JPH07127725A - Oil pressure controller for automatic transmission - Google Patents

Abstract

PURPOSE:To delay attainment of a traveling range so as to reduce shift shock during selection by switching a solenoid valve for supplying a master pressure for control to a shift valve without having any relation to attainment of the traveling range at the time of making selection to the traveling range. CONSTITUTION:An automatic transmission is provided with a plurality of frictional clamping elements comprising a clutch and a brake which attains gear shift stage by supplying the master pressure for control to a shift valve by operation of a solenoid valve. In this case, in an oil pressure circuit for supply/ discharge operation oil to/from the respective frictional clamping elements, for example, in the case of selecting a gear from a neutral range to a reverse range by a manual valve, the first solenoid valve 76 which is in an OFF state so as to have no relation to attainment of the reverse range and supplies line pressure to 1-2 shift valve 71 is switched to a drain side, that is, ON side. Line pressure supplied to 1-2 shift valve 71 via the first control line 106 is drained and the reduced line pressure is supplied to the reverse clutch, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for an automatic transmission, and more particularly to a shock reduction measure when selecting a running range.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic control device for an automatic transmission, for example, as disclosed in Japanese Patent Publication No. Hei 5-26063, a speed change gear mechanism and a plurality of friction engagement elements are provided, and each friction The source pressure for control can be supplied to multiple shift valves corresponding to the fastening elements by operating solenoid valves such as individual solenoid valves, and the source pressure for control by the solenoid valve selected from the above solenoid valves. It is known that the shift valve is switched by the supply of the pressure control element to supply the original pressure for engagement to the desired frictional engagement element via the shift valve to engage the frictional engagement element to achieve the gear stage. There is. Then, in this case, when the travel range is selected, the solenoid valve that is involved in achieving the starting stage of the travel range and that supplies the source pressure to the shift valve is temporarily switched to the drain side, so that the shift valve To reduce the supply amount of the control original pressure to the control valve and to reduce the supply amount of the connection source pressure used for the connection from the shift valve to suppress the rising speed of the source pressure (engagement hydraulic pressure). Therefore, the achievement of the starting stage of the driving range is delayed, and the torque shock at the time of engaging the friction engagement element, that is, the shift shock at the time of selecting to the driving range is reduced.

[0003]

However, in the above-mentioned conventional hydraulic control device, at the time of selecting to the traveling range, the source pressure for controlling and engaging the shift valve that is involved in achieving the starting stage of the traveling range is controlled. Since the supply is reduced by the solenoid valve, a separate shift valve and solenoid valve for supplying the engaging oil to the friction engagement element at the starting stage of the desired travel range are required, and the hydraulic control device is expensive. Will be things.

The present invention has been made in view of the above points, and an object of the present invention is to reduce the hydraulic pressure of the entire original pressure by effectively utilizing the shift valve that is not involved in the achievement of the starting stage, and to reduce the cost of the hydraulic pressure. The purpose of the present invention is to reduce the shift shock at the time of selecting to the driving range by the control device.

[0005]

In order to achieve the above-mentioned object, a solution means provided by the invention as set forth in claim 1 is to provide a gear shift mechanism and a source pressure for control to a shift valve by operating a solenoid valve. It is premised on a hydraulic control device for an automatic transmission, which is provided with a plurality of friction engagement elements that are supplied to achieve a shift speed.
Then, at the time of selecting to the travel range, the solenoid valve which is not involved in the achievement of the starting stage of the travel range and which supplies the shift valve with the control original pressure is switched to the drain side.

Further, the solution means taken by the invention according to claim 2 specifies the solenoid valve according to the invention according to claim 1, which is not related to the achievement of the starting stage of the reverse range and is used for controlling the shift valve. Use a solenoid valve that supplies the original pressure. And
This solenoid valve is configured to be switched to the drain side when selecting the reverse range.

Furthermore, the solution means taken by the invention of claim 3 specifies the solenoid valve of the invention of claim 1 or claim 2 and is not involved in the achievement of the starting stage of the travel range and the shift valve The solenoid valve that supplies the control source pressure to. Then, this solenoid valve is configured to be switched to the drain side at a predetermined reduction point of the turbine speed of the automatic transmission when the travel range is selected.

[0008]

With the above construction, in the invention according to claim 1,
When selecting a driving range, the solenoid valve that supplies the control source pressure to the shift valve can be switched to the drain side without being involved in achieving the starting stage of that range, so the total supply amount of the source pressure is reduced. However, the rising speed of the original pressure for engagement, that is, the engagement hydraulic pressure, supplied to the friction engagement element is suppressed, the achievement of the starting stage of the travel range is delayed, and the torque during engagement of the friction engagement element is delayed. The shock, that is, the shift shock at the time of selecting to the driving range is reduced. As a result, in order to reduce the shift shock at the time of selecting to the desired traveling range, the frictional engagement element for that starting stage, like switching the solenoid valve of the shift valve, which is involved in achieving the starting stage of the traveling range, to the drain side. Since it is not necessary to separately provide a shift valve and a solenoid valve for supplying the original pressure for fastening to the hydraulic control device, the hydraulic control device becomes inexpensive.

According to the second aspect of the invention, the solenoid valve that supplies the control source pressure to the shift valve that is not involved in achieving the start stage of the reverse range when the reverse range is selected is switched to the drain side. As a result, the total supply amount of the original pressure is reduced, the rising speed of the engagement hydraulic pressure to the friction engagement element is suppressed, the achievement of the start stage of the reverse range is delayed, and the shift shock at the time of selecting to the reverse range is reduced. It will be. This eliminates the need for individual shift valves and solenoid valves, such as solenoid valves, involved in achieving the reverse range starting stage, and makes the hydraulic control device similarly inexpensive.

Further, according to the third aspect of the invention, the solenoid valve that supplies the control source pressure to the shift valve that is not involved in achieving the starting stage of the traveling range when selecting the traveling range (reverse range) is , Since it is switched to the drain side at the predetermined reduction point of the turbine speed of the automatic transmission, the solenoid valve is not switched to the drain side in the rotation range higher than the predetermined reduction point of the turbine speed, so During selection, the response speed at the time of shifting to the engaging operation of the friction engaging element at the starting stage of the travel range is not impaired and is quick.

[0011]

As described above, according to the hydraulic control device for an automatic transmission of the invention described in claim 1, the solenoid valve of the shift valve which is not involved in the achievement of the starting stage of the traveling range is drained when the traveling range is selected. By switching to the side, the amount of original pressure supplied to the friction engagement element was reduced to suppress the rising speed of the engagement hydraulic pressure, and the achievement of the starting stage of the running range was delayed.
By using an inexpensive hydraulic control device that does not require a separate shift valve and solenoid valve, it is possible to reduce the shift shock at the time of selecting to the travel range.

According to the hydraulic control device for an automatic transmission of the present invention, the solenoid valve of the shift valve, which is not involved in the achievement of the reverse range starting stage, is switched to the drain side when the reverse range is selected. As a result, the rising speed of the engaging hydraulic pressure was suppressed by reducing the amount of the source pressure supplied to the friction engagement element, and the achievement of the start stage of the reverse range was delayed, so an inexpensive hydraulic control device can be used to select the travel range. Shift shock can be reduced.

Further, according to the hydraulic control device for an automatic transmission in the third aspect of the present invention, the electromagnetic valve of the shift valve which is not involved in the achievement of the starting stage of the traveling range is set to the turbine speed when the traveling range is selected. By switching to the drain side at a predetermined drop point, the achievement of the starting stage of the running range was delayed from the middle, so the response when shifting to the engaging operation of the friction engagement element at the starting stage of the running range when selecting to the running range The speed can be increased.

[0014]

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

FIG. 1 shows an automatic transmission Z having four forward gears and one reverse gear.
1 is an engine output shaft, 2 is a torque converter including a pump 2a connected to the engine output shaft 1, a stator 2b, and a turbine 2c, and the stator 2b is a turbine converter that connects the stator 2b to the turbine. Case 4 via one-way clutch 3 to prevent rotation in the opposite direction to 2c
It can be fixed to. Further, 5 is a converter output shaft 2 connected to the turbine 2c of the torque converter 2.
It is a multi-step transmission gear mechanism connected to d.

The multi-stage speed change gear mechanism 5 includes a Ravigneaux type planetary gear mechanism 7 therein, and the planetary gear mechanism 7 includes a small-diameter sun gear 8 and a large-diameter sun gear 9 arranged in front and rear.
Short pinion gear 10 meshing with the small diameter sun gear 8
And the large-diameter sun gear 9 and the short pinion gear 1
A long pinion gear 11 that meshes with 0 and a ring gear 12 that meshes with the long pinion gear 11. The small-diameter sun gear 8 has an output shaft of the torque converter 2 via a forward clutch 15 disposed behind the sun gear 8 and a first one-way clutch 16 that blocks reverse drive of the converter output shaft 2d connected in series to the clutch 15. It is connected to 2d. Further, a coast clutch 17 is connected and arranged in parallel on the system path in which the forward clutch 15 and the first one-way clutch 16 are connected in series. 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. There is. Further, a low & reverse brake 21 for fixing the long pinion gear 11 via the rear carrier 20 to the long pinion gear 11, and a second one-way permitting rotation of the long pinion gear 11 in the same direction as the engine output shaft 1 are provided. 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 lockup 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.

In the above structure, the clutch of each shift speed,
Table 1 shows the operating state of the brake.

[0018]

[Table 1]

Next, a hydraulic circuit for supplying / discharging hydraulic oil to / from each friction element such as the 2-4 brake 18 will be described with reference to FIGS.

In the hydraulic circuit 60, first, a pressure / pressure adjusting means for adjusting the pressure of the hydraulic oil discharged from the oil pump 28 shown in FIG.
A regulator valve 61 is provided. In the vicinity of the pressure regulator valve 61, a throttle valve 62 that generates a throttle pressure according to the throttle valve opening of the engine, a throttle modulator valve 63 that adjusts the throttle pressure, and the pressure regulator. A backup valve 93 that generates a backup pressure that increases the line pressure generated by the valve 61 when the second or low range is selected is provided.

In the hydraulic circuit 60, the line pressure generated by the pressure regulator valve 61 is selectively sent to each hydraulic line according to the selected range, and a manual valve 64 is operated depending on the gear position. 1-2, 2- to selectively supply the line pressure to each of the above friction elements
3, 3-4 shift valves 71, 72, 73 are provided.

The manual valve 64 has an input port f into which the line pressure is introduced from the main line 100 and first to fifth output ports a to e, and the input port f is changed by the movement of the spool 64a. , The first, second and third output ports a, b and c in the drive range, and the fifth output port e in the reverse range. The first to fifth output lines 101 to 105 are connected to the output ports a to e, respectively.

The 1-2, 2-3, 3-4 shift valves 71, 72, 73 are respectively provided with spools 71a,
72a and 73a are urged to the right side in the drawing by springs, and the spools 71a, 72a and 73a are
The control ports 71b, 72b, 73b are provided on the right side of the. The first control line 106 branched from the main line 100 is connected to the control port 71b of the 1-2 shift valve 71, and the 2-3, 3-4 shift valve 7 is provided.
The second and third control lines 10 branched from the first output line 101 are connected to the control ports 72b and 73b of the second and the third 73, respectively.
7, 108 are respectively connected, and the control lines 106, 107, 108 are respectively provided with first, second and third solenoid valves 76, 77, 78. These solenoid valves 76-78
Respectively, when they are OFF, control pressure is introduced into the control ports 71b to 73b of the shift valve, and the spool 7
1a to 73a are located on the left side in the drawing, and the control pressures in the control ports 71b to 73b are drained when they are turned on to position the spools 71a to 73a on the right side.

Here, these solenoid valves 76 ...
The solenoid valve 78 is controlled to be turned on and off in accordance with the gear speed to be set according to the vehicle speed of the automobile and the throttle valve opening degree of the engine. The combination pattern of ON and OFF of 78 is set as shown in Table 2.

On the other hand, of the first to fifth output lines 101 to 105 connected to the output ports a to e of the manual valve 64, they are communicated with the main line 100 in forward, second, and low forward ranges. The first output line 101 is guided to the forward clutch 15 via the one-way orifice 80. Therefore, the forward clutch 15 is always engaged in the drive, second and low range. The first output line 101 is provided with an ND accumulator 81 for buffering when the forward clutch is engaged.

A line 111 is branched from the first output line 101 to be guided to the 1-2 shift valve 71, and the branch line 111 has the first solenoid valve 76 turned on. Spool 71a
Is moved to the right side, it is communicated with the servo ply line 150 reaching the hydraulic apply chamber 35b of the servo mechanism 35 (described later) of the 2-4 brake 18. Therefore, the first solenoid valve 76 is ON in drive, second, low range.
At that time, that is, the second, third and fourth speeds in the drive range, the second and third speeds in the second range, and the second speed in the low range, the servo apply pressure is introduced into the apply chamber 35b.

Next, the internal structure of the servo mechanism 35 for operating the 2-4 brake 18 (friction engaging element) will be described. The servo mechanism 35 includes a piston 35a that cooperates with the 2-4 brake 18, and a hydraulic apply chamber 35 as a coupling-side oil chamber that is divided by the piston 35a into left and right in the figure.
b and a hydraulic pressure release chamber 35c as a release side oil chamber, and a spring 35d that is compressed in the hydraulic pressure release chamber 35c and biases the piston 35a toward the apply chamber 35b. The pressure receiving area of the piston 35a is
The release chamber 35c is formed to have a larger size and a release chamber 35b to have a smaller size. Due to the difference in the pressure receiving area, the release chamber 35b is irrespective of whether the fastening pressure (line pressure) is applied or not. Release pressure (line pressure)
Is actuated, the release pressure is used to move the piston 35a to the left in the drawing to operate the 2-4 brake 18 to the open side. On the other hand, when the 2-4 brake 18 is requested to be fastened, the fastening pressure is introduced into the apply chamber 35b and the release pressure of the release chamber 35c is exhausted to move the piston 35a to the right in the drawing, thereby the 2-4 brake. 18 is fastened.

The apply chamber 3 of the servo mechanism 35 is also provided.
A one-way orifice 36 is provided in the line 150 as a fastening passage communicating with 5b. The one-way orifice 36 includes a throttle portion 36b having an opening portion 36a having an area smaller than the opening area of the line 150, and a spring 36c for urging the throttle portion 36b toward the downstream side (direction toward the servo mechanism 35). ing. Therefore, the one-way orifice 36 is provided in the apply chamber 3 of the servo mechanism 35.
When the oil in the apply chamber 35b is discharged, the spring 36c is normally contracted by the hydraulic pressure and the throttle portion 36a is separated, so that the throttle action is lost. Thus, the spring 36c has a relatively strong urging force, and during deceleration operation of the engine, the line pressure (servo mechanism 35
(The fastening pressure supplied to the valve) also decreases, and when the fastening pressure is equal to or less than the value of the set throttle valve opening value of the low opening, the biasing force overcomes the fastening pressure and seats the throttle portion 36a. With this configuration, when the fastening force is equal to or less than the set value, the fastening pressure is discharged while the line 150 is narrowed.

A piston-side accumulator 83 for suppressing a rapid increase in the fastening pressure of the servo mechanism 35 to the apply chamber 35b is arranged in the line 150b on the downstream side of the one-way orifice 36. The accumulator 83
Is a piston 83a, an oil chamber 83b for moving the oil in the line 150 to move the piston 83a leftward in the drawing,
The oil chamber 83b is provided with a compressed spring 83c, and the line pressure acts on the piston 83a as a back pressure via a line 151. Therefore, the biasing force of the spring 83c is set to a large value, and the line 1 is increased by the amount of the force.
By moving the piston 83a from a stage where the hydraulic pressure of 50 is at a small value, the piston 35a of the servo mechanism 35 is gradually moved, and the 2-4 brake 18 is gently engaged.

Further, in FIGS. 2 to 5, the second output line 102 communicating with the main line 100 in the drive or second range is led to the 2-3 shift valve 72. Then, the line 102 is connected to the 3-4 clutch line 113 that reaches the actuator 43a of the 3-4 clutch 43 via the one-way orifice 84 when the second solenoid valve 77 is OFF and the spool 72a is located on the left side. Therefore, when the second solenoid valve 77 is OFF in the drive and the second range, that is, the third and fourth speeds of the drive range and the third range of the third range.
The 3-4 clutch 24 is engaged at high speed. still,
The 3-4 clutch line 113 is provided with a bypass valve 85 and a 2-3 timing valve 86 in parallel with the one-way orifice 84 so as to adjust the engagement timing of the 3-4 clutch 24. Three
The -4 clutch line 113 is also provided with a 2-3 accumulator 87 for buffering when the 3-4 clutch is engaged.

Further, the line 114 branched from the 3-4 clutch 113 and the line 115 branched from the first output line 101 are led to the 3-4 shift valve 73. Then, the third solenoid valve 78 becomes O
The line 114 branched from the 3-4 clutch line 113 when the spool 73a is located on the left side in the FF is connected to the servo release line 116 that reaches the release chamber 35c of the servo mechanism 35 through the one-way orifice 88, and the first output line. The line 115 branched from 101
Coast clutch 1 via one-way orifice 89
7 are connected to the coast clutch lines 117. Therefore, when both the second and third solenoid valves 77 and 78 are OFF in the drive and the second range, that is, in the drive range third speed and the second range third speed,
The servo release pressure is introduced into the release chamber 35c of the servo mechanism 35 to release the 2-4 brake 18, and the third solenoid valve 7 is driven in the drive, second and low ranges.
When 8 is OFF, that is, the third speed of the drive range, the third speed of the second range, the second speed of the low range, and the second speed and the third speed when the hold switch of the second range is operated.
The coast clutch 17 is engaged in the first speed and the second speed during the operation of the hold switch for the high speed and the low range.

Here, the above-mentioned 3-4 clutch line 113
And a 3-2 timing valve 90 for adjusting the discharge timing of the 3-4 clutch pressure and the servo release pressure via the respective branch lines 118, 119 between the line 114 and the line 114 branched from the line 113. A 3-2 capacity valve 91 is provided. Further, the coast clutch line 117 is provided with a bypass line 120 that bypasses the one-way orifice 89, and a 3-4 capacity valve 92 that opens and closes the line 120. The valve 92 is configured such that when the 3-4 clutch pressure is generated and when the manual valve 64 is selected to the second range or the low range, the third output line 103 is set to the main line 100.
The bypass line 120 is opened to communicate the coast clutch pressure discharge timing.

The fourth output line 104, which communicates with the main line 100 in the low range by the manual valve 64, includes a low reduce valve 94 and a line 122.
Through the 1-2 shift valve 71. Then, in the line 122, the first solenoid valve 76 is turned off.
When the spool 71a is located on the left side in the FF, it is communicated with the low & reverse brake line 123 reaching the low & reverse brake 21 via the one-way orifice 95 and the shuttle valve 96. Therefore, when the first solenoid valve 76 is OFF in the low range, that is, in the first speed in the low range, the low & reverse brake 21 is engaged.

Further, in the reverse range, the main line 10
The fifth output line 105 communicating with 0 communicates with the low & reverse brake line 123 via the one-way orifice 97 and the shuttle valve 96, and
From the fifth output line 105, the one-way orifice 9
A reverse clutch line 124, which leads to the reverse clutch 19 via 8, is branched. Therefore, in the reverse range, the low & reverse brake 21 and the reverse clutch 19 are always engaged. In this case, when the reverse range is selected by the manual valve 64, the control line pressure is supplied to the 1-2 shift valve 71 via the first solenoid valve 76, while the 1-2 shift valve 71 is controlled. The line pressure for fastening is not supplied, and when the first solenoid 76 is selected to the reverse range, it does not contribute to the achievement of the starting stage of the reverse range and the 1-2 shift valve 71 is controlled by the source of the control. It is configured as a solenoid valve that supplies pressure. The reverse clutch line 124 is also provided with an NR accumulator valve 99 for buffering when the reverse clutch is engaged. A line 125 branched from the fifth output line 105 is guided to the pressure increasing side of the regulator valve 61 to increase the line pressure in the reverse range.

In addition to the above configuration, this hydraulic circuit 6
Reference numeral 0 indicates a lockup valve 2 for operating the lockup clutch 26 in the torque converter 2 shown in FIG.
01 is provided. A torque converter line 202 is led from the pressure regulator valve 61 to the valve 201, and the control line 2 at one end is also introduced.
Connected as 03. Then, the control line 20
Lock-up solenoid valve 204 provided in No. 3
When is turned on, the control pressure in the control port 201b is drained and the spool 201a is positioned on the right side, so that the torque converter line 202 communicates with the line 205 that communicates with the torque converter 2. The internal pressure of the converter 2 increases and the lockup clutch 27 is engaged. When the solenoid valve 204 is turned off and control pressure is introduced into the control port 201b to move the spool 201a to the left, the torque converter line 202 communicates with the lockup release line 206 and the torque converter 2
The lock-up release pressure is introduced into the lock-up clutch 27 so that the lock-up clutch 27 is released.

Table 2 collectively shows the relationship between the first, second and third speeds and the operating states of the first to third solenoids 76 to 78. In Table 2, the third solenoid valve 7 is provided on the low speed side (V ≦ 2) of the neutral range.
Only 8 is turned on in order to avoid the shift shock at the time of drive range selection by passing through the high speed stage (3rd speed pattern when V ≧ 5 km / h) at the time of N → drive selection. In addition, the high speed side of the neutral range (V ≦
The reason why each solenoid valve 76, 77, 78 adopts the same pattern as in the third speed range in 5) is to avoid the deceleration action by engine braking. Further, the first solenoid 76 is turned on in the reverse range in order to determine the signal from the inhibitor switch for selecting the reverse range in the neutral range.

[0037]

[Table 2]

As can be seen from Table 1 above, the reverse clutch 19 and the low & reverse brake 21 are engaged at the time of selecting from the neutral range to the reverse range by the manual valve 64, that is, at the time of the N → R shift. 6 to effectively reduce the
As shown in FIG. 3, the control is in the OFF control state without being involved in the achievement of the start stage of the reverse range, and the 1-2 shift valve 7
First solenoid valve 76 supplying line pressure to 1
Is switched to the drain side, that is, the ON control, and the line pressure supplied to the 1-2 shift valve 71 via the first control line 106 is drained midway to affect the line pressure.
Reduce the overall line pressure. The reverse clutch 19 and the low & reverse brake 21 are engaged by the line pressure reduced by this drain.

Therefore, when selecting from the neutral range to the reverse range, the first control in the OFF control state is performed.
By temporarily switching the solenoid valve 76 to the ON control state, the line pressure supplied to the 1-2 shift valve 71 is drained on the way, resulting in N → R.
The overall line pressure drops during the transition period during the shift. That is, the amount of oil supplied to the reverse clutch 19 and the low & reverse brake 21, which is used for engaging the reverse clutch 19 and the low & reverse brake 21, is set to N
→ The first solenoid valve 76 not involved in achieving the R shift
Is changed to the drain side, and the increase in the engagement pressure required for engaging the reverse clutch 19 and the low & reverse brake 21 is delayed.

Next, the control for correcting the line pressure at the time of shifting to the reverse range by the N → R shift will be described based on the flow of FIG.

After the start, in step S1,
If the signal from the inhibitor switch is present, and if the signal from the inhibitor switch is present, the range of the select range of the manual valve 64 is either the parking range, the neutral range, the drive range, the second range or the low range. Judgment to prepare for the subsequent judgment, but there is no signal from the inhibitor switch NO
If it is, it is determined that the select range of the manual valve 64 may be the reverse range, and the step S
2, and in this step S2, for a fixed time, for example, 2s
After waiting for ec, it is finally determined whether or not the select range of the manual valve 64 is the reverse range. Then, after a lapse of a certain period of time, if the signal from the inhibitor switch is YES, the process returns to step S1, while if there is no signal from the inhibitor switch after the lapse of the certain period of time, the turbine of the automatic transmission Z is returned to the step S3. After reading the rotation speed, the process proceeds to step S4.

Then, in this step S4, it is judged whether or not the decrease in the turbine speed is equal to or more than a certain value,
When the decrease of the turbine speed is equal to or less than the fixed value, that is, NO, which is not so small, the process returns to step S1, while when the decrease of the turbine speed is the fixed value or more, that is, is considerably decreased, the process proceeds to step S5, which is step S5.
In the above, the first solenoid valve 76, which is not involved in the achievement of the start stage of the reverse range and supplies the line pressure to the 1-2 shift valve 71, is set to the drain side, that is, the ON side for a certain time when the reverse range is selected. After switching, the process returns to step S1 repeatedly.

In this case, in step S5, the first solenoid valve 76 is switched to the ON side for a certain period of time, but the first solenoid valve 76 is turned on until the turbine speed falls to a desired lowering point. You may make it switch to the side.

Therefore, in the above embodiment, N →
During the R shift, the first solenoid valve 76, which supplies the line pressure for control to the 1-2 shift valve 71, which is in the OFF state without being involved in achieving the start stage of the reverse range, is the automatic transmission Z. ON when the turbine rotation speed drops significantly above a certain value (drain side)
Since the switching is performed for a predetermined time, the supply amount of the line pressure for engagement used for engaging the reverse clutch 19 and the low & reverse brake 21 is reduced, and the rising speed of the engagement hydraulic pressure is suppressed. The achievement of the start stage is delayed, and the torque shock when the reverse clutch 19 and the low & reverse brake 21 are engaged, that is, the shift shock when selecting to the reverse range is reduced. With this, in order to reduce the shift shock at the time of selecting to the desired travel range, the friction engagement element for that start stage is used, like switching the solenoid of the shift valve that is involved in achieving the start stage of the travel range to the drain side. On the other hand, it is not necessary to provide a separate shift valve and solenoid for supplying the line pressure for fastening, and the hydraulic control device becomes inexpensive. As a result, it is possible to reduce the shift shock at the time of selecting to the reverse range with an inexpensive hydraulic control device.

Moreover, during the N → R shift as described above, the first solenoid valve 76 is switched to the ON state when the decrease in the turbine speed of the automatic transmission Z exceeds a certain value, and the decrease in the turbine speed is caused. Do not switch to the drain side below a certain value to impair the response speed when shifting to the engaging operation of the reverse clutch 19 and the low & reverse brake 21 at the start stage of the reverse range during N → R gear shifting. Can be quick without.

The present invention is not limited to the above embodiment, but includes various other modifications.
For example, in the above embodiment, the control for correcting the line pressure at the time of shifting to the reverse range by the N → R shift has been described, but it does not contribute to the achievement of the starting stage of the drive range at the time of shifting to the drive range by the N → D shift. Of course, it can be applied to the control for correcting the line pressure by the solenoid.

Further, in the above embodiment, the first solenoid valve 76 is switched to the ON state when the decrease in the turbine speed becomes a certain value or more during the N → R shift, and when the decrease in the turbine speed is less than the certain value, the drain is drained. Although the configuration is not switched to the side, the configuration may be such that the first solenoid valve is switched to the drain side without depending on the turbine rotation speed during the N → R shift.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a vicinity of a transmission main body in a hydraulic control circuit of the automatic transmission.

FIG. 3 is a hydraulic circuit diagram similarly showing the vicinity of the manual valve.

FIG. 4 is a hydraulic circuit diagram showing the vicinity of 1-2 and 2-3 shift valves.

FIG. 5 is a hydraulic circuit diagram similarly showing the vicinity of the 3-4 shift valve.

FIG. 6 is a diagram showing a change state of an engagement pressure and a torque shock of a friction engagement element by correction control of a first solenoid valve.

FIG. 7 is a flowchart showing line pressure correction during N → R shift.

[Explanation of symbols]

 5 Multi-speed transmission gear mechanism (gear transmission mechanism) 15 Forward clutch (friction engagement element) 17 Coast clutch (friction engagement element) 18 2-4 Brake (friction engagement element) 24 3-4 Clutch (friction engagement element) 71 1-2 Shift valve 72 2-3 Shift valve 73 3-4 Shift valve 76 First solenoid valve 77 Second solenoid valve 78 Third solenoid valve Z Automatic transmission

Claims (3)

[Claims] 1. A hydraulic control device for an automatic transmission, comprising: a gear speed change mechanism; and a plurality of friction engagement elements for supplying a control source pressure to a shift valve by operating a solenoid valve to achieve a shift speed. On the other hand, when selecting a driving range, the solenoid valve that is not involved in the achievement of the starting stage of the driving range and that supplies the source pressure for control to the shift valve is switched to the drain side. Hydraulic control device for automatic transmission. 2. The solenoid valve is a solenoid valve that is not involved in achieving the starting stage of the reverse range and supplies the shift valve with the control source pressure, and is switched to the drain side when selecting to the reverse range. The hydraulic control device for the automatic transmission according to claim 1, wherein 3. The solenoid valve is a solenoid valve that is not involved in the achievement of the starting stage of the travel range and supplies the shift valve with the control source pressure. The hydraulic control device for an automatic transmission according to claim 1 or 2, wherein the hydraulic pressure control device is switched to the drain side at a predetermined reduction point of the turbine rotational speed.