Valve Body: Description and Operation
CONTROL VALVE
Component Location
Component Descriptions
Manual Valve
The manual valve switches the hydraulic path for the line pressure generated by the oil pump.
When the selector lever is moved, the manual valve moves also, until it is located in a position where line pressure (7) is distributed to each line pressure circuit for each P, R, N, D, S and L range. Line pressures (1), (3), (5), and (6) are distributed to each valve. When line pressure (7) is not in a distribution position the line pressures (1), (3), (5) and (6) are drained at the X position.
1-2 Shift Valve
The 1-2 shift valve automatically shifts between 1st and 2nd. The 1-2 shift valve switches the paths for the line pressure applied to the 1-2 shift valve. The shift solenoid A ON-OFF signal is controlled by the transmission control module.
With the shift solenoid A OFF, line pressure (12) becomes equal to line pressure (7), and pushes the valve to the left side, shifting to 1st gear. When vehicle speed becomes high, the transmission control module turns ON the shift solenoid A and line pressure (12) is drained from the shift solenoid A. Consequently, spring force and line pressure (7) working on the left end of the valve push the valve to the right, shifting to 2nd gear. Even when line pressure (12) is drained, line pressure (7) does not change, due to there being an orifice. In 2nd gear, line pressure (1) is transmitted to (9), engaging the 2-4 brake band with a slow pressure increase by the 1-2 accumulator operation. Also, in L range, low reducing pressure (10) is transmitted to (11) in 1st gear, engaging the low and reverse brake. In 2nd gear, (11) is drained, releasing the low and reverse brake.
NOTE: If the R range is selected when vehicle is driven at high speed, the low and reverse brake pressure is drained from the 1-2 shift valve to prevent transaxle damage.
2-3 Shift Valve
The 2-3 shift valve automatically shifts between 2nd and third gear.
The 2-3 shift valve switches the paths for the line pressure applied to the 2-3 shift valve. The shift solenoid B ON-OFF signal is controlled by the transmission control module.
With the shift solenoid B ON, line pressure (14) is drained by the shift solenoid B. Consequently, spring force and line pressure (7) push the valve to the right, moving the valve to 2nd gear position. In 2nd gear, line pressure path (3) is closed and line pressure (13) is drained.
In S and L ranges, line pressure (16) from the 3-4 shift valve is transmitted to (28), applying the coasting clutch. When vehicle speed becomes high, the transmission control module turns OFF the shift solenoid B. As a result, line pressure (14) becomes equal to line pressure (1) and surpasses the combination of spring force and line pressure (7). This forces the valve to move to the left, shifting to third gear.
In third gear, line pressure (3) is transmitted to (13), applying the 3-4 clutch with a slow pressure increase by the bypass valve and 2-3 accumulator operation.
3-4 Shift Valve
The 3-4 shift valve automatically shifts between third and fourth gear.
The 3-4 shift valve switches paths for line pressure applied to the 3-4 shift valve. The shift solenoid C ON-OFF signal is controlled by the transmission control module.
With the shift solenoid C OFF, line pressure (17) becomes equal to line pressure (1), surpassing the combination of spring force and line pressure (7). As a result, the valve is pushed to the left side and moves to third gear position.
With the valve in third gear, line pressure (1) joins line pressure (16), engaging the coasting clutch through the 2-3 shift valve. When vehicle speed becomes high, the transmission control module turns ON the shift solenoid C, allowing line pressure (17) to be drained from the shift solenoid C. Consequently, the combination of spring force and line pressure (7) push the valve to the right side, shifting to fourth. In gear position, (15) is drained, releasing coasting clutch and engaging the 2-4 brake band.
Torque Converter Clutch Shift Valve
The torque converter clutch shift valve controls torque converter clutch operation based on the torque converter clutch control solenoid valve ON-OFF signal controlled by the powertrain control module.
With the torque converter clutch control solenoid valve OFF, line pressure is applied to the right side of the torque converter clutch shift valve; it move the valve to the left side by overcoming the combined force of the spring and solenoid reducing pressure. As a result, the hydraulic pressure (ATF) working on the torque converter front chamber passes through the pressure regulator valve, distributes the ATF, and inhibits torque converter clutch engagement.
With the torque converter clutch control solenoid valve ON, line pressure is drained through the torque converter clutch control solenoid valve; the torque converter clutch shift solenoid valve moves to the right side due to the spring force. consequently, the hydraulic pressure applied to the torque converter front chamber is drained through the torque converter clutch control valve, engaging torque converter clutch.
Pressure Regulator Valve
The oil pressure regulator valve adjusts the line pressure generated by the oil pump to match driving conditions.
Line pressure (7) that is generated in the oil pump works on chambers (A) and (B). The line pressure applied to chamber (A) moves the pressure regulator valves to the left side due to a difference between the surface areas of the two valves. Line pressure is then drained from chamber (C).
As a result, the pressure regulator valve balances at the point which the (A) chamber line pressure acting toward the left balances with the spring force and modifier pressure (21) acting toward the right force.
The line pressure (7) that works on chamber (A) becomes torque converter pressure (23) which is sent into the torque converter through the lockup control valve and lockup shift valve A.
When the accelerator pedal is depressed, modifier pressure (21) rises and is added to spring force to move the pressure regulator valve to the right side. This makes drainage of line pressure (7) from chamber (c) difficult; therefore, the pressure regulator valve balances at a high level line pressure (7). In R range, line pressure (6) is applied to the pressure regulator valve, moving the valve to the right. This makes drainage of line pressure (7) in chamber (c) difficult; therefore, the pressure regulator valve balances at a considerably high level line pressure (7).
When line pressure or coasting clutch applied pressure are not applied to the cutback valve, modifier pressure (22) is applied to the right end of the pressure regulator valve, moving the valve to the left side. This makes drainage of line pressure (7) in chamber (A) easy; therefore, the pressure regulator valve balances at a low level line pressure (7).
Pressure Modifier Valve
The pressure modifier valve converts solenoid reducing pressure to modifier pressure that matches throttle valve opening angle (engine load).
The solenoid reducing pressure generated by the solenoid reducing valve is constantly applied to the step in the right side of the pressure modifier valve. When the throttle valve opening angle is small, the duty value of the pressure control solenoid is low.
The hydraulic pressure applied to the left side of the pressure modifier valve drops due to the pressure control solenoid action, moving the modifier valve to the left. The resultant modifier pressure is low. When the throttle valve opening angle is large, the duty value of the pressure control solenoid is high. The hydraulic pressure applied to the left side of the pressure modifier valve is not easily drained by the pressure control solenoid, moving the pressure modifier valve to the right. The resultant modifier pressure is high. Through this process, modifier pressure is controlled depending on the throttle valve opening angle.
Pressure Modifier Accumulator
This valve stabilizes the modifier pressure adjusted by the pressure modifier valve to prevent modifier pressure pulsation.
The valve is pushed to the left by modifier pressure (21) and to the right by spring force. When modifier pressure (21) pulsates at high pressure, the valve moves to the left. When it pulsates at low pressure, the valve moves to the right. This operation stabilizes modifier pressure.
Converter Relief Valve
The converter relief valve prevents torque converter pressure from exceeding a specified level.
Torque converter pressure (23) generated by the pressure regulator valve is constantly applied to the right end of the converter relief valve. Spring force, however, moves the valve to the right side. When torque converter pressure (23) increases, it overcomes spring force and pushes the converter relief valve to the left side. The pressure (23) is drained and maintained under a specified level.
Solenoid Reducing Valve
The solenoid. reducing valve converts line pressure to solenoid reducing pressure which acts on the pressure control solenoid. The solenoid reducing pressure has a constant pressure of 360 - 400 kPa (3.6 - 4.1 kgf/cm2, 52 - 58 psi.
Solenoid reducing pressure (20) pushes an the solenoid reducing valve to the right, while spring force pushes to the left. When solenoid reducing pressure (20) increases, the solenoid reducing valve moves to the right until pressure is drained. This maintains a constant pressure to keep the spring force and line pressure (7) balanced. Solenoid reducing pressure becomes fixed.
Cutback Valves
The cutback valves control the modifier pressure applied to the pressure regulator valve.
The cutback valves are composed of cutback valves A and B.
Coasting clutch application pressure (28) is applied to the left side of cutback valve A, and line pressure (7) controlled by the 1-2 shift valve is applied to the right side of cutback valve A. Modifier pressure (21) is applied to cutback valve B.
When coasting clutch application pressure (28) or line pressure (7) is applied, the valve moves to the right, closing the modifier pressure (22) circuit.
When either coasting clutch application pressure (28) or line pressure (7) is working, the modifier pressure (22) circuit opens to apply pressure to the right end of the pressure regulator valve.
As a result, the pressure regulator valve is pushed to the left side, lowering line pressure. This condition is called "cutback".
Bypass Valve
The bypass valve controls 3-4 clutch application timing and shifting shock during 2nd -> third gear shifting.
Spring force and modifier pressure (21) normally push the valve to the right side, thus transmitting line pressure (13) to 3-4 clutch application pressure (18), 3-4 clutch application pressure (18) works on the right end of the valve, and moves the valve to the left side.
As 3-4 clutch application pressure (18) increases, the valve moves to the left, in spite of spring force and modifier pressure (21) pushing the valve to the right. Therefore, during 2nd -> third gear shifting, line pressure (13) is transmitted to the 3-4 clutch application pressure through the bypass valve, quickening 3-4 clutch engagement.
Beyond a certain level, the valve closes the path for line pressure (13); the line pressure goes through the orifice check valve, causing a slow increase in 3-4 clutch application pressure.
The modifier pressure (21) applied to the left end of the valve assures that 3-4 clutch application timing matches throttle valve opening angle.
This process controls 3-4 clutch application timing and shifting shock.
Coast Timing Valve
The coast timing valve controls the coasting clutch application timing.
Line pressure (1), distributed by the manual valve, constantly works on the right end of the valve and moves the valve to the left side by overcoming spring force.
In third gear, 2-4 brake band release pressure (15) works on the left side of the valve, trying to push the valve to the right side. At the same time, the 2-4 brake band release pressure (15), which is also- acting on the center of the valve, passes through the valve, engaging the clutch.
The orifice check valve controls the application timing.
Low Reducing Valve
The low reducing valve reduces low and reverse brake application pressure and capacity, thereby reducing shock when shifting from 2nd to L range 1st.
The valve is normally pushed to the left side by spring force. When L range is selected, line pressure (5) is transmitted to low reducing pressure (10).
Low reducing pressure (10) is then also applied to the left end of the valve, pushing it to the right side. As a result, line pressure (5) is disconnected from (101, and the low reducing pressure is drained. Thus, the pressure is lowered.
If the low reducing pressure (10) decreases, the force that pushes the valve to the right side also decreases, allowing the valve to move to the left side by spring force.
This closes the drain path. In this way the valve balances with spring force, and low reducing pressure (10) becomes lower than line pressure (5).
2-3 Timing Valve
The 2-3 timing valve controls the 2-4 brake release pressure and 3-4 clutch pressure during 2nd -> third gear shifting.
When shifting from 2nd to third gear, 3-4 clutch application pressure (18) works on the left side of the valve, trying to move it to the right side.
When the throttle valve opening angle is small, low 3-4 clutch application pressure (18) pushes the valve to the right, causing 2-4 brake release pressure (15) to pass through the valve and to work on the coasting clutch.
When the throttle valve opening angle is large, high 3-4 clutch application pressure (18) pushes the valve to the right side, allowing 2-4 brake release pressure (15) to work on the coasting clutch.
3-2 Timing Valve
The 3-2 timing valve temporarily switches the 3-4 clutch released line pressure and 2-4 brake band released line pressure that are applied to the 3-2 timing valve to reduce shifting shock. The valve operates based on the 3-2 timing solenoid valve ON-OFF signal controlled by the transmission control module.
Normally, line pressure (12) is retained because the 3-2 timing solenoid valve is turned OFF. The line pressure overcomes spring force to push the valve to the left side.
When shifting from 1st to 2nd, 2-4 brake application pressure (9) passes through the 3-2 timing valve to engage the 2-4 brake band with the solenoid valve ON. Brake band application pressure (9) from the other circuit also engages the 2-4 brake band.
When shifting from third gear to 2nd, the 3-2 timing valve drains 2-4 brake release pressure (15) to achieve shifting timing. When 2-4 brake band application side pressure reaches the specified pressure, the 3-2 timing solenoid valve goes OFF, and the 3-2 timing valve moves to the left to close outlet port (9).
As a result, the 2-4 brake application side pressure increases gradually, improving 1st to 2nd upshift response, and reducing shift shock.
N-D Accumulator
The N-D accumulator moderates a rapid increase in hydraulic pressure during forward clutch engagement. This reduces shift shock generated when D range is selected from N range.
In N range, line pressure (7) is constantly applied to the right side of the piston, pushing it to the left side.
When D range is selected from N range, line pressure (1), which engages the forward clutch, is applied to the piston by the manual valve.
As a result, the combination of line pressure (1) and spring force overcomes the combination of line pressure (7) and spring force, moving the piston gradually to the right side.
This movement of the piston moderates a rapid increase in line pressure (1).
N-R Accumulator
The N-R accumulator moderates a rapid increase in the hydraulic pressure during reverse clutch engagement. This reduces shift shock generated when R range is selected from Neutral position.
In Neutral position, spring force and line pressure (7) are applied to the right side of the piston, pushing it to the left side. When R range is selected while in Neutral position, the line pressure (6), which engages the reverse clutch, is applied to the N-R accumulator. As a result, line pressure (6) overcomes spring force, and the piston moves to the right side. This movement of the piston moderates a rapid increase in line pressure (6).
1-2 Accumulator
The 1-2 accumulator reduces shifting shock generated when shifting to 2nd and fourth gear by moderating a rapid increase in hydraulic pressure when the 2-4 brake band is engaged.
In 1st gear, the line pressure (7) is applied to the left end of the piston, pushing it to the right side. When the shift solenoid A turns ON to shift to 2nd gear, 2-4 brake band application pressure (9) is applied to the piston by the 1-2 shift valve. This moves the piston to the left. This movement of the piston moderates a rapid increase in line pressure (9).
When shifting from third gear to fourth gear, 2-4 brake band application pressure (9) is temporarily drained while still in third gear, the 2-4 brake band is newly applied, and then shifted to fourth gear. As a result, line pressure (7) and 3-4 clutch pressure (19) work as a backup pressure of the piston, making the counteractive line pressure (9) shift high. This provides optimal 2-4 brake band application timing during third to fourth gear shifting.
2-3 Accumulator
The 2-3 accumulator reduces shift shock generated when shifting to third gear by moderating a rapid increase in hydraulic pressure when the 3-4 clutch is engaged.
In 2nd gear, the line pressure (7) is applied to the right end of the piston. The line pressure overcomes spring force to move the piston to the left side. When the shift solenoid B turns OFF to shift to third gear, the 2-3 shift valve exerts 3-4 clutch application pressure (18) on the left end of the 2-3 accumulator. As a result, the 2-3 accumulator piston moves to the right side, moderating a rapid increase in 3-4 clutch application pressure (18).