A/T System Description - Hydraulic Flow
A/T System Description - Hydraulic Flow
Hydraulic Flow
Distribution of Hydraulic Pressure
As the engine turns, the ATF pump starts to operate. Automatic transmission fluid (ATF) is drawn through the ATF strainer (filter) and discharged into the hydraulic circuit. Then, ATF flowing from the ATF pump becomes line pressure that is regulated by the regulator valve. Torque converter pressure from the regulator valve enters the torque converter through the lock-up shift valve, and it is discharged from the torque converter. The torque converter check valve prevents torque converter pressure from rising.
The PCM switches the shift solenoid valves ON and OFF. The shift solenoid valve intercepts line pressure from the ATF pump via the manual valve when the shift solenoid valve is OFF. When the shift solenoid valve is turned ON by the PCM, line pressure changes to shift solenoid valve pressure at the shift solenoid valve, then the shift solenoid valve pressure flows to the shift valve. Applying shift solenoid pressure to the shift valves moves the position of the shift valve, and switches the port of the hydraulic circuit. The PCM also controls A/T clutch pressure control solenoid valves A, B, and C. The A/T clutch pressure control solenoid valves regulate hydraulic pressure, and applies pressure to the clutches to engage smoothly. The clutches receive optimum clutch pressure which is regulated by the A/T clutch pressure control solenoid valves for comfortable driving and shifting under all conditions.
Hydraulic Pressure at the Port for use in the hydraulic circuit:
Hydraulic Flow (cont'd)
N Position
The PCM controls the shift solenoid valves. The conditions of the shift solenoid valves and the positions of the shift valves are as follows:
- Shift solenoid valve A: OFF, and shift valve A remains on the right side
- Shift solenoid valve B: ON, and shift valve B moves to the left side
- Shift solenoid valve C: ON, and shift valve C moves to the left side
- Shift solenoid valve D: OFF, and shift valve D remains on the left side
- Shift solenoid valve E: OFF, and shift valve E remains on the left side
Line pressure (1) flows to the shift solenoid valves and A/T clutch pressure control solenoid valve A. Under this condition, hydraulic pressure is not applied to the clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting to D from N
The shift solenoid valves remain the same as in N when shifting to D from N. The manual valve is moved to the D position, and uncovers the line pressure port (4) leading to A/T clutch pressure control solenoid valve C. Hydraulic pressure to the 1st clutch from A/T clutch pressure control solenoid valve A is created as shift solenoid valve A OFF, and B and C remain ON. A/T clutch pressure control solenoid valve A pressure (55) changes to 1st clutch pressure (10) at shift valve B, and flows to the 1st clutch. The 1st clutch is engaged gently when shifting to D from N.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in 1st Gear
The PCM turns shift solenoid valve A ON, B and C remain ON, and D and E remain OFF. Shift solenoid valve A pressure (SA) is applied to the right side of shift valve A. Shift valve A is moved to the left side to uncover the line pressure port leading to the 1st clutch, and to cover the A/T clutch pressure control solenoid valve pressure port.
Fluid flows to the 1st clutch by way of:
Line pressure (1) -> Shift valve D-Line pressure (1A) -> Shift valve A-Line pressure (1B) -> Manual valve-Line pressure (5A) -> Shift valve C-Line pressure (5B) -> Shift valve B-1st clutch pressure (10) -> 1st clutch
1st clutch pressure (10) is applied to the 1st clutch, and the 1st clutch is engaged securely.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting between 1st Gear and 2nd Gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve A OFF, B and C remain ON, and D and E remain OFF. Shift solenoid valve A pressure (SA) in the right side of shift valve A is released. Shift valve A is moved to the right side uncovering the A/T clutch pressure control solenoid valve A and B pressure port leading to the 1st and 2nd clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve A pressure (55) changes to 1st clutch pressure (10) at shift valve B. A/T clutch pressure control solenoid valve B pressure (56) changes to (5E) at shift valve C and to (5F) at shift valve B, and becomes 2nd clutch pressure (20) at shift valve A. The 1st and 2nd clutches are engaged gently.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in 2nd Gear
The PCM turns shift solenoid valves C OFF, D ON, A and E remain OFF, and B remains ON. Shift solenoid valve C pressure (SC) in the right side of shift valve C is released. Shift valve C moves to the right side to switch the ports. This movement covers the ports to block A/T clutch pressure control solenoid valve pressure at shift valves C and A, and uncover the line pressure port leading to the 2nd clutch.
Fluid flows to 2nd clutch by way of:
Line pressure (1) -> Manual valve-Line pressure (4) -> Shift valve C-Line pressure (5E) -> Shift valve B-Line pressure (5F) -> Shift valve A-2nd clutch pressure (20) -> 2nd clutch
2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged securely.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting between 2nd Gear and 3rd Gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve C ON, A and E remain OFF, and B and D remain ON. Shift solenoid valve C pressure (SC) is applied to the right side of shift valve C. Shift valve C is moved to the left side uncovering the A/T clutch pressure control solenoid valve B and C pressure ports leading to the 2nd and 3rd clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve B pressure (56) changes to 2nd clutch pressure (20) at shift valve A. A/T clutch pressure control solenoid valve C pressure (57) changes to (5H) at shift valve C and to (5K) at shift valve B, and becomes 3rd clutch pressure (30) at shift valve A. The 2nd and 3rd clutches are engaged gently.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in 3rd Gear
The PCM turns shift solenoid valves B and D OFF, A and E remain OFF, and C remains ON. Shift solenoid valve B pressure (SB) in the right side of shift valve B is released, and shift valve B is moved to the right side. Shift solenoid valve D pressure (SD) in the left side of shift valve D is released, and shift valve D is moved to the left side. This valve movement causes A/T clutch pressure control solenoid valve C pressure to be directed to the port leading to the 3rd clutch.
A/T clutch pressure control solenoid valve C pressure (57) changes to (5J) at shift solenoid valve D and to (5K) at shift valve B, and becomes 3rd clutch pressure (30) at shift valve A. 3rd clutch pressure (30) is applied to the 3rd clutch, and the 3rd clutch is engaged securely.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting between 3rd Gear and 4th Gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve C OFF, and A, B, D, and E remain OFF. Shift solenoid valve C pressure (SC) in the right side of shift valve C is released. Shift valve C is moved to the right side uncovering the A/T clutch pressure control solenoid valve B and C pressure ports leading to the 3rd and 4th clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve C pressure (57) changes to 3rd clutch pressure (30) at shift valve A. A/T clutch pressure control solenoid valve B pressure (56) changes to (5G) at shift valve C, and becomes 4th clutch pressure (40) at shift valve B. The 3rd and 4th clutches are engaged gently.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in 4th Gear
The PCM turns shift solenoid valve A ON, and B, C, D, and E remain OFF. Shift solenoid valve A pressure (SA) is applied to the right side of shift valve A. Shift valve A is moved to the left side to cover the A/T clutch pressure control solenoid valve A and C pressure ports leading to the 2nd and 3rd clutches.
A/T clutch pressure control solenoid valve B pressure (56) changes to (5G) at shift valve C, and becomes 4th clutch pressure (40) at shift valve B. 4th clutch pressure (40) is held high by A/T clutch pressure control solenoid valve B, and the 4th clutch is engaged securely.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting between 4th Gear and 5th Gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve D ON, A remains ON, and B, C, and E remain OFF. Shift solenoid valve D pressure (SD) is applied to the left side of shift valve D. Shift valve D is moved to the right side uncovering the A/T clutch pressure control solenoid valve C pressure port leading to the 5th clutch. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve B pressure (56) changes to 4th clutch pressure (40) at shift valve B. A/T clutch pressure control solenoid valve C pressure (57) changes to (5L) at shift valve D and to (5N) at shift valve B, and becomes 5th clutch pressure (50) at shift valve A. The 4th and 5th clutches are engaged gently.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in 5th Gear
The PCM turns shift solenoid valve C ON, A and D remain ON, and B and E remain OFF. Shift solenoid valve C pressure (SC) is applied to the right side of shift valve C. Shift valve C is moved to the left side. This directs A/T clutch pressure control solenoid valve B pressure to shift valve B where it is blocked. The pressure in the 4th clutch is released through shift valve C.
A/T clutch pressure control solenoid valve C pressure (57) changes to (5L) at shift valve D and to (5N) at shift valve B.
5th clutch pressure (50) is held high by A/T clutch pressure control solenoid valve C, and the 5th clutch is engaged securely.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Shifting to R from P or N
When shifting to R, the PCM turns shift solenoid valves B and E ON, and A, C, and D are turned OFF. Shift solenoid valve B pressure (SB) is applied to the right side of shift valve B, and shift valve B is moved to the left side. Shift solenoid valve E pressure (SE) is applied to the left side of shift valve E, and shift valve E is moved to the right side. Line pressure (1) changes to (3) at the manual valve, and flows to the servo valve via shift valve E. The servo valve is moved to the reverse range position. Movement of shift valves B and E, and the servo valve creates 4th clutch pressure line between the 4th clutch and A/T clutch pressure control solenoid valve A. 4th clutch pressure (40) is applied to the 4th clutch, and the 4th clutch is engaged gently.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
Driving in R
The vehicle is moved backward by engaging the 4th clutch and reversing the mainshaft rotation with the reverse idler gear, the PCM turns shift solenoid valve A ON, B and E remain ON, and C and D remain OFF. Shift solenoid valve A pressure (SA) is applied to the right side of shift valve A to cover the A/T clutch pressure control solenoid valve A pressure port, and to uncover the line pressure port leading to the 4th clutch creating full line pressure. The 4th clutch is engaged securely with line pressure.
Reverse Inhibitor Control
When R is selected while the vehicle is moving forward, the PCM commands shift solenoid valve A to turn OFF, and E to remain OFF. Shift solenoid valve A pressure (SA) is not applied to shift valve A so that line pressure (3A) is not applied to the servo valve. Also shift solenoid valve E pressure (SE) is not applied to shift valve E so that line pressure (3') is not applied to the servo valve. The servo valve cannot be shifted to the reverse position, and hydraulic pressure is not applied to the 4th clutch from the servo valve for reverse; as a result, power is not transmitted to the reverse direction.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
P Position
The PCM turns shift solenoid valves B and E ON, and A, C, and D OFF. Line pressure (1) flows to the shift solenoid valves and A/T clutch pressure control solenoid valve A. Line pressure (3) changes to (3') at shift valve E, and flows to the servo valve. The servo valve is moved to the reverse/park position. Hydraulic pressure is not applied to the clutches.
