# Patent

## Title
Hydraulic control apparatus for a multi-stage automatic transmission

## Abstract

A hydraulic control apparatus for a multi-stage automatic transmission includes solenoid valves such as the linear solenoid valves that are formed as normally closed valves. A first clutch apply relay valves that outputs a forward range pressure as a reverse input pressure during an all-solenoid-off mode, and a second clutch apply relay valve that switches between a left half position that inputs a reverse input pressure to a discharge port and a right half position that inputs the reverse pressure to the discharge port are provided. The second clutch apply relay valve is set to the right half position during normal engine startup and locked based on the lock pressure by feeding the line pressure as a lock pressure and is set at the left half position that interrupts the lock pressure after the engine is restarted during all-solenoids-off.

## Background
INCORPORATION BY REFERENCE
This application claims priority from Japanese Patent Application Nos. 2005-378389, 2005-378390, and 2005-378391, all filed on Dec. 28, 2005, the disclosures of which, including the specifications, drawings and abstracts, are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic control apparatus for a multi-stage automatic transmission that is mounted, for example, in a vehicle, and in particular, relates to a hydraulic control apparatus for a multi-stage automatic transmission that ensures the ability of the vehicle to travel during an all-solenoids-off failure.
2. Description of the Related Art
Conventionally, a staged automatic transmission that is mounted, for example, on a vehicle enables multi-speed shifting by controlling the engagement state of a plurality of friction engagement elements (clutches and brakes) by using a hydraulic control apparatus and forming transmission paths in the speed change mechanism at each shift speed. This hydraulic control apparatus is provided with a plurality of switching valves and regulating valves, and is also provided with a plurality of solenoid valves for electrically controlling the operation of these valves. The control of the multi-speed shifting as described above may be carried out by actuating these solenoid valves.
However, in such a hydraulic control apparatus described above, a state in which electrical signals from the solenoid valves are not sent, which is referred to as a all-solenoids-off fail state, may occur when, for example, there is a severed wire or short, or when, for example, some type of failure is detected in the hydraulic control apparatus. Enabling the establishment of shift speeds by hydraulic control in order to guarantee the ability of the vehicle to travel such a state has been proposed (refer to Japanese Patent Application Publication No. 2004-28277).
This device is structured such that even if an all-solenoids-off fail occurs, for example, during travel in the drive (D) range, when traveling forward in the third forward speed or in the fourth forward speed, travel is locked, for example, at the fourth forward speed, and for example, when traveling forward in the first forward speed or in the second forward speed, travel is locked at the first forward speed. Furthermore, this device is structured so as to change or lock in the first forward speed because of an engine stop after locking in the fourth forward speed.
However, in recent years, with the goal of enhancing the fuel economy of vehicles, the development of multiple speeds (for example, eight forward speeds) in a staged automatic transmission has been progressing, and in this multi-stage automatic transmission, the shift speeds are structured so as to be segmented into broad gear ratios ranging from a low gear ratio to a high gear ratio. In such a multi-stage automatic transmission, during the all-solenoids-off fail while traveling as described above, there is a concern that downshifting of two or more stages (for example, from fifth to third speed) may occur due to separating and locking the shift speed at two predetermined stages (relatively high and low speeds), and downshifting of two or more steps occurring when this is not intended or preferred by the driver. However, simply locking at the high speed makes restarting the vehicle after temporarily stopping the vehicle difficult, and there is a concern that a vehicle that is experiencing failure will not be capable of self-propulsion if it is simply locked at a high speed.
SUMMARY OF THE INVENTION
Thus, it is an aspect of the present invention to provide a hydraulic control apparatus for a multi-stage automatic transmission that locks the shift speed at a relatively high speed during an all-solenoids-off fail state while traveling and enables restarting of the vehicle.
According to the first aspect of the invention, during a failure in which all of the solenoid valves are de-energized, the first switching valve outputs a forward range pressure as a reverse input pressure, the second switching valve, which is locked at the second position due to the lock pressure, supplies an engagement pressure to the second hydraulic servo by inputting the reverse input pressure to the discharge port of the second engagement pressure control solenoid valve, and the second switching valve, which is set at the first position by interrupting the lock pressure after restarting the engine, supplies an engagement pressure to the first hydraulic servo by inputting a reverse input pressure to the discharge port of the first engagement pressure control solenoid valve. Therefore, while the vehicle is traveling, it is possible to lock the shift speed at a relatively high speed. In addition, while the downshifting of two or more speeds can be prevented, by restarting the engine, for example, after temporarily stopping the vehicle, it is possible to set the shift speed at a relatively low speed, and it is possible to enable restarting of the vehicle.
According to the second aspect of the invention, because the second switching valve feeds line pressure to serve as lock pressure when at the second position, during the normal engine start-up, it is possible to lock the shift speed at the second position based on the line pressure. Thus, while the vehicle is traveling, it is possible to lock the shift speed at a relatively high speed even during a failure in which all of the solenoid valves are de-energized. In addition, by stopping the engine, the locking of the second switching valve is released based on the line pressure and the second switching valve can be set at the first position that interrupts the line pressure. Thus, by restarting the engine, it is possible to set the shift speed at a relatively low speed and it is possible to enable restarting of the vehicle.
According to the third aspect of the invention, a fail solenoid valve is provided that outputs a signal pressure during a de-energized state and interrupts the signal pressure after reverting to the energized state at least during a normal engine start-up. The second switching valve inputs the signal pressure of the fail solenoid valve before being locked by the lock pressure during a failure in which all of the solenoid valves are de-energized and is switched to the first position due to this signal pressure. Therefore, by restarting the engine, it is possible to set the shift speed at a relatively low speed.
According to the fourth aspect of the invention, a delay device is provided that communicates with a second switching valve by delaying the lock pressure that is fed by the second switching valve. Therefore, during a failure in which all of the solenoid valves are de-energized, the second switching valve can switch reliably to the first position due to the signal pressure of the fail solenoid valve before being locked by the lock pressure.
According to the fifth aspect of the invention, the delay device includes a third switching valve that switches to a communicating position that communicates the lock pressure to the second switching valve when the lock pressure is input against the urging of the first urging device. Therefore, when the engine starts up normally and the line pressure is output, the lock pressure is communicated to the second switching valve, and it is possible to lock the second switching valve.
According to a sixth aspect of the invention, the delay device includes a third switching valve that switches to a communicating position that communicates a lock pressure to the second switching valve when the forward range pressure is input against the first urging device. Therefore, when the shift position is set to the forward range normally, the lock pressure is communicated to the second switching valve, and it is possible to lock the second switching valve.
According to the seventh aspect of the invention, the second spool of the second switching valve is set to the second position by abutting the second spool to the third spool when the third spool of the third switching valve is at the urging position. Therefore, even when, for example, a state occurs in which the third spool of the third switching valve sticks and the lock pressure is not communicated to the second switching valve, it is possible to maintain the second spool at the second position due to the abutment of the third spool. Thereby, even when, for example, the third spool sticks, it is possible to prevent the second spool from being set at the first position, at which an engagement pressure is supplied to the first hydraulic server. In addition, even during a failure in which all of the solenoid valves are de-energized while the vehicle is traveling, it is possible to reliably lock the shift speed at a relatively high speed and it is possible to reliably prevent the downshifting of two or more speeds from occurring.
According to the eighth aspect of the invention, the first switching valve is switched to a reverse input pressure output position that communicates and outputs forward range pressure as reverse input pressure when a signal pressure of the fail solenoid valve is output against the urging of the second urging device. Therefore, during a failure in which all of the solenoid valves are de-energized, the output of the reverse input pressure by the first switching valve and the switching of the second switching valve between the first position and the second position become possible due to the signal pressure of the first fail solenoid valve.
According to the ninth aspect of the invention, the first switching valve outputs a reverse input pressure directly to a discharge port of the third engagement pressure control solenoid valve during a failure in which all of the solenoid valves are de-energized and supplies an engagement pressure to the third hydraulic servo that engages and disengages the friction engagement elements that engage at a relatively low speed and a relatively high speed. Therefore, it is possible to enable establishing a relatively low speed and a relatively high speed.
According to the tenth aspect of the invention, the fourth engagement pressure control solenoid valve inputs a lock pressure to an input port via the second switching valve as a line pressure. Therefore, before all of the solenoid valves become de-energized, it is possible to determine whether or not the first switching valve feeds the lock pressure normally depending on whether or not the shift speed that is established normally by the friction engagement element engaged by the fourth hydraulic servo has been attained. Thereby, for example, in the case in which the first switching valve is not locked by the lock pressure, all of the solenoids are set to be de-energized, and it is possible to prevent the occurrence of unintended downshifting and thereby ensure safe travel of the vehicle.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a skeleton drawing showing an automatic transmission to which an exemplary embodiment of the present invention can be applied;
FIG. 2 is an operating table of an exemplary embodiment of the present automatic transmission;
FIG. 3 is a velocity diagram of an exemplary embodiment of the present automatic transmission;
FIG. 4 is a schematic drawing showing the overall hydraulic control apparatus according to an exemplary embodiment of the present invention;
FIG. 5 is a partial drawing showing the forward shift function portion in the hydraulic control apparatus according to an exemplary embodiment of the present invention;
FIG. 6 is a partial drawing showing the simultaneous engagement preventing function portion in the hydraulic control apparatus according to an exemplary embodiment of the present invention;
FIG. 7 is a partial drawing showing the reverse shift function portion in the hydraulic control apparatus according to an exemplary embodiment of the present invention;
FIG. 8A to FIG. 8C are drawings showing the switching positions of the second clutch apply relay valve according to an exemplary embodiment of the present invention, in which FIG. 8A is a drawing showing the engine-off, FIG. 8B is a drawing showing all-off during travel, and FIG. 8C is a drawing showing the engine restart during all-off; and
FIG. 9A to FIG. 9E are drawings showing the switching positions of the second clutch apply relay valve in another exemplary embodiment of the present invention, in which FIG. 9A is a drawing showing the engine-off, FIG. 9B is a drawing showing an engine start-up during normal operation, FIG. 9C is a drawing showing normal travel, FIG. 9D is a drawing showing all-off during travel, and FIG. 9E is a drawing showing the engine restart during all-off.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Below, exemplary embodiments of the present invention will be explained with reference to FIG. 1 through FIG. 8A to FIG. 8C.
Configuration of Automatic Transmission
First, a schematic structure of the multi-stage automatic transmission (below, referred to simply as an “automatic transmission”) in which an exemplary embodiment of the present invention can be applied will be explained with reference to FIG. 1. As shown in FIG. 1, a preferable automatic transmission 1 that is used, for example, in an FR type (front engine, rear drive) vehicle has an input shaft 11 for the automatic transmission 1 that is able to connect to an engine (not illustrated), and is provided with a torque converter 7 that is disposed concentrically with the input shaft 11 in the axial direction and a speed change mechanism 2.
The torque converter 7 has a pump impeller 7a that is connected to the input shaft 11 of the automatic transmission 1 and a turbine runner 7b to which the rotation of the pump impeller 7a is transmitted via a working liquid. The turbine runner 7b is connected to the input shaft 12 of the speed change mechanism 2 disposed coaxially to the input shaft 11. In addition, the torque converter 7 is provided with a lock-up clutch 10, and when the lock-up clutch 10 is engaged by the hydraulic control of the hydraulic control apparatus described below, the rotation of the input shaft 11 of the automatic transmission 1 described above is directly transmitted to the input shaft 12 of the speed change mechanism 2.
This speed change mechanism 2 is provided with a planetary gear DP and a planetary gear unit PU on the input shaft 12 (and the intermediate shaft 13). This planetary gear DP is provided with a sun gear S1, a carrier CR1, and a ring gear R1. In the carrier CR1, a pinion P1 that meshes with the sun gear S1 and a pinion P2 that meshes with the ring gear R1 mesh together to form what is referred to as a double pinion planetary gear.
In addition, the planetary gear unit PU has four rotating elements: a sun gear S2, a sun gear S3, a carrier CR2 (CR3), and a ring gear R3 (R2), and in the carrier CR2, a long pinion P4 that meshes with the sun gear S2 and a ring gear R3 and a short pinion P3 that meshes with the long pinion P4 and the sun gear S3 mesh together to form what is referred to as a Ravigneaux-type planetary gear.
The rotation of the sun gear S1 of the planetary gear DP described above is held stationary by being connected to a boss portion 3b that is integrally attached, for example, to the transmission case 3. In addition, the carrier CRI described above is connected to the input shaft 12 to rotate together with the rotation of the input shaft 12 (below, referred to as “input rotation”), and at the same time is connected to the fourth clutch C-4 (a friction engagement element). Furthermore, the ring gear R1 provides a reduced rotation in which the input rotation is reduced due to the stationary sun gear S1 and the carrier CR1 that provides the input rotation, and at the same time is connected to a first clutch C-1 (a friction engagement element) and a third clutch C-3 (a friction engagement element).
The sun gear S2 of the planetary gear unit PU described above is able to fasten freely to the transmission case 3 by connecting to the first brake B-1 (a friction engagement element), which serves as a locking device, and at the same time, connects to the fourth clutch C-4 and the third clutch C-3. The input rotation of the carrier CR1 via the fourth clutch C-4 and the reduced rotation of the ring gear R1 via the third clutch C-3 can each be freely and separately input. In addition, the sun gear S3 is connected to the first clutch C-1 and the reduced rotation of the ring gear R1 can be freely input.
Furthermore, the carrier CR2 is connected to the second clutch C-2 (a friction engagement element), to which the rotation of the input shaft 12 is input via the intermediate shaft 13, and the input rotation can be freely input via the second clutch C-2. In addition, the carrier CR2 is connected to the one-way clutch F-1 and the second brake B-2 (a friction engagement element), which serve as locking device, the one-way clutch F-1 restricts the rotation in one direction with respect to the transmission case 3, and the rotation can be held stationary or permitted by the second brake B-2. In addition, the ring gear R3 is connected to the output shaft 15, which outputs a rotation to the vehicle's driven wheels (not illustrated).
Transmission Path of Each Shift Speed
Next, based on the configuration described above, the operation of the speed change mechanism 2 will be explained with reference to FIG. 1, FIG. 2, and FIG. 3. Note that in the velocity diagram shown in FIG. 3, the vertical axes show the rotation of the respective rotation elements (each gear), and the horizontal axes show the correspondence with the gear ratios of these rotation elements. In addition, in the part of the velocity diagrams showing the planetary gear DP, the vertical axis that is the closest to the end in the transverse direction (the left side in FIG. 3) corresponds to the sun gear S1 and the vertical axes in sequence towards the right side of the figure correspond to the ring gear R1 and the carrier CR1. Furthermore, in the part of the velocity diagram showing the planetary gear unit PU, the vertical axis that is closest to the end in the transverse direction (the right side in FIG. 3) corresponds to the sun gear S3, and the vertical axes in sequence towards the left side of the figure correspond to the ring gear R3 (R2), the carrier CR2 (CR3), and the sun gear S2.
In the D (drive) range, for example, at the first forward speed (1st), as shown in FIG. 2, the first clutch C-1 and the one-way clutch F-1 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S3 via the first clutch C-1. In addition, the rotation of the carrier CR2 is restricted to one direction (the normal rotation direction), or specifically, the rotation of the carrier CR2 is held stationary by preventing the reverse rotation of the carrier CR2. Thus, the reduced rotation input to the sun gear S3 is output to the ring gear R3 via the stationary carrier CR2, and a normal rotation is output from the output shaft 15 as the first forward speed.
Note that during engine braking (during coasting), the carrier CR2 is held stationary by locking the second brake B-2, and thus the normal rotation of the carrier CR2 is prevented. Thereby, the state of the first forward speed is maintained. In addition, at the first forward speed, because the reverse rotation of the carrier CR2 is prevented by the one-way clutch F-1 and normal rotation is possible, attaining the first forward speed when, for example, switching from a non-traveling range to a traveling range can be carried out smoothly by the automatic engagement of the one-way clutch F-1.
In the second forward speed (2nd), as shown in FIG. 2, the first clutch C-1 is engaged, and the first brake B-1 is locked. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S3 via the first clutch C-1. In addition, the rotation of the sun gear S2 is held stationary by the locking of the first brake B-1. Thus, the carrier CR2 acquires a reduced rotation that is lower than that of the sun gear S3, the reduced rotation that is input to the sun gear S3 is then input to the ring gear R3 via the carrier CR2, and the normal rotation is output from the output shaft 15 as the second forward speed.
In the third forward speed (3rd), as shown in FIG. 2, the first clutch C-1 and the third clutch C-3 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S3 via the first clutch C-1. In addition, the reduced rotation of the ring gear R1 is input to the sun gear S2 by the engagement of the third clutch C-3. That is, because the reduced rotation of the ring gear R1 is input to the sun gear S2 and the sun gear S3, the planetary gear unit PU becomes directly linked to the reduced rotation, the reduced rotation is input directly into the ring gear R3, and the normal rotation is output from the output shaft 15 as the third forward speed.
In the fourth forward speed (4th), as shown in FIG. 2, the first clutch C-1 and the fourth clutch C-4 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S3 via the first clutch C-1. In addition, the input rotation of the carrier CR1 is input to the sun gear S2 due to the engagement with the fourth clutch C-4. Thus, the carrier CR2 acquires a reduced rotation that is higher than that of the sun gear S3, the reduced rotation that is input by the sun gear S3 is then output to the ring gear R3 via the carrier CR2, and the normal rotation is output from the output shaft 15 as the fourth forward speed.
In the fifth forward speed (5th), as shown in FIG. 2, the first clutch C-1 and the second clutch C-2 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S3 via the first clutch C-1. In addition, the input rotation is input to the carrier CR2 due to the engagement with the second clutch C-2. Thus, a reduced rotation that is higher than that of the fourth forward speed described above due to the reduced rotation input to the sun gear S2 and the input rotation input to the carrier CR2 is output to the ring gear R3, and the normal rotation is output from the output shaft 15 as the fifth forward speed.
In the sixth forward speed (6th), as shown in FIG. 2, the second clutch C-2 and the fourth clutch C-4 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the input rotation of the carrier CR1 is input to the sun gear S2 due to the engagement with the fourth clutch C-4. In addition, the input rotation of the carrier CR2 is input due to the engagement with the second clutch C-2. That is, because the input rotation is input to the sun gear S2 and to the carrier CR2, the planetary gear unit PU is coupled directly to the input rotation, the input rotation is output directly to the ring gear R3, and the normal rotation is output from the output shaft 15 as the sixth forward speed.
In the seventh forward speed (7th, OD1), as shown in FIG. 2, the second clutch C-2 and the third clutch C-3 are engaged. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S2 via the third clutch C-3. In addition, the input rotation is input to the carrier CR2 due to the engagement with the second clutch C-2 via the third clutch C-3. Thus, an increased rotation that is slightly higher than the input rotation due to the reduced rotation that is input to the sun gear S2 and the input rotation that is input to the carrier CR2 is output to the ring gear R3, and the normal rotation is output from the output shaft 15 as the seventh forward speed (the first overdrive speed, which is faster than the directly coupled speed).
In the eighth forward speed (8th, OD2), as shown in FIG. 2, the second clutch C-2 is engaged, and the first brake B-1 is locked. Thus, as shown in FIG. 1 and FIG. 3, the input rotation is input to the carrier CR2 due to the engagement with the second clutch C-2. In addition, the rotation of the sun gear S2 is held stationary due to the locking of the first brake B-1. Thus, the input rotation of the carrier CR2 by the stationary sun gear S2 becomes an increased rotation that is higher than that of the seventh forward speed described above, this rotation is input to the ring gear R3, and the normal rotation is output from the output shaft 15 as the eighth forward speed (the second overdrive speed, which is faster than the direct coupling speed.
In the first reverse speed (Rev1), as shown in FIG. 2, the third clutch C-3 is engaged, and the second brake B-2 is locked. Thus, as shown in FIG. 1 and FIG. 3, the rotation of the ring gear R1, whose rotation is reduced by the stationary sun gear S1 and by the carrier CR1, which is the input rotation, is input to the sun gear S2 via the third clutch C-3. In addition, the rotation of the carrier CR2 is held stationary by being locked by the second brake B-2. Thus, the reduced rotation that is input to the sun gear S3 is output to the ring gear R3 via the stationary carrier CR2, and the reverse rotation is output from the output shaft 15 as the first reverse speed.
In the second reverse speed (Rev2), as shown in FIG. 2, the fourth clutch C-4 is engaged, and the second brake B-2 is locked. Thus, as shown in FIG. 1 and FIG. 3, the input rotation of the carrier CR1 due to the engagement with the clutch C-4 is input to the sun gear S2. In addition, the rotation of the carrier CR2 is held stationary by being locked by the second brake B-2. Thus, the input rotation that is input to the sun gear S2 is output to the ring gear R3 via the stationary carrier CR2, and the reverse rotation is output from the output shaft 15 as the second reverse speed.
Note that in an exemplary embodiment of the present automatic transmission, the fourth clutch C-4 and the second brake B-2 are engaged while in the reverse range due to the hydraulic control by the hydraulic control apparatus 20 that will be described in detail below, and thus, only a second reverse speed is established. However, this can be modified in various manners, and only a first reverse speed or both a first reverse speed and a second reverse speed may be established.
In addition, in the P (parking) range and the N (neutral) range, the first clutch C-1, the second clutch C-2, the third clutch C-3, and the fourth clutch C-4 are released. Thereby, the carrier CR1 and the carrier CR2 are disengaged. In addition, the ring gear R1, the sun gear S2, and the sun gear S3 are disengaged, and thereby the planetary gear DP and the planetary gear unit PU are disengaged. Additionally, the input shaft 12 (intermediate shaft 13) and the carrier CR2 are disengaged. Thereby, the transfer of the driving force between the input shaft 12 and the planetary gear unit PU is disengaged, and thus, the transfer of the driving force between the input shaft 12 and the output shaft 15 is disengaged.
Overall Configuration of Hydraulic Control Apparatus
Next, the hydraulic control apparatus 20 of the automatic transmission according to an exemplary embodiment of the present invention will be explained. First, the overall hydraulic control apparatus 20 will be broadly explained with reference to FIG. 4. Note that in the present exemplary embodiment, there is one spool in each valve, and in order to explain the spool's switching position and the control position, the state in the right half portion shown in FIG. 4 through FIG. 7 is referred to as the “right half position” and the state in the left half portion shown therein is referred to as the “left half position”.
As shown in FIG. 4, generally in order to regulate and generate oil pressures that provide various types of primary pressures, the hydraulic control apparatus 20 is provided with a strainer 22, an oil pump 21, a manual shift valve (range pressure output device) 23, a primary regulator valve (line pressure generating device) 25, a secondary regulator valve 26, a solenoid modulator valve 27, and a linear solenoid valve SLT (not illustrated).
In addition, in order to selectively switch or regulate the oil pressures in each of the oil paths based on the various types of primary pressures, the hydraulic control apparatus 20 is provided with valves that switch and control the spool position. These valves include a lock-up relay valve 31, a second clutch apply relay valve (second switching valve) 32, a lock pressure delay valve (delay device, third switching valve) 33, a first clutch apply relay valve (second switching valve) 34, a B-2 apply control valve 35, a B-2 control valve 36, a B-2 check valve 37, a first clutch apply control valve 41, a signal check valve 42, a second clutch apply control valve 43, a B-1 apply control valve 44, a C-4 relay valve 45, and the like.
Furthermore, in order to electrically control and supply oil pressure to each type of relay valve and each type of control valve described above, the hydraulic control apparatus 20 is provided with a linear solenoid valve SL1, a linear solenoid valve SL2, a linear solenoid valve SL3, a linear solenoid valve SL4, a linear solenoid valve SL5, a linear solenoid valve SLU, a solenoid valve (a fail solenoid valve) SR, and a solenoid valve SL.
Note that the solenoid valves other than the solenoid valve SR in the hydraulic control apparatus 20, or specifically, the linear solenoid valves SL1 to SL5, SLU, and the solenoid valve SL interrupt the input port and the output port while de-energized (referred to as being “off” below), and communicate the same while energized (referred to as being “on” below). In other words, what is termed as a normally closed (N/C) type valve is used. In contrast, a normally open (N/O) type valve is used only in the solenoid valve SR.
In addition, the hydraulic control apparatus 20 is provided with a hydraulic servo 51 that can engage and disengage the first clutch C-1, a hydraulic servo 52 that can engage and disengage the second clutch C-2, a hydraulic servo 53 that can engage and disengages the third clutch C-3, a hydraulic servo 54 that can engage and disengage the fourth clutch C-4, a hydraulic servo 61 that can engage and disengage the first brake B-1, and a hydraulic servo 62 that can engage and disengage the second brake B-2. The engagement between the clutches and the hydraulic servos is based on the engagement pressures that are regulated and are supplied by the types of valves described above.
Next, the portions in the hydraulic control apparatus 20 that generate each type of primary pressure described above, that is, the line pressure, secondary pressure, and the modulator pressure, will be explained. Note that the portions that generate the line pressure, the secondary pressure, and the modulator pressure are identical to those of a common hydraulic control apparatus for an automatic transmission, and they are well-known. Thus, the explanation thereof will be brief.
The oil pump 21 generates oil pressure, for example, by being connected to and rotated by the pump impellor 7a of the torque converter 7 described above or being connected to and driven by the rotation of the engine, and drawing oil from an oil pan (not illustrated) through the strainer 22. In addition, the hydraulic control apparatus 20 is provided with a linear solenoid valve SLT (not illustrated), and this linear solenoid valve SLT uses the modulator pressure PMOD regulated by the solenoid modulator valve 27 described below as a primary pressure, and regulates and outputs a signal pressure PSLT that depends on the throttle opening degree.
The primary regulator valve 25 regulates the oil pressure generated by the oil pump 21 so as to attain a line pressure PL by discharging a portion thereof based on a signal pressure PSLT of the linear solenoid valve SLT that is input to the spool having applied thereto the urging force of the spring of the primary regulator valve 25. This line pressure PL is supplied to a manual shift valve 23, a solenoid modulator valve 27, the second clutch apply relay valve 32, the linear solenoid valve SL5, the first clutch apply control valve 41, a second clutch apply control valve 43, and a B-1 apply control valve 44, as described below.
In addition, the oil pressure discharged by the primal regulator valve 25 is regulated so as to attain a secondary pressure PSEC by discharging a portion thereof based on the signal pressure PSLT of the linear solenoid valve SLT described above that is input to the spool having the urging force of the spring of the secondary regulator valve 26 applied thereto by the secondary regulator valve 26. This secondary pressure PSEC is supplied to a lubricating oil path and the like (not illustrated), and at the same time is supplied to the lock-up relay valve 31 and used as the primary pressure for the control of the lock-up clutch 10.
In addition, the solenoid modulator valve 27 regulates the line pressure PL, which is regulated by the primary regulator valve 25, so as to attain respectively constant modulator pressures PMOD when the line pressure PL is equal to or greater than a prescribed pressure due to the urging force of the spring of the solenoid modulator valve 27. These modulator pressures PMOD are supplied as primary pressures to the linear solenoid valve SLT (not illustrated), the solenoid valve LS (normally closed), the solenoid valve SR (normally open), and the linear solenoid valve SLU (normally closed).
Configuration of Forward Shifting Function Portion in Hydraulic Control Apparatus
Next, the functional portion that mainly carries out the forward shifting control in the hydraulic control apparatus 20 according to an exemplary embodiment of the present invention will be explained with reference to FIG. 5. First, the manual shift valve 23 has a spool 23p that is mechanically (or electrically) driven by a shift lever that is provided at the driver's seat (not illustrated), and the line pressure PL described above is input to the input port 23a. When the shift position is set to the D (drive) range based on the operation of a shift lever, the input port 23a and the output port 23b communicate based on the position of the spool 23p, and the forward (D) range pressure PD is output from the output port 23b with the line pressure PL serving as the primary pressure.
The output ports 23b and 23c are connected to the input port SL1 a of the linear solenoid valve SL1, the input port SL3a of the linear solenoid valve SL3, the input port 34k of the first clutch apply relay valve 34, and the input port 35d of the B-2 apply control valve 35, which will be explained in detail below, and when driving in the forward range, the forward range pressure PD is output to these ports.
In addition, when the shift position is set to the R (reverse) range based on the operation of the shift lever, the input port 23a and the output port 23d communicate based on the position of the spool 23p, and the reverse (R) range pressure PR is output by the output port 23d, where the line pressure PL serves as the primary pressure for the reverse (R) range pressure PR. The output port 23d is connected to the input port 34i of the first clutch apply relay valve 34 and the input port 36d of the B-2 control valve 36, which will be explained in detail below, and while driving in the reverse range, the reverse range pressure PR is output to these ports.
Note that when the P (parking) range and the N (neutral) range have been set based on the operation of the shift lever, the input port 23a and the output ports 23b, 23c, and 23d are interrupted by the spool 23p, and thus the range pressure is not output.
The solenoid valve SR inputs a modulator pressure PMOD to the input port Sa (shared with the solenoid valve SL). During normal operation (except during engine braking in the first forward speed described below), the solenoid valve SR becomes energized and does not output a signal pressure PSR from the output port SRb. The solenoid valve SR outputs a signal pressure PSR from the output port SRb while de-energized, for example, during engine braking in the first forward speed or during the all-solenoids-off mode described below (refer to FIG. 2). When the output port SRb is connected to the oil chamber 32a of the second clutch apply relay valve 32, the oil chamber 34a of the first clutch apply relay valve 34, and the input port 34b, and turned off, the signal pressure PSR is output to the oil chamber and the ports, and as will be explained in detail below, when the first clutch apply relay valve 34 is locked at the right half position, the signal pressure PSR is also output to the oil chamber 35a of the B-2 apply control valve 35.
The linear solenoid valve (the engagement pressure control solenoid valve) SLU inputs the modulator pressure PMOD to the input port SLUa, and while energized, outputs the signal pressure PSLU from the output port SLUb (refer to FIG. 2). The output port SLUb is connected to the oil chamber 36a of the B-2 control valve 36 via the lock-up relay valve 31, and outputs the signal pressure PSLU to this oil chamber 36a when the lock-up relay valve 31 is in the right half position (refer to FIG. 4 and FIG. 7).
The linear solenoid valve (the first engagement pressure control solenoid valve) SL1 includes an input port SL1a that inputs a forward range pressure PD, an output port SL1b that regulates and outputs the forward range pressure PD as an engagement pressure PC1 to the hydraulic servo (the first hydraulic servo) 51 when energized, a feedback port SL1c, and a discharge port SL1d mainly for discharging the engagement pressure PC1 of the hydraulic servo 51. The discharge port SL1d is connected to a port 32f of the second clutch apply relay valve 32 described below, and during normal operation, the engagement pressure PC1 is drained by the drain port EX of the second clutch apply relay valve 32. Note that the output port SL1b is connected to the hydraulic servo 51 via the first clutch apply control valve 41 described below (refer to FIG. 4 and FIG. 6).
The linear solenoid valve (the second engagement pressure control solenoid valve) SL2 includes an input port SL2a that inputs the forward range pressure PD via the B-2 apply control valve 35 described below, an output port SL2b that regulates and outputs the forward range pressure PD to the hydraulic servo (the second hydraulic servo) 52 as the engagement pressure PC2 when energized, a feedback port SL2c, and a discharge port SL2d mainly for discharging the engagement pressure PC2 of the hydraulic servo 52. During normal operation, the discharge port SL2d communicates with the port 32d and port 32e of the second clutch apply relay valve 32, the port 34d of the first clutch apply relay valve 34, and the drain port EX, and the engagement pressure PC2 is drained by the drain port EX.
The linear solenoid valve (the third engagement pressure control solenoid valve) SL3 includes an input port SL3a that inputs the forward range pressure PD, an output port SL3b that regulates and outputs the forward range pressure PD to the hydraulic servo (the third hydraulic servo) 53 as the engagement pressure PC3 when energized, a feedback port SL3c, and a discharge port SL3d mainly for discharging the engagement pressure PC3 of the hydraulic servo 53. The discharge port SL3d is connected to the port 34e of the first clutch apply relay valve 34 described below, and during normal operation, the engagement pressure PC3 is drained by the drain port EX of the first clutch apply relay valve 34.
The linear solenoid valve (the fourth engagement pressure control solenoid valve) SL4 includes an input port SL4a that inputs the line pressure PL (lock pressure) that is fed through the second clutch apply relay valve 32 to be described below, an output port SL4b that regulates and outputs the line pressure PL to the hydraulic servo (the fourth hydraulic servo) 54 as the engagement pressure PC4 when energized, a feedback port SL4c, and a drain port EX that drains the engagement pressure PC4 of the hydraulic servo 54. Note that the output port SL4b is connected to the hydraulic servo 54 via the C-4 relay valve 45 and the second clutch apply control valve 43 (refer to FIG. 4, FIG. 6, and FIG. 7).
The linear solenoid valve (the engagement pressure control solenoid valve) SL5 includes an input port SL5a that inputs the line pressure PL, an output port SL5b that regulates and outputs the line pressure PL to the hydraulic servo 61 as the engagement pressure PB1 when energized, a feedback port SL5c, and a drain port EX that drains the engagement pressure PB1 of the hydraulic servo 61. Note that the output port SL5b is connected to the hydraulic servo 61 via the B-1 apply control valve 44, which will be described below (refer to FIG. 4 and FIG. 6).
The B-2 apply control valve 35 includes a spool 35p, a spring 35s that urges the spool 35p upward in the figure, and in addition, above the spool 35p in the figure, includes an oil chamber 35a, an input port 35b, an output port 35c, an input port 35d, an output port 35e, and an oil chamber 35f. The spool 35p of the B-2 apply control valve 35 is disposed in the right half position when the signal pressure PSR is input to the oil chamber 35a, and otherwise, is disposed in the left half position due to the urging force of the spring 35s. In addition, the spool 35p is fastened in the left half position irrespective of the input of the signal pressure PSR when any of the engagement pressures PC3, PC4, and PB1 described below are input to the oil chamber 35f. 
The forward range pressure PD is input to the input port 35d and the output port 35e is connected to the input port SL2a of the linear solenoid valve SL2. When the spool 35p is in the left half position, the forward range pressure PD is output to the linear solenoid valve SL2. In addition, the output port 35c is connected to the input port 36c of the B-2 control valve 36 described below, and when the signal pressure PSR is input to the oil chamber 35a and the spool 35p is at the right half position, the output port 35c outputs the forward range pressure PD to the B-2 control valve 36.
The B-2 control valve 36 includes a spool 36p and a spring 36s that urges this spool 36p upward in the figure, and in addition, above the spool 36p in the figure, includes an oil chamber 36a, an output port 36b, an input port 36c, an input port 36d, an output port 36e, and a feedback oil chamber 36f. The spool 36p of the B-2 apply control valve 36 is controlled so as to move from the right half position to the left half position when the signal pressure PSLU is input to the oil chamber 36a. 
When driving in the forward range (the first forward speed during engine braking), the forward range pressure PD is input to the input port 36c via the B-2 apply control valve 35, and the engagement pressure PB2 is regulated and output by the output port 36b based on the signal pressure PSLU of the oil chamber 36a and the feedback pressure of the oil chamber 36f. In addition, while driving in the reverse range, the reverse range pressure PR is input to the port 36d by the manual shift valve 23, and the engagement pressure PB2 is output by the output port 36e. 
The B-2 check valve 37 includes an input port 37a, an input port 37b, and an output port 37c, and one of either the oil pressure input to the input port 37a or the input port 37b is output by the output port 37c. Specifically, when the engagement pressure PB2 is input to the input port 37a from the output port 36b of the B-2 control valve 36, this engagement pressure PB2 is then output to the hydraulic servo 62 from the output port 37c. When the engagement pressure PB2 is input to the input port 37b from the output port 36c of the B-2 control valve 36, this engagement pressure PB2 is then output to the hydraulic servo 62 from the output port 37c. 
The first clutch apply relay valve 34 includes a spool 34p and a spring (second urging device) 34s that urges the spool 34p upward in the figure, and above the spool 34p in the figure, also includes an oil chamber 34a, an input port 34b, an output port 34c, an output port 34d, an output port 34e, an input port 34k, an input port 34f, an output port 34g, and an oil chamber 34j. 
In the oil chamber 34a, during normal operation (excluding engine braking in the first forward speed), when the solenoid valve SR is turned on, the signal pressure PSR is not input, and due to the urging force of the spring 34s, the spool 34p is set in the right half position. In addition, when the spool 34p is in the right half position, the engagement pressure PC1 is input from the linear solenoid valve SL1 to the input port 34f, the engagement pressure PC1 is output to the oil chamber 34j from the output port 34g, and the spool 34p is locked in the right half position.
While the spool 34p is in the right half position, the forward range pressure PD that is input to the input port 34k and the reverse range pressure PR that is input to the input port 34i are interrupted. In addition, when the spool 34p is locked in the right half position by the engagement pressure PC1, the spool 34p is maintained in the right half position even when the signal pressure PSR is input to the oil chamber 34a, and the signal pressure PSR that is input to the input port 34b is output to the oil chamber 35a of the B-2 apply control valve 35 from the output port 34c. In addition, the output port 34d and the output port 34e are connected to the discharge port SL3d of the linear solenoid valve SL3 and discharge port SL2d of the linear solenoid valve SL2 via the second clutch apply relay valve 32, which will be described below. When the engagement pressure PC3 is discharged by the linear solenoid valve SL3 and the engagement pressure PC2 is discharged by the linear solenoid valve SL2, the engagement pressure PC3 and the engagement pressure PC2 are input to and drained by the drain port EX.
In contrast, during the all-solenoids-off mode, which will be described in detail below, the signal pressure PSR is input to the oil chamber 34a, the engagement pressure PC1 from the linear solenoid valve SL1 is interrupted, and the spool 34p is set to the left half position. When this spool 34p is in the left half position, in the forward range, the forward range pressure PD that is input to the input port 34k is output from the output port 34d and the output port 34e, and is then output as reverse input pressure to the discharge port SL3d of the linear solenoid valve SL3 and the input port 34e of the second clutch apply relay valve 32, which will be explained below. In addition, in the reverse range, the reverse range pressure PR that is input to the input port 34i is output to the input port 35b of the B-2 apply control valve 35 from the output port 34h, and this reverse range pressure PR is output to the input port 36c of the B-2 control valve 36 via the B-2 apply control valve 35, which is in the left half position, without the signal pressure PSR being input to the oil chamber 35a. Thereby, as described above, even when the B-2 control valve 36 sticks, locks in the left half position, and the communication between the input port 36d and the output port 36e is interrupted, the reverse range pressure PR is reliably supplied to the hydraulic servo 62 by the communication between the input ports 36c and 36b. 
The second clutch apply relay valve 32 includes a spool (second spool) 32p, a spring 32s that urges the spool 32p upward in the figure, and above the spool 32p in the figure, also includes an oil chamber 32a, an input port 32b, an output port 32c, an output port 32d, an input port 32e, an input port 32f, and an oil chamber 32g. In addition, a lock pressure delay valve 33 that has a spool (third spool) 33p that can abut and press against the spool 32p is integrally provided at the bottom of the second clutch apply relay valve 32. The lock pressure delay valve 33 includes a spool 33p and a spring (first urging device) 33s that urges this spool 33p upward in the figure, and also includes an oil chamber 33a in which the oil pressure acts so as to press the spool 33p downward in the figure and an input port 33b that communicates with the oil chamber 32g of the second clutch apply relay valve 32. In addition, orifices (delay device) 71 and 72 are provided in the oil duct that connects the output port 32d of the second clutch apply relay valve 32 and the input port 33b of the lock pressure delay valve 33.
During normal operation (and during the all-solenoids-off mode while the engine is starting up as described below), the spool 32p of the second clutch apply relay valve 32 is set at the right half position due to the urging force of the spring 32s and the spring 33s. When the spool 32p is in the right half position, the line pressure PL that is input to the input port 32b is input to the input port SL4a of the linear solenoid valve SL4 from the output port 32c and to the oil chamber 33a and the input port 33b of the lock pressure delay valve 33, and the lock pressure delay valve 33 is locked in the left half position due to the oil pressure of the oil chamber 33a. As a result, because the oil chamber 33b and the oil chamber 32g communicate, the oil pressure from the oil chamber 33b is supplied to the oil chamber 32g, and the spool 32p is locked in the right half position.
In addition, when this spool 32p is in the right half position, the output port 32f is connected to the discharge port SL1d of the linear solenoid valve SL1, and when the engagement pressure PC1, is discharged by this linear solenoid valve SL1, the engagement pressure PC1, is input and drained from the drain port EX. Furthermore, the output port 32d is connected to the discharge port SL2d of the linear solenoid valve SL2, and at the same time, the input port 32e is connected to the output ports 34d and 34e of the first clutch apply relay valve 34. When the engagement pressure PC2 is discharged from the linear solenoid valve SL2, the engagement pressure PC2 is input from the output port 32d and is drained from the drain port EX of the first clutch apply relay valve 34 via the input port 32e. 
In contrast, after the engine start-up during the all-solenoids-off mode, which will be described in detail below, the spool 32p is in the left half position, the line pressure PL that is input to the input port 32b is interrupted, and then the input port 32e and the output port 32f communicate.
Operation of Each Forward Shift Speed
In the hydraulic control apparatus 20 having the functional portions that carry out the forward shift control described above, in the first forward speed while driving in the forward range, the linear solenoid valve SL1 is turned on, the forward range pressure PD that is input to the input port SL1a is regulated and output to the hydraulic servo 51 as the engagement pressure PC1, and the first clutch C-1 is engaged. Thereby, coupled with the locking of the one-way clutch F-1, the first forward speed is attained.
In addition, while using engine braking in the first forward speed, the solenoid valve SR is turned off and the signal pressure PSR is output from the output port SRb. At this time, the second clutch apply relay valve 32 is locked at the right half position by the line pressure PL (lock pressure), and the first clutch apply relay valve 34 is locked at the right half position by the engagement pressure PC1. Thus, the signal pressure PSR of the solenoid valve SR is input to the oil chamber 35a of the B-2 apply control valve 35, the forward range pressure PD of the input port 35b is input to the input port 36c of the B-2 control valve 36 from the output port 35c, and the spool 36p is controlled by the signal pressure PSLU of the linear solenoid valve SLU. Thus, the forward range pressure PD is regulated and output to the hydraulic servo 62 via the B-2 check valve 37 as engagement pressure PB2, and the second brake B-2 is locked. Thereby, coupled with the engagement of the first clutch C-1, the engine brake in the first forward speed is attained.
In the second forward speed, in addition to the linear solenoid valve SL1 being turned on, the linear solenoid valve SL5 is turned on, the line pressure PL that is input to the input port SL5a is regulated and output to the hydraulic servo 61 as the engagement pressure PB1, and the first brake B-1 is engaged. Thereby, coupled with the engagement of the first clutch C-1, the second forward speed is attained.
Note that in the forward range, in the neutral control (N cont) which enhances the fuel economy by releasing the first clutch C-1, control that is similar to that of the second forward speed is carried out, and the linear solenoid valve SL1 regulates the engagement pressure PC1 such that the first clutch C-1 remains just prior to engaging (a state in which the rotational play has been reduced). Thereby, the neutral state is set such that, the second forward speed is formed immediately after the neutral control (N cont) is released.
In the third forward speed, in addition to the linear solenoid valve SL1 being turned on, the linear solenoid valve SL3 is turned on, the forward range pressure PD that is input to the input port SL3a is regulated and output to the hydraulic servo 53 as the engagement pressure PC3, and the third clutch C-3 is engaged. Thereby, coupled with the engagement of the first clutch C-1, the third forward speed is attained.
In the fourth forward speed, in addition to the linear solenoid valve SL1 being turned on, the linear solenoid valve SL4 is turned on, the line pressure PL that is input to the input port SL4a via the second clutch apply relay valve 32 is regulated and output to the hydraulic servo 54 as engagement pressure PC4, and the fourth clutch C-4 is engaged. Thereby, coupled with the engagement of the first clutch C-1, the fourth forward speed is attained.
Note that, in the worst case, when the fourth forward speed is not attained, a state may have occurred in which the line pressure PL is not input to the input port SL4abecause the second clutch apply relay valve 32 is stuck in the left half position, and thus the fourth clutch C-4 is not engaged, and the transition to the all-solenoids-off mode to be described below is thereby prohibited.
Specifically, when the spool 32p of the second clutch apply relay valve 32 is in the left half position, in the all-solenoids-off mode to be described below, the forward range pressure PD, which is input to the input port 32e of the second clutch apply relay valve 32 as reverse input pressure, is input to the discharge port SL1d of the linear solenoid valve SL1 from the output port 32f as reverse input pressure, output from the output port SL1b, supplied to the hydraulic servo 51, and thereby the first clutch C-1 is engaged. That is, due to the third forward speed being attained, in this state, when transitioning to the all-solenoids-off mode at a high speed equal to or greater than, for example, the fifth forward speed, downshifting of two or more speeds will occur.
In the fifth forward speed, in addition to the linear solenoid valve SL1 being turned on, the linear solenoid valve SL2 is turned on, the forward range pressure PD, which is input to the input port SL2a via the B-2 apply control valve 35, is regulated and output to the hydraulic servo 52 as the engagement pressure PC2, and the second clutch C-2 is engaged. Thereby, coupled with the engagement of the first clutch C-1 described above, the fifth forward speed is attained.
In the sixth forward speed, in addition to the linear solenoid valve SL2 being turned on, the linear solenoid valve SL4 is turned on, the line pressure PL, which is input to the input port SL4a via the second clutch apply relay valve 32, is regulated and output to the hydraulic servo 54 as the engagement pressure PC4, and the fourth clutch C-4 is engaged. Thereby, coupled with the engagement of the second clutch C-2 described above, the sixth forward speed is attained.
Note that at this time, similarly, when the sixth forward speed has not been attained, a state may have occurred in which the line pressure PL is not input to the input port SL4a because the second clutch apply relay valve 32 is stuck in the left half position, and transitioning to the all-solenoids-off mode is prohibited.
Note that similarly while the spool 32p of the second clutch apply relay valve 32 is in the left half position, in the all-solenoids-off mode described below, the forward range pressure PD, which is input to the input port 32e of the second clutch apply relay valve 32 as reverse input pressure, is input to the discharge port SL1d of the linear solenoid valve SL1 from the output port 32f as reverse input pressure, is then output by the output port SL1b, supplied to the hydraulic servo 51, and the first clutch C-1 is thereby engaged. That is, due to the third forward speed being attained, in this state, when transitioning to the all-solenoids-off mode at a high speed equal to or greater than, for example, the fifth forward speed, downshifting of two or more speeds will occur.
In the seventh forward speed, in addition to the linear solenoid valve SL2 being turned on, the linear solenoid valve SL3 is turned on, the forward range pressure PD, which is input to the input port SL3a, is regulated and output to the hydraulic servo 53 as the engagement pressure PC3, and the clutch C-3 is engaged. Thereby, coupled with the engagement of the second clutch C-2 described above, the seventh forward speed is attained.
In the eighth forward speed, in addition to the linear solenoid valve SL2 being turned on, the linear solenoid valve SL5 is turned on, the line pressure PL, which is input to the input port SL5a, is regulated and output to the hydraulic servo 61 as the engagement pressure PB1, and the first brake B-1 is engaged. Thereby, coupled with the engagement of the second clutch C-2 described above, the eighth forward speed is attained.
Note that, in the worst case, when the fifth forward speed through the eighth forward speed are not attained, a state may have occurred in which the forward range pressure PD is not input to the input port SL2a because the B-2 apply control valve 35 is stuck at the right half position, and thus, the second clutch C-2 is not engaged. When such a state has been identified, a fail-safe operation will be carried out.
Configuration of the Simultaneous Engagement Prevention Mechanism Portion in the Hydraulic Control Apparatus
Next, the functional portion in the hydraulic control apparatus 20 that mainly carries out the simultaneous engagement prevention will be explained with reference to FIG. 6. A first clutch apply control valve 41 is interposed between the output port SL1b of the linear solenoid valve SL1 and the hydraulic servo 51 as described above. The output port SL3b of the linear solenoid valve SL3 is directly connected to the hydraulic servo 53. A second clutch apply control valve 43 is interposed between the output port SL4b of the linear solenoid valve SL4 and the hydraulic servo 54 as described above. The B-1 apply control valve 44 is interposed between the output port SL5b of the linear solenoid valve SL5 and the hydraulic servo 61 as described above.
In addition, as described above, the B-2 apply control valve 35 and the linear solenoid valve SL3 are interposed between the manual shift valve 23 (refer to FIG. 4 and FIG. 5) and the hydraulic servo 52, and at the same time, the B-2 apply control valve 35, the B-2 control valve 36, and the B-2 check valve 37 are interposed between the manual shift valve 23 and the hydraulic servo 62.
The first clutch apply control valve 41 includes a spool 41p whose land portion is formed such that the diameter thereof gradually becomes larger from the top to the bottom of the figure, a spring 41sa that urges the spool 41p upwards in the figure, a plunger 41r that can abut the spool 41p, and a spring 41sb that is disposed in a compressed state between the spool 41p and the plunger 41r. In addition, in sequence from the above of the spool 41p in the figure, the first clutch apply control valve 41 includes an oil chamber 41a, an oil chamber 41b, an oil chamber 41c, an input port 41d, an output port 41e, and an oil chamber 41f. 
The engagement pressure PC2 that is supplied to the hydraulic servo 52 is input to the oil chamber 41a, and the largest engagement pressure among the PC3, PC4, and PB1 engagement pressures that are supplied to the hydraulic servos 53, 54, and 61 are input to the oil chamber 41 b by the signal check valve 42, and furthermore, the engagement pressure PC1 to be supplied to the hydraulic servo 51 is input to the oil chamber 41c. In contrast, the line pressure PL is input to the oil chamber 41f, and coupled with the urging force of the spring 41sa, the spool 41p is urged upward (to the left half position).
Thereby, for example, when the engagement pressure PC1 that is input to the oil chamber 41c, the engagement pressure PC2 that is input into the oil chamber 41, or any of the engagement pressures PC1, PC3, and PB1 that are input to the oil chamber 41f are simultaneously input, the input port 41d is interrupted because the line pressure PL of the oil chamber 41f and the urging force of the spring 41sa are overcome, and the supply of the engagement pressure PC1 to the hydraulic servo 51 is stopped. Thus, the simultaneous engagement between the first clutch C-1, the second clutch C-2, and the third clutch C-3, the simultaneous engagement between the first clutch C-1, the second clutch C-2, and the fourth clutch C-4, and the simultaneous engagement between the first clutch C-1, the second clutch C-2, and the first brake B-1 are prevented, and the engagement between the second clutch C-2 and the third clutch C-3, the second clutch C-2 and the fourth clutch C-4, and the second clutch C-2 and the first brake B-1 are permitted.
Note that when no oil pressure is generated because the engine is stopped, because the spring 41sb locks only the plunger 41r in the right half position, during normal operation, the plunger 41r of the first clutch apply control valve 41 being supported in the left half position is prevented, and in cases other than failure, when no oil pressure is generated because the engine has stopped, while operating during a failure, the prevention of an actual hindrance when actually moving to the right half position can be implemented by moving only the plunger 41r to the right half position.
The second clutch apply control valve 43 includes a spool 43p whose land portion is formed such that the diameter thereof gradually becomes larger from the top to the bottom of the figure, a spring 43sa that urges the spool 43p upwards in the figure, a plunger 43r that can abut the spool 43p, and a spring 43sb that is disposed in a compressed state between the spool 43p and the plunger 43r. In addition, in sequence from the above of the spool 43p in the figure, the second clutch apply control valve 43 includes an oil chamber 43a, an oil chamber 43b, an input port 43c, an output port 43d, and an oil chamber 43e. 
The engagement pressure PC3 that is supplied to the hydraulic servo 53 is input to the oil chamber 43a, and the engagement pressure PC4 that is supplied to the hydraulic servo 54 is input to the oil chamber 43b. In contrast, the line pressure PL is input to the oil chamber 43e, and coupled with the urging force of the spring 43sa, the spool 43p is pressed upward (to the left half position).
Thereby, when, for example, the engagement pressure PC4 is input to the oil chamber 43b and the engagement pressure PC3 is input to the oil chamber 41asimultaneously, the input port 43c is interrupted due to the line pressure PL of the oil chamber 41e and the urging force of the spring 43sa being overcome, the supply of the engagement pressure PC4 to the hydraulic servo 54 is stopped, and the simultaneous engagement between the third clutch C-3 and the fourth clutch C-4 is thereby prevented, and the engagement of the third clutch C-3 is thereby permitted.
Note that when no oil pressure is generated because the engine is stopped, the spring 43sb locks only the plunger 43r in the right half position, and thus during normal operation, the plunger 43r of the second clutch apply control valve 43 being maintained continuously in the left half position is prevented. In cases other than failure, when no oil pressure is generated because the engine has stopped, only the plunger 43r is operated in the right half position, and thus while operating during a failure, the prevention of an actual hindrance when actually moving to the right half position can be implemented by moving only the plunger 43r to the right half position.
The B-1 apply control valve 44 includes a spool 44p whose land portion is formed such that the diameter thereof gradually becomes larger from the top to the bottom of the figure, a spring 44sa that urges the spool 44p upward in the figure, a plunger 44r that can abut the spool 44p, and a spring 44sb that is disposed in a compressed state between the spool 44p and the plunger 44r. In addition, in sequence from the above of the spool 44p in the figure, the B-1 apply control valve 44 includes an oil chamber 44a, an oil chamber 44b, an oil chamber 44c, an input port 44d, an output port 44e, and an oil chamber 44f. 
The engagement pressure PC4 that is supplied to the hydraulic servo 54 is input to the oil chamber 44a, the engagement pressure PC3 that is supplied to the hydraulic servo 53 is input to the oil chamber 44b, and the engagement pressure PB1 that is supplied to the oil chamber 61 is input to the oil chamber 43c. In contrast, the line pressure PL is input to the oil chamber 44f, and coupled with the urging force of the spring 44sa, the spool 44p is pressed upward (to the left half position).
In the B-1 apply control valve 44, while the engagement pressure PB1 that is supplied to the hydraulic servo 61 of the first brake B-1 is input to the oil chamber 44c, the spool 44p and the plunger 44r are in the right half position when one of the engagement pressure PC3 of the third clutch C-3 and the engagement pressure PC4 of the fourth clutch C-4, which are not simultaneously engaged by the second clutch apply control valve 43, is input to the oil chamber 44a or the oil chamber 44b. 
Thereby, when, for example, the engagement pressure PB1 is input to the oil chamber 44c, the engagement pressure PC4 is input to the oil chamber 44a, or the engagement pressure PC3 is input to the oil chamber 44b simultaneously, due to the input port 44d is interrupted because the line pressure PL of the oil chamber 44f and the urging force of the spring 44sa being overcome, and the supply of the engagement pressure PB1 to the hydraulic servo 61 is stopped. Thus, the simultaneous engagement of the first brake B-1, the third clutch C-3, and the fourth clutch C-4 is prevented, and the engagement of the third clutch C-3 and the fourth clutch C-4 is permitted.
Note that when no oil pressure is generated because the engine is stopped, the spring 44sb locks only the plunger 44r in the right half position, and thus during normal operation, the plunger 44r of the B-1 apply control valve 44 being held continuously in the left half position is prevented. In cases other than failure, when no oil pressure is generated because the engine has stopped, while operating during a failure, the prevention of an actual hindrance when actually moving to the right half position can be implemented by moving only the plunger 44r to the right half position.
The B-2 apply control valve 35 is locked in the left half position when any of the engagement pressures PC3, PC4 , or PB1 are input to the oil chamber 35f as described above, irrespective of the input of the signal pressure PSR. In addition, when none of the engagement pressure PC3, PC4 , or PB1 is input to the oil chamber 35f and the signal pressure PSR of the solenoid valve SR is input, the B-2 apply control valve 35 is set to the right half position due to the urging force of the spring 35s being overcome.
Thereby, when any of the engagement pressures PC3, PC4 , or PB1 are input to the oil chamber 35f, the forward range pressure PD is supplied only to the linear solenoid valve SL2, and thus because the forward range pressure PD is not supplied to the hydraulic servo 62, the simultaneous engagement of any of the third clutch C-3, the fourth clutch C-4, and the first brake B-1 with the second brake B-2 is prevented. In addition, when the input port 35d and the output port 35e to SL2 are communicating, because the communication between the input port 35d and the output port 35c to the B-2 control valve 36 is interrupted, the simultaneous engagement between the second clutch C-2 and the second brake B-2 is prevented.
As has been described above, the simultaneous engagement of two among the third clutch C-3, the fourth clutch C-4, and the first brake B-1 can be prevented by the second clutch apply control valve 43 and the B-1 apply control valve 44. In addition, the simultaneous engagement of any of the third clutch C-3, the fourth clutch C-4, and the first brake B-1 with the second brake B-2 can be prevented, and the simultaneous engagement between the second clutch C-2 and the second brake B-2 can be prevented by the B-2 apply control valve 35. Furthermore, the simultaneous engagement of any among the third clutch C-3, the fourth clutch C-4, the first brake B-1 with the second clutch C-2 and the first clutch C-1 is prevented by the first clutch apply control valve 41. Thereby, in the forward range, necessarily only the first clutch C-1 can engage simultaneously with the second brake B-2, while the simultaneous engagement of three friction engagement elements (clutches and brakes) can be reliably prevented.
Configuration of the Reverse Shifting Function and the Lock-up Function Portions in the Hydraulic Control Apparatus
Next, the functional portions that mainly carry out the reverse shifting control and the lock-up control in the hydraulic control apparatus 20 according to an exemplary embodiment of the present invention will be explained with reference to FIG. 7. Note that the manual shift valve 23, the linear solenoid valve SL4, the B-2 control valve 36, the B-2 check valve 37 and the like have been explained in relation to the forward shift control described above, and thus the explanation thereof has been omitted.
The solenoid valve SL is a normally closed valve, and inputs a modulator pressure PMOD to the input port Sa (also used by the solenoid valve SR described above). The solenoid valve SL is turned on while the vehicle is operating in reverse and while the lock-up clutch 10 is actuated, and outputs the signal pressure PSL from the output port SLb. The output port SLb is connected to the oil chamber 31a of the lock-up relay valve 31 described below and the oil chamber 45a of the C-4 relay valve 45, and while turned on, outputs the signal pressure PSL to the oil chambers 31a and 45a. 
The lock-up relay valve 31 includes a spool 31p and a spring 31s that urges the spool 31p upward in the figure, and above the spool 31p in the figure, includes an oil chamber 31a, an input port 31b, an output port 31c, an input port 31d, an input port 3 1e, an input/output port 31f, and an oil chamber 31g. 
During the disengagement of the lock-up clutch 10 while the vehicle is traveling forward, the signal pressure PSL is not input to the oil chamber 31a because the solenoid valve SL is turned off, and due to the urging force of the spring 31s, the spool 31p is set in the right half position. In addition, when the spool 31p is in the right half position, the signal pressure PSLU is input to the input port 31b from the linear solenoid valve SLU, and the signal pressure PSLU is output to the oil chamber 36a of the B-2 control valve 36 from the output port 31c. 
In addition, a secondary pressure PSEC, which is regulated by the secondary regulator valve 26 described above, is input to the input port 31e, and when the spool 31p is set in the right half position, the secondary pressure PSEC is output to the lock-up-off port 10a of the torque converter 7 from the input/output port 31d. The secondary pressure PSEC that is input into the torque converter 7 from the port 10a is circulated and discharged from the port 10a, which is also used for lock-up-on, and drained by the drain port (not illustrated) via the input/output port 31f (or supplied to a lubricating fluid path or the like (not illustrated)).
During the engagement of the lock-up clutch 10 while traveling forward, when the solenoid valve SL is tuned on, the signal pressure PSL is input to the oil chamber 3a, and the spool 31p is set in the left half position due to the urging force of the spring 31s being overcome. Thus, the signal pressure PSLU that is input to the input port 31b is interrupted, and at the same time, the secondary pressure PSEC that is input to the input port 31e is output to the lock-up-on port 10b from the input/output port 31f, and the lock-up clutch 10 is engaged by being pressed.
When the vehicle is traveling in reverse, the reverse range pressure PR is input to the oil chamber 31g from the manual shift valve 23, and the spool 31p of the lock-up relay valve 31 is locked in the right half position. Thereby, even if the signal pressure PSL is input to the oil chamber 31a, the urging force of the spring 31s and the reverse range pressure PR of the oil chamber 31g are coupled, and the spool 31p is maintained in the right half position.
The C-4 relay valve 45 includes a spool 45p and a spring 45s that urges the spool 45p downward in the figure, and above the spool 45p in the figure, includes an oil chamber 45a, an input port 45b, an output port 45c, an input port 45d, and an oil chamber 45e. 
When the vehicle is traveling in the forward range (that is, when the reverse range pressure PR is not output) and the solenoid valve SL is turned off (that is, while the lock-up clutch 10 is disengaged), the signal pressure PSL is not output to the oil chamber 45a, but the spool 45p is set in the left half position due to the urging force of the spring 45s. In addition, when the vehicle is traveling in the forward range, even if the solenoid valve SL is turned on (that is, while the lock-up clutch 10 is engaged) and the signal pressure PSL is input to the oil chamber 45a, coupled with the urging force of the spring 45s, the spool 45p is set in the left half position.
When the spool 45p is in the left half position, the engagement pressure PC4 from the linear solenoid valve SL4 is input to the input port 45d and is output to the hydraulic servo 54 from the output port 45c, and thus, in the fourth forward speed and the sixth forward speed, the hydraulic servo 54 is regulated and controlled linearly by the linear solenoid valve SL4.
Next, the control during reverse travel will be explained. In the reverse range during normal operation, the reverse range pressure PR is output from the output port 23d of the manual shift valve 23. Thus, in the C-4 relay valve 45, the reverse range pressure PR is input to the oil chamber 45e, but since the solenoid valve SL is turned on, the signal pressure PSL is input to the oil chamber 45a, and coupled with the urging force of the spring 45s, the spool 45p is set in the left half position. Thereby, even during reverse travel, the engagement pressure PC4 from the linear solenoid valve SL4 is output to the hydraulic servo 54.
In addition, in the B-2 control valve 36, because the signal pressure PSLU of the linear solenoid valve SLU is not output, the B-2 control valve 36 is locked in the right half position, and the reverse range pressure PR that is input to the input port 36d is output as the engagement pressure PB2 from the output port 36e. The engagement pressure PB2 that is output from the output port 36e is input to the input port 37b of the B-2 check valve 37, and is output by the output port 37c to supply the hydraulic servo 62. Thereby, the fourth clutch C-4 and the second brake B-2 are engaged, and the second reverse speed is attained.
Note that, in the reverse range, there are cases where the engagement pressure PB2 from the output port 36e is not output due to the B-2 control valve 36 becoming stuck in the left half position. Thus, when the sticking of the B-2 control valve 36 is detected by, for example, the reverse speed not being attained, the B-2 control valve 36 is switched to the left half position by turning the solenoid valve SR off and by applying the signal pressure PSR to the first clutch apply relay valve 34, and thereby the reverse range pressure PR is input to the input port 35b via the port 34i and the port 34h, and the reverse range pressure PR is output to the B-2 control valve 36 from the output port 35c. 
However, the manual shift valve 23 is constructed so as to be connected to a shift lever disposed at the driver's seat via a detent mechanism and a link mechanism (or a shift-by-wire apparatus) that are not illustrated, the spool 23p is driven in the spool movement direction (linear movement direction) by a linkage to a fan-shaped detent plate, which is rotated by the operation of the shift lever. At the same time, due to the detent lever that urges the detent plate in each shift range position, the manual shift valve 23 does not stop at an intermediate position within these range positions. This detent plate that is rotated has a support axle that is integrally attached at the center of rotation, and an angle sensor that detects the angle of rotation of the support axle is provided on the end of this support axle. Specifically, this angle sensor detects the angle of the detent plate, that is, it can detect the spool position of the manual shift valve 23 that is driven by the linkage to the detent plate.
Based on the detection of this angle sensor (below, referred to simply as a “spool position sensor” to facilitate understanding), when detecting that the vehicle is operating in the forward range, the linear solenoid valve SL1, for example, is turned on by an electronic control unit (for example, an ECU), the first forward speed is attained as described above (a second forward speed or a third forward speed may be formed). When it is detected that the vehicle is traveling in the reverse range, the solenoid valve SL and the linear solenoid valve SL4 are turned on, and the second reverse speed described above is attained.
However, for example, in the case in which the spool position sensor has failed, the shift position cannot be detected, and there is a concern that whether one of the solenoid valves should be turned on cannot be determined. In addition, in the case in which, for example, the shift position cannot be detected, none of the solenoid valves are turned on, which device that engagement pressure is not supplied to any of the hydraulic servos, and thus, the vehicle is in a neutral state in which the drive power from the engine is not transferred to the vehicle wheels via the shift change mechanism 2.
Thus, in the hydraulic control apparatus according to an exemplary embodiment of the present invention for an automatic transmission, in the case in which the shift position cannot be not detected, the solenoid valve that is turned on is identical to the first forward speed, that is, only the manual solenoid valve SL1 is turned on. At this time, if the actual shift position is in the forward range, the first forward speed described above is formed as explained above, and thus the explanation of the first forward speed is omitted.
In the case in which the shift position cannot be detected and the actual shift position is in the reverse range, because first the linear solenoid valve SL1 is turned on and the forward range pressure PD is not supplied to the input port SL1a of the linear solenoid valve SL1 (refer to FIG. 4 and FIG. 5), the engagement pressure PC1 is not supplied to the hydraulic servo 51, and thus, the first clutch C-1 is not engaged.
In contrast, as shown in FIG. 7, in the case in which the solenoid valve SL and the linear solenoid valve SL4 are turned off, after the reverse range pressure PR has been output from the output port 23d of the manual shift valve 23, it is input to the oil chamber 45e of the C-4 relay valve 45, and against the urging force of the spring 45s, the spool 45p is set in the right half position. Thereby, the reverse range pressure PR that is input to the input port 45b is output from the output port 45c, is supplied to the hydraulic servo 54, and the fourth clutch C-4 is thereby engaged.
In addition, in the B-2 control valve 36, the spool 36p is set in the right half position due to the urging force of the spring 36s, the reverse range pressure PR that is input to the input port 36d is output from the output port 36e and supplied to the hydraulic servo 62 via the B-2 check valve 37, and the second brake B-2 is thereby engaged. Thus, the fourth clutch C-4 and the second brake B-2 are engaged and the second reverse speed is attained.
In this manner, even in the case in which, for example, the shift position cannot be detected, in the present exemplary embodiment, the hydraulic control apparatus 20 for an automatic transmission, due to the actual spool position in the manual shift valve 23, the first forward speed or the second reverse speed can be attained.
Note that in the present exemplary embodiment, the case was explained in which the spool position sensor fails and the linear solenoid valve SL4 and the solenoid valve SL are turned off (de-energized) due to carrying out forward start control irrespective of the shift position. However, during the all-solenoids-off fail mode described below in detail, the case is the same, that is, even when the linear solenoid valve SL4 and the solenoid valve S1 are turned off due to the all-solenoids-off condition, the engagement of the fourth clutch C-4 is enabled due to the reverse range pressure PR.
Operation during All-Solenoids-Off Fail
Next, the all-solenoids-off fail state, which is an essential aspect of an exemplary embodiment of the present invention, will be explained with reference to FIG. 5 and FIG. 8A to FIG. 8C. In the present hydraulic control apparatus 20 according to an exemplary embodiment of the present invention for an automatic transmission, excluding the case in which, for example, the sticking of the linear solenoid valve SL4 described above has been detected, when a failure of the other solenoid valves, any of the switching valves, any of the control valves or the like, has been detected, all of the solenoid valves transit to the all-solenoids-off fail mode. Note that, for example, even in the case in which a severed wire or short has occurred, similarly all of the solenoids are set to off, and thus in the present specification, these states are also included in the all-solenoids-off fail mode.
First, during normal operation, even if the engine starts up and the line pressure PL is generated from the primary regulator valve 25 by actuating the oil pump 21 because the ignition and the solenoid valve SR have been turned on, the signal pressure PSR is not output. Thus, as shown in FIG. 8A, in the second clutch apply relay valve 32, the urging force of the spring 32s and, via the spool 33p, the urging force of the spring 33s, act upward in the drawing on the spool 32p, and the spool 32p is thereby set in the upper position (second position).
When this spool 32p is in the upper position, the line pressure PL that is input to the input port 32b is output as lock pressure from the output port 32c to the input port SL4a of the linear solenoid valve SL4, the oil chamber 33a of the lock pressure delay valve 33, and the input port 33b. Thus, as shown in FIG. 8B, the spool 33p of the lock pressure delay valve 33 is pressed towards to the lower position (the communicating position), which is in the lower part of the figure, the input port 33b and the oil chamber 32g are communicated, the line pressure PL is input to the oil chamber 32g as a lock pressure, and the spool 32p is locked in the upper position. In this locked state, the engine is stopped, the oil pump 21 is stopped, and the locked state is maintained until the line pressure PL is no longer generated.
Here, for example, when the all-solenoids-off fail mode occurs due to some cause while a vehicle is traveling in the forward range, in the second clutch apply relay valve 32, all of the solenoid valves are turned off (a failure has occurred) when the spool 32p is locked by the lock pressure based on the line pressure PL. At this time, because all of the solenoid valves are turned off, only the solenoid valve SR, which is a normally open valve, outputs the signal pressure PSR, and because the other solenoid valves have stopped the output of the signal pressures and the engagement pressures, in particular, in the linear solenoid valves SL1, SL2, and SL3, the output ports SL1b, SL2b, and SL3b and the discharge ports SL1d, SL2d, and SL3d, are communicated (refer to FIG. 5).
In contrast, in the second clutch apply relay valve 32, as shown in FIG. 8B, the signal pressure PSR is input to the oil chamber 32a, but because the line pressure PL is input to the oil chamber 32g as lock pressure, the spool 32p is maintained locked in the upper position.
Note that in the worst case, even if the lock pressure delay valve 33 is stuck in the upper position in the upper portion of the figure and the line pressure PL is not input as lock pressure to the oil chamber 32g of the second clutch apply relay valve 32, the spool 33p of the lock pressure delay valve 33 is structured so as to abut the spool 32p of the second clutch apply relay valve 32, and the state in which the spool 32p is similarly thereby locked in the upper position is maintained.
In addition, as shown in FIG. 5, in the first clutch apply relay valve 34, the signal pressure PSR of the solenoid valve SR is input to the oil chamber 34a, and the spool 34p is set in the left half position (the reverse input pressure output position) because the urging force of the spring 34s is overcome. Thereby, the forward range pressure PD that is input to the input port 34k is output from the output ports 34d and 34e as reverse input pressure, and then is input to the discharge port SL3d of the linear solenoid valve SL3 and the input port 32e of the second clutch apply relay valve 32.
The forward range pressure PD that has been input to the discharge port SL3d of the linear solenoid valve SL3 as reverse input pressure is output from the output port SL3b of the linear solenoid valve SL3, is supplied to the hydraulic servo 53, and the third clutch C-3 is thereby engaged. In addition, as shown in FIG. 8B, because the spool 32p is locked in the upper position, the forward range pressure PD that is input as reverse input pressure to the input port 32e of the second clutch apply relay valve 32 is input to the discharge port SL2d of the linear solenoid valve SL2 from the output port 32d as the reverse input pressure, then output from the output port SL2b, supplied to the hydraulic servo 52, and the second clutch C-2 is thereby engaged.
As shown above, in the all-solenoids-off fail mode while the vehicle is traveling in the forward range, the seventh forward speed, in which the second clutch C-2 and the third clutch C-3 have been engaged, is set.
In contrast, subsequently, for example, when the vehicle is temporarily stopped and the engine is stopped, the line pressure PL is no longer generated, and as shown in FIG. 8A, in the second clutch apply relay valve 32 and the lock pressure delay valve 33, both the spool 32p and the spool 33p are set in the upper position due to the urging pressure of the spring 32s and the spring 33s. In addition, subsequent to this, when the engine is restarted, the oil pump 21 is actuated and line pressure PL is thereby generated, but as shown in FIG. 8C, because the solenoid valve SR is turned off and the signal pressure PSR is input to the oil chamber 32a, the signal pressure PSR acts downward in the figure against the urging force of the spring 32s and the urging force of the spring 33s, and the spool 32p is switched to the lower position. Thereby, the line pressure PL is not output from the output port 32c because the input port 32b is interrupted, and the line pressure PL is not input to the oil chamber 32g as lock pressure.
In addition, in this case, even if, for example, the line pressure PL flows from the input port 32b and a small amount of the lock pressure is output from the output port 33c before the spool 32p is switched to the lower position, because the inflow of lock pressure from the orifices 71 and 72 is dampened and time is required for the spool 33p of the lock pressure delay valve 33 to be switched to the lower position, and the input of the lock pressure to the oil chamber 32g is delayed, the signal pressure PSR is input to the oil chamber 32a before the spool 32p is locked in the upper position, and the spool 32p is reliably switched thereby to the lower position.
Note that in the present exemplary embodiment, the case was explained in which the line pressure PL acted as a lock pressure on the oil chamber 33a of the lock pressure delay valve 33, but this may be modified such that the forward range pressure PD will act instead of the lock pressure (i.e. the line pressure PL). In this case, because the engine is restarted and the oil pressure does not act on the oil chamber 33a until the shift position is set in the forward range, inputting the lock pressure to the oil chamber 32g can be delayed more reliably.
In addition, in the second clutch apply relay valve 32, when the spool 32p is switched to the lower position, the forward range pressure PD that has been output from the output ports 34d and 34e of the first clutch apply relay valve 34 described above and input to the input port 32e is input, as shown in FIG. 5, as a reverse input pressure to the discharge port SL1d of the linear solenoid valve SL1 from the output port 32f, is output from the output port SL1b, is supplied to the hydraulic servo 51, and the first clutch C-1 is thereby engaged.
As explained above, after the engine has restarted in the all-solenoids-off fail mode, the third forward speed, in which the first clutch C-1 and the third clutch C-3 have been engaged, is set.
Another Embodiment
Next, another embodiment in which a portion of the embodiment described above is modified will be explained with reference to FIG. 9A to FIG. 9E. In this embodiment, instead of the second clutch apply relay valve 32 and the lock pressure delay valve 33 described above, the second clutch apply relay valve (the second switching valve) 132 and the lock pressure inflow valve 133 shown in FIG. 9A to FIG. 9E are used. In addition, the solenoid valve SR is a normally closed valve.
As shown in FIG. 9A, in the second clutch apply relay valve 132, the spool 132p is urged upward in the figure due to the spring 132s, and at the same time, in the lock pressure inflow valve 33, the spool 133p is urged upward in the figure due to the spring 133s that is disposed in a compressed state with respect to the spool 132p, and the oil chamber 133a is connected to the output port SRb of the solenoid valve SR.
In addition, the line pressure PL is input to the input port 132c, and at the same time, the output port 132b is connected to oil chamber 132a and the input port SL4a of the linear solenoid valve SL4. Furthermore, the input port 132e is connected to the output port 34d of the first clutch apply relay valve 34, the output port 132d is connected to the discharge port SL2d of the linear solenoid valve SL2, and the output port 132f is connected to the discharge port SL1d of the linear solenoid valve SL1.
First, as shown in FIG. 9A, while the engine is stopped and the oil pressure is not generated because the oil pump 21 is stopped, both the spool 132p and the spool 133p are set in the upper position. In addition, when the engine is started during normal operation, as shown in FIG. 9B, the solenoid valve SR is temporarily turned on and the signal pressure PSR is input to the oil chamber 133a. Thereby, both the spool 132p and the spool 133p are set in the lower position, and the line pressure PL is input to the input port 132c, is output from the output port 132b as lock pressure, and flows into the oil chamber 132a. 
Subsequently, in the normal state of normal operation , as shown in FIG. 9C, the line pressure PL that is input to the oil chamber 132a as lock pressure locks the spool 132p in the lower position (second position). In this state, similarly to the embodiment described above, the line pressure PL is output to the input port SL4a of the linear solenoid valve SL4. In addition, the engagement pressure PC2 that is discharged from the discharge port SL2d of the linear solenoid valve SL2 is output to the drain port EX of the first clutch apply relay valve 34 via the output port 132d and the input port 132e, and drained. Furthermore, the engagement pressure PC1 that is discharged from the discharge port SL1d of the linear solenoid valve SL1 is output to the drain port EX from the output port 132f, and drained.
Here, for example, while the vehicle is traveling in the forward range, when the all-solenoids-off fail mode occurs due to some cause, as shown in FIG. 9D, while the spool 132p is locked in the lower position due to the lock pressure that is based on the line pressure PL, in the second clutch apply relay valve 132, all of the solenoid valves are turned off (a failure state). In addition, as described above, the forward range pressure PD, which is input to the input port 34k of the first clutch apply relay valve 34, is output from the output ports 34d and 34e as reverse input pressure, and is then input to the discharge port SL3d of the linear solenoid valve SL3 and the input port 132e of the second clutch apply relay valve 132.
Thereby, the forward range pressure PD is supplied to the hydraulic servo 53 via the linear solenoid valve SL3, and at the same time, is input to the linear solenoid valve SL2 via the input port 132e and the output port 132d as reverse input pressure, is supplied to the hydraulic servo 52, and the second clutch C-2 is thereby engaged. Thereby, similarly, in the all-solenoids-off fail mode while the vehicle is traveling in the forward range, the seventh forward speed, in which the second clutch C-2 and the third clutch C-3 have been engaged, is set.
In contrast, subsequently, when, for example, the vehicle is temporarily stopped and the engine is stopped, the line pressure PL is no longer generated, and as shown in FIG. 9A, both the spool 132p and the spool 133p are set in the upper position (first position) due to the urging of the spring 132s and the spring 133s. In addition, subsequent to this, when the engine is restarted, the oil pump 21 is actuated and the line pressure PL is generated, but as shown in FIG. 9E, the signal pressure PSR is not input to the oil chamber 32a because the solenoid valve SR is turned off, and thus both the spool 132p and the spool 133p are maintained in the upper position. Thereby, because the input port 132c is interrupted and there is thus no line pressure PL output from the output port 132b, the line pressure PL is not output to the oil chamber 132a as a lock pressure.
In addition, in the second clutch apply relay valve 132, when the spool 132p is maintained in the upper position, the forward range pressure PD that is output from the output ports 34d and 34e and input to the input port 132e is input to the linear solenoid valve SL1 from the output port 132fas reverse input pressure, is supplied to the hydraulic servo 51, and the first clutch C-1 is thereby engaged. Thereby, similarly, after restarting the engine in the all-solenoids-off fail mode, the third forward speed, in which the first clutch C-1 and the third clutch C-3 have been engaged, is set.
OUTLINE OF THE PRESENT INVENTION
As explained above, according to an exemplary embodiment of the present invention, during a failure in which all of the solenoid valves are de-energized (an all-solenoids-off mode), the first clutch apply relay valve 34 outputs the forward range pressure PD as a reverse input pressure, the second clutch apply relay valve 32 (or 132), which is locked in the second position due to the line pressure PL acting as a lock pressure, supplies an engagement pressure PC2 to the hydraulic servo 52 by inputting a reverse input pressure to the discharge port SL2d of the linear solenoid valve SL2, and the second clutch apply relay valve 32 (or 132), which is set at the first position because the lock pressure is interrupted after restarting the engine, supplies an engagement pressure PC1, to the hydraulic servo 51 by inputting a reverse input pressure to the discharge port SL1d of the linear solenoid valve SL1. Thereby, during vehicle travel, it is possible to lock the speed shift while in the seventh forward speed, which is a relatively high speed, and the occurrence of downshifting by two or more steps can be prevented. After temporarily stopping the vehicle, it is possible to set the shift speed to the third forward speed, which is a relatively low shift speed, by restarting the engine, for example, and thus it is possible to make the vehicle move again.
In addition, a fail solenoid valve SR is provided that outputs a signal pressure PSR when de-energized and interrupts the signal pressure PSR when energized at least when the engine is started during normal operation. During a failure in which all of the solenoid valves are de-energized, the second clutch apply relay valve 32 inputs a signal pressure PSR of the solenoid valve SR before being locked by the lock pressure, and switches to the first position due to the signal pressure PSR. Thereby, it is possible to restart the engine, and it is possible to set the shift speed to the third forward speed, which is a relatively low shift speed.
Furthermore, because a lock pressure delay valve 33 is provided that communicates with the second clutch apply relay valve 32 by delaying the lock pressure that is fed by the second clutch apply relay valve 32, during a failure in which all solenoid valves are de-energized, the second clutch apply relay valve 32 can be reliably switched to the first position due to the signal pressure PSR of the solenoid valve SR before being locked due to the lock pressure.
In addition, because the lock pressure delay valve 33 switches to the communicating position to communicate the lock pressure to the second clutch apply relay valve 32 when the lock pressure is input against the urging force of the spring 33s, during normal operation the engine can be started, the lock pressure is communicated to the second clutch apply relay valve 32 when the line pressure PL is output, and the second clutch apply relay valve 32 can thereby be locked.
In addition, the lock pressure delay valve 33 can be structured so as to switch to the communicating position in which the lock pressure is communicated to the second clutch apply relay valve 32 when the forward range pressure PD is input against the urging force of the spring 33s, and when the shift position is in the forward range during normal operation, it is possible communicate the lock pressure to the second clutch apply relay valve 32 and to lock the second clutch apply relay valve 32.
In addition, because the spool 32p of the second clutch apply relay valve 32 is set to the right half position in FIG. 5 due to the abutment of the spool 33p when the spool 33p of the lock pressure delay valve 33 is in the right half position in FIG. 5, even if, for example, a state occurs in which the spool 33p sticks and the lock pressure is not communicated to the oil chamber 33g of the second clutch apply relay valve 32, it is possible to maintain the spool 32p in the right half position in FIG. 5 due to the abutment of the spool 33p. Thereby, even if, for example, the spool 33p sticks, it is possible to prevent the spool 32p from being set in the left half position in FIG. 5, in which the engagement pressure PC1 is supplied to the hydraulic servo 51, and even if the all-solenoids-off fail state occurs while the vehicle is traveling, the shift speed can reliably be locked in the seventh forward speed, and the occurrence of downshifting by two steps or more can be reliably prevented.
Furthermore, because the first clutch apply relay valve 34 switches to the reverse input pressure output position, in which the forward range pressure PD is communicated and is output as a reverse input pressure when the signal pressure PSR of the solenoid valve SR is input against the urging force of the spring 34s, during a failure in which all the solenoid valves are de-energized, the output of reverse input pressure by the first clutch apply relay valve 34 and the switching of the second clutch apply relay valve 32 between the first position and the second position are made possible due to the signal pressure PSR of the one solenoid valve SR.
In addition, during a failure in which all solenoid valves are de-energized, because the first clutch apply relay valve 34 outputs the reverse input pressure directly to the discharge port SL3d of the linear solenoid valve SL3 and supplies the engagement pressure PC3 to the hydraulic servo 53 that engages and disengages to the third clutch C-3, which is engaged in the third forward speed, a relatively low speed, or the seventh forward speed, a relatively high speed, it is possible to attain the third forward speed, a relatively low speed, and the seventh forward speed, a relatively high speed.
Furthermore, because the linear solenoid valve SL4 inputs a lock pressure to the input port SL4a via the second clutch apply relay valve 32 as a line pressure PL, before all solenoid valves become de-energized, it can be determined whether or not the fourth forward speed and the sixth forward speed, which are attained by the fourth clutch C-4 engaged by the hydraulic servo 54, have been established normally, and whether or not the second clutch apply relay valve 32 is feeding the lock pressure normally. Thereby, in the case in which, for example, the second clutch apply relay valve 32 is not locked by the lock pressure, all the solenoid valves become de-energized, and it is possible to prevent the occurrence of unintended downshifting to guarantee the safe travel of the vehicle.
Note that in the present exemplary embodiment as explained above, the case in which the hydraulic control apparatus 20 according to an exemplary embodiment of the present invention is applied to a multi-stage automatic transmission 1 capable of eight forward speeds and one reverse speed was explained as one example, but of course this is not limiting. Although an automatic transmission having many forward speeds is especially advantageous, the present invention can be applied to any staged automatic transmission.
In addition, in the present exemplary embodiment as explained above, an example was explained in which a line pressure PL is used as a lock pressure that locks the second clutch apply relay valve 32, but this is not limiting. Any pressure may be used as a lock pressure if the pressure is an oil pressure that is generated while the vehicle is traveling. For example, using a forward range pressure PD as such a pressure can be considered, and in this case, in an all-solenoids-off fail state, by restarting the engine and temporarily changing the shift position to one other than the D range (P, R, and N range), the lock of the second clutch apply relay valve 32 can be released, and for example, the shift speed can be switched to the third forward speed.

## Claims

1. A hydraulic control apparatus, for a multi-stage automatic transmission, having a plurality of shift speeds according to an engagement state of a plurality of friction engagement elements that are engaged and disengaged by respective hydraulic servos, the hydraulic control apparatus comprising:
an oil pump that generates an oil pressure in correspondence with the engine speed;
a line pressure generating device that generates an oil pressure in the oil pump at a line pressure;
a range pressure output device that can input the line pressure and output a forward range pressure based on a shift position;
a first hydraulic servo among the respective hydraulic servos that engages and disengages a respective one of the friction engagement elements that engages at a relatively low speed;
a second hydraulic servo among the respective hydraulic servos that engages and disengages a respective one of the friction engagement elements that engages at a relatively high speed;
a plurality of engagement pressure control solenoid valves that include a first engagement pressure control solenoid valve that supplies an engagement pressure to the first hydraulic servo, and a second engagement pressure control solenoid valve that supplies the engagement pressure to the second hydraulic servo, wherein, when in a de-energized state, the plurality of engagement pressure control solenoid valves interrupt an input port that inputs oil pressure based on the line pressure and an output port and communicate the output port and a discharge port, and, when in an energized state, the plurality of engagement pressure control solenoid valves communicate the input port and the output port to thereby regulate the engagement pressure supplied to the respective hydraulic servos;
a first switching valve that, during a failure in which all solenoid valves are de-energized, is switched to a reverse input pressure generating position that outputs the forward range pressure as a reverse input pressure; and
a second switching valve that switches between a first position at which the reverse input pressure is input to the discharge port of the first engagement pressure control solenoid valve and a second position at which the reverse input pressure is input to the discharge port of the second engagement pressure control solenoid valve; wherein:
the second switching valve is set at the second position during a normal engine startup and is locked at the second position based on a lock pressure by feeding the lock pressure, and during a failure in which all solenoid valves are de-energized, is set to a first position that interrupts the lock pressure after the engine is restarted.

2. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 1, wherein the second switching valve provides the lock pressure by feeding the line pressure when in the second position.

3. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 2, further comprising:
a fail solenoid valve that outputs a signal pressure in the de-energized state and interrupts the signal pressure after being set to an energized state at least during the normal engine start-up; wherein:
the second switching valve inputs a signal pressure of the fail solenoid valve before being locked by the lock pressure and switches to the first position due to the signal pressure during the failure in which all of the solenoid valves are de-energized.

4. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 3, further comprising a delay device that communicates with the second switching valve by delaying the lock pressure that is fed by the second switching valve.

5. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 4, wherein the delay device includes a third switching valve that switches between an urging position that is urged by a first urging device and a communicating position that communicates the lock pressure to the second switching valve when the lock pressure is input against the urging of the first urging device.

6. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 5, wherein:
the second switching valve comprises a second spool that switches between the first position and the second position;
the third switching valve comprises a third spool that switches between the urging position and the communicating position, and is disposed so as to be able to abut the second spool concentrically; and
the second spool of the second switching device is set to the second position due to the abutment of the third spool when the third spool of the third switching valve is in the urging position.

7. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 4, wherein the delay device includes a third switching valve that switches between an urging position that is urged by a first urging device and a communicating position that communicates the lock pressure to the second switching valve when the forward range pressure is input against the urging of the first urging device.

8. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 7, wherein:
the second switching valve comprises a second spool that switches between the first position and the second position;
the third switching valve comprises a third spool that switches between the urging position and the communicating position, and is disposed so as to be able to abut the second spool concentrically; and
the second spool of the second switching device is set to the second position due to the abutment of the third spool when the third spool of the third switching valve is in the urging position.

9. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 3, wherein:
the first switching valve switches between an interrupt position that interrupts the forward range pressure by being urged by a second urging device and a reverse input pressure output position that communicates and outputs the forward range pressure as reverse input pressure when the signal pressure of the fail solenoid valve is input against the urging of the second urging device.

10. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 1, further comprising:
a fail solenoid valve that outputs a signal pressure in the de-energized state and interrupts the signal pressure after being set to an energized state at least during the normal engine start-up; wherein:
the second switching valve inputs a signal pressure of the fail solenoid valve before being locked by the lock pressure and switches to the first position due to the signal pressure during the failure in which all of the solenoid valves are de-energized.

11. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 10, further comprising a delay device that communicates with the second switching valve by delaying the lock pressure that is fed by the second switching valve.

12. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 11, wherein the delay device includes a third switching valve that switches between an urging position that is urged by a first urging device and a communicating position that communicates the lock pressure to the second switching valve when the lock pressure is input against the urging of the first urging device.

13. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 12, wherein:
the second switching valve comprises a second spool that switches between the first position and the second position;
the third switching valve comprises a third spool that switches between the urging position and the communicating position, and is disposed so as to be able to abut the second spool concentrically; and
the second spool of the second switching device is set to the second position due to the abutment of the third spool when the third spool of the third switching valve is in the urging position.

14. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 11, wherein the delay device includes a third switching valve that switches between an urging position that is urged by a first urging device and a communicating position that communicates the lock pressure to the second switching valve when the forward range pressure is input against the urging of the first urging device.

15. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 14, wherein:
the second switching valve comprises a second spool that switches between the first position and the second position;
the third switching valve comprises a third spool that switches between the urging position and the communicating position, and is disposed so as to be able to abut the second spool concentrically; and
the second spool of the second switching device is set to the second position due to the abutment of the third spool when the third spool of the third switching valve is in the urging position.

16. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 10, wherein:
the first switching valve switches between an interrupt position that interrupts the forward range pressure by being urged by a second urging device and a reverse input pressure output position that communicates and outputs the forward range pressure as reverse input pressure when the signal pressure of the fail solenoid valve is input against the urging of the second urging device.

17. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 1, further comprising:
a third hydraulic servo that engages and disengages a friction engagement element that is engaged at the relatively low speed and the relatively high speed; wherein:
the plurality of engagement pressure control solenoid valves include a third engagement pressure control solenoid valve that supplies the engagement pressure to the third hydraulic servo; and
the first switching valve outputs the reverse input pressure directly to the discharge port of the third engagement pressure control solenoid valve during the failure in which all of the solenoid valves are de-energized.

18. The hydraulic control apparatus, for the multi-stage automatic transmission, according to claim 1, further comprising:
a fourth hydraulic servo that engages and disengages a friction engagement element that engages at a shift speed that is different from the relatively low speed and the relatively high speed; wherein:
the plurality of engagement pressure control solenoid valves include a fourth engagement pressure control solenoid valve that supplies the engagement pressure to the fourth hydraulic servo; and
the fourth engagement pressure control solenoid valve inputs the lock pressure to the input port via the second switching valve as the line pressure.