JP2742267B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transmission gear mechanism having a hydraulic chamber as a friction element for speed change, which is fastened by supplying a fastening pressure to the hydraulic chamber. A second friction element that is actuated by a hydraulic actuator having an application chamber and a release chamber and that is supplied only when a fastening pressure is supplied to the application chamber and a release pressure in the release chamber is discharged; The present invention relates to a shift control device for an automatic transmission provided with:

[Conventional technology]

Conventionally, as shown in, for example, Japanese Patent Application Laid-Open No. Sho 62-233547, a first friction element including a predetermined clutch element (3-4 clutch), an apply chamber and a release chamber are used as a shift friction element of a transmission gear mechanism. A second friction element including a predetermined brake element (2-4 brake) that is actuated by a hydraulic actuator having the engagement pressure supplied to the application chamber and released only when the release pressure in the release chamber is discharged. In the automatic transmission provided with the above, at the specific high speed stage where the predetermined clutch element is engaged and the predetermined brake element is released, while the release of the predetermined brake element is achieved, the engagement pressure of the apply chamber is changed according to the operating state. 2. Description of the Related Art There is known a shift control device configured to switch between a supply state and an engagement pressure discharge state. In other words, this device achieves the release of the predetermined brake element at the specific high speed stage according to the vehicle speed, for example, in a high-speed traveling state while supplying the engagement pressure to the apply chamber, and in the low-speed traveling state, from the apply chamber. It is intended to be achieved with the fastening pressure discharged,
With this configuration, when shifting down from the state of the specific high speed stage to the specific low speed stage where the predetermined clutch element is switched to disengagement and the predetermined brake element is switched to engagement, the engagement of the predetermined brake element is quickly performed in the high speed running state. In the low-speed running state, the rapid engagement of the brake element is appropriately suppressed, and there is an advantage that the shift shock is reduced.

[Problems to be solved by the invention]

According to the conventional device, when downshifting from the specific high speed stage to the specific low speed stage in a state where the fastening pressure is discharged from the apply chamber, hydraulic pressure is gradually supplied to the apply chamber by the action of an accumulator or the like, As a result, the predetermined brake element shifts to the engaged state. Normally, such a control is performed in a low-speed running state or the like, so that the shift operation is appropriately performed. There is such a problem. That is, in a hydraulic control circuit that generally controls a friction element of a transmission gear mechanism, the line pressure is adjusted according to the throttle opening and the like so that a line pressure matching the engine torque is obtained. At times, the line pressure is reduced. The rise speed of the fastening pressure supplied to the apply chamber via an accumulator or the like is affected by the line pressure. The lower the line pressure, the slower the rise speed. Therefore, when the specific high gear is downshifted to the specific low gear in a state where the engagement pressure is discharged from the apply chamber as described above, when the line pressure is low, the engagement of the predetermined brake element is performed by the predetermined clutch element. Release can be significantly delayed. When such a delay in the engagement of the predetermined brake element occurs, a state occurs in which the predetermined clutch element is already released but the predetermined brake element does not reach the engagement during this delay period, thereby causing a load applied to the engine. , Which could cause a sudden decrease in engine speed (excessive increase in engine speed).

The present invention has been made in view of the above circumstances, and when downshifting from the specific high speed stage to the specific low speed stage in a state where the fastening pressure is discharged from the apply chamber, when the line pressure of the hydraulic control circuit is low. Another object of the present invention is to provide a shift control device for an automatic transmission that can prevent a situation in which an engine blows due to a delay in engagement of a second friction element with respect to release of a first friction element.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a first friction element that has a hydraulic chamber and is fastened by supplying a fastening pressure to the hydraulic chamber as a shifting friction element of the speed change gear mechanism; A second friction element that is actuated by a hydraulic actuator having an apply chamber and a release chamber, the second friction element being engaged only when the apply pressure is supplied to the apply chamber and the release pressure in the release chamber is discharged, During a downshift from a first gear to a specific low gear,
The friction element is switched from the engaged state to the released state, and
In an automatic transmission configured so that the second friction element can be switched from a disengaged state to a engaged state, a vehicle speed detecting means for detecting a value relating to a vehicle speed, and a line serving as a base pressure of the fastening pressure supplied to the apply chamber Line pressure detecting means for detecting a value relating to the magnitude of pressure; hydraulic pressure supply / discharge control means for controlling supply / discharge of hydraulic pressure to / from the hydraulic chamber, apply chamber and release chamber; and detection of the vehicle speed detecting means and line pressure detecting means Control means for controlling the hydraulic supply / discharge control means based on the result, wherein the control means is connected to each of the apply chamber, the release chamber, and the hydraulic chamber when the vehicle speed is higher than a predetermined vehicle speed at the specific high speed stage. The vehicle speed is lower than the predetermined vehicle speed while the first hydraulic pressure supply state in which hydraulic pressures as the pressure, the release pressure, and the engagement pressure are supplied. In accordance with the vehicle speed, a second hydraulic supply state is provided in which the engagement pressure of the apply chamber is discharged and the release chamber and the hydraulic chamber are respectively supplied with the release pressure and the hydraulic pressure as the engagement pressure. Controlling the hydraulic supply / discharge control means, and controlling the first friction during a downshift from the specific high gear to the specific low gear when the vehicle speed is lower than the predetermined vehicle speed and the line pressure is lower than the predetermined pressure. In order to prevent the engine from blowing due to a delay in the engagement of the second friction element with respect to the release of the element, the shift to the specific low gear after passing through the specific high gear in the first hydraulic pressure supply state is performed. The hydraulic supply / discharge control means is controlled so as to start.

[Action]

According to the above configuration, at the time of downshifting from the specific high speed stage to the specific low speed stage while the engagement pressure is being discharged from the apply chamber, when the line pressure is low, the second friction element is engaged. Prior to the start of the release of the release pressure from the release chamber and the start of the discharge of the engagement pressure of the first friction element from the hydraulic chamber, the supply of the engagement pressure to the apply chamber is performed, and The relative delay in the engagement of the second friction element is corrected.

〔Example〕

FIG. 1 shows the overall structure of an automatic transmission to which the device of the present invention is applied. This automatic transmission has a torque converter 2 connected to an output shaft 1 of an engine, and a transmission gear mechanism 10 provided on the output side of the torque converter 2. The torque converter 2 includes an output shaft 1 of the engine.
And a stator 5 provided on a fixed shaft 7 via a one-way clutch 6.

The transmission gear mechanism 10 includes an oil pump driving central shaft 12 having a base end fixed to the output shaft 1 of the engine and a front end connected to the oil pump 100. A hollow turbine shaft 13 having an end connected to the turbine 4 of the torque converter 2 is provided. A Ravigneaux type planetary gear device 14 is provided on the turbine shaft 13. The planetary gear device 14 includes a small-diameter sun gear 15, a large-diameter sun gear 16, a long pinion gear 17, a short pinion gear 18, and a ring gear 19. The following various friction elements are incorporated in the planetary gear device 14.

On the side remote from the engine, the turbine shaft 13
And a forward clutch between the small-diameter sun gear 15 and
20 and the coast clutch 21 are arranged in parallel. The forward clutch 20 is a first one-way clutch.
The transmission of power from the turbine shaft 13 to the small-diameter sun gear 15 is interrupted via the
Is for intermittently transmitting power between the turbine shaft 13 and the small-diameter sun gear 15.

A 2-4 brake 23 having a brake drum 23a connected to the large-diameter sun gear 16 and a brake band 23b applied to the brake drum 23a is disposed radially outward of the coast clutch 21. When the 2-4 brake 23 is engaged, the large-diameter sun gear 16 is fixed. On the side of the 2-4 brake 23, a reverse clutch 24 for reverse running which interrupts power transmission between the large-diameter sun gear 16 and the turbine shaft 13 via the brake drum 23a is arranged. Further, the carrier 14 of the planetary gear device 14 is provided outside the planetary gear device 14 in the radial direction.
a low reverse brake for engaging and disengaging the carrier 14a and the case 10a between the transmission gear mechanism 10 and the case 10a of the transmission gear mechanism 10.
25, and a second one-way clutch 26 is arranged in parallel with this.

Further, a 3-4 clutch 27 for intermittently transmitting power between the carrier 14a and the turbine shaft 13 is disposed on a side of the planetary gear device 14 on the engine side. An output gear 28 connected to the ring gear 19 is arranged on the side of the 3-4 clutch 27, and the gear 28 is attached to an output shaft 28a. Note that 2
Reference numeral 9 denotes a lock-up clutch for directly connecting the output shaft 1 of the engine and the turbine shaft 13 without passing through the torque converter 2.

The transmission gear mechanism 10 itself has four forward speeds and one reverse speed.
A desired gear can be obtained by appropriately operating the clutches 20, 21, 24, 27 and the brakes 23, 25. Here, Table 1 shows the operating relationship between each gear and the clutch and brake.

As understood from Table 1 and FIG. 1, the forward clutch 20 is engaged in each of the forward travel ranges D, 2, and 1, and in this state, the 2-4 brakes 23 and 3 are engaged.
By changing the state of the -4 clutch 27, the gear ratio changes, and the state from the first gear to the fourth gear is obtained. Therefore, the 2-4 brake 23 and the 3-4 clutch 27 correspond to a second friction element and a first friction element for shifting.

FIG. 2 shows a hydraulic control circuit in the automatic transmission. In this figure, the 2-4 brake 23 is
It is operated by a hydraulic actuator 23c having an apply chamber 23d and a release chamber 23e, and is engaged only when a fastening pressure is supplied to the apply chamber 23d and a release pressure in the release chamber 23e is discharged. 3-4 clutch 27
Has a hydraulic chamber, and is engaged and released according to the supply and discharge of hydraulic pressure to the hydraulic chamber, and the other clutches 20, 21, and 24 and the low / reverse brake 25 also respond to supply and discharge of hydraulic pressure, respectively. Is concluded and released.

The hydraulic control circuit has an oil pump 100 driven by the crankshaft 1.
Hydraulic oil is discharged to 1. The hydraulic oil discharged from the pump 100 to the oil passage 101 is guided to the regulator valve 102. The regulator valve 102 regulates the hydraulic pressure (line pressure) of the working oil from the pump 100 and supplies the regulated hydraulic pressure to the port g of the select valve 103. This select valve 103 is manually operated
Shift to the R, N, D, 2.1 range, and supply the hydraulic oil from the port g to a predetermined port in each range. The port g communicates with the ports a, d, and e when the select valve 103 is set to one range, and communicates with the ports a, c, and d when the select valve is set to two ranges. When port is set to D range
They are communicated to a and c, and are communicated to port f when the select valve is set to the R range.

The port a of the select valve 103 is connected via an oil passage 171 to 1-2.
While connected to the shift valve 110, the 1-2 shift valve 110
Is connected to a later-described neutral valve 160 via an oil passage 172 that bypasses the forward clutch 20, and the forward clutch 20 is engaged by hydraulic pressure supplied to the forward clutch 20 via the neutral valve 160.

The 1-2 shift valve 110 has a pilot pressure acting against the spring 110a, and a pilot pressure for the 1-2 solenoid valve 11 is used.
Controlled by 0b, switching operation is performed between the first speed and the second speed and the like, and the supply and discharge of hydraulic pressure to the apply chamber 23d of the actuator 23c of the 2-4 brake 23 are performed.
That is, when the 1-2 solenoid valve 110b is turned off, the line pressure led from the oil passage 101 acts as the pilot pressure on the 1-2 shift valve 110, so that the spool moves to the left side in the figure, Apply oil passage 1 to the above-mentioned apply chamber 23d.
It communicates with the drain side via 73. When the 1-2 solenoid valve 110b is turned on, the spool is moved to the right side in the drawing by draining the pilot pressure, and the line pressure guided from the oil passage 171 is changed from the oil passage 173 to the 3-4 shift valve 130. To the above-mentioned application room 23d via the. Reference numeral 135 denotes an accumulator provided for the apply chamber 23d.

Further, at the time of the first speed in one range, the 1-2 shift valve 110 is connected to the low pressure reducing valve 1 through the port e of the select valve 103.
Low and reverse brake hydraulic fluid supplied via 40
25 and throttle backup valve at the same time
The hydraulic pressure is sent to 141.

The port a of the select valve 103 is also connected to the 2-3 shift valve 120 via an oil passage 174, and applies a pilot pressure against the spring 120a of the 2-3 shift valve 120. The pilot valve is controlled by a 2-3 solenoid valve 120b, the 2-3 shift valve 120 is switched between a second speed and a third speed, and the hydraulic pressure is supplied to and removed from the 3-4 clutch 27. And the supply of hydraulic pressure to the release chamber 23e of the actuator 23c of the 2-4 brake 23 in cooperation with the 3-4 shift valve 130. That is, when the 2-3 solenoid valve 120b is turned off, the line pressure guided from the oil passage 174 becomes 2-
By acting on the three-shift valve 120, its spool moves to the left in the figure. In this state, the line pressure supplied from the port c of the select valve 103 via the oil passage 175 is supplied to the 3-4 clutch 27 via a circuit in which the servo control valve 142 and the 2-3 timing valve 143 are incorporated. The oil is also sent to an oil passage 176 connected to the 3-4 shift valve 130. Also, 2-3 solenoid valve 120b
Is turned on, the spool moves to the right side in the figure by draining the pilot pressure. In this state, the 3-4 clutch 27 is connected to the drain side via the oil passage 177, and the oil passage 176 connected to the 3-4 shift valve 130 is connected to the 3-2 capacity valve 149 and the 3-2 timing. The valve 150 is communicated with the drain through a built-in circuit. 148 is an accumulator provided for the 3-4 clutch 27.

The 3-4 shift valve 130 includes the 2-3 shift valve 120.
Similarly, the oil passages 174, 1
The line pressure via 78 is provided as pilot pressure. The 3-4 shift valve 130 has its pilot pressure controlled by the 3-4 solenoid valve 130b, is switched between the third speed and the fourth speed, and the like, and is applied to the apply chamber of the 2-4 brake 23.
It is involved in supplying hydraulic pressure to 23d and supplying and removing hydraulic pressure to release chamber 23e. That is, when the 3-4 solenoid valve 130b is turned off, the line pressure acts on the 3-4 shift valve 130 as the pilot pressure, and the spool moves to the left side in the figure. In this state, the above 1-
3-4 shift valve 130 from 2 shift valve 110 through oil passage 173
Line pressure sent to the supply chamber 2 via the oil passage 179.
An oil passage 176 that is supplied to 3d and communicates with a circuit connected to the 2-3 shift valve 120 and an oil passage that communicates with the release chamber 23e.
180 is communicated. When the 3-4 shift valve 130 is turned on, the spool is moved to the right side in the figure by draining the pilot pressure. In this state, the above 1-2
The line pressure sent from the shift valve 110 to the 3-4 shift valve 130 is applied to the supply chamber 23d through an oil passage 181 having an orifice.
And the hydraulic pressure in the release chamber 23e is drained via the 3-4 capacity valve 145.

Further, the 3-4 shift valve 130 has a port a of the select valve 103 when the 3-4 solenoid valve 130b is off.
From the oil passages 172 and 182 to the coast clutch 21 via the neutral valve 160 and the ND accumulator 144, and when the 3-4 solenoid valve 130b is off, the hydraulic pressure of the coast clutch 21 is drained. .

A lock-up control valve 151 is provided in the hydraulic oil passage of the lock-up clutch 29. The lock-up control valve 151 is switched and operated according to the pilot pressure controlled by the lock-up solenoid 151a, and when the lock-up solenoid 151a is turned on, the lock-up clutch 29
Is to be concluded.

The throttle backup valve 141 receives the hydraulic pressure from the low pressure reducing valve 140 as pilot pressure against a spring, and receives a port d of the select valve 103.
Is supplied to the regulator valve 102 or cut off.
Is set to one range or two ranges and the pilot pressure is not received, hydraulic fluid is supplied from the port d of the select valve 103 to the regulator valve 102.
To increase the pressure and ensure engine braking capacity. In addition, the regulator valve 102 is supplied with a hydraulic pressure adjusted by a throttle valve 146 and a throttle modulator valve 147. The throttle valve 146 generates a hydraulic pressure according to the accelerator opening. Is appropriately reduced and supplied to the regulator valve 102, whereby a line pressure matching the engine torque is obtained.

The servo control valves 142 and 2-
The 3 timing valve 143 is for reducing the shock generated at the time of shifting from the second speed to the third speed, and the servo control valve 142 is a hydraulic pressure applied to the release chamber 23e of the actuator 23c of the 2-4 brake 23. And the 2-3 timing valve 143 adjusts the engagement timing of the fourth clutch device 27 according to the accelerator opening.

The 3-4 capacity valve 145 is provided to reduce an impact at the time of upshifting from the third speed to the fourth speed, and hydraulic oil is supplied from the release chamber 23d of the actuator 23c of the 2-4 brake 23. The characteristic of the change in hydraulic pressure of the release chamber 23b when drained is adjusted appropriately.

The 3-2 capacity valve 149 and the 3-2 timing valve 150 are provided to reduce an impact at the time of shifting from the third speed to the second speed in accordance with the throttle opening. City valve 149 is 3-4
Similarly to the capacity valve 145, the characteristic of the hydraulic pressure change at the time of drain is adjusted, and the 3-2 timing valve 150 controls the drain delay time according to the throttle modulator pressure.

The neutral valve 160 is operated in accordance with a pilot pressure controlled by the idle cut solenoid valve 161. When the idle cut solenoid valve 161 is off, the neutral valve 160 connects the oil passage 183 and the oil passage 172 communicating with the forward clutch 20. By doing so, the line pressure from the port a is supplied to the first clutch device 20. On the other hand, when the idle cut solenoid valve 161 is on, the oil passage 183 communicates with the oil passage 184 communicating with the port d. . The port d is drained when the select valve 103 is set to the D range, and the idle cut solenoid valve 161 is turned on when the brake is operated in a state corresponding to idle operation. Thus, while the vehicle is stopped in the D range that satisfies these conditions, the forward clutch 20 is released to prevent the vehicle body from vibrating.

According to such a hydraulic control circuit, the 2-4 brake 23 and the 3-4 clutch which determine the gear ratio in the forward traveling range are provided.
The state of 27 is 1-2, 2-3, 3- according to ON / OFF of each solenoid valve 110b, 120b, 130b for 1-2, 2-3, and 3-4.
4 is determined by the state of each shift valve 110, 120, 130. That is, the 3-4 clutch 27 is connected to the 2-3 solenoid valve 120b.
Is turned off when hydraulic pressure is supplied, and is opened when the hydraulic pressure is drained by turning on the 2-3 solenoid valve 120b. On the other hand, 2-
As described above, the 4 brake 23 is engaged only when the hydraulic pressure in the release chamber 23e is drained and the hydraulic pressure is supplied to the apply chamber 23d. When the hydraulic pressure is supplied to the release chamber 23e, the 23d is released irrespective of the hydraulic supply state or the drain state.
Supply of hydraulic pressure to the drain, supply of hydraulic pressure to the drain and apply chamber 23d, and drainage are performed by the solenoid valves 110b, 1
It changes according to the combination of ON and OFF of 20b and 130b. Therefore,
Each of the solenoid valves 110b, 120b, and 130b and each of the shift valves 110, 120, and 130 operated by the solenoid valves constitute a hydraulic supply / discharge control unit.

Here, Table 2 shows each of the above solenoid valves (SL in the table).
8) shows eight patterns of ON / OFF combinations of 110b, 120b, and 130b, the state of the 2-4 brake 23, 3-4 clutch 27 determined by these patterns, and the shift speed corresponding thereto. In this table, for the 2-4 brake 23 and the 3-4 clutch 27, the mark ○ indicates engagement, and the mark × indicates release, and for the apply chamber 23d and the release chamber 23e of the 2-4 brake 23, the mark ○ indicates hydraulic supply, The mark “x” indicates drain.

The line pressure of the hydraulic control circuit is adjusted by the throttle valve 146 and the like as described above, and the relationship with the throttle opening (the opening of the throttle valve in the intake passage of the engine) is as shown in FIG. in, is lowered when the throttle opening is small, predetermined to the throttle opening theta _{1 (e.g.} 3/8 of the fully open) is raised at a relatively large rate of change as the throttle opening increases, the predetermined throttle opening theta ₁
In the above, the value is adjusted to be a sufficiently high value and the rate of increase is small.

Each of the solenoid valves 110b, 120b, and 130b is controlled by a control circuit 200 using a microcomputer or the like shown in FIG. The control circuit 200 includes a turbine speed signal 201 from a turbine sensor, a throttle opening signal 202 from a throttle opening sensor, a selection signal 203 from a range selection sensor, and a vehicle speed signal 204 from a vehicle speed sensor (vehicle speed detecting means). Is input. Then, the control circuit 200 selects a gear position according to the operating state based on a predetermined gear shift characteristic, selects a pattern of each of the solenoid valves 110b, 120b, and 130b corresponding to the gear position, and performs gear shifting. When necessary, a signal is output to each of the solenoid valves 110b, 120b, and 130b to change the pattern, thereby performing the shift control.

Further, the control circuit 200 detects a value related to the magnitude of the line pressure, which is the original pressure of the fastening pressure supplied to the apply chamber, and determines a state where the line pressure is low and a state where the line pressure is high. Pressure detecting means) 200a and control means 20
0b. When the vehicle speed is higher than a predetermined vehicle speed when the vehicle is in the third speed, the control means 200b performs the above-described 2-4.
The first hydraulic pressure supply state in which hydraulic pressures as the engagement pressure, the release pressure, and the engagement pressure are supplied to the apply chamber 23d, the release chamber 23e of the actuator 23c of the brake 23, and the hydraulic chamber of the 3-4 clutch 27, respectively. On the other hand, when the vehicle speed is lower than the predetermined vehicle speed, the second hydraulic pressure in which the engagement pressure in the apply chamber 23d is discharged and the release pressure and the hydraulic pressure are supplied to the release chamber 23e and the hydraulic chamber, respectively, as the second hydraulic pressure In the first hydraulic pressure supply state, at the time of a downshift from the third speed to the second speed when the vehicle speed is lower than the predetermined vehicle speed and the line pressure is lower than the predetermined pressure. The hydraulic pressure supply / discharge control means is controlled to start shifting to the second speed after passing through the third speed.

That is, in the control circuit 200, the following Table 3 (D
As shown in (Example of Range), a pattern selected in advance from the above-mentioned Table 2 is set for each shift speed. In the present embodiment, especially at the third speed, at high vehicle speeds, The first pattern (corresponding to the pattern B in Table 2) for achieving the third speed stage in a state where the fastening pressure is supplied to the apply chamber 23d, and the apply chamber 23 for low vehicle speed.
A second pattern (corresponding to pattern A in Table 2) for achieving the third speed stage in a state where the fastening pressure is discharged from d is set. Further, an intermediate pattern is set as a pattern that is temporarily adopted when downshifting from the state in which the second pattern is selected to the second gear and when the line pressure is low. This intermediate pan is the same as the first pattern.

Further, the determination by the determination means 200a of the control circuit 200 is performed based on the throttle opening in the present embodiment,
The throttle opening is above a predetermined throttle opening theta ₁ is less than when the line pressure is low, the predetermined throttle opening theta ₁
In the above case, it is determined that the line pressure is high.

The control circuit 200 performs control based on the flowchart shown in FIG.

To explain this control operation, the throttle opening degree θ in step S _1, the vehicle speed V, the inputs the range signal or the like. In step S _2, checks whether the time shift depending on whether gear position determined based on the matching or the like of the shift pattern and the operation state has changed in the previous and the current. If not during the shift, in step S _3, it is determined whether or not the current gear position is the third speed stage. And if it is other than the third speed stage, the flow returns to leave the step S ₁ was maintained pattern corresponding to the speed at that time.

If it in step S ₃ is the third speed stage is determined, the vehicle speed V is the predetermined speed at Step S ₄ (e.g., 40 km /
h) It is determined whether or not the vehicle is in the high-speed running state. And when the high-speed running state, in step S _5, and selects and outputs the first pattern of the Table 3 in, i.e. 1-
The solenoid valve 110b for 2 is turned on, and the solenoid valve 120b for 2-3 and the solenoid valve 130b for 3-4 are turned off.
Further, when the vehicle speed V is lower low-speed traveling state than a predetermined vehicle speed, in step S _6, selects and outputs the second pattern of the Table 3 in, that each of the solenoid valves 110b, 120b, 13
Turn off all 0b.

When it is determined that performing the shift at step S _2,
Checks shift or not from the third speed stage to the second speed stage in step S _7. When the determination is NO at step S _7, step S
_{In step 8} , based on the settings shown in Table 3 above, the pattern is changed according to the gear position of the shift destination, and the pattern is output to perform the shift.

When it is determined from the third speed stage in step S ₇ is a time shift to the second speed stage checks whether the vehicle speed V is lower than a predetermined vehicle speed in step S _9. NO is determined in step S ₉
Time, means that the first pattern in step S ₅ is shifting from a state of being selected, this time as it proceeds to step S _10, the pattern corresponding to the second speed stage (3rd Output), that is, each solenoid valve 110
Turn on b, 120b, and 130b. Further, when the determination in step S ₉ is YES, the said means that the second pattern in step S ₆ is shifting from a state of being selected, in further steps S ₁₁ In this case, the throttle opening degrees theta is checked whether a predetermined throttle opening theta ₁ is less than.

Then, Turning directly to step S ₁₀ when the determination is NO in step S _11, when the determination is YES in step S _11, in step S ₁₂ to S _14, selects the intermediate pattern of the Table 3 in outputs Te, from keeping the intermediate pattern before the timer count value T reaches the predetermined time above T _1, and outputs a pattern corresponding to the second speed stage shifts to step S _10.

According to the above control, when the vehicle is running at the third speed, in which the 3-4 clutch 27 is engaged and the 2-4 brake 23 is released, and the vehicle is in a high-speed running state at a predetermined vehicle speed or higher, By selecting 1 pattern,
2-4 Apply chamber 23d of actuator 23c of brake 23
When the engagement pressure is supplied to the release chamber 23, the release of the 2-4 brake 23 is achieved by the release pressure applied to the release chamber 23e (see Table 3). Therefore, from this state, when downshifting to the second speed stage where the 3-4 clutch 27 is released and the 2-4 brake 23 is engaged is performed, the solenoid valve 11
0b, 120b, 130b
As the release pressure is drained from 23e, 2-4 brake 2
3 is quickly brought into the engaged state, and downshifting is performed with good responsiveness.

On the other hand, when the vehicle is in the low vehicle speed state in traveling at the third speed, the second pattern is selected, whereby
The release of the 2-4 brake 23 is achieved in a state where the fastening pressure is drained from the apply chamber 23d of the actuator 23c of the -4 brake 23 (see Table 3). If that is shifted down from this state to the second gear position, when the throttle opening theta is when a predetermined throttle opening theta ₁ or more (the line pressure is high), the down-shifting signal is output, 3- The discharge of the engagement pressure of the four clutch 27 and the discharge of the release pressure of the release chamber 23e are started, and the supply of hydraulic oil to the apply chamber 23d is started. And the accumulator
The hydraulic pressure supplied to the apply chamber 23d via 135 causes the 2-4 brake 23 to gradually shift to the engaged state, so that the shift shock is reduced.

By the way, at the time of the downshift in the running state where the line pressure is high and the line pressure is high, the engagement speed of the 2-4 brake 23 is appropriately adjusted by the above-described operation, but the throttle opening is small and the line pressure is reduced. 5, the rising speed of the hydraulic pressure supply to the apply chamber 23d is reduced, as shown in FIG. Meanwhile, Release Room 23 above
The discharge of the hydraulic pressure from the e and the 3-4 clutch 27 is performed relatively quickly without being greatly affected by the line pressure. Accordingly, when the hydraulic pressure in the apply chamber 23d is discharged, the shift from the third speed to the second speed is immediately performed, and the release chamber 23e and the 3-4 clutch 27 as indicated by the two-dot chain line in FIG. When the rise of the oil pressure in the apply chamber 23d is greatly delayed as compared with the discharge of the oil pressure from the clutch, the engagement of the 2-4 brake 23 tends to be significantly delayed with respect to the release of the 3-4 clutch 27.

In contrast, in the control shown in the flowchart, when the throttle opening is small and the line pressure is low, a predetermined time
For shifting to the second speed stage after via T ₁ only the intermediate pattern, while a intermediate pattern as indicated by a solid line in Fig. 5 the release chamber 23e and the 3-4 clutch 27 is a hydraulic pressure supply While maintaining the state, the hydraulic pressure is supplied to the apply chamber 23d, and after the hydraulic pressure in the apply chamber 23d has increased to some extent, the release chamber 23e and the 3-4 clutch 2
The hydraulic pressure of 7 is discharged, and the relative delay of the application of the 2-4 brake 23 to the release of the 3-4 clutch 27 is corrected.

〔The invention's effect〕

As described above, the shift control device for an automatic transmission according to the present invention includes:
At a specific high speed where the first friction element is in the engaged state and the second friction element is in the released state, when the vehicle speed is higher than a predetermined vehicle speed, the apply chamber, the release chamber, and the first friction element of the actuator of the second friction element. While a first hydraulic pressure supply state is provided in which hydraulic pressures as a fastening pressure, a release pressure, and a fastening pressure are supplied to the respective hydraulic chambers, when the vehicle speed is lower than a predetermined vehicle speed, the fastening pressure in the apply chamber is discharged and A release pressure and a hydraulic pressure are respectively supplied to the release chamber and the hydraulic pressure chamber as a second hydraulic pressure supply state in which the hydraulic pressure is supplied as the engagement pressure. When the vehicle speed is lower than the predetermined vehicle speed and the line pressure is lower than the predetermined pressure, At the time of the downshift from the specific high gear to the specific low gear, the shift to the specific low gear is started after passing through the specific high gear in the first hydraulic pressure supply state. It has to. For this reason, after the hydraulic pressure is supplied to the apply chamber, the shift by the discharge of the hydraulic pressure of the release chamber and the discharge of the hydraulic pressure of the hydraulic chamber of the first friction element is started, whereby the release of the first friction element is prevented. A relative delay in the engagement of the second friction element is corrected, and it is possible to prevent the engine from blowing due to such a delay.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram schematically showing a transmission mechanism of an automatic transmission according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a circuit configuration of a hydraulic control circuit for the transmission mechanism, and FIG. 3 is a flowchart showing a control operation. FIG. 4 is a characteristic diagram showing the relationship between the throttle opening and the line pressure of the hydraulic control circuit. FIG. 5 is a time chart showing a change in hydraulic pressure with respect to a brake element. 10: gear mechanism, 14: planetary gear, 23: 2-
4 brakes (predetermined brake elements), 23c ... actuator, 23d ... apply chamber, 23e ... release chamber, 27 ...
3-4 clutch (predetermined clutch element), 110 ... 1-2
Shift valve, 120 ... 2-3 shift valve, 130 ... 3-4 shift valve, 110b ... 1-2 Solenoid valve for 1-2, 120b ... 2-3
Solenoid valve for 130b ... 3-4 solenoid valve for 3-4, 200
... Control circuit, 200a ... Discriminating means, 200b ... Control means.

Claims (1)

(57) [Claims] A hydraulic device having a hydraulic chamber and a first friction element that is fastened by supplying a fastening pressure to the hydraulic chamber and a hydraulic chamber that has an apply chamber and a release chamber as a shift friction element of the transmission gear mechanism. A second friction element that is actuated by a type actuator and is engaged only when the engagement pressure is supplied to the apply chamber and the release pressure in the release chamber is discharged, and the shift from the specific high speed stage to the specific low speed stage is performed. In an automatic transmission configured to switch the first friction element from the engaged state to the disengaged state and to switch the second friction element from the disengaged state to the engaged state during downshifting, a value related to vehicle speed is detected. Vehicle speed detecting means, a line pressure detecting means for detecting a value relating to a magnitude of a line pressure which is a source pressure of the fastening pressure supplied to the apply chamber, A hydraulic supply and discharge control means for controlling the hydraulic supply and discharge for the chambers and the release chamber,
Control means for controlling the hydraulic pressure supply / discharge control means based on the detection results of the vehicle speed detection means and the line pressure detection means, wherein the control means, when the vehicle speed is higher than a predetermined vehicle speed at the specific high speed, Room,
While the first chamber is in a first hydraulic supply state in which hydraulic pressures as a fastening pressure, a release pressure, and a fastening pressure are supplied to the release chamber and the hydraulic chamber, respectively, when the vehicle speed is lower than the predetermined vehicle speed, the fastening pressure in the apply chamber is discharged. The hydraulic pressure supply / discharge control means is controlled in accordance with the vehicle speed so as to be in a second hydraulic pressure supply state in which a release pressure and a hydraulic pressure as a fastening pressure are supplied to the release chamber and the hydraulic chamber, respectively.
When the vehicle speed is lower than the predetermined vehicle speed and the line pressure is lower than the predetermined pressure, when the downshift from the specific high gear to the specific low gear is performed, the engagement of the second friction element with respect to the release of the first friction element is performed. In order to prevent idle blowing of the engine due to the delay, the hydraulic supply / discharge control means is configured to start shifting to the specific low gear after passing through the specific high gear in the first hydraulic supply state. A shift control device for an automatic transmission, wherein the shift control device is configured to control the shift.