JP2003262268A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an automatic transmission capable of accurately controlling approval and refusal of fail-safe operation. <P>SOLUTION: In the control device for the automatic transmission controlling engagement and release for a plurality of frictional elements 2 to 4 by means of oil pressure of operating oil and switching speed change gears, a first fail-safe valve 23, a second fail-safe valve 24, and a third fail-safe valve 25 are provided in the control device. The first fail-save valve 23 transmits applied oil pressure fed to a third frictional element 4 to the second fail-safe valve 24 when applied oil pressure fed to a first frictional element 2 exceeds a first fixed value. The second fail-safe valve 24 transmits oil pressure fed from the first fail-safe valve 23 to the third fail-safe valve 25 when applied oil pressure fed to a second frictional element 3 exceeds a second fixed value. The third fail-safe valve 25 adjusts applied oil pressure fed to the second frictional element 3 to pressure necessary for releasing when oil pressure fed from the second fail-safe valve 24 exceeds a third fixed value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission control device for hydraulically controlling a speed change mechanism of an automatic transmission.

[0002]

2. Description of the Related Art Conventionally, a hydraulic control system for an automatic transmission, which is often used for vehicles, controls the hydraulic pressure of hydraulic oil applied to a plurality of friction elements to engage or release the friction elements. Change gears. In the automatic transmission, a combination of friction elements to be engaged is determined for each gear stage, and generally two friction elements are engaged for one gear stage. Therefore, the hydraulic control device controls the hydraulic pressure applied to each friction element so that an appropriate friction element is engaged at each gear stage of the automatic transmission.

In a hydraulic control device, when the hydraulic pressure applied to a certain friction element becomes uncontrollable due to a failure of the device, for example, the line pressure, which is the original pressure of the hydraulic pressure applied to each friction element, is increased in order to maintain the gear position. Each applied oil pressure is increased by, for example, stopping energization of the solenoid valve that controls each applied oil pressure. Then, even the hydraulic pressure applied to the friction elements in the released state becomes high, so that three or more friction elements are simultaneously engaged. Such simultaneous engagement of three or more friction elements (hereinafter, simply referred to as “simultaneous engagement”) is dangerous because it may lock the input / output shaft of the automatic transmission or damage the automatic transmission. Therefore, the hydraulic control device disclosed in Japanese Patent No. 2917272 is provided with a fail-safe means for preventing simultaneous engagement by fail-safe operation. The fail-safe means stops the supply of the hydraulic pressure to one friction element when the relative ratio of the hydraulic pressure applied to the predetermined friction element to the variable line pressure becomes large.

[0004]

In the hydraulic control device, the hydraulic pressure of the hydraulic oil changes due to various factors such as changes in the oil temperature and manufacturing variations of the hydraulic circuit. The error due to
Therefore, in the above fail-safe means for determining whether or not to allow fail-safe operation based on the relative ratio of hydraulic pressure,
Since it is difficult to guarantee the determination error due to all the factors, erroneous determination easily occurs.

By the way, in the hydraulic control device, when it is difficult to control the hydraulic pressure applied to each friction element, for example, at an extremely low temperature or at an extremely low vehicle speed, the three friction elements are momentarily engaged during shifting. If this is done, the shift performance such as the inhibition of shift shock and the responsiveness of switching between shift stages may be improved. on the other hand,
In the hydraulic control device including the fail-safe means as described above, the three friction elements cannot be simultaneously engaged by the fail-safe operation. Therefore, a method has been considered in which the fail-safe operation is prohibited by forcibly increasing the line pressure, which is the reference for determination, in the fail-safe means. However, since the line pressure may be increased even when the hydraulic pressure applied to the friction element becomes uncontrollable, the fail-safe means for prohibiting the fail-safe operation by the increase of the line pressure, which is the criterion, prevents simultaneous engagement. An object of the present invention, which sometimes prohibits fail-safe operation even when it should be, is to provide an automatic transmission control device capable of accurately controlling whether or not to allow fail-safe operation.

[0006]

Claims 1 and 2 of the present invention
According to the automatic transmission control device described in (1), the first fail-safe means changes the hydraulic pressure applied to the third friction element to the second hydraulic pressure when the hydraulic pressure applied to the first friction element exceeds the first fixed value. Communicate to fail-safe means. The second fail-safe means, when the hydraulic pressure applied to the second friction element exceeds the second fixed value, changes the hydraulic pressure applied to the third friction element transmitted from the first fail-safe means to the third fail-safe. Communicate to the means. Alternatively, the second fail-safe means applies the hydraulic pressure applied to the second friction element to the third fail element when the hydraulic pressure applied to the third friction element transmitted from the first fail-safe means exceeds the second fixed value. Communicate to safe means. Then, as the fail-safe operation of the third fail-safe means, the hydraulic pressure applied to the third friction element or the hydraulic pressure applied to the second friction element transmitted from the second fail-safe means exceeds the third fixed value. At this time, the hydraulic pressure applied to any one of the first, second, and third friction elements is adjusted to the pressure required for release. Therefore, when the first, second, and third fail-safe means determines that the applied hydraulic pressures corresponding to the first, second, and third fixed values are exceeded, the friction element is changed to any one of the friction elements. The applied hydraulic pressure is set to the pressure required for releasing, and simultaneous engagement of the three friction elements is prevented.

Further, according to the automatic transmission control device of the present invention, the judgment in the first, second and third fail-safe means is based on the first, second and third fixed values. Is going. That is, the determination by each fail-safe means is made based on the absolute pressure of the corresponding applied hydraulic pressure. Therefore, it is possible to reduce the determination error due to various factors such as the change of the oil temperature and the manufacturing variation of the hydraulic circuit.

Further, according to the automatic transmission control device according to the first and second aspects of the present invention, by adopting the above-mentioned configuration, the line pressure which is the source pressure of the applied hydraulic pressure for the determination in each fail-safe means is obtained. It can be implemented without reference.
Therefore, whether the fail-safe operation is permitted or not can be correctly determined regardless of whether the line pressure is increased or decreased.

According to the automatic transmission control device of the third aspect of the present invention, the operation control solenoid valve transforms the output pressure applied to the third fail-safe means by electromagnetic control, whereby the third fail-safe means. The fail-safe operation of is prohibited. Therefore, fail-safe operation can be reliably prohibited when it is desired to simultaneously engage the three friction elements.

According to the automatic transmission control device of the fourth aspect of the present invention, the fail-safe means, as its fail-safe operation, applies hydraulic pressure to the first friction element, the second friction element and the third friction element, respectively. When both of them become the pressure necessary for engagement, the hydraulic pressure applied to any one of the first friction element, the second friction element and the third friction element is adjusted to the pressure necessary for releasing. The operation control solenoid valve prohibits the failsafe operation of the failsafe means by transforming the output pressure applied to the failsafe means by electromagnetic control. Therefore, when it is desired to simultaneously engage the three friction elements, the fail-safe operation can be reliably prohibited without increasing the line pressure that is the source pressure of the applied hydraulic pressure. Therefore, even if the applied hydraulic pressure is increased and the line pressure is increased in order to maintain the shift speed when the applied hydraulic pressure cannot be controlled, it is possible to accurately determine whether the fail-safe operation is permitted or not.

According to the transmission control device of the fifth aspect of the present invention, the operation control solenoid valve prohibits the fail-safe operation of the third fail-safe means or the fail-safe means at the time of shifting. As a result, it becomes possible to engage the three friction elements at extremely low temperatures where it is difficult to control the hydraulic pressure applied to each friction element during gear shifting, at extremely low vehicle speeds, and the like. Therefore, it is possible to improve gear shifting performance such as gear shift shock inhibition and gear shift switching responsiveness.

According to the automatic transmission control device of the sixth and seventh aspects of the present invention, it is applied to a friction element different from the first friction element, the second friction element and the third friction element among the plurality of friction elements. The solenoid valve that controls the hydraulic pressure is also used as the operation control solenoid valve. Therefore, since it is not necessary to newly provide an operating electromagnetic control valve in the automatic transmission control device, the manufacturing cost can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of examples showing an embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) A first embodiment in which the automatic transmission control device of the present invention is applied to a hydraulic control device for an automatic transmission of four forward speeds is shown in FIGS. 1 and 2. Reverse clutch (R / C) 1, overdrive clutch (H / C) 2, 2-4 brake (2-4 / B) 3, underdrive clutch (L /
The C) 4 and the low reverse brake (LR / B) 5 are friction elements that are engaged or released by hydraulic pressure to switch the shift speed. FIG. 3 shows a combination of engagement and disengagement of the friction elements 1 to 5 which are predetermined for each shift speed of the automatic transmission. As shown in FIG. 3, H / C2 corresponds to at least a friction element to be engaged at two stages on the forward high speed side,
4 / B3 corresponds to a friction element that is engaged at least in one forward low speed side and one forward high speed side, and L / C4 is a friction element that is engaged in at least two forward low speed sides and one forward high speed side. LR / B5 corresponds to a friction element that is engaged at least in the reverse gear and is engageable in the forward gear.
Incidentally, the engagement of LR / B5 is shown in parentheses in FIG. 3 because the LR together with L / C4 is used to apply the engine brake.
This is because / B5 may be engaged. The transfer clutch (TRF) 6 is a friction element that is engaged or released by hydraulic pressure.

The hydraulic pump 40 sucks hydraulic oil from an oil pan 41 and supplies the hydraulic oil to the communication passage 100. The solenoid valve 44 is a control device (ECU; Electric Contr) not shown.
ol Unit) to generate a command pressure according to the command value. The line pressure control valve 42 includes the friction elements 1 to 1.
6 and the line pressure which is the source pressure of the hydraulic pressure applied to the lockup clutch 51 are generated based on the command pressure of the solenoid valve 44.
Specifically, the line pressure control valve 42 is connected to the solenoid valve 44 by a communication passage 115 that transmits the command pressure of the solenoid valve 44. The line pressure control valve 42 is connected to the communication passages 101 and 102 branched from the communication passage 100. The line pressure control valve 42 controls the command pressure of the solenoid valve 44 and the communication passage 102.
By discharging a part of the hydraulic oil introduced from the communication passage 101 to the oil pan 41 based on the hydraulic pressure of the communication passage 100,
The hydraulic pressure of is controlled as a line pressure. The hydraulic pump 40, the line pressure control valve 42, and the solenoid valve 44 constitute a line pressure generating means. The line pressure control valve 42 also discharges part of the hydraulic oil to the communication passage 103 connected to the secondary valve 43. Communication passage 11 branched from the line pressure communication passage 100
0, 120, 127, 140 are the pressure reducing control valves 4 respectively.
5, the manual valve 38, the clutch pressure control valve 26, and the clutch pressure control valve 32 are connected.

In the pressure reducing control valve 45, the output pressure from the communication passage 111 is used as a feedback pressure, and the feedback pressure works in a direction to reduce the output pressure. As a result, the pressure reducing control valve 45 reduces the line pressure transmitted through the communication passage 110, and generates an output pressure that does not exceed the line pressure. This output pressure is called the modulated pressure. The decompression control valve 45 is connected to the solenoid valve 44 by a communication passage 111 that transmits the modulated pressure and a communication passage 114 that branches from the communication passage 111.

The manual valve 38 is connected to a shift lever operated by a driver via a link. In the manual valve 38, one of the line pressure communication passage 120 and the drain pressure drain passage 121 is connected to the communication passages 122 and 123 by moving a valve member (not shown) in accordance with the operation of the shift lever. Switch to. Communication passage 122
The communication passages 195 and 196 branching from each are R / C
1, connected to LR / B5. The communication passages 124, 125, 126 branched from the communication passage 123 are connected to the clutch pressure control valves 10, 16, 20, respectively. The switching position of the manual valve 38 has four positions of "P, R, N, D" corresponding to the range of the shift lever. "P" and "N" have the same communication pattern. The R range is
This corresponds to the shift stage indicated by R in FIG. Communication passages 123, 12
The hydraulic pressures of 4, 125, and 126 are set to the line pressure when the D range is selected by the shift lever, and are set to the drain pressure when a range other than the D range is selected. The hydraulic pressure in the communication passages 122, 195, and 196 is set to the line pressure when the R range is selected by the shift lever, and is set to the drain pressure when a range other than the R range is selected.

Clutch pressure control valve 10 and solenoid valve 12, clutch pressure control valve 16 and solenoid valve 18, clutch pressure control valve 20
And the solenoid valve 22, the clutch pressure control valve 26 and the solenoid valve 28, the clutch pressure control valve 32 and the solenoid valve 34 are respectively R / C1.
The hydraulic pressure applied to each of the friction elements 2, 3, 4, 5, 6 other than is controlled.

The solenoid valves 12, 18, 22, 28, 34 are
Communication passage 15 branched from the modulation pressure communication passage 111
0, 151, 152, 153, 154, respectively. The solenoid valves 12, 18, 22, 28, 34 correspond to the corresponding clutch pressure control valves 10, 16, 20, 26, 32.
To the communication paths 162, 163, 164, 165, respectively.
They are connected by 166. The clutch pressure control valve 10 and the H / C2 are connected by the communication passage 168, and the clutch pressure control valves 16 and 2-4 / B3 are connected by the communication passages 169 and 170 sandwiching the third fail-safe valve 25.
0 and L / C4 by a communication passage 171, the clutch pressure control valve 26 and LR / B5 by a communication passage 188, 189 sandwiching the fourth fail-safe valve 30, and the clutch pressure control valve 32 and TRF6 by a communication passage 161. Connected by each.

Each solenoid valve 12, 18, 22, 28, 34
The duty ratio is controlled based on the duty ratio input from the ECU. Hereinafter, the solenoid valves 12, 18, 22,
28 and 34 are called duty solenoid valves. The duty ratio of the duty solenoid valves 12, 18, 22, 28, 34 is controlled so that the communication passages 150, 151, 152, respectively.
The command pressure corresponding to the duty ratio is generated using the modulated pressure of 153 and 154 as the original pressure. Each duty solenoid valve 1
2, 18, 22, 28, 34 apply the generated command pressure to the clutch pressure control valves 10, 16, 20, 26, 32 through the communication passages 162, 163, 164, 165, 166.

Clutch pressure control valves 10, 16, 20, 2
Reference numerals 6 and 32 are pressure control valves. Each clutch pressure control valve 10, 16, 20, 26, 32 generates an output pressure by using the hydraulic pressure of the communication passages 124, 125, 126, 127, 140 as a source pressure. Each clutch pressure control valve 10, 1
6, 20, 26, 32, the duty solenoid valves 12, 1
According to the command pressure of 8, 22, 28, 34, the friction element 2,
The output pressure applied to 3, 4, 5, and 6 is controlled. In the clutch pressure control valves 10, 16, 20, 26, 32, as the command pressures of the duty solenoid valves 12, 18, 22, 28, 34 increase, the communication paths 124, 125, 126, 1 also increase.
The output pressure is increased as the source pressure of 27 and 140 increases. However, the clutch pressure control valves 10, 16, 20, 2
6, 32, the communication passages 168, 169, 171, 18
The output pressure from 8, 161 is used as the feedback pressure, and the feedback pressure acts in the direction of decreasing the output pressure. Therefore, the clutch pressure control valves 10, 1
The output pressures of 6, 20, 26, and 32 are controlled to pressures (engagement hydraulic pressures described below) that do not exceed the maximum hydraulic pressures that can be applied to the friction elements 2, 3, 4, 5, and 6, respectively. Dampers 61, 6
Numerals 2 and 63 are arranged in the communication passages 162, 163 and 164, respectively, and remove the pulsation from the command pressure of the duty solenoid valves 12, 18 and 22.

The operation control solenoid valve 36 is a three-port two-position switching solenoid valve, and the energization of the solenoid 36a is on / off controlled according to a command value input from the ECU. The operation control solenoid valve 36 is connected to the communicating passage 1 of the modulated pressure.
11 is connected to a communication passage 180 branched from 11, a drain passage 194 for drain pressure, and a communication passage 181 connected to the third fail-safe valve 25. The operation control solenoid valve 36, when the energization of the solenoid 36a is turned off,
The communication between the communication passage 181 and the communication passage 180 is blocked, and the communication passage 181 and the drain passage 194 are connected. Accordingly, the operation control solenoid valve 36 sets the output pressure to the communication passage 181 to the drain pressure. When the solenoid 36a is energized, the operation control solenoid valve 36 shuts off the communication between the communication passage 181 and the drain passage 194, and connects the communication passage 181 and the communication passage 180. As a result, the operation control solenoid valve 36 sets the output pressure to the communication passage 181 to a modulated pressure that is higher than the drain pressure.

The first fail-safe valve 23, the second fail-safe valve 24, the third fail-safe valve 25 and the fourth fail-safe valve 30 are respectively directional control valves. In this embodiment, the first fail-safe valve 23, the second fail-safe valve 24 and the third fail-safe valve 25.
Respectively configure "first fail-safe means", "second fail-safe means", and "third fail-safe means" described in the claims, and these three fail-safe valves 23, 24, 25 are Together, they constitute the "fail safe means" recited in the claims. Further, in this embodiment, H / C2, 2-4 / B3 and L / C4
Respectively constitute the "first friction element", the "second friction element" and the "third friction element" described in the claims.

The first fail-safe valve 23 is connected to the communication passage 16
8 is connected to a communication passage 172 that branches from 8, a communication passage 173 that branches from the communication passage 171, a communication passage 174 that connects to the second fail-safe valve 24, and a drain passage 190 for drain pressure. First fail-safe valve 23
Includes a spring 23a and a spool (not shown) biased by the spring 23a. In the first fail-safe valve 23, the hydraulic pressure applied to the H / C2 is transmitted from the clutch pressure control valve 10 through the communication passage 172, and the force generated by the transmitted hydraulic pressure acts on the spool in the direction opposite to the urging force of the spring 23a. There is. Therefore, in the first fail-safe valve 23, the spool moves according to the balance between the force of the hydraulic pressure transmitted through the communication passage 172 and the urging force of the spring 23a.

When the transmission oil pressure of the communication passage 172 exceeds the first fixed value, the spool of the first fail-safe valve 23 blocks the communication between the communication passage 174 and the drain passage 190 and connects the communication passage 174 and the communication passage 173. Move to the position to communicate. As a result, the first fail-safe valve 23 transmits the L / C4 transmitted from the clutch pressure control valve 20 through the communication passage 173.
The hydraulic pressure applied to the communication passage 174 is transmitted. Further, when the transmission hydraulic pressure of the communication passage 172 becomes equal to or lower than the first fixed value, the spool of the first fail-safe valve 23 blocks the communication between the communication passage 174 and the communication passage 173 and connects the communication passage 174 and the drain passage 190. Move to the position to communicate. Thereby, the first fail-safe valve 23 sets the hydraulic pressure in the communication passage 174 to the drain pressure. For the first fixed value, H / C2
H / C2 lower than the engagement hydraulic pressure required to hold the
Is set to a pressure value higher than the drain pressure required to hold and release.

The second fail-safe valve 24 is connected to the communication passage 16
9 are connected to a communication passage 175 branched from 9, a communication passage 174, a communication passage 176 connected to the third fail-safe valve 25, and a drain passage 191 for drain pressure. The second fail-safe valve 24 has a spring 24a.
And a spool (not shown) biased by the spring 24a. In the second fail-safe valve 24, 2-
The hydraulic pressure applied to 4 / B3 is transmitted from the clutch pressure control valve 16 through the communication passage 175, and the force generated by the transmitted hydraulic pressure acts on the spool in the direction opposite to the urging force of the spring 24a. Therefore, in the second fail-safe valve 24,
The spool moves in accordance with the balance between the force of the transmitted hydraulic pressure of the communication passage 175 and the urging force of the spring 24a.

When the transmission hydraulic pressure of the communication passage 175 exceeds the second fixed value, the spool of the second fail-safe valve 24 blocks the communication between the communication passage 176 and the drain passage 191 and connects the communication passage 176 and the communication passage 174. Move to the position to communicate. As a result, the second fail-safe valve 24 is connected to the communication passage 1
The hydraulic pressure applied to the L / C 4 or the drain pressure transmitted from 74 is transmitted to the communication passage 176. Further, when the transmission hydraulic pressure of the communication passage 175 becomes equal to or lower than the second fixed value, the second fail-safe valve 2
The fourth spool moves to a position where it blocks communication between the communication passage 176 and the communication passage 174 and allows the communication passage 176 and the drain passage 191 to communicate with each other. Thereby, the second fail-safe valve 24 sets the hydraulic pressure of the communication passage 176 to the drain pressure. It should be noted that the second fixed value is set to a pressure value lower than the engagement hydraulic pressure required to hold 2-4 / B3 in engagement and higher than the drain pressure required to release and hold 2-4 / B3. To be done.

The third fail-safe valve 25 is provided in the communication passage 16
9, 170, 176, 181, and the drain pressure drain passage 192, respectively. The third fail-safe valve 25 includes a spring 25a and a spring 25a.
a spool (not shown) biased by a. In the third fail-safe valve 25, the hydraulic pressure or drain pressure applied from the communication passage 176 to the L / C 4 is transmitted, and the force due to the transmitted hydraulic pressure acts on the spool in the direction opposite to the urging force of the spring 25a. Further, in the third fail-safe valve 25, the output pressure of the operation control solenoid valve 36 is transmitted from the communication passage 181, and the force due to the transmitted output pressure acts on the spool in the same direction as the urging force of the spring 25a. That is, the force due to the output pressure of the operation control solenoid valve 36 and the force due to the hydraulic pressure transmitted through the communication passage 176 act on the spool in opposite directions. Therefore, in the third fail-safe valve 25, the spool moves according to the balance between the force of the hydraulic pressure transmitted through the communication passage 176 and the force of the spring 25a and the output pressure of the operation control solenoid valve 36.

When the output pressure of the operation control solenoid valve 36 is the drain pressure on the low pressure side and the transmission hydraulic pressure of the communication passage 176 exceeds the third fixed value, the spool of the third fail-safe valve 25 has the communication passage 170 and the communication passage 169. It is moved to a position where the communication with the drain passage 192 is blocked and the communication with the drain passage 192 is blocked. Thereby, the third fail-safe valve 25 is connected to the communication passage 1
Set the hydraulic pressure of 70 to the drain pressure. Hereinafter, this operation is referred to as fail-safe operation. Further, the operation control solenoid valve 36
Output pressure is the drain pressure and the transmission hydraulic pressure of the communication passage 176 becomes the third fixed value or less, or the operation control solenoid valve 3
When the output pressure of 6 is the high-pressure side modulated pressure, the spool of the third fail-safe valve 25 blocks the communication between the communication passage 170 and the drain passage 192 and connects the communication passage 170 and the communication passage 169. Move to. As a result, the third fail-safe valve 25 transmits the hydraulic pressure applied from the clutch pressure control valve 16 through the communication passage 169 to the 2-4 / B3 to the communication passage 170. Regarding the third fail-safe valve 25, the pressure receiving area of a land (not shown) is set so that the output pressure of the operation control solenoid valve 36 becomes the modulated pressure, and thus the passage is not communicated / communicated. The state can be maintained regardless of the hydraulic pressure of the communication passage 176. Further, the third fixed value is set to a pressure value that is lower than the engagement hydraulic pressure required to hold the L / C 4 engaged and higher than the drain pressure required to hold the L / C 4 released.

The fourth fail-safe valve 30 has a communication passage 16
8 is connected to the communication passage 183 branched from the communication passage 170, the communication passage 185 branched from the communication passage 170, the communication passages 188 and 189, and the drain passage 193 for drain pressure. The fourth fail-safe valve 30 has a spring 30a.
And a spool (not shown) biased by the spring 30a. In the fourth fail-safe valve 30,
The hydraulic pressure applied to the H / C2 is transmitted from the clutch pressure control valve 10 through the communication passage 183, and the force generated by the transmitted hydraulic pressure acts on the spool in the direction opposite to the biasing force of the spring 30a. Furthermore, in the fourth fail-safe valve 30, 2
The hydraulic pressure or drain pressure applied to −4 / B3 is transmitted from the third fail-safe valve 25 through the communication passage 185, and the force generated by the transmitted hydraulic pressure acts on the spool in the direction opposite to the urging force of the spring 30a. Therefore, in the fourth fail-safe valve 30, the spool moves according to the balance between the force due to the hydraulic pressure transmitted through the communication passage 183 and the force due to the hydraulic pressure transmitted through the communication passage 185, and the biasing force of the spring 30a.

When the transmission oil pressure of the communication passage 183 exceeds the fourth fixed value or when the transmission oil pressure of the communication passage 185 exceeds the fifth fixed value, the spool of the fourth fail-safe valve 30 has a communication passage 189 and a communication passage 188. It is moved to a position where the communication with is cut off and the communication passage 189 and the drain passage 193 are communicated with each other. As a result, the fourth fail-safe valve 30 sets the hydraulic pressure in the communication passage 189 to the drain pressure. Further, when the transmission hydraulic pressure of the communication passage 183 becomes equal to or lower than the fourth fixed value and the transmission hydraulic pressure of the communication passage 185 becomes equal to or lower than the fifth fixed value, the spool of the fourth fail-safe valve 30 is connected to the communication passage 189 and the drain passage 193. To the position where the communication passage 189 and the communication passage 188 are communicated with each other. As a result, the fourth fail-safe valve 30 transmits the hydraulic pressure applied from the clutch pressure control valve 26 to the LR / B 5 transmitted through the communication passage 188 to the communication passage 189. The fourth fixed value is set in the same manner as the first fixed value, and the fifth fixed value is set in the same manner as the second fixed value. The high-pressure selection valve 29 selects the high-pressure side of the communication passages 189 and 196 to communicate with the LR / B5.

The lockup clutch 51 connects or disconnects the output shaft on the engine side and the input shaft on the automatic transmission side, and when the lockup clutch 51 is connected, it bypasses the torque converter 50 and the automatic transmission from the engine. Transmit power to. The lockup duty solenoid valve 53 controls the command pressure for switching the lockup relay valve 54. The lockup clutch control valve 52 uses the lockup clutch 51 based on the command pressure of the lockup duty solenoid valve 53.
Control the hydraulic pressure applied to the.

Next, the hydraulic control operation of the hydraulic control system of the first embodiment will be described. [Normal operation] First, the duty solenoid valves 12, 18, 2
The normal operation that can be controlled by the ECU 2 will be described. The hydraulic oil is sucked from the oil pan 41 by the hydraulic pump 40 and discharged into the communication passage 100 as a high pressure. The solenoid valve 44 receives a command from the ECU to set an appropriate line pressure according to the operating state of the vehicle such as throttle opening, engine torque, turbine torque, etc., and controls the command pressure to be sent to the line pressure control valve 42. To do. The line pressure control valve 42 controls the line pressure in the communication passage 100 according to the command pressure of the electromagnetic valve 44.

The pressure reducing control valve 45 regulates the pressure (modulation pressure) of the communication passage 111 so as not to exceed the line pressure. The modulated pressure regulated by the pressure reducing control valve 45 is the duty solenoid valves 12, 18, 22, 28, 34.
Will be the source pressure. Duty solenoid valves 12, 18, 22, 2
Reference numerals 8 and 34 regulate the modulated pressure of the original pressure according to the input duty ratio from the ECU, and apply the obtained command pressure to the clutch pressure control valves 10, 16, 20, 26 and 32.
The clutch pressure control valves 10, 16, 20, 26, 32 follow the command pressures of the duty solenoid valves 12, 18, 22, 28, 34, and the communication passages 124, 125, 126, 127, 140.
The output pressure is controlled by using the hydraulic pressure of as the original pressure. At this time, the hydraulic pressure in the communication passages 124, 125, 126 is set to the line pressure or the drain pressure according to the operating state of the manual valve 38.
The hydraulic pressure in the communication passages 127 and 140 is always set to the line pressure. The clutch pressure control valves 10, 16, 20, 2 for keeping the friction elements 2, 3, 4, 5, 6 engaged in a normal state.
The engagement hydraulic pressures output by 6 and 32 are set to pressure values lower than the line pressure by a predetermined amount.

The output pressure of the clutch pressure control valve 10 is the communication passage 1
The output pressure of the clutch pressure control valve 20 is applied to the L / C 4 through the communication passage 171 and the output pressure of the clutch pressure control valve 32 is applied to the TRF 6 through the communication passage 161. The third fail-safe valve 25 is the communication passage 1
When connecting 69 and 170 to each other, the clutch pressure control valve 1
The output pressure of 6 is 2-4 / B through the communication passages 169 and 170.
3 is applied. Fail-safe valve 30 is communication passage 188
And 189 are communicated with each other, and the high pressure selection valve 29 is connected to the communication passage 1
When 89 is communicated with LR / B5, the output pressure of the clutch pressure control valve 26 is passed through the communication passages 188 and 189 to LR / B5.
5 is applied. The hydraulic pressure applied to the R / C1 from the communication passage 195 becomes the line pressure when the R range is selected by the shift lever, and becomes the drain pressure when the other range is selected.

Here, in order to explain the operation of the fail-safe valves 23, 24, 25, 30 and the operation control solenoid valve 36 at the normal time, the case where the D range is selected by the shift lever is taken as an example, and The hydraulic control operation of the hydraulic control device during the shift and the shift will be described in more detail.
The non-shift state means a state in which a predetermined friction element is engaged and the shift speed is maintained. Further, “during gear shifting” refers to the time when the gear shift command is issued from the ECU to switch the gears by changing the friction element.

First, the operation during non-shifting will be described. In the non-shift mode, the operation control solenoid valve 36 is deenergized to the solenoid 36a according to a command from the ECU, and the drain pressure of the drain passage 194 is used as the output pressure to establish the communication passage 18.
1 is applied. The third fail-safe valve 25 that has received the drain pressure from the communication passage 181 receives the drain pressure from the communication passage 170 as long as the hydraulic pressure in the communication passage 176 does not exceed the third fixed value.
The communication of 69 and the non-communication state of the drain passage 192 can be maintained.

When the gear stage is held at the first speed during non-shifting, the output pressure of the clutch pressure control valve 20 is set to the engagement hydraulic pressure, and the output pressure of the clutch pressure control valves 10, 16, 26 is set to the drain pressure. Is set to. As a result, the second fail-safe valve 24 receives the output drain pressure of the clutch pressure control valve 16 from the communication passage 175, so it is determined that the hydraulic pressure applied to 2-4 / B3 is equal to or less than the second fixed value, and the communication passage is determined. The hydraulic pressure of 176 is set to the drain pressure. The third fail-safe valve 25 determines that the hydraulic pressure in the communication passage 176 is equal to or lower than the third fixed value, and applies the output drain pressure of the clutch pressure control valve 16 received from the communication passage 169 to 2-4 / B3. The fourth fail-safe valve 30 receives the above 2-4 / received from the communication passage 185.
It is determined that the hydraulic pressure applied to B3 is less than or equal to the fifth fixed value.
The fourth fail-safe valve 30 is the clutch pressure control valve 1
Since the output drain pressure of 0 is received from the communication passage 183, H
It is determined that the hydraulic pressure applied to / C2 is less than or equal to the fourth fixed value. Therefore, the fourth fail-safe valve 30 is connected to the communication passage 188.
The output drain pressure of the clutch pressure control valve 26 that is received more is transmitted to the communication passage 189. In the D range, since the hydraulic pressure in the communication passage 196 becomes the drain pressure, the high pressure selection valve 29 is set in the communication passage 1
The drain pressure of 96 or the communication passage 189 is transmitted to LR / B5. As described above, L / C4 is engaged and H / C2, 2-4 / B3 and LR / B5 are released as shown in FIG.

When the second speed is maintained, the output pressures of the clutch pressure control valves 16 and 20 are set to the engagement hydraulic pressure, and the output pressures of the clutch pressure control valves 10 and 26 are set to the drain pressure. As a result, the first fail-safe valve 23 receives the output drain pressure of the clutch pressure control valve 10 from the communication passage 172. Therefore, it is determined that the hydraulic pressure applied to the H / C2 is equal to or lower than the first fixed value, and the communication pressure of the communication passage 174 is reduced. Turn hydraulic pressure to drain pressure. The second fail-safe valve 24 is the clutch pressure control valve 16
Since the output engagement hydraulic pressure of is received from the communication passage 175, 2-4
It is determined that the hydraulic pressure applied to / B3 exceeds the second fixed value, and the drain pressure received from the communication passage 174 is set to the communication passage 176.
Apply to. The third fail-safe valve 25 determines that the hydraulic pressure in the communication passage 176 is equal to or lower than the third fixed value, and applies the output engagement hydraulic pressure of the clutch pressure control valve 16 received from the communication passage 169 to 2-4 / B3. . Fourth fail-safe valve 30
Determines that the hydraulic pressure applied to the 2-4 / B3 received from the communication passage 185 exceeds the fifth fixed value. Therefore, the fourth fail-safe valve 30 sets the hydraulic pressure in the communication passage 189 to the drain pressure. The high-pressure selection valve 29 transmits the drain pressure of the communication passage 196 or the communication passage 189 to LR / B5. As described above, as shown in FIG. 3, 2-4 / B3 and L / C4 are engaged, and H / C2 and LR / B5 are released.

When the shift speed is held at the third speed, the output pressure of the clutch pressure control valves 10 and 20 is set to the engagement hydraulic pressure, and the output pressure of the clutch pressure control valves 16 and 26 is set to the drain pressure. As a result, the second fail-safe valve 24 and the third fail-safe valve 25 operate in the same manner as in the above-described first speed. As a result, the output drain pressure of the clutch pressure control valve 16 is applied to 2-4 / B3. Since the fourth fail-safe valve 30 receives the output engagement hydraulic pressure of the clutch pressure control valve 10 from the communication passage 183, it is determined that the hydraulic pressure applied to the H / C2 exceeds the fourth fixed value. Therefore, the fourth fail-safe valve 30 sets the hydraulic pressure in the communication passage 189 to the drain pressure. The high pressure selection valve 29 is connected to the communication passage 196 or the communication passage 1
The drain pressure of 89 is transmitted to LR / B5. By the above, H / C2 and L / C4 are engaged as shown in FIG.
2-4 / B3 and LR / B5 are released.

When the shift speed is held at the fourth speed, the output pressure of the clutch pressure control valves 10 and 16 is set to the engagement hydraulic pressure, and the output pressure of the clutch pressure control valves 20 and 26 is set to the drain pressure. As a result, the first fail-safe valve 23 receives the output engagement hydraulic pressure of the clutch pressure control valve 10 from the communication passage 172, so it is determined that the hydraulic pressure applied to the H / C2 exceeds the first fixed value, and the communication passage is determined. The output drain pressure of the clutch pressure control valve 20 received from 173 is applied to the communication passage 174. Since the second fail-safe valve 24 receives the output engagement hydraulic pressure of the clutch pressure control valve 16 from the communication passage 175, it is 2-4 / B3.
It is determined that the hydraulic pressure applied to the hydraulic pressure exceeds the second fixed value, and the drain pressure received from the communication passage 174 is applied to the communication passage 176. The third fail-safe valve 25 has its communication passage 17
It is determined that the hydraulic pressure of 6 is the third fixed value or less, and the communication passage 16
The output engagement oil pressure of the clutch pressure control valve 16 received from
-4 / B3. The fourth fail-safe valve 30 is
It is determined that the hydraulic pressure applied to the 2-4 / B3 received from the communication passage 185 exceeds the fifth fixed value. Further, since the fourth fail-safe valve 30 receives the output engagement hydraulic pressure of the clutch pressure control valve 10 from the communication passage 183, it is determined that the hydraulic pressure applied to the H / C2 exceeds the fourth fixed value. Therefore,
The fourth fail-safe valve 30 makes the hydraulic pressure in the communication passage 189 the drain pressure. The high-pressure selection valve 29 transmits the drain pressure of the communication passage 196 or the communication passage 189 to LR / B5. As described above, as shown in FIG. 3, H / C2 and 2-4 / B3 are engaged, and L / C4 and LR / B5 are released.

In this way, during normal non-shifting, the hydraulic pressure in the communication passage 176 does not exceed the third fixed value and the fail-safe operation is not performed by the third fail-safe valve 25, so the desired friction element is engaged. Or it can be released.

Secondly, the operation during shifting will be described.
When the downshift to the 1st speed and the upshift from the 1st speed are excluded during gear shifting, the operation control solenoid valve 36 is
The energization of the solenoid 36a is turned on by the command of the CU, and the modulated pressure in the communication passage 180 is applied to the communication passage 181 as an output pressure. By receiving the modulation pressure from the communication passage 181, the third fail-safe valve 25 is connected to the communication passage 1
Communication of the communication passage 169 with respect to 70 and the drain passage 19
The second non-communication state can be maintained regardless of whether the hydraulic pressure in the communication passage 176 is high or low. That is, the fail-safe operation of the third fail-safe valve 25 can be prohibited.

Under this condition, if the control condition of the hydraulic pressure applied to each friction element is severe, for example, at an extremely low temperature or an extremely low vehicle speed, EC
When U judges, the duty solenoid valves 12, 18,
22 increases each command pressure according to a command from the ECU, and adjusts the output pressure of the clutch pressure control valves 10, 16 and 20 to the engagement hydraulic pressure.

Then, since the first fail-safe valve 23 receives the output engagement hydraulic pressure of the clutch pressure control valve 10 from the communication passage 172, it is determined that the hydraulic pressure applied to the H / C2 exceeds the first fixed value, The output engagement hydraulic pressure of the clutch pressure control valve 20 received from the communication passage 173 is applied to the communication passage 174. Since the second fail-safe valve 24 receives the output engagement hydraulic pressure of the clutch pressure control valve 16 from the communication passage 175, it is determined that the hydraulic pressure applied to 2-4 / B3 exceeds the second fixed value, and the communication passage 174. The engagement hydraulic pressure received from the above is applied to the communication passage 176. However, in the third fail-safe valve 25, the communication passage 17
Since the fail-safe operation is prohibited even when the hydraulic pressure of No. 6 becomes the above-mentioned engaging hydraulic pressure applied to L / C4, the output engaging hydraulic pressure of the clutch pressure control valve 16 received from the communication passage 169 is 2-4.
/ B3. From the above, H / C2, 2-4 /
B3 and L / C4 are simultaneously engaged. At this time, the fourth fail-safe valve 30 and the high pressure selection valve 29 are set to the above-mentioned 4
Since LR / B5 operates in the same manner as in the case of holding speed, LR / B5 is released.

The time for which the friction elements 2, 3, 4 are simultaneously engaged is set to, for example, about 0.5 seconds. Further, the fail-safe operation of the third fail-safe valve 25 may be prohibited only at least while the friction elements 2, 3, 4 are simultaneously engaged, and for example, only when the above-mentioned simultaneous engagement is prohibited. Alternatively, the switching may be prohibited from the start of the shift of the shift speed to the end of the shift. In the latter case, E
The control content of the operation control solenoid valve 36 by the CU can be simplified.

When the ECU judges that the control conditions of the hydraulic pressure applied to each friction element are strict during the normal gear shift, the fail-safe operation of the third fail-safe valve 25 is prohibited and the three friction elements 2, 3 are used. Since 4 and 4 are engaged simultaneously at the same time, it is possible to improve the shift performance such as the shift shock suppression property and the speed change response.

[Operation in Abnormal State] Next, the operation in an abnormal state in which at least one of the duty solenoid valves 12, 18, and 22 cannot be controlled by the ECU will be described. EC
When U detects the above-mentioned abnormality, it stops the shift command when shifting and shifts to the non-shifting state. During shifting, after shifting to the shifting state, and during non-shifting, the operation control solenoid valve 36 turns off the energization of the solenoid 36a according to a command from the ECU, and the drain pressure of the drain passage 194 is applied to the communication passage 181 as output pressure. To do. By receiving the drain pressure from the communication passage 181, the third fail-safe valve 25 is brought into a state capable of fail-safe operation.

Further, during shifting, after the shift to the above shifting state, and during non-shifting, the duty solenoid valves 12, 18,
Even if any of 22 becomes uncontrollable, the clutch pressure control valve 10, 1 corresponding to the solenoid valve that becomes uncontrollable
Energization to all of the duty solenoid valves 12, 18, 22 is stopped by a command from the ECU so that the output pressure of the solenoid valves 6 and 20 becomes the engagement hydraulic pressure, and the command pressure of the solenoid valve 44 is transformed to change the line pressure control valve. At 42, the line pressure of the communication passage 100 is increased. At this time, the clutch pressure control valve 10, 1 corresponding to a normal solenoid valve among the duty solenoid valves 12, 18, 22
In Nos. 6 and 20, the output pressure is limited to the engagement hydraulic pressure by the feedback use of the output pressure although the line pressure of the original pressure increases.

As a result of the above operation, the first fail-safe valve 23 transfers the output engagement hydraulic pressure of the clutch pressure control valve 10 to the communication passage 1.
Since it is received from 72, it is determined that the hydraulic pressure applied to H / C2 exceeds the first fixed value, and the output engagement hydraulic pressure of the clutch pressure control valve 20 received from the communication passage 173 is applied to the communication passage 174. The second fail-safe valve 24 is the clutch pressure control valve 1
Since the output engagement hydraulic pressure of No. 6 is received from the communication passage 175,
It is determined that the hydraulic pressure applied to 4 / B3 exceeds the second fixed value, and the engaging hydraulic pressure received from the communication passage 174 is applied to the communication passage 17
6 is applied. The third fail-safe valve 25 determines that the hydraulic pressure of the communication passage 176, that is, the hydraulic pressure applied to the L / C 4 exceeds the third fixed value, and thus the non-communication of the communication passage 169 with respect to the communication passage 170 and the drain passage 192. Realize the communication state. As a result, the hydraulic pressure in the communication passage 170 is set to the drain pressure, and the output engagement hydraulic pressure of the clutch pressure control valve 16 becomes 2
-4 / B3 is no longer applied. That is, the fail-safe operation is performed by the third fail-safe valve 25. As described above, since H / C2 and L / C4 are engaged, 2-4 / B3 is released, engagement of the three friction elements 2, 3, 4 can be prevented.

At this time, the fourth fail-safe valve 30 and the high-pressure selection valve 29 operate in the same manner as in the case of holding the third speed in the normal state described above, so that the LR / B5 is released. Therefore, in this embodiment, the friction elements 2, 3, 4, 5 are
Engagement of more than two of them can also be prevented.

According to the hydraulic control system of the first embodiment described above, the first, second and third fail safe valves 23, 2 are provided.
The determinations at 4 and 25 are based on the first, second and third fixed values that are absolute values. Therefore, it is possible to suppress a determination error due to factors such as a change in the oil temperature and a manufacturing variation of the hydraulic circuit, so that erroneous determination is reduced.

According to the hydraulic control system of the first embodiment,
The judgment at each fail-safe valve 23, 24, 25 is carried out without referring to the line pressure. Further, the operation control solenoid valve 36 is arranged so as to allow the fail-safe operation of the third fail-safe valve 25 when an abnormality occurs.
The hydraulic pressure output to is set to the drain pressure that is not affected by the line pressure. Therefore, the fail-safe operation of the third fail-safe valve 25 can be correctly performed even if the line pressure is increased in the abnormal state.

Further, according to the hydraulic control system of the first embodiment, by controlling the output pressure of the operation control solenoid valve 36, it is possible to control the permission / prohibition of the fail-safe operation of the third fail-safe valve 25 with high accuracy. .

(Second Embodiment) FIG. 4 shows an automatic transmission hydraulic control device according to a second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals. According to the second embodiment, the duty solenoid valve 28 also has the function of the operation control solenoid valve 36 used in the first embodiment. That is, in the present embodiment, the duty solenoid valve 28 constitutes the "operation control solenoid valve" described in the claims, and the LR / B5 in which the applied hydraulic pressure is controlled by the duty solenoid valve 28 is described in the claims. It constitutes "a friction element different from the first friction element, the second friction element and the third friction element".

The communication passage 165 for transmitting the command pressure of the duty solenoid valve 28 is branched to form a communication passage 200.
A third fail-safe valve 25 ′ corresponding to the third fail-safe valve 25 of the first embodiment is connected to the communication passage 200. The duty solenoid valve 28 can transform the output command pressure into an arbitrary pressure between the drain pressure transmitted from the drain passage 201 and the modulated pressure transmitted from the communication passage 153 according to the duty ratio input from the ECU. Therefore, in this embodiment, by utilizing this function, the drain pressure or the modulation pressure, which is the output pressure from the duty solenoid valve 28 to the third fail-safe valve 25 ', can be transmitted through the communication passage 200.

In the third fail-safe valve 25 ', the force due to the transmission command pressure in the communication passage 200 acts on the spool in the same direction as the urging force of the spring 25a and in the opposite direction to the force due to the transmission oil pressure in the communication passage 176. ing. Therefore, in the third fail-safe valve 25 ', the duty solenoid valve 28
The spool moves in accordance with the balance between the force due to the command pressure and the urging force of the spring 25a and the force due to the hydraulic pressure transmitted through the communication passage 176.

The spool of the third fail-safe valve 25 'is connected to the communication passage 170 when the command pressure of the duty solenoid valve 28 is the drain pressure on the low pressure side and the transmission hydraulic pressure of the communication passage 176 exceeds the third fixed value. The passage 169 is cut off and the drain passage 192 is moved to a position where it is communicated. As a result, the third fail-safe valve 25 'sets the hydraulic pressure in the communication passage 170 to the drain pressure. In addition, the duty solenoid valve 2
When the command pressure of No. 8 is the drain pressure and the transmitted hydraulic pressure of the communication passage 176 is less than or equal to the third fixed value, or when the command pressure of the duty solenoid valve 28 is the high-pressure side modulated pressure, the third fail-safe valve 25 ′. The spool has a communication passage 170
To the drain passage 192 and the communication passage 169
Move to the position to communicate. As a result, the third fail-safe valve 25 'receives 2-4 / B from the communication passage 169.
The hydraulic pressure applied to No. 3 is transmitted to the communication passage 170. In the third fail-safe valve 25 'according to the first embodiment, the non-communication / communication state of the passage when the command pressure of the duty solenoid valve 28 becomes the modulated pressure does not depend on the hydraulic pressure of the communication passage 176. Make it sustainable. Further, the third fixed value of this embodiment is also set to a pressure value lower than the engaging hydraulic pressure required to hold and hold the L / C4 and higher than the drain pressure necessary to hold and release the L / C4. It

Next, the hydraulic control operation of the hydraulic control system of the second embodiment will be described. [Normal operation] First, the duty solenoid valves 12, 18, 2
The operation of the normal operation in which 2 can be controlled will be described. In the following, the case where the D range is selected by the shift lever is taken as an example, and the description will be made separately for non-shifting and shifting.

Duty solenoid valve 28 during non-shifting
Applies the drain pressure of the drain passage 201 to the communication passages 165 and 200 as a command pressure according to a command from the ECU. The third fail-safe valve 25 ′ that has received the drain pressure from the communication passage 200 is in the communication state of the communication passage 169 with respect to the communication passage 170 and the non-communication state of the drain passage 192 as long as the hydraulic pressure of the communication passage 176 does not exceed the third fixed value. Can be maintained. Also,
The clutch pressure control valve 26 receiving the drain pressure from the communication passage 165 outputs the drain pressure. Therefore, in the second embodiment, even when the gear stage is held at any of the first speed to the fourth speed,
Each fail-safe valve 23, 24, 2 according to the first embodiment
5 ', 30 is activated. Therefore, during normal non-shifting, the hydraulic pressure in the communication passage 176 does not exceed the third fixed value and the third fail-safe valve 25 ′ does not perform fail-safe operation, so that a desired friction element can be engaged or released. it can.

On the other hand, when the downshift to the 1st speed and the upshift from the 1st speed are excluded during the shift, the duty solenoid valve 28 uses the modulating pressure of the communicating path 153 as the command pressure according to the command of the ECU. , 200. By receiving the modulated pressure from the communication passage 200, the third fail-safe valve 25 ′ can maintain the communication of the communication passage 169 with respect to the communication passage 170 and the non-communication state of the drain passage 192 regardless of the hydraulic pressure of the communication passage 176. . That is, the fail-safe operation of the third fail-safe valve 25 'can be prohibited. Further, the clutch pressure control valve 26 that receives the modulation pressure from the communication passage 165 is
The engagement hydraulic pressure applied to B5 is output.

In this state, when the ECU determines that the control condition of the hydraulic pressure applied to each friction element is severe, the duty solenoid valves 12, 18, 22 are controlled by the ECU according to the first embodiment.
Command to adjust the output pressure of the clutch pressure control valves 10, 16 and 20 to the engagement hydraulic pressure. Then, similarly to the case of the first embodiment, the hydraulic pressure of the communication passage 176 exceeds L which is the third fixed value.
/ C4, the fail-safe operation is prohibited by the third fail-safe valve 25 ', so that the output engagement oil pressure of the clutch pressure control valve 16 received from the communication passage 169 is 2-4. / B3. Therefore, H / C2, 2-4 / B3 and L / C4 are simultaneously engaged. In this way, when the ECU determines that the control conditions of the hydraulic pressure applied to each friction element are strict when shifting normally, the fail-safe operation of the third fail-safe valve 25 'is prohibited, and the three friction elements 2, 3, 4 are used. The gears are instantaneously engaged at the same time, so that the gear shifting performance can be improved.

By the way, as described above, the friction element 2,
At the time of a gear shift in which 3 and 4 are instantaneously engaged simultaneously, at least one of the hydraulic pressure applied to H / C2 and the hydraulic pressure applied to 2-4 / B3 is compatible between the start and the end of switching of the shift speed. Exceeds the fourth fixed value or the fifth fixed value. Therefore, during the period from the start of switching the shift speed to the end of switching, the hydraulic pressure of the communication passage 189 is set to the drain pressure by the fourth fail-safe valve 30, and the drain pressure of the communication passage 196 or the communication passage 189 is set by the high pressure selection valve 29. Is LR / B5
Be transmitted to. Therefore, as described above, the third fail-safe valve 2 is operated from the start of switching the shift speed to the end of the switching.
When the duty solenoid valve 28 is operated so as to inhibit the failsafe operation of 5 ′, the fourth failsafe valve 30 is activated even though the hydraulic pressure output by the clutch pressure control valve 26 becomes the engaging hydraulic pressure in the communication passage 188. With the operation of, the shift control can be executed with the LR / B5 released.

[Operation in Abnormal State] Next, the operation in an abnormal state in which at least one of the duty solenoid valves 12, 18, and 22 cannot be controlled by the ECU will be described. In this case, the duty solenoid valve 28 receives a command from the ECU after shifting to the shift state by the ECU at the time of gear shift, and applies the drain pressure of the drain passage 201 to the communication passages 165, 200 as a command pressure. By receiving the drain pressure from the communication passage 200, the third fail-safe valve 25 '
Is in a state where the fail safe operation is possible.

Further, after shifting to the above-mentioned shift state at the time of shifting, and at the time of non-shifting, in accordance with the first embodiment, energization of the duty solenoid valves 12, 18, 22 is stopped by the command of the ECU, and the solenoid valve 44 is stopped. The command pressure is transformed and the line pressure control valve 42 increases the line pressure in the communication passage 100. As a result, all the output pressures of the clutch pressure control valves 10, 16 and 20 are set to the engagement hydraulic pressure. At this time, since the duty solenoid valve 28 holds the command pressure at the drain pressure, the output pressure of the clutch pressure control valve 26 is set to the drain pressure.

As a result of the above operation, each fail-safe valve 2
3, 24 and 25 'perform the operation according to the first embodiment. That is, the first fail-safe valve 23, which determines that the hydraulic pressure applied to the H / C 2 exceeds the first fixed value, applies the output engagement hydraulic pressure of the clutch pressure control valve 20 to the communication passage 174,
The second fail-safe valve 24, which determines that the hydraulic pressure applied to 4 / B3 exceeds the second fixed value, applies the engaging hydraulic pressure of the communication passage 174 to the communication passage 176. Then, the third fail-safe valve 25 ', which has determined that the hydraulic pressure applied to the L / C4, which is the hydraulic pressure of the communication passage 176, exceeds the third fixed value, sets the hydraulic pressure of the communication passage 170 to the drain pressure, and the clutch pressure. The transmission of the engagement hydraulic pressure from the control valve 16 to 2-4 / B3 is prohibited. That is, the third fail-safe valve 25 'performs the fail-safe operation. From the above, H / C2 and L / C
4 is engaged, while 2-4 / B3 is released,
The engagement of the three friction elements 2, 3, 4 can be prevented.

Further, according to the first embodiment, the fourth fail-safe valve 30, which determines that the hydraulic pressure applied to the H / C2 exceeds the fourth fixed value, sets the hydraulic pressure in the communication passage 189 to the drain pressure. The high-pressure selection valve 29 transmits the drain pressure of the communication passage 196 or the communication passage 189 to LR / B5. Therefore, also according to the second embodiment, engagement of three or more of the friction elements 2, 3, 4, 5 can be prevented.

According to the hydraulic control system of the second embodiment described above, the third fail-safe valve 25 'makes a determination with the third fixed value, which is an absolute value, as a reference, so that there is little erroneous determination. Further, according to the hydraulic control system of the second embodiment, the third fail-safe valve 25 'makes a determination without referring to the line pressure, and when an abnormality occurs, the duty solenoid valve 28 causes the fail-safe valve of the third fail-safe valve 25' to fail-safe. In order to allow the operation, the drain pressure that is not affected by the line pressure is applied as a command pressure to the third fail-safe valve 25 '. Therefore, the third fail-safe valve 25 'can accurately perform the fail-safe operation even if the line pressure is increased at the time of abnormality.

Further, according to the hydraulic control system of the second embodiment, by controlling the command pressure by the duty solenoid valve 28, it is possible to control with high accuracy whether or not the fail-safe operation is to be performed in the third fail-safe valve 25 '. .

In the above-described plurality of embodiments, H /
C2, 2-4 / B3, and L / C4 constituted the first, second, and third friction elements, respectively, but the first, second, and third friction elements were each a plurality of friction elements. A suitable one can be selected. For example, the first, second and third friction elements may be H / C2, L / C4 and 2 respectively.
-4 / B3, or the first, second and third friction elements are L / C4, 2-4 / B3 and H / C2 respectively.
It may be set to.

Further, in the above embodiments, the third fail-safe valves 25, 25 'as the third fail-safe means.
The target of pressure regulation was the hydraulic pressure applied to the second friction element 2-4 / B3. On the other hand, the pressure adjustment target of the third fail-safe means may be set to the hydraulic pressure applied to the first friction element or the third friction element (H / C2 or L / C4 in the above embodiment).

Further, in the above-described embodiments, in the second fail-safe valve 24 as the second fail-safe means, the judgment is made based on the hydraulic pressure applied to the second friction element 2-4 / B3. Further, in the above-described embodiments, the third fail-safe valve 2 as the third fail-safe means is used.
5, 25 ', the first fail-safe valve 23 to the second fail-safe valve 2 as the first fail-safe means.
The determination was made based on the hydraulic pressure applied to the third friction element L / C4 which was transmitted to the No. 4 and further transmitted from the second fail-safe valve 24. On the other hand, for example, a modification of the first embodiment may be shown in FIG. That is, in the second fail-safe means (second fail-safe valve) 24 ″, the hydraulic pressure applied to the third friction element (L / C) 4 transmitted from the first fail-safe means (first fail-safe valve) 23. The third fail-safe means (third fail-safe valve) 25 ″ is applied to the second friction element (2-4 / B) 3 transmitted from the second fail-safe means 24 ″. The determination may be made based on the hydraulic pressure.

Furthermore, in the second embodiment, the duty solenoid valve 28 for controlling the hydraulic pressure applied to the LR / B 5 also functions as the operation control solenoid valve in the hydraulic control apparatus for the automatic transmission of the fourth forward speed. A solenoid valve for controlling the hydraulic pressure applied to other friction elements may be used as the operation control solenoid valve depending on the configuration of the above, or a solenoid valve for controlling the hydraulic pressure applied to other constituent elements than the friction element. May be used as the operation control solenoid valve.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a main part of a hydraulic control device for an automatic transmission according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a hydraulic control device for an automatic transmission according to a first embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the friction element of the hydraulic control device for an automatic transmission according to the first and second embodiments of the present invention.

FIG. 4 is a hydraulic circuit diagram showing a hydraulic control device for an automatic transmission according to a second embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram for explaining a modified example of the hydraulic control device for an automatic transmission according to the first embodiment of the present invention.

[Explanation of symbols]

2 H / C (first friction element) 3 2-4 / B (second friction element) 4 L / C (third friction element) 5 LR / B (another friction element) 23 First fail-safe valve (first One fail-safe means) 24, 24 '' Second fail-safe valve (second fail-safe means) 25, 25 ', 25''Third fail-safe valve (third fail-safe means) 28 Duty solenoid valve (operation control solenoid) 30) Fourth fail-safe valve 36 Operation control solenoid valve

Claims (7)

[Claims] 1. An automatic transmission control device for controlling engagement and disengagement of a plurality of friction elements including a first friction element, a second friction element and a third friction element by hydraulic pressure of a working fluid to switch a gear stage. And a first fail-safe means, a second fail-safe means and a third fail-safe means, wherein the first fail-safe means has a hydraulic pressure applied to the first friction element exceeding a first fixed value. At this time, the hydraulic pressure applied to the third friction element is transmitted to the second failsafe means, and the second failsafe means is transmitted from the hydraulic pressure applied to the second friction element and the first failsafe means. When one of the predetermined hydraulic pressures exceeds a second fixed value, the hydraulic pressure applied to the second friction element and the hydraulic pressure transmitted from the first fail-safe means are preset. Decided Transmitted to the third fail-safe means, the third fail-safe means, when the hydraulic pressure transmitted from the second fail-safe means exceeds a third fixed value, the first friction An automatic transmission control device, characterized by performing a fail-safe operation for adjusting a hydraulic pressure applied to any one of the element, the second friction element and the third friction element to a pressure necessary for releasing. 2. The first friction element, the second friction element, and the third friction element are respectively engaged with at least two stages of forward high speed side friction elements, and at least one stage of low forward speed side and high forward speed side. The friction element to be engaged in one step and the friction element to be engaged in at least two steps on the forward low speed side and one step on the high forward speed side do not overlap, and the third fail-safe means controls the applied hydraulic pressure. The automatic transmission control device according to claim 1, wherein the frictional element to be pressure-adjusted is a frictional element that is engaged at least in the first lower speed side and the first higher speed side. 3. An operation control solenoid valve for inhibiting the failsafe operation of the third failsafe means by transforming the output pressure applied to the third failsafe means by electromagnetic control. Claim 1
Alternatively, the automatic transmission control device described in 2. 4. An automatic transmission control device for controlling engagement and disengagement of a plurality of friction elements including a first friction element, a second friction element and a third friction element by hydraulic pressure of a working fluid, and switching gear stages. And when the hydraulic pressure applied to the first friction element, the hydraulic pressure applied to the second friction element, and the hydraulic pressure applied to the third friction element are all pressures necessary for engagement Fail-safe means for performing fail-safe operation for adjusting the hydraulic pressure applied to any one of the first friction element, the second friction element, and the third friction element to a pressure necessary for releasing, and the fail-safe. And an operation control solenoid valve for inhibiting the fail-safe operation of the fail-safe means by transforming the output pressure applied to the means by electromagnetic control. 5. The automatic transmission control device according to claim 3, wherein the operation control solenoid valve prohibits the fail-safe operation during gear shifting. 6. A solenoid valve for controlling a hydraulic pressure applied to a friction element different from the first friction element, the second friction element and the third friction element among the plurality of friction elements is an operation control electromagnetic valve. The automatic transmission control device according to claim 3, 4 or 5, which also functions as a valve. 7. The solenoid valve according to claim 6, wherein the operation control solenoid valve is an solenoid valve that controls hydraulic pressure applied to at least a friction element that is engaged in a reverse stage and engageable in a forward stage. Automatic transmission control device.