a drain is provided on the downstream side of the throttle means of the release pressure supply passage, and a bypass passage is provided to bypass the throttle means of the fastening pressure supply passage. By opening the drain opening / closing means at the time of shifting when the friction element is engaged by supplying the engagement pressure, the release pressure can be quickly discharged and the friction element can be smoothly engaged. At the time of shifting in which the friction element is released by releasing the engagement pressure, the opening and closing means of the bypass passage can be opened to increase the discharge amount of the engagement pressure, so that the friction element can be smoothly released. This shift control exerts a great effect during cold times when the viscosity increases.

Further, by controlling the opening time of the bypass passage by a timer, it is possible to prevent all of the fastening pressure from being discharged from the operating mechanism and to quickly perform the subsequent fastening operation.

Further, the opening and closing means for the drain and the opening and closing means for the bypass passage are integrated in an interlocked manner, and the drain and the bypass passage are set so as to be opened in synchronization with each other. Can be performed at one time, and downsizing of the apparatus can be achieved by reducing the number of parts.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 11 show an embodiment of a shift control device for an automatic transmission according to the present invention. FIG. 1 is a schematic configuration diagram of a gear train of the automatic transmission, and FIG. FIG. 3 is a schematic configuration diagram of a shift control device of an automatic transmission, FIG. 4 is a cross-sectional view of an operation mechanism of a friction element, and FIG. 5 is a hydraulic circuit to which the shift control device of the present invention is applied. FIG. 6 is a schematic configuration diagram illustrating a main part of FIG. 6, FIG. 6 is a flowchart illustrating an example of a process for executing a shift control,
FIG. 7 is a flowchart showing another processing example for executing the shift control, FIG. 8 is a characteristic diagram showing the relationship between the opening / closing means and the turbine rotation, and FIG. FIG. 10 is an explanatory view showing the supply relationship of hydraulic oil, and FIG.
FIG. 11 is a characteristic diagram showing a change in a warm release pressure at the time of three-shift up, and FIG. 11 is a characteristic diagram showing a change of a cold engagement pressure at the time of 2-3 shift-up.

That is, the automatic transmission 10 to which the transmission control device of the present embodiment is applied has two planetary gear mechanisms of a first planetary gear 12 and a second planetary gear 14 as shown in FIG. , These first and second planetary gears 1
Each of the power transmission paths 2 and 14 has a forward clutch 1
A friction element such as a 6,3-4 clutch 18, a reverse clutch 20, a low and reverse brake 22, a 2-4 brake 24, and a one-way clutch 26 are provided. The engagement and release of each of the friction elements is controlled by an operating oil pressure supplied from an oil pump (not shown), so that a shift speed corresponding to operating conditions such as a vehicle speed and an accelerator opening can be obtained. The forward clutch 16, the 3-4 clutch 18, the reverse clutch 20, and the low and reverse brake 22 are each configured as a multi-plate clutch, and the 2-4 brake 24 is configured as a band brake.

An engine (not shown) is disposed on the right side of the automatic transmission 10 in the figure, and the rotation of the engine is input to an input shaft 30 of the automatic transmission 10 via a torque converter 28. Is transmitted to a differential gear 36 via an output drive gear 32 and an output driven gear 34 after being appropriately shifted in a gear train. The torque converter 28 includes a pump impeller 28a driven by the rotation of the engine, a turbine runner 28b coupled to the input shaft 30 so as to face the pump impeller 28a, and a power supply between the pump impeller 28a and the turbine runner 28b. Stator 28 interposed in
c.

As shown in FIG. 2, the automatic transmission 10 having the gear train having the above-described configuration has a forward clutch 16 (Fwd CL) and a 3-4 clutch 18 (3-d).
4 CL), the reverse clutch 20 (Rev CL), the low and reverse brake 22 (L / R Br), and the 2-4 brake 24 (2-4 Br) are engaged and released.
st (1st forward speed), 2nd (2nd forward speed), 3rd (3rd forward speed)
Speed, 4th (4th forward speed) and Rev (reverse speed). In the figure, ○ indicates a fastened state and X indicates an open state. FIG. 3 also shows the operating state of the one-way clutch (OWC), where L indicates a locked state and F indicates a free state.

The hydraulic pressure for engaging and releasing the friction elements of the forward clutch 16, 3-4 clutch 18, reverse clutch 20, and low and reverse brake 22, 2-4 brake 24 is controlled by a control valve 38 shown in FIG. Supply and discharge are controlled. That is, FIG.
Schematically shows a shift control device 40 of the automatic transmission 10,
A shift signal is input to the control valve 38 from a controller 42 constituted by a microcomputer. The controller 42 is provided with speed change means 44 for controlling the speed change signal, and mainly uses a throttle opening signal and a vehicle speed signal input from a throttle opening degree sensor 46 and a vehicle speed sensor 48 to input a shift map which is input in advance. The shift signal is processed according to the following. The controller 42 receives a hydraulic oil temperature signal from an oil temperature sensor 50 and a turbine speed signal of the turbine runner 28 b from a turbine speed sensor 52.

By the way, the forward clutches 16, 3-4 constituted as a clutch type among the above-mentioned friction elements.
The clutch 18, the reverse clutch 20, and the low-and-reverse brake 22 are engaged when a hydraulic pressure is supplied to the clutch chamber from a control valve unit (not shown). On the other hand, as shown in FIG. 4, a 2-4 brake 24 configured as a band brake type includes a brake band 24a and a band servo 24 as an operation mechanism.
and the band servo 24b is fastened and released by supplying and discharging the fastening pressure and the release pressure to and from the band servo 24b.

That is, the band servo 24b is in case 5
A stem 54b abutting on one end of the brake band 24a is attached to a servo piston 54a housed in the brake cylinder 4, and the servo piston 54a is lifted to tighten the brake band 24a, thereby fastening the 2-4 brake 24. It has become. The servo piston 54a
Is the brake band 24 by the return spring 54c.
a, in which the servo piston 54a is provided with a release pressure chamber 54d above the servo piston 54a, and a fastening pressure chamber 54d is provided below the servo piston 54a. 54e are provided. The fastening pressure chamber 54e
By releasing the central portion to the atmosphere, the release pressure chamber 54
The pressure receiving area is set smaller than d.

Therefore, when the hydraulic pressure is not supplied to both the release pressure chamber 54d and the engagement pressure chamber 54e, the servo piston 54a is lowered by the return spring 54c and the 2-4 brake 24 is released. You. Further, the fastening pressure chamber 5 is connected via the fastening pressure supply passage 56.
When the engagement pressure is supplied to 4e, the servo piston 54a rises to engage the 2-4 brake 24, and further,
In this fastened state, the release pressure chamber 5
When the release pressure is supplied to 4d, the servo piston 54a descends due to the pressure receiving area difference, and the 2-4 brake 24
Is to be released.

FIG. 5 shows a hydraulic circuit for supplying a fastening pressure and a releasing pressure to the band servo 24b.
The system includes a 1-2 shift valve 60, a 2-3 shift valve 62, and a 3-4 shift valve 64 for supplying and discharging hydraulic pressure to and from each friction element. These shift valves 60, 6
2 and 64 are first, second and third solenoid valves (So
l) The pressure is switched by the switching pressure output by turning ON / OFF the switches 60a, 62a and 64a, and the line pressure PL supplied from a manual valve (not shown) is supplied and discharged. 1-
The two-shift valve 60 outputs the line pressure PL when the first solenoid valve 60a is in the ON state, and the output line pressure PL is transmitted to the band servo 2 via the engagement pressure supply passage 56.
4b is supplied as a fastening pressure to the fastening pressure chamber 54e. 2-
The 3 shift valve 62 applies the line pressure PL to the 3-4 clutch 18 (3-4) when the second solenoid valve 62a is in the OFF state.
CL) and to the 3-4 shift valve 64 via a passage 66. The line pressure PL supplied to the 3-4 shift valve 64 is supplied as the release pressure to the release pressure supply passage 58 when the third solenoid valve 64a is in the OFF state. The 1-2 shift valve 60 is connected to the engagement pressure supply passage 56 when the first solenoid valve 60a is in the OFF state.
And the 3-4 shift valve 64 drains the release pressure of the release pressure supply passage 58 when the third solenoid valve 64a is ON.

The fastening pressure supply passage 56 is provided with an orifice 68 as a throttle means and an accumulator 70 for forming a shelf pressure at the time of fastening. On the other hand, orifices 72 and 74 as throttling means are arranged in series in the release pressure supply passage 58, and one-way valves 76 and 78 in opposite directions are arranged in parallel with the orifices 72 and 74, respectively.

In this embodiment, a bypass passage 80 for bypassing the orifice 68 is provided in the fastening pressure supply passage 56, and a downstream side of the orifice 72, that is, the orifice 72 is provided in the release pressure supply passage 58. 72
A drain port 86 to be described later is provided between the
A drain passage 82 leading to a is branched. An orifice 84 is provided in the drain passage 82. Further, a 3-2 timing valve 86 as an opening / closing means is provided across the bypass passage 80 and the drain passage 82. A one-way valve 88 is provided on the upstream side of the 3-2 timing valve 86 in the bypass passage 80 to allow the discharge of the fastening pressure.

The 3-2 timing valve 86 is switched by turning on and off the fourth solenoid valve 90.
By turning on the fourth solenoid valve 90, the bypass passage 80 is communicated, and the drain passage 82 is opened to communicate with the drain port 86a. On the other hand, when the fourth solenoid valve 90 is turned off, the bypass passage 80 is shut off and the drain passage 82 is closed.

The shift control device 40 having the above-described configuration includes:
FIG. 6 shows the case where the gear is shifted up from the first gear to the second gear (1 → 2)
The shift control is performed according to the flowchart shown in FIG. 7, and when shifting up from the second speed to the third speed (2 → 3), the shift control is performed according to the flowchart shown in FIG.

That is, the upshift from the first speed to the second speed is performed by engaging the 2-4 brake 24 as shown in FIG. 2, but in the flowchart of FIG.
When the 1 → 2 shift up is determined in step S1, the solenoid pattern of the second speed predetermined in step S2, that is, in this embodiment, all of the first, second, and third solenoid valves 60a, 62a, and 64a are reset. An ON signal is output, and the fourth solenoid valve 90 is turned ON in step S3. Therefore, by the second-speed solenoid pattern, the fastening pressure chamber 54e of the band servo 24b is connected from the 1-2 shift valve 60 via the fastening pressure supply passage 56.
Is output to the fourth solenoid valve 9.
When 0 is turned on, the 3-2 timing valve 86 communicates with the bypass passage 80 and opens the drain port 86a to connect the drain path 82 with the drain port 86a.

Next, in step S4, a change in the turbine speed is read to determine whether or not the turbine speed has reached a point where the turbine speed shifts from rising to falling. That is, as shown in FIG. 8, the turbine speed gradually increases because it is in the torque phase region up to the actual shift start point A, and after the actual shift start point A, the turbine enters the inertia phase region and rotates. The number is lowered. In step S5, when it is determined in step S4 that the turbine rotation has started to decrease, that is, when it is determined that the actual shift start point A has been reached, the fourth solenoid valve 90 is set to OFF. Then, the drain port 86a of the 3-2 timing valve 86 is closed, and a circuit for supplying a normal fastening pressure is formed.
Then, after the fourth solenoid valve 90 is turned off, it is determined in step S6 whether the 1 → 2 shift has been completed, and if the shift has been completed, the process proceeds to another control.

On the other hand, in the upshift from 2 to 3, the 3-4 clutch 18 is engaged as shown in FIG.
The operation is performed by releasing the brake 24.
In the flowchart of FIG. 6, first, when it is determined that the upshift is 2 → 3 in step S10, the hydraulic oil temperature is set to a predetermined set value (for example, 30 degrees C) in step S12.
If the hydraulic oil temperature is equal to or higher than the set value, it is determined that the viscosity of the hydraulic oil is low.
The gearshift is controlled by the standard solenoid pattern from step 3 to step S18, and when the set value is not reached, the gearshift is controlled by the cold solenoid pattern from step S20 to step S26.

That is, in step S13, the third-speed standard solenoid pattern, that is, in this embodiment, the first solenoid valve 60a is turned on and the second and third solenoid valves 62a and 64a are turned on as shown in FIG.
The signal to be flipped is output. Also, in conjunction with the output of this standard pattern, the fourth solenoid valve 9
Turn on 0. Then, in a state where the engagement pressure is output from the 1-2 shift valve 60 according to the standard solenoid pattern of the third speed, the 2-3 shift valve 62 to the 3-4 clutch 1
8 and the 3-4 shift valve 6
4 outputs the release pressure to the release pressure supply passage 58.
The brake 24 is operated in the releasing direction. At this time,
When the fourth solenoid valve 90 is turned on, the 3-2 timing valve 86 is switched, and the drain passage 82 of the release pressure supply passage 58 is connected to the drain port 86a.

Next, in step S15, a timer T1 for determining the ON time of the fourth solenoid valve 90 is started and added as T1 = T1 + 1. In step S16, the timer T1 reaches a preset warm setting value. It is determined whether or not the timer T1 has expired.
17 turns off the fourth solenoid valve 90.
Then, the 3-2 timing valve 86 is switched, the drain port 86a is closed, and the release pressure is supplied to the release pressure chamber 54d of the band servo 24b as usual. If it is determined in step S18 that the 2 → 3 shift has been completed,
The control is shifted to another control.

On the other hand, if it is determined in step S12 that the oil temperature has not reached the set value, then in step S20 the third-speed solenoid pattern in the cold state, that is, in the present embodiment, as shown in FIG. First, a signal for turning off the second solenoid valves 60a and 62a and for turning on the third solenoid valve 64a is output. The fourth solenoid valve 90 is turned on in step S21 in combination with the output of the cold pattern. Accordingly, the 1-2 shift valve 60 is switched to drain the engagement pressure supply passage 56 by the third speed cold solenoid pattern, and the 3-4 shift valve 64 is also switched to drain the release pressure supply passage 58. At this time, the fourth solenoid valve 9
0 is turned on, the 3-2 timing valve 8
6 communicates with the bypass passage 80 of the fastening pressure supply passage 56.

Next, in step S22, a timer T2 for determining the ON time of the fourth solenoid valve 90 is started and added as T2 = T2 + 1. In step S23, the timer T2 reaches a preset warm setting value. It is determined whether or not the timer T2 has expired.
24 turns off the fourth solenoid valve 90.
Then, the 3-2 timing valve 86 is switched to shut off the bypass passage 56, and the drain port 86a is closed. If it is determined in step S25 that the 2 → 3 shift has been completed, a standard 3-speed solenoid pattern is output in step S26, and the process proceeds to another control.

With the above configuration, the shift control device for an automatic transmission according to the present embodiment has a
When the solenoid valve 90 is turned on to connect the bypass passage 80 and the drain passage 82 to the drain port 86a, the release pressure chamber 54d of the band servo 24b is released to the atmosphere via the drain port 86a. For this reason, the hydraulic oil remaining in the release pressure chamber 54d is discharged from the drain port 86a with the movement of the servo piston 54a due to the introduction of the fastening pressure into the engagement pressure chamber 54e. Therefore, the servo piston 54a moves smoothly without receiving a large resistance due to the remaining hydraulic pressure,
-4 It is possible to quickly perform the engagement operation of the brake 24 to prevent the engine from idling, and to significantly reduce the shock generated due to the variation in the remaining hydraulic pressure.

Although the bypass passage 80 is communicated, the supply of hydraulic pressure is prevented by the operation of the one-way valve 88, so that the fastening pressure is supplied through the orifice 68, and the accumulator is supplied. There is no hindrance in forming the shelf pressure of 70. Further, since the orifice 84 is provided in the drain passage 82, the drain port 86a
Is released, all of the hydraulic oil in the release pressure chamber 54d is prevented from being discharged all at once.

By the way, the fourth solenoid valve 90
Is turned off when the turbine rotation reaches the actual shift start point A and the 2-4 brake 24 substantially shifts to the engagement operation. Therefore, the OF of the fourth solenoid valve 90 is
F allows the 3-2 timing valve 86 to be drain port 86a
Can be closed to prevent unnecessary release of the release pressure. Therefore, since the release pressure can remain in the release pressure chamber 54d when the drain port 86a is closed, when the release pressure changes from the discharge state to the supply state, for example, the gear shifts from the second gear to the third gear. In this case, the time required for filling the release pressure in the release pressure chamber 54d is reduced, so that the upshift can be performed quickly and the drag of the 2-4 brake 24 can be prevented.

In this embodiment, since the timing of closing the drain port 86a can be switched directly by the detection signal of the actual shift start point A, the 3-2 timing valve 86 can be switched. Can be quickly and easily controlled.

In the 2 → 3 upshift control performed in the flowchart of FIG. 7, when the 2-4 brake 24 is operated in the direction of releasing the 2-4 brake 24 in the warm standard solenoid pattern executed in steps S13 to S18. Since the fourth solenoid valve 90 is turned on to pass the drain passage 82 of the release pressure supply passage 58 to the drain port 86a, a part of the release pressure is discharged from the drain port 86a while the flow rate is restricted by the orifice 84. For this reason, FIG.
As shown by 0, the amount of hydraulic oil supplied to the release pressure chamber 54d of the band servo 24b can be reduced in the initial release period shown in the section P1 in the figure, so that the release pressure (S / R)
, The release timing of the 2-4 brake 24 can be delayed, and the idling of the engine can be prevented.

The control for partially draining the release pressure is performed in the section P1.
When the timer T1 expires, the drain port 86a is closed by turning off the fourth solenoid valve 90, and the release pressure is supplied as usual. Therefore, the drain port 86
When a is closed, the release pressure quickly rises in the portion Q1 in FIG. 10, so that the 2-4 brake 24 can be released quickly without dragging.

On the other hand, from step S20 to step S26
The 2 → 3 upshift control at the time of cold operation executed in the above corresponds to the case where the viscosity of the hydraulic oil is high, and the 1-2 shift valve 60 drains the engagement pressure supply passage 56 to operate the 2-4 brake 24. It is designed to be released. At this time, since the bypass passage 80 is communicated by turning on the fourth solenoid valve 90, as shown in FIG.
Is quickly discharged through both the orifice 68 and the bypass passage 80 in the section P2 in FIG. Therefore, when the viscosity of the hydraulic oil increases and the pipe resistance increases, the release of the 2-4 brake 24 can be performed more smoothly and properly, and the brake drag phenomenon can be prevented.

The communication time (section P2) of the bypass passage 80 is set by a timer T2. When the timer T2 expires, the bypass passage 80 is shut off by turning off the fourth solenoid valve 90. The discharge of the fastening pressure is performed slowly in the section Q2 in FIG. Therefore, the discharging of the engagement pressure is carried out slowly in this manner, so that the 2-4 brake 24
Can be prevented from occurring when the gear is released. The bypass passage 8 set by the timer T2
It is desirable that the communication time of 0 is controlled based on at least one of the oil temperature and the accelerator opening.

[0046]

As described above, in the shift control device for an automatic transmission according to the first aspect of the present invention, when the engagement pressure is supplied to the operation mechanism of the friction element, the release pressure is supplied to the release pressure supply passage. By opening the provided drain opening / closing means, the release pressure can be quickly discharged and the fastening pressure can be smoothly introduced into the operating mechanism. It is possible to prevent air blowing.
Further, since the opening / closing means in the open state is closed by the detection signal of the actual shift start point at which the turbine rotation changes from rising to falling, the release pressure is unnecessarily released from the drain after the friction element actually shifts to the fastening operation. Can be prevented from being discharged, and the release pressure can remain in the operating mechanism. Therefore, when the supply state of the fastening pressure is changed to the supply state of the release pressure, the release pressure can be quickly supplied to the operating mechanism, so that the friction element can be released smoothly and the drag phenomenon can be eliminated. it can. Further, the timing for closing the drain can be directly controlled by the detection signal of the actual shift start point, so that the closing operation of the opening / closing means can be quickly and easily controlled.

According to a second aspect of the present invention, there is provided a shift control device for an automatic transmission, comprising: a drain provided on a downstream side of a throttle means for a release pressure supply passage; Opening / closing means is provided in the bypass passage that bypasses the means, so that the opening / closing means of the drain is opened at the time of gear shifting to supply the fastening pressure and fasten the friction element, thereby quickly discharging the release pressure. In addition to smoothly engaging the friction element, it is possible to increase the discharge amount of the engagement pressure by opening the opening / closing means of the bypass passage at the time of shifting in which the friction element is released by releasing the engagement pressure. . Therefore, the friction element can be smoothly released, and in particular, by executing this shift control during a cold time when the viscosity of the hydraulic oil becomes high, it is possible to prevent a delay in releasing the friction element and prevent drag. Can be.

Further, according to the third aspect of the present invention, since the opening time of the bypass passage is controlled by a timer, it is possible to prevent all of the fastening pressure from being discharged from the operating mechanism when the timer expires. Then, after that, the fastening operation when the friction element is fastened by supplying the fastening pressure again can be quickly performed.

Further, in claim 4 of the present invention,
By integrally opening and closing the drain opening and closing means and the bypass opening and closing means, and by setting the drain and the bypass passage so as to be opened in synchronization, it is possible to control each opening and closing means at once. In addition to the above, various excellent effects can be achieved such that the number of parts can be reduced and the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a gear train showing an embodiment of an automatic transmission to which a shift control device of the present invention is applied.

FIG. 2 is an explanatory diagram illustrating an operation state of a friction element at each shift speed of the automatic transmission according to the embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a shift control device for an automatic transmission, showing one embodiment of the present invention.

FIG. 4 is a sectional view of an operation mechanism of a friction element showing one embodiment of the present invention.

FIG. 5 is a schematic configuration diagram illustrating a main part of a hydraulic circuit to which the shift control device according to one embodiment of the present invention is applied;

FIG. 6 is a flowchart illustrating an example of a process for executing a shift control according to the present invention.

FIG. 7 is a flowchart illustrating another processing example for executing the shift control of the present invention.

FIG. 8 is a characteristic diagram showing a relationship between an opening / closing means used in one embodiment of the present invention and turbine rotation.

FIG. 9 is an explanatory diagram showing a supply relationship of hydraulic oil between warm and cold at the time of 2-3 shift-up used in one embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a change in release pressure during warming at the time of 2-3 shift-up used in one embodiment of the present invention.

FIG. 11 is a characteristic diagram showing a change in a fastening pressure in a cold state at the time of 2-3 shift-up used in one embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 automatic transmission 24 2-4 brake (friction element) 24b band servo (operation mechanism) 54d release pressure chamber 54e fastening pressure chamber 40 shift control device 42 controller 56 fastening pressure supply passage 58 release pressure supply passage 60 1-2 shift valve 60a 1st solenoid valve 62 2-3 shift valve 62a 2nd solenoid valve 64 3-4 shift valve 64a 3rd solenoid valve 68 Orifice (throttle means) 72 Orifice (throttle means) 80 Bypass passage 82 Drain passage 86 3-2 Timing Valve (opening / closing means) 86a Drain port 90 4th solenoid valve

Continuation of the front page (56) References JP-A-7-259980 (JP, A) JP-A-4-307169 (JP, A) JP-A-4-254059 (JP, A) JP-A-4-307167 (JP) , A) JP-A-7-151223 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-63/48

Claims (4)

(57) [Claims] 1. A shift of an automatic transmission having an operating mechanism of a friction element that is engaged by supplying a fastening pressure from a released state of the friction element and is released by supplying a release pressure in the engaged state. In the control device, a drain is provided in the release pressure supply passage, and an opening / closing means that is opened to supply the fastening pressure and discharges the release pressure remaining in the operating mechanism is provided in the drain, and the engine speed is automatically shifted. An automatic transmission characterized by detecting an actual shift start point at which the turbine rotation of the fluid coupling transmitted to the transmission changes from ascending to descending, and closing the opening / closing means in the open state by a detection signal of the actual shift start point. Transmission control device. 2. A shift of an automatic transmission having an operating mechanism of a friction element that is engaged by supplying a fastening pressure from a released state of the friction element and is released by supplying a release pressure in the engaged state. In the control device, a throttle unit is provided in each of the release pressure supply passage and the fastening pressure supply passage, and a drain is provided on a downstream side of the throttle unit of the release pressure supply passage. A bypass passage that bypasses the throttling means is provided, and opening and closing means are respectively provided in the drain and the bypass passage to open and close the drain opening and closing means at the time of shifting to supply the fastening pressure and fasten the friction element; The opening and closing means of the bypass passage is opened at the time of shifting to release the friction element by releasing the engagement pressure, and the release of the friction element during cold is performed by discharging the engagement pressure and the release pressure. Shift control device for an automatic transmission, which comprises forming. 3. The shift control device for an automatic transmission according to claim 2, wherein an opening time of the bypass passage is controlled by a timer. 4. The drain opening / closing means and the bypass passage opening / closing means are linked and integrated so that the drain and the bypass passage are opened in synchronization with each other. Transmission control device for automatic transmission.