JP2005163916A - Oil pressure control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a switching operation of a fail-safe valve preventing interlock of a gear shift mechanism in failure of a solenoid. <P>SOLUTION: In this oil pressure control device for an automatic transmission having at least three engagement elements C-3, B-1, C-4 and being tied up when two of them are engaged with each other, the fail-safe valves are respectively mounted between a hydraulic servo 53, 55, 54 of each engagement element and an oil pressure source 20, the supply and cutoff of oil pressure to the hydraulic servos 53, 55 of the first fail-safe valve 43 and the second fail-safe valve 45 are switched by a first solenoid valve 36 and a second solenoid valve 37 respectively mounted corresponding thereto, and the third fail-safe valve 44 can be switched by a third fail-save valve switching oil pressure applied through both of the first fail-safe valve and the second fail-safe valve. Thereby the fail-safe valves can be surely switched by solenoid valves less than the number of the fail valves. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an automatic transmission mounted on a vehicle, and more particularly to a hydraulic control device that controls an engagement element in the transmission mechanism.

In an automatic transmission mounted on a vehicle, a hydraulic control device that controls the transmission mechanism includes a solenoid-operated control valve inserted in each supply oil passage from a hydraulic source to a hydraulic servo of each engagement element. By adopting a circuit configuration that controls the supply of hydraulic pressure to the hydraulic servo by actuating according to the control mechanism, the speed change mechanism is based on the failure of each control valve or the failure of each control valve itself (usually stick failure) In order to cope with this interlock, a fail-safe shut-off valve composed of a switching valve is disposed in the oil passage upstream of each control valve. These fail-safe valves are usually operated by applying the hydraulic pressure of each fail-safe valve in a superimposed manner in order to detect a combination of supply states that are interlocked from the hydraulic pressure supply relationship between the supply oil passages. is there. As an example of adopting such a circuit configuration, there are conventional techniques disclosed in Patent Document 1 and Patent Document 2.
Japanese Patent No. 2715420 Japanese Patent No. 2839937

  By the way, in the prior art, since the pressure-receiving area difference is set in the fail-safe valve and the switching is performed using the relationship between the signal pressure applied to the spool and the area, the tie-up is performed when simultaneously engaged. At the time of gear shifting by changing the combination of the combination elements, it is necessary to prevent the fail-safe valve from switching during the gear shifting due to the hydraulic balance of the fail-safe valve, resulting in poor controllability.

  Accordingly, the present invention provides a hydraulic control device for an automatic transmission that includes a fail-safe valve that avoids interlocking of the transmission mechanism due to tie-up of an engagement element, and ensures the switching operation of the fail-safe valve and also provides a shift controllability. The general purpose is to improve Furthermore, an object of the present invention is to enable the switching operation of the fail-safe valve with fewer solenoid valves.

In order to achieve the above object, the present invention has at least three engaging elements (C-3, B-1, C-4), and any two of the three engaging elements are engaged. In the hydraulic control device for an automatic transmission that ties up, a fail-safe valve is disposed between the hydraulic servo (53, 55, 54) and the hydraulic source (20) of each engagement element, Of these, the first fail-safe valve (43) and the second fail-safe valve (45) are a first solenoid valve which is arranged to supply and shut off the hydraulic pressure to the hydraulic servo (53, 55) by them. (36) and the second solenoid valve (37), respectively, and the third failsafe valve (44) is a third failsafe applied via both the first failsafe valve and the second failsafe valve. Characterized in that it is a switching mechanism by off valve switching hydraulic pressure.
More specifically, the third fail-safe valve switching hydraulic pressure is applied to the third fail-safe valve when both the first fail-safe valve and the second fail-safe valve are in a hydraulic pressure supply state, The third fail-safe valve is switched to a hydraulic pressure supply state, and in a shift transient state, the first fail-safe valve and the second fail-safe valve are brought into a hydraulic pressure supply state by the first solenoid valve and the second solenoid valve. When the fail-safe valve is also in a hydraulic pressure supply state and the shift is completed, the settings of the first solenoid valve and the second solenoid valve are returned to the settings for achieving the shift stage. The third fail-safe valve is switched to a hydraulic pressure supply state by a hydraulic pressure applied when both the first fail-safe valve and the second fail-safe valve are in a hydraulic pressure cut-off state.
The automatic transmission is always engaged with a fourth engagement element (C-1) that is always engaged to achieve each gear position on the low speed stage side and each gear stage on the high speed stage side. A fifth engagement element (C-2), and each shift stage is achieved by simultaneous engagement of these engagement elements or any one of these engagement elements and any of the three engagement elements. It is effective.

According to the present invention, the hydraulic pressure supplied to the engaging element that ties up when the fail-safe valves are simultaneously engaged is not switched as a signal pressure by a delicate hydraulic balance, but is switched on and off by a switching solenoid valve. Since it did in this way, switching of a fail safe valve becomes reliable, for example, the malfunction of the fail safe valve in the state where the applicability of the oil_pressure | hydraulic at the time of a very low oil temperature is bad can be prevented. In addition, since the operation state of other fail-safe valves can be switched by a combination of solenoid valve operations without simply providing a switching solenoid valve for each fail-safe valve, the number of installed solenoid valves can be reduced. it can.
Further, in the configuration in which the fail-safe valve is switched by using the hydraulic pressure supplied to the engaging element that ties up when simultaneously engaged as a signal pressure, the fail-safe valve at the time of shifting by re-holding the set of engaging elements that tie up when simultaneously engaged. The fail-safe valve needs to be prevented from switching during the gear shifting due to the hydraulic balance of the engine, so the controllability is poor, but the solenoid valve setting is changed between the gear shifting transient state and the gear shifting end state. For example, in the shift transition state in which the engagement element is changed, all the engagement elements can be set to the hydraulic pressure supply state, so that the controllability at the time of the change is improved. Further, in the configuration in which the third fail-safe valve is switched to the hydraulic pressure supply state by the hydraulic pressure supplied when the first fail-safe valve and the second fail-safe valve are in the hydraulic cutoff state, the first and second fail-safe valves The hydraulic pressure can be supplied to the engagement element that is hydraulically supplied via the third fail-safe valve without setting both of the engagement elements that are hydraulically supplied via the third fail-safe valve. Tie-up can be reliably prevented.

  The automatic transmission according to the application of the present invention is preferably a transmission mechanism in which two engagement elements are selectively engaged at the same time in order to achieve all the shift stages. A clutch or a brake in which another engagement element is selectively simultaneously engaged with the input clutch as the fourth engagement element or the fifth engagement element that is maintained in engagement across the other. A transmission mechanism is suitable for application of the present invention. As a result, tie-up of a multi-stage transmission that requires a large number of engagement elements can be prevented with a small number of fail-safe valves.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a skeleton of a gear train of an automatic transmission of 8 forward speeds and 1 reverse speed as one application object of the present invention. As shown in the figure, this automatic transmission is a vertical type for a front engine and a rear drive, and includes a torque converter 2 with a lock-up clutch and a planetary gear transmission 1.

  The planetary gear transmission 1 includes a Ravigneaux type planetary gear unit G and a speed reduction planetary gear G1 that inputs speed reduction rotation to the planetary gear unit G. The planetary gear unit G includes a large-diameter sun gear S2, a small-diameter sun gear S3, a short pinion P3 that meshes with each other and meshes with the small-diameter sun gear S3, a long pinion P2 that meshes with the large-diameter sun gear S2, and a pair of them. It comprises a carrier C3 that supports the pinion and a ring gear R3 that meshes with the long pinion P2. The reduction planetary gear G1 includes a sun gear S1, a pinion P1 meshing with the sun gear S1, a pinion P1 ′ meshing with the pinion P1, a carrier C1 supporting both the pinions P1 and P1 ′, and a ring gear R1 meshing with the pinion P1 ′. It consists of a double pinion planetary gear consisting of three elements.

  The small-diameter sun gear S3 in the planetary gear unit G is connected to the ring gear R1 of the reduction planetary gear G1 by a first clutch C-1 (hereinafter abbreviated as C1 clutch). The large-diameter sun gear S2 is connected to the ring gear R1 of the reduction planetary gear G1 by a third clutch C-3 (hereinafter abbreviated as C3 clutch), and a fourth clutch C-4 (hereinafter referred to as C4 clutch). It is connected to the carrier C1 of the reduction planetary gear G1 by abbreviation) and can be locked to the case 10 by a first brake B-1 (hereinafter abbreviated as B1 brake). Further, the carrier C3 is connected to the input shaft 11 by a second clutch C-2 (hereinafter abbreviated as C2 clutch), and a case by a second brake B-2 (hereinafter abbreviated as B2 brake). 10 can be locked to the case 10 by a one-way clutch F-1 arranged in parallel with the B2 brake. The ring gear R3 is connected to the output shaft 19. The reduction planetary gear G1 has its sun gear S1 fixed to the transmission case 10, the carrier C1 is connected to the input shaft 11, and is connected to the large-diameter sun gear S2 of the planetary gear unit G via the C4 clutch, and the ring gear R1 is connected to the C1 clutch. Is connected to the small-diameter sun gear S3 of the planetary gear unit G through the C3, and is connected to the large-diameter sun gear S2 of the planetary gear unit G through the C3 clutch.

  As described above, each of the clutches and brakes of the planetary gear transmission 1 configured as described above includes a hydraulic servo including a friction member and a piston / cylinder mechanism that engages / releases them. The control by the electronic control device and the hydraulic control device which will be described later is applied to each hydraulic servo by the hydraulic control device attached to the transmission case 10 based on the vehicle load in the speed range corresponding to the range selected by the driver. The friction member is engaged / released by the supply / discharge of hydraulic pressure, and the speed is changed.

  FIG. 2 is a speed diagram illustrating the operation of the planetary gear transmission 1 by engaging and releasing the clutches and brakes and the one-way clutch. In this speed diagram, the vertical axis indicates each shift element described above them, the gear ratio is indicated by the mutual width between the vertical axes, and the input rotational speed to the planetary gear transmission 1 is indicated by the length in the vertical axis direction. A speed ratio of 1 is shown. In the figure, the mark ● represents the engagement of the engagement element immediately indicated, and the mark ○ represents the output rotational speed ratio of the planetary gear transmission 1.

  In this gear train, in the present embodiment, the shift stage on the low speed stage, which is the first to fourth speeds, is based on the input of the reduced speed rotation to the small-diameter sun gear S3 by the engagement of the C1 clutch as the fourth engagement element. This is achieved by selectively simultaneously engaging any of the other three engagement elements. That is, the first speed (1ST) is achieved by automatic engagement of the one-way clutch F-1 corresponding to the engagement of the B2 brake. In this case, referring to FIG. 1, the rotation decelerated from the input shaft 11 via the reduction planetary gear G1 is input to the small-diameter sun gear S3 via the C1 clutch and is locked by the engagement of the one-way clutch F-1. As shown in FIG. 2, the reduced rotation with the maximum gear ratio of the ring gear R 3 is output to the output shaft 19.

  Next, the second speed (2ND) is achieved by simultaneous engagement of the B1 brake. In this case, referring to FIG. 1, the rotation reduced from the input shaft 11 via the reduction planetary gear G1 is input to the small-diameter sun gear S3 via the C1 clutch, and is applied to the large-diameter sun gear S2 locked by the engagement of the B1 brake. Taking the reaction force, the reduced rotation of the ring gear R3 is output to the output shaft 19. The reduction ratio at this time is smaller than the first speed (1ST) as shown in FIG.

  The third speed (3RD) is achieved by simultaneous engagement of the C3 clutch. In this case, referring to FIG. 1, the rotation reduced from input shaft 11 via reduction planetary gear G1 is simultaneously input to large-diameter sun gear S2 and small-diameter sun gear S3 via C1 clutch and C3 clutch, and planetary gear unit G is directly connected. Therefore, the rotation of the ring gear R3 having the same speed as the input rotation to both sun gears is output from the ring gear R3 as a reduced rotation with respect to the input rotation (speed ratio = 1) as shown in FIG.

  Further, the fourth speed (4TH) is achieved by simultaneous engagement of the C4 clutch. In this case, referring to FIG. 1, the rotation decelerated from the input shaft 11 via the reduction planetary gear G1 is input to the small-diameter sun gear S3 via the C1 clutch, and is input from the input shaft 11 via the C4 clutch on the other hand. The non-decelerated rotation is input to the large-diameter sun gear S2, and the rotation of the intermediate speed of the two input rotations is the rotation of the ring gear R3 slightly increased with respect to the decelerated rotation of the planetary gear for deceleration as shown in FIG. Is output.

  Next, the speed stage on the high speed side, which is the fifth to eighth speeds in this embodiment, is based on the input of non-decelerated rotation to the carrier C3 due to the engagement of the C2 clutch as the fifth engagement element. This is achieved by selectively simultaneously engaging any one of the three engaging elements. That is, the fifth speed (5TH) is achieved by simultaneous engagement of the C1 clutch. In this case, referring to FIG. 1, the rotation decelerated from the input shaft 11 via the reduction planetary gear G1 is input to the small-diameter sun gear S3 via the C1 clutch, and is input from the input shaft 11 via the C2 clutch on the other hand. The non-decelerated rotation is input to the carrier C3, and the rotation at the intermediate speed between the two input rotations is output as the rotation of the ring gear R3 slightly decelerated with respect to the non-decelerated input rotation as shown in FIG.

  Next, the sixth speed (6TH) is achieved by simultaneous engagement of the C4 clutch. In this case, referring to FIG. 1, non-decelerated rotation input from the input shaft 11 via the C4 clutch is input to the large-diameter sun gear S2, and on the other hand, non-decelerated input from the input shaft 11 via the C2 clutch. Since the rotation is input to the carrier C3 and the planetary gear unit G is directly connected, the rotation of the ring gear R3 at the same speed as the input rotation to the sun gear S2 and the carrier C3 is the input rotation (speed ratio = 1) as shown in FIG. ) Is output to the ring gear R3.

  Further, the seventh speed (7TH) is achieved by simultaneous engagement of the C3 clutch. In this case, referring to FIG. 1, the rotation reduced on the one hand from the input shaft 11 via the reduction planetary gear G1 is inputted to the large-diameter sun gear S2 via the C3 clutch, and on the other hand, inputted from the input shaft 11 via the C2 clutch. The non-decelerated rotation is input to the carrier C3, and the rotation of the ring gear R3 is output as a rotation slightly increased from the input rotation as shown in FIG.

  The eighth speed (8TH) is achieved by simultaneous engagement of the B1 brake. In this case, referring to FIG. 1, non-decelerated rotation is input from the input shaft 11 via the C2 clutch only to the carrier C3, and a reaction force is applied to the large-diameter sun gear S2 locked by the engagement of the B1 brake. The further increased rotation of the ring gear R3 as shown in FIG.

  The reverse (R) is achieved based on the engagement of the B2 brake. In this case, as another engagement element to be simultaneously engaged, either the C3 clutch or the C4 clutch can be selected according to the setting of the reverse gear ratio. When the C3 clutch is a simultaneous engagement element, referring to FIG. 1, the rotation reduced from the input shaft 11 via the reduction planetary gear G1 is input to the large-diameter sun gear S2 via the C3 clutch, and the B2 brake is engaged. A reverse rotation having a large gear ratio of the ring gear R3 taking a reaction force on the locked carrier C3 is output to the output shaft. Further, when the C4 clutch is a simultaneous engagement element, as can be seen with reference to FIG. 2, the reverse speed ratio increases in the reverse rotation direction by the amount that the rotation input to the large-diameter sun gear S2 becomes the non-deceleration rotation. However, the relationship between input and output elements is the same.

  Next, FIG. 3 shows the above-described relationship between the operation of the clutches and brakes in the planetary gear transmission 1 and the shift speed achieved thereby. In the figure, ◯ indicates engagement, and X indicates release. In this chart, a C3 clutch is used as a simultaneous engagement element during reverse (R).

  Next, in the gear train shown in FIG. 1, the configuration of the hydraulic control device for achieving each of the shift speeds shown in the operation chart of FIG. 3 will be described. FIG. 4 shows a circuit configuration of the hydraulic control device. The circuit on the hydraulic pressure source side in this hydraulic circuit adjusts the hydraulic pressure that is sucked up by the oil pump 20 as a hydraulic pressure source and discharged to the line pressure oil passage by the regulator valve 21, and is an engagement element corresponding to the running load of the vehicle. A line pressure PL required to maintain the engagement of the drive is produced, and the drive range pressure (hereinafter referred to as the D range pressure) output from the “D” range port directly or through the manual valve 25 as the control base pressure. (D) or a circuit for supplying and discharging the hydraulic servos 51 to 56 of each engagement element as a reverse pressure (R) output from the “R” port. The regulator valve 21 is configured such that both pressures are applied to both ends of the spool so that the regulator valve 21 is regulated by a line pressure regulated by itself and a signal pressure (throttle pressure) reflecting the vehicle running load. The throttle linear solenoid valve 23 that outputs the throttle pressure applies the throttle pressure to the regulator valve 21 based on the hydraulic pressure (modulator pressure) Pm that is reduced by the modulator valve 22 that is supplied with the line pressure via the strainer. ing. The modulator pressure Pm is also supplied to the lock-up linear solenoid valve 24. Based on this pressure, the lock-up linear solenoid valve 24 supplies hydraulic pressure to a lock-up circuit (not shown) and also supplies signal pressure (lock to the shift-side circuit). Up pressure).

  As shown in FIG. 4, the circuit on the speed change side supplies the hydraulic pressure supplied to each hydraulic servo except the hydraulic servos 51 to 56 for the C1 to C4 clutch and the B1 and B2 brakes and the hydraulic servo 56 for the B2 brake to the solenoid signal. Control valves 31 to 35 operated by linear solenoids SLC1 to SLC4 and SLB1 controlled by application are provided as main components of the respective supply paths. For the B2 brake, a control valve 40 that operates only by hydraulic pressure is provided. Among these control valves, the control valves 31, 32 and 34 for the C1, C2 clutch and C4 clutch are normally open valves which have a maximum output when no solenoid signal is applied, and are control valves for the C3 clutch and the B1 brake. Reference numerals 33 and 35 are normally closed valves that are closed when no solenoid signal is applied. Further, a B2 control valve 40 for controlling the supply hydraulic pressure by the circuit pressure is inserted in the supply path of the hydraulic servo 56 for the B2 brake in this circuit. Further, dedicated cut-off valves 41 to 46 are inserted as fail-safe valves in the supply paths to the hydraulic servos of the clutches and brakes. Among these cut-off valves, the C3, B1, B2 cut-off valves 43, 45, and 46 output a switching signal pressure to each cut-off valve when the solenoid signal is applied with the modulator pressure as a base pressure to be controlled by a solenoid signal. The normally-closed on / off solenoid valves 36 to 38 are provided in association therewith. Further, as another fail-safe valve, a C4 check valve 47 is disposed so as to be inserted in an oil passage connecting the fail-safe valves. A hydraulic switch 48 is also provided in the signal pressure oil passage connecting the three failsafe valves 45, 44, 42.

  To explain the circuit configuration more specifically, the supply oil path to the hydraulic servo 51 of the C1 clutch is connected to the supply oil path of the D range pressure, and the C1 cut-off valve 41 is located upstream of the C1 clutch control valve 31. Has been placed. The C1 cut-off valve 41 in the oil passage is in a hydraulic pressure supply state of any one of the C3, C4 clutch hydraulic servos 53 and 54, or the B1 brake hydraulic servo 55 and supplies hydraulic pressure to the C2 clutch hydraulic servo 52. Sometimes, it is provided to shut off the supply of the base pressure (D range pressure) to the C1 clutch control valve 31, and is composed of a three-port type spool switching valve. When communicating, the D range pressure is imported by the C1 clutch control valve. It connects to the outport to 31, and when shutting down, the import is closed and the outport is connected to the drain. A line pressure is always applied to one end (upper end in the figure) of the spool of the C1 cut-off valve 41, and hydraulic pressure is supplied to the C2 clutch hydraulic servo 52 at the other end (lower end in the figure) that receives the load of the return spring. The line pressure that is sometimes supplied via the C3, B1, and C4 cutoff valves 43, 45, and 44 is further applied via the C2 cutoff valve. Therefore, the supply of the base pressure to the C1 clutch control valve 31 is in the hydraulic supply state of any of the C3, C4 clutch hydraulic servos 53 and 54, or the B1 brake hydraulic servo 55 and to the C2 clutch hydraulic servo 52. When the hydraulic pressure is supplied, the tie-up with the C2 clutch and any of the C3 clutch, the C4 clutch, and the B1 brake at the time of the C1 clutch control valve failure (stick in the opened state or solenoid signal off-fail) is prevented.

  A supply oil path to the hydraulic servo 53 of the C3 clutch is connected to a supply oil path of the D range pressure, and a C3 cut-off valve 43 is disposed on the upstream side of the C3 clutch control valve 33. The C3 cut-off valve 43 in the oil passage is controlled by application of solenoid pressure by a normally closed on-off solenoid valve 36, and is switched by turning on the solenoid signal to supply a base pressure to the C3 clutch control valve 33. It is provided to cut off the supply by turning off the signal. This C3 cut-off valve 43 is composed of an eight-port spool type switching valve in which three three-port switching valves are combined with a common drain port, and the first to third ports (the port numbers of the respective valves are described below). For the sake of convenience, the order from the upper side of the drawing excluding the pressure receiving port to which the signal pressure is applied is assumed to be the D range pressure import, out port and drain port, respectively, and the fourth and fifth ports are also the D range. The pressure outport and import, and the sixth to eighth ports are the line pressure drain port, outport and import, respectively. The first and fifth ports are D-range pressure supply oil passages, the second and seventh ports are different imports of the B1 cut-off valve 45, the fourth port is an import of the C3 clutch control valve 33, and the eighth port is a line. Connected to pressure supply oil passage. A solenoid pressure output from the solenoid valve 36 is applied to one end (upper end in the drawing) of the spool of the C3 cut-off valve 43, and a load of a return spring is applied to the other end (lower end in the drawing).

  When the solenoid valve 36 is on, the C3 cutoff valve 43 communicates the eighth port with the seventh port, supplies the line pressure to the B1 cutoff valve 45, and communicates the fifth port with the fourth port. The D range pressure is supplied to the C3 clutch control valve 33 as a base pressure, and further, the first port is shut off and the drive range pressure to the B1 cut-off valve 45 is cut off. Further, when the solenoid valve 36 is off, the 8th port is shut off to cut off the supply of line pressure to the B1 cut-off valve 45, and the 5th port is shut off to cut off the base pressure supply to the C3 clutch control valve 33. In addition, the first port communicates with the second port to supply the D range pressure to the B1 cutoff valve.

  The supply oil path to the hydraulic servo 55 for the B1 brake is connected to the supply oil path for the D range pressure, and the B1 cut-off valve 45 is disposed upstream of the B1 brake control valve 35. The B1 cut-off valve 45 in the oil passage is controlled by application of solenoid pressure by a normally closed on-off solenoid valve 37, and is switched by the solenoid signal being turned on to supply a base pressure to the B1 brake control valve 35. It is provided to cut off the supply by turning off the signal. This B1 cutoff valve 45 is composed of a 9-port spool type switching valve that combines three 3-port switching valves with a shared drain port. The third port is an import of line pressure via the C3 cutoff valve 43. Similarly, the fifth port is the D range pressure imported via the C3 cut-off valve 43, the ninth port is the base range D range pressure imported, the second port is the out port relative to the third port, and the fourth port is the second port. The third port or the fifth port is an out port, the eighth port is a D range pressure out port for base pressure, and the remaining ports are drain ports. On the import side, the third, fifth, and eighth ports are connected to the line pressure out port, the D range pressure out port, and the D range pressure oil passage of the C3 cut-off valve 43, respectively. The port is connected to the plunger pressure receiving portion of the C4 cutoff valve 44 and the C2 cutoff valve 42, the fourth port is connected to the import of the C4 cutoff valve 44, the sixth port is connected to the C4 check valve 47, the eighth The port is connected to the import of B1 clutch control valve. A solenoid pressure output from the solenoid valve 37 is applied to one end (upper end in the drawing) of the spool of the B1 cut-off valve 45, and a load of a return spring is applied to the other end (lower end in the drawing).

  When the solenoid valve 37 is on, the B1 cut-off valve 45 communicates the ninth port with the eighth port to supply the D range pressure to the B1 brake control valve 35 as a base pressure, and the fifth port to the sixth port. The D range pressure supplied via the C3 cut-off valve 43 is supplied to the import of the C4 cut-off valve 44, and the third port is connected to the second port via the C3 cut-off valve 43. The line pressure thus supplied is applied to the plunger-spool pressure receiving portion of the C4 cut-off valve 44 and the plunger end pressure receiving portion of the C2 cut-off valve 42. Further, when the solenoid valve 37 is off, the 9th port is shut off, the base pressure supply to the B1 brake control valve 35 is cut off, the 5th port communicates with the 6th port and the D range via the C3 cut-off valve 43. Pressure is applied to the plunger end pressure receiving portion of the C4 cut-off valve 44 and the C4 check valve 47 is supplied to the import, and the third port is switched to the communication with the fourth port to import the C4 cut-off valve 44. The D range pressure supply is switched to the line pressure supply and the operation of draining the application of the signal pressure to the C4 cutoff valve 44 and the C2 cutoff valve 42 is performed.

  The supply oil path to the hydraulic servo 54 of the C4 clutch is directly connected to the supply oil path of the line pressure, and in this supply oil path, a connection in which a C4 cut-off valve 44 is inserted downstream of the C4 clutch control valve 34. It is said that. The C4 cut-off valve 44 in the oil passage is controlled by application of the D range pressure or line pressure from the B1 cut-off valve 45, whereby the hydraulic pressure after pressure regulation by the C4 clutch control valve 34 is transferred to the C4 clutch hydraulic servo. It is provided to enable supply. The C4 cut-off valve 44 is configured by a 9-port spool type switching valve, and has a pressure receiving plunger at one end of the spool. The first port of this valve is D range pressure or line pressure import, the second port is its out port, the third port is D range pressure import, the fourth and seventh ports are reverse pressure import, the fifth port is The servo pressure outport, the sixth port is the servo pressure import, the eighth port is the reverse pressure outport, and the ninth port is the drain port. In each port, the first port is the fourth port of the B1 cutoff valve 45, the second port is the B2 cutoff valve 46 pressure receiving portion, the third port is the out port of the C4 check valve, and the fourth and seventh ports are The reverse pressure supply oil path, the fifth port is connected to the C4 clutch hydraulic servo, the sixth port is connected to the out port of the C4 clutch control valve 34, and the eighth port is connected to the spring load side spool end pressure receiving part of the B2 cutoff valve. Yes.

  The C4 cut-off valve 44 has a hydraulic pressure supply state to the C4 clutch hydraulic servo 54 (return spring load on the right side in the figure) when the D range pressure or line pressure via the B1 cut-off valve 45 is applied to the plunger end or spool end. A pressed state against the above). Therefore, the solenoid valve 36 and the solenoid valve 37 are pushed down only when both are on or off, and when either one of these solenoid valves is off, the hydraulic pressure from the C4 clutch control valve 34 is shut off (illustrated). The left side is pushed up). When both the solenoid valve 36 and the solenoid valve 37 are on or off, the hydraulic pressure is supplied from the C4 clutch control valve 34, and the D range pressure supplied via the B1 cut-off valve 45 and the C4 check valve 47 is supplied. , The D range pressure is supplied to the spring load load side spool end pressure receiving portion of the B2 cutoff valve 46, the communication of the D range pressure to the B2 brake hydraulic servo is cut off, and the C2 cutoff valve 42 Supply to the second port from the bottom. On the other hand, when either one of the solenoid valve 36 and the solenoid valve 37 is pushed up, the line pressure or the D range pressure supplied via the C3 cutoff valve 43 and the B1 cutoff valve 45 is C2 cut. Supplyed to the seventh port of the off valve 42 and applied to the spring load side spool end pressure receiving portion of the B2 cut-off valve 46 to cut off the communication of the D range pressure to the B2 brake hydraulic servo 46, and from the C4 clutch control valve 34 Shut off the hydraulic pressure.

  A supply oil path to the hydraulic servo 52 of the C2 clutch is connected to a supply oil path of the D range pressure, and a C2 cut-off valve 42 is disposed on the upstream side of the C2 clutch control valve 32. The C2 cut-off valve 42 in this oil passage has a line pressure applied via the C3 cut-off valve 43 and the B1 cut-off valve 45 applied to the plunger end pressure receiving portion, or the C2 clutch servo pressure is C2 cut. A switching operation is performed by applying the pressure to the spool end side pressure receiving portion of the off valve 42 so that the D range pressure as a base pressure can be supplied to the C2 clutch control valve 32. The C2 cut-off valve 42 is composed of a 7-port spring return type spool type switching valve, and has a pressure receiving plunger at one end of the spool. The C2 cut-off valve 42 has a second port as a base pressure outport, a third port as a base pressure import, a fourth port as a D range pressure outport, a sixth port as a D range pressure outport, and a seventh port. The ports are D range pressure imports, and the remaining ports are drain ports. The second port is the import of the C2 clutch control valve 32, the third port is the D range pressure supply oil passage, the fourth port is the third port of the B2 cutoff valve, and the sixth port is the spring of the C1 cutoff valve 41. The load side spool end pressure receiving portion and the seventh port are connected to the second port of the C4 cutoff valve 44 and the spring load side spool end pressure receiving portion of the B2 cutoff valve 46, respectively. The plunger end side pressure receiving portion of the C2 cutoff valve 42 is connected to the second port of the B1 cutoff valve 45 and the spool end side pressure receiving portion of the C4 cutoff valve 44. The spool end side pressure receiving portion is connected to the C2 clutch hydraulic servo. Connected to the supply oil path.

  The C2 cut-off valve 42 is in communication with the line pressure supplied via the C3 cut-off valve 43 and the B1 cut-off valve 45 by turning on both the solenoid valve 36 and the solenoid valve 37 during a shift transition. The base pressure of the C2 clutch control valve 32 is set to the supply state. In this state, when the hydraulic pressure is supplied to the C2 clutch hydraulic servo 52, either the solenoid valve 36 or the solenoid valve 37 is turned off by supplying the C2 clutch servo pressure to the spool end side pressure receiving portion of the C2 cutoff valve 42. Even if the application of the line pressure to the plunger end pressure receiving portion is interrupted, the hydraulic pressure supply state in which the spool is pushed down is maintained.

  The B2 control valve 40 is inserted in a supply path that connects the B2 brake hydraulic servo 56 to a reverse pressure supply oil path. The B2 control valve 40 includes a three-port spool valve having a pressure adjusting spool that abuts the pressure receiving plunger via a return spring, and the first port is connected to the second port of the B2 cut-off valve 46. The control pressure import, the third port is the reverse pressure import connected to the eighth port of the C4 cut-off valve 44, and the second port is the out port connected to the B2 brake hydraulic servo 56. The spool end side pressure receiving part of this valve is connected to the out port via an orifice, the contact side pressure receiving part to the plunger via the spring is connected to the reverse pressure supply oil passage, and the plunger end pressure receiving part is connected via the orifice. The lock-up linear solenoid valve 24 is connected to the out port.

  The B2 control valve 40 adjusts the hydraulic pressure with the lock-up pressure during the first speed (1st) engine braking. Further, at the time of reverse (R), the reverse pressure is supplied to the pressure receiving portion that contacts the plunger via the spring, so that the spool is pushed up in the direction of communication with the first port and the second port (left side in the figure), The reverse pressure supplied via the B2 cut-off valve 46 is supplied to the B2 brake hydraulic servo 56.

  The B2 cut-off valve 46 is interposed between the C2 cut-off valve 42 and the B2 control valve 40, and is controlled by application of solenoid pressure by a normally closed on / off solenoid valve 38. The B2 cut-off valve 46 is switched by turning on the solenoid signal. The base pressure is supplied to the B2 control valve 40. This B2 cut-off valve 46 is composed of a spring-returned three-port spool valve. The first port is connected to a reverse pressure supply oil passage through a backflow throttle valve, and the second port is used as an outport for B2 control. The first port of the valve 40 is connected, and the third port is connected to the fourth port of the C2 cutoff valve 42 as an import of the B2 control pressure. The spool end side pressure receiving portion of the B2 cutoff valve 46 is connected to the out port of the on / off solenoid valve 38, and the spring load side pressure receiving portion is the second port of the C4 cutoff valve 44 and the seventh port of the C2 cutoff valve 42. It is connected to the.

  The B2 cut-off valve 46 is depressed by turning on the on / off solenoid valve 38 at the time of first speed (1st) engine braking (the state on the left side in the drawing), so that the base pressure can be supplied to the B2 control valve 40. . When shifting from the first speed (1st) engine brake to another forward speed, the on / off solenoid valve 38 is turned off and the spool is pushed up, so that the B2 brake servo pressure is supplied to the reverse pressure. (Drained in the forward gear) At the time of reverse (R), it is pushed up by the return spring force (right side in the figure), and the reverse pressure can be supplied.

  The C4 check valve 47 is a spring-returned three-port spool valve, the first port is connected to the third port of the C4 cut-off valve 44 with the drain port and the second port as the out port, and the third port is As an import, it is connected to the sixth port of the B1 cut-off valve 45. The C4 check valve 47 is switched when supplied to the C4 clutch hydraulic servo, and supplies the D range pressure to the spring load side pressure receiving portion of the B2 cut-off valve 45 via the C4 cut-off valve 44. To shut off the base pressure. Further, the same D range pressure is supplied to the seventh port of the C2 cut-off valve 42, and the C1, C4 clutch or B1 brake is engaged, and when the C2 clutch is engaged, the C1 clutch hydraulic servo is engaged. To shut off the base pressure.

  The hydraulic switch 48 is connected to an oil passage that connects the second port of the B1 cutoff valve 45 and the plunger end side pressure receiving portion of the C2 cutoff valve 42. The hydraulic switch 48 always supplies hydraulic pressure to all of the C3 clutch, B1 brake, C4 clutch, and C2 clutch when both the solenoid valve 36 and the solenoid valve 37 (or the respective fail-safe valves) fail when the hydraulic pressure is supplied. In this state, if the C3 clutch control valve 33, the B1 brake control valve 35, the C4 clutch control valve 34, and the C2 clutch control valve 32 fail, the tie-up may occur. In addition, it is provided to detect the oil pressure of the oil passage (line pressure for switching between the C4 cut-off valve and the C2 cut-off valve) supplied when both the solenoid valve 36 and the solenoid valve 37 are on. Therefore, the hydraulic switch 48 detects the failure of the solenoid valve 36 and the solenoid valve 37 by comparing the command to the solenoid valve 36 and the solenoid valve 37 with the state of the hydraulic switch 48, and prevents tie-up. Is for.

  FIG. 4 graphically illustrates the operation of each solenoid valve that is signal controlled to achieve each gear. The symbols in the horizontal column in this chart indicate the solenoids of the respective solenoid valves. In each shift stage, the ◯ mark indicates signal on, the X mark indicates signal off, and the ∆ mark indicates signal level control.

  When the hydraulic pressure supply based on the solenoid operation is viewed at each shift stage, at the first speed (1st), the normally open type C1 clutch control valve 31 is in the output state by the solenoid SLC1 signal off, and the normally open type C2 clutch control. Valve 32 is closed with solenoid SLC2 signal on, normally open C3 clutch control valve 33 solenoid SLC3 is closed with signal off, normally closed C4 clutch control valve 34 is closed with solenoid SLC4 signal on, three on / off By setting all the solenoids SL1 to SL3 of the solenoid valves 36 to 38 to the closed state, the base pressure is applied to the C1 clutch control valve 31 via the C1 cut-off valve 41 in which the D range pressure is depressed by the application of the line pressure. And supplied to the C1 clutch hydraulic servo 51 through the valve 31. Thus, the first speed is achieved by automatic engagement of the C1 clutch and the one-way clutch F-1 (see FIG. 1). At this time, the D range pressure reaches the C4 check valve 47 via the C3 cut-off valve 43 and the B1 cut-off valve 45, but is cut off there. The D range pressure is also supplied to the B2 cut-off valve 46 via the C2 cut-off valve 42, which is also shut off there. At the next first speed engine brake (1stE / G), the solenoid SL3 of the on / off solenoid valve 38 is turned on, so that the B2 cut-off valve 46 is pushed by the application of the solenoid pressure output of the on / off solenoid valve 38. In order to switch to the lowered state, the D range pressure that was shut off at the first speed is supplied to the B2 control valve 40 via the B2 cut-off valve 46, and is also supplied to the B2 brake hydraulic servo 56 via the valve 40. . Then, the engine brake is activated by the B2 brake engagement.

  At the second speed (2nd), the solenoid SLB1 of the B1 brake control valve 35 is turned on and the solenoid SL2 of the on / off solenoid valve 37 is turned on with respect to the first speed state, so that the B1 cutoff valve 45 is pushed. The state is switched to the lowered state, and the D range pressure that has been shut off in the supply state to the valve 45 is supplied to the B1 brake control valve 35 via the valve 45 as a base pressure. This hydraulic pressure is supplied to the B1 brake hydraulic servo 55 through the B1 brake control valve 35 which is in an open state. Thus, the second speed is achieved by simultaneous engagement of the C1 clutch and the B1 brake.

  At the third speed (3rd), the solenoids SLB1 and SLC3 of the B1 brake control valve 35 and the C3 clutch control valve 33 are switched on and off with respect to the second speed state, and the solenoids of the on / off solenoid valve 37 and the on / off solenoid valve 36 are switched. By switching the on / off state of SL2 and SL1, the C3 cut-off valve 43 is switched to the pushed-down state, and the D range pressure that has been cut off thereby is supplied to the C3 clutch control valve 33 via the C3 cut-off valve 43. This hydraulic pressure is supplied to the C3 clutch hydraulic servo 53 through the opened C3 clutch control valve 33. Thus, the third speed is achieved by simultaneous engagement of the C1 clutch and the C3 clutch.

  At the fourth speed (4th), only the solenoid SLC2 of the C2 clutch control valve 32 is turned on, and the C1 clutch control valve 31 and the C4 clutch control valve 34 are opened. At this time, the output hydraulic pressure reaches the C4 cut-off valve 44 by opening the C4 clutch control valve 34 that is constantly supplied with the line pressure. On the other hand, the C4 cut-off valve 44 is such that both the C3 cut-off valve 43 and the B1 cut-off valve 45 are in the push-up state to return the spring force, so that the D range pressure via both the valves 43 and 44 is supplied to the plunger pressure receiving portion. Since the pressure is applied and is in the depressed state, the hydraulic pressure reaching the C4 cutoff valve 44 is supplied to the C4 clutch hydraulic servo 54 via the valve 44. Thus, the fourth speed is achieved by simultaneous engagement of the C1 clutch and the C4 clutch.

  At the next fifth speed (5th), only the solenoid SLC4 of the C4 clutch control valve 34 is turned on, and the C1 clutch control valve 31 and the C2 clutch control valve 32 are opened. At this time, the solenoid valve 36 and the solenoids SL1 and SL2 of the solenoid valve 37 are simultaneously turned on by the control only at the time of the shift transition, and the C3 cut-off valve 43 and the B1 cut-off valve 45 are pushed down, so that the line pressure is reduced. The pressure is applied to the plunger end pressure receiving portion of the C2 cut-off valve 42 via the both valves 43 and 45, whereby the C2 cut-off valve 42 is switched to the depressed state. As a result, the D range pressure supplied to the C2 cut-off valve 42 is supplied to the C2 clutch control valve 32 via the valve 42 and supplied to the C2 clutch hydraulic servo 52 via the opened valve 32. Thus, the fifth speed is achieved by simultaneous engagement of the C1 clutch and the C2 clutch. When the hydraulic pressure supply to the C2 clutch hydraulic servo 52 is established, the hydraulic pressure is applied to the spool end pressure receiving portion of the C2 cut-off valve 42, so that the valve 42 is held at its own pressure. Therefore, the signals of solenoids SL1 and SL2 of solenoid valve 36 and solenoid valve 37 are turned off after the end of shifting.

  At the next sixth speed (6th), only the solenoid SLC1 of the C1 clutch control valve is turned on, and the C2 clutch control valve 32 and the C4 clutch control valve 34 are opened. At this time, the supply of the D range pressure to the C1 clutch control valve 31 is performed by the C3 cut-off valve 43, the B1 cut-off valve 45, the C4 check valve 47, the C4 cut-off valve 44, and the C2 cut-off valve 42. The application of the D range pressure to the spring load side pressure receiving portion of the off valve 41 is interrupted by the valve 41 being pushed up and shut off due to the pressure receiving balance of the valve 41, and the C1 clutch control valve 31 itself is closed by C1. The clutch hydraulic servo 51 is drained by the C1 clutch control valve 31. Instead, the hydraulic pressure is supplied to the C4 clutch hydraulic servo 54 via the C4 cut-off valve 44 by opening the C4 clutch control valve 34 that is constantly supplied with the line pressure. In this case, since the D range pressure via the C3 cut-off valve 43 and the B1 cut-off valve 45 is applied to the plunger end pressure receiving portion to the C4 cut-off valve 44, the C4 cut-off valve 44 is in a depressed state. The hydraulic pressure is supplied to the C4 clutch hydraulic servo 54 via the valve 44. Thus, the sixth speed is achieved by simultaneous engagement of the C2 clutch and the C4 clutch.

  At the seventh speed (7th), the solenoids SLC1, SLC3, SLC4, SL1 of the C1 clutch control valve 31, the C3 clutch control valve 33, the C4 clutch control valve 34, and the on / off solenoid valve 36 are turned on, and the C2 clutch control valve 32 and the C3 clutch control valve 33 are opened. In this state, the solenoid pressure output of the on / off solenoid valve 36 causes the C3 cut-off valve 43 to be pushed down, and the D range pressure is supplied to the C3 clutch control valve 33 via the valve 43 and passes through the opened valve 33. The hydraulic pressure is supplied to the C3 clutch hydraulic servo 53. In this case, the hydraulic pressure supply to the C2 clutch hydraulic servo 52 is the same as that at the fifth speed and the sixth speed. Thus, the seventh speed is achieved by simultaneous engagement of the C2 clutch and the C3 clutch.

  At the eighth speed (8th), the solenoids SLC1, SLC2, SLB1, and SL2 of the C1 clutch control valve 31, the C4 clutch control valve 34, the B1 brake control valve 35, and the on / off solenoid valve 37 are turned on, and the C2 clutch The control valve 32 and the B1 brake control valve 34 are opened. In this state, the D range pressure is supplied to the B1 brake control valve 35 via the B1 cut-off valve 45 pressed by the solenoid valve 37, and is supplied to the B1 brake hydraulic servo 55 via the opened valve 35. In this case, the hydraulic pressure supply to the C2 clutch hydraulic servo 52 is the same as that at the fifth, sixth and seventh speeds. Thus, the eighth speed is achieved by simultaneous engagement of the C2 clutch and the B1 brake.

  Further, at the time of shifting transition, the solenoids SLC1 to SLC4 and SLB1 of all the control valves are set to the control state under the signal level adjustment, and further, the signals of the solenoids S1 and S2 of the on / off solenoid valves are turned on. The valve is in an open state under control, and the solenoid valve 36 and the solenoid valve 37 are in a solenoid pressure output state. In this state, the C1 cut-off valve 41 is pushed down by applying line pressure, the C3 cut-off valve 36 and the B1 cut-off valve 45 are pushed down by applying solenoid pressure, and the C4 cut-off valve 44 and C2 cut-off valve 42 are turned on. It is pushed down by applying line pressure via the C3 cut-off valve 36 and the B1 cut-off valve 45, the D range pressure via the C1 cut-off valve 41 is applied to the C1 clutch control valve 31, and the C3 cut is applied to the C3 clutch control valve 33. D range pressure via OFF valve 43, direct line pressure to C4 clutch control valve 34, D range pressure via B1 cutoff valve 45 to B1 brake control valve 35, C2 cutoff valve to C2 clutch control valve 32 The D range pressure via 42 is supplied, and the hydraulic pressure under the control of each control valve is C for the C4 clutch hydraulic servo 54. Via cut-off valve 44 is directly supplied to the other hydraulic servo.

  Further, during reverse (Rev), the constantly supplied line pressure reaches the C4 cut-off valve 44 when the C4 clutch control valve 34 is opened, and on the other hand, the always supplied line pressure is C3 cut when the solenoid valve 34 is pushed down. Supplyed to the C4 clutch hydraulic servo 54 via the valve 44 which is applied to the spool end pressure receiving portion of the C4 cut-off valve 44 via the B1 cut-off valve 45 which is pushed down by the off valve 43 and the solenoid valve 37 and is switched to the pushed state. Is done. Further, the reverse pressure output by switching the manual valve 25 is supplied to the B2 control valve 40 via the B2 cut-off valve via the backflow throttle valve, and is supplied to the B2 brake hydraulic servo 56. Thus, reverse is achieved by simultaneous engagement of the C4 clutch and the B2 brake.

  When an all-off failure of the solenoid signal occurs in response to the hydraulic circuit operation when each solenoid valve operation signal is normal, the C3 clutch control valve 33 and the B1 brake control valve 35 are set as normally closed valves. Since the C3 clutch hydraulic servo 53 and the B1 brake hydraulic servo 55 receiving the hydraulic pressure supply from these valves are drained, and the on / off solenoid valve 38 is also normally closed, the D range pressure of the B2 cut-off valve 46 is shut off, and B2 The operation of draining the brake hydraulic servo 56 occurs. When the failure occurs on the high speed side of the engagement of the C2 clutch, the C1 clutch control valve 31 is cut off (refer to the operation of the C1 cut-off valve 41), and therefore the hydraulic servo 52 for the C2 clutch and the C4 clutch. , 54 are in the supply state, and the sixth speed is achieved. When a failure occurs on the low speed side where the C2 clutch is not engaged, the base pressure of the C2 clutch control valve 32 is shut off by the C2 cut-off valve 42, so that the hydraulic servos 51 of the C1 clutch and the C4 clutch 54 becomes a supply state, and the fourth speed is achieved. Thus, even when the vehicle is traveling on the high speed stage side or when the vehicle is traveling on the low speed stage side, an extreme jump shift does not occur, so that the vehicle traveling can be stably maintained.

  In addition, when the 6th speed is achieved by the all-off, when the vehicle is once stopped and restarted, if the manual valve is switched to DND, the supply pressure of the C2 clutch hydraulic servo is changed. Is drained once, the self-pressure maintaining C2 cut-off valve 42 cuts off the base pressure of the C2 clutch control valve 32, and thereby the D range via the C1 cut-off valve 41 maintained in communication with the line pressure. The normally open C1 clutch control valve 31 that receives the supply of pressure and the normally open C4 clutch control valve 34 that receives the supply of line pressure are in the supply state, and the fourth speed due to the simultaneous engagement of the C1 clutch and the C4 clutch is increased. Can be achieved. In addition, as described above, the supply state to the C4 clutch hydraulic servo 54 is ensured even when all-off is performed, and the supply to the B2 brake hydraulic servo is performed without using a solenoid signal. Achieved.

  Thus, according to this embodiment, the hydraulic pressure supplied to the engaging element that ties up when the fail-safe valve is simultaneously engaged is not switched as a signal pressure, but is switched by an on / off solenoid valve for switching. Therefore, for example, it is possible to prevent a malfunction of the fail-safe valve in a state where the hydraulic applicability at an extremely low oil temperature is poor. Also, without providing a solenoid valve corresponding to each fail-safe valve, the operating state of a fail-safe valve (in this example, the C4 cut-off valve 44) that does not have an on-off solenoid valve is determined by a combination of operations of the on-off solenoid valve. Since it can be switched, the number of on / off solenoid valves can be reduced. Further, since the fail-safe valve excluding the C4 cut-off valve 44 is arranged upstream of the control valve, the leakage of the engagement pressure can be reduced, and the control responsiveness is improved.

  Further, in the fail-safe valve that switches the hydraulic pressure supplied to the engaging element that ties up when simultaneously engaged as a signal pressure, the hydraulic pressure of the fail-safe valve at the time of shifting by re-holding the set of engaging elements that tie up when simultaneously engaged. Since it is necessary to prevent the fail-safe valve from switching in the middle of gear shifting due to the balance, the controllability is poor, whereas in this embodiment, the C4 cutoff valve switching hydraulic pressure is the C3 cutoff valve and the B1 cutoff valve. Are supplied to the C4 cut-off valve when the oil pressure is in the hydraulic pressure supply state (right side in the figure) (however, it is not supplied when at least one of the C3 cut-off valve and the B1 cut-off valve is in the oil pressure cut-off state). The off valve switches to the hydraulic pressure supply state (right side in the figure). In the shift transition state, the C3 cut-off valve and the B1 cut-off valve are set to the hydraulic pressure supply state, whereby the C4 cut-off valve is also set to the hydraulic pressure supply state. Since the solenoid has been reset, all engagement elements can be set to the hydraulic pressure supply state in a transitional state such as when the engagement elements are being re-grown. Controllability is improved.

  Further, the C4 cut-off valve is supplied with the D range pressure supplied when the C3 cut-off valve and the B1 cut-off valve are in a hydraulic cutoff state (however, at least one of the C3 cut-off valve and the B1 cut-off valve is supplied with hydraulic pressure). Therefore, the hydraulic pressure can be supplied to the C4 clutch hydraulic servo without setting both the C3 clutch hydraulic servo and the B1 brake hydraulic servo switched to the hydraulic pressure supply state. Tie-up of C3 clutch, B1 brake and C4 clutch can be surely prevented.

  In this embodiment, the C3 cut-off valve 43 and the B1 cut-off valve 45 are provided upstream of the C3 clutch control valve 31 and the B1 brake control valve 35 as control valves for the engagement elements, respectively. Even if these cut-off valves corresponding to the first fail-safe valve and the second fail-safe valve in the invention are provided on the downstream side of the control valve, the effect according to the object of the invention can be achieved.

It is a skeleton figure which shows the gear train of the 8-speed automatic transmission controlled by the hydraulic control apparatus based on the Example of this invention. It is a speed diagram which shows the action | operation of a gear train. It is an action | operation chart which shows the action | operation of the gear train by a hydraulic control apparatus. It is a circuit diagram of a hydraulic control device. It is an operation | movement diagram of each solenoid valve in a hydraulic control apparatus.

Explanation of symbols

C-1 C1 clutch (fourth engagement element)
C-2 C2 clutch (fifth engagement element)
C-3 C3 clutch (engagement element)
C-4 C4 clutch (engagement element)
B-1 B1 brake (engaging element)
20 Oil pump (hydraulic power source)
36 On-off solenoid valve (first solenoid valve)
37 On-off solenoid valve (second solenoid valve)
43 C3 cutoff valve (first fail-safe valve)
44 C4 cutoff valve (third fail-safe valve)
45 B1 cut-off valve (second fail-safe valve)
53 C3 clutch hydraulic servo 54 C4 clutch hydraulic servo 55 B1 brake hydraulic servo

Claims (4)

In a hydraulic control device for an automatic transmission having at least three engagement elements (C-3, B-1, C-4),
A fail-safe valve is disposed between the hydraulic servo (53, 55, 54) and the hydraulic source (20) of each engagement element,
The first fail-safe valve (43) and the second fail-safe valve (45) among the fail-safe valves are arranged correspondingly to supply and shut off the hydraulic pressure to the hydraulic servo (53, 55). The first solenoid valve (36) and the second solenoid valve (37) can be switched respectively.
The automatic transmission characterized in that the third fail-safe valve (44) can be switched by a third fail-safe valve switching hydraulic pressure applied via both the first fail-safe valve and the second fail-safe valve. Hydraulic control device. The third fail-safe valve switching hydraulic pressure is applied to the third fail-safe valve when both the first fail-safe valve and the second fail-safe valve are in a hydraulic pressure supply state, and the third fail-safe valve is turned on. Switch to hydraulic supply state,
In the shift transient state, the first fail-safe valve and the second fail-safe valve are brought into a hydraulic pressure supply state by the first solenoid valve and the second solenoid valve, whereby the third fail-safe valve is also brought into a hydraulic pressure supply state.
2. The hydraulic control device for an automatic transmission according to claim 1, wherein when the shift is completed, the settings of the first solenoid valve and the second solenoid valve are returned to the settings for achieving the shift stage.   3. The automatic operation according to claim 1, wherein the third fail-safe valve is switched to a hydraulic pressure supply state by a hydraulic pressure applied when both the first fail-safe valve and the second fail-safe valve are in a hydraulic cutoff state. Hydraulic control device for transmission.   The automatic transmission is always engaged in order to achieve each shift stage on the high speed side, and a fourth engagement element C-1) that is always engaged to achieve each shift stage on the low speed stage side. A fifth engagement element (C-2), and each shift stage is achieved by simultaneous engagement of these engagement elements or any one of these engagement elements and any one of the three engagement elements. The hydraulic control device for an automatic transmission according to claim 1, 2, or 3.

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