Main Structure
The driving power, which is transmitted from the engine via the torque converter --> primary reduction gear --> primary pulley --> secondary pulley --> secondary reduction gear --> forward/reverse changeover mechanism, is distributed to the front and rear axles by the active torque split AWD system. The front driving power is output to the front axle via the transfer gear --> front differential.
The rear driving power is output to the propeller shaft.
Scheme 44
Oil Pump
To reduce pumping loss, a compact internal tooth gear pump is adopted. Sufficient flow rate is secured by using a oil pump drive shaft as a separate shaft that rotates at a higher rotation speed than the engine shaft by means of a sprocket and chain mechanism.
Scheme 45
Pulley&Chain
- The system consists of a primary pulley, secondary pulley, and chain.
- It presses the chain to the pulleys by the pressure generated from the hydraulic pressure chambers of the pulleys and thus generates friction force between the pulley banks and the chain to transmit the power.
Scheme 46
- It achieves continuously variable speed change by controlling the hydraulic pressures of the primary and secondary pulleys and thus changing the pulley widths. In addition, the larger transmission ratio intervals support both the drivability and the fuel economy.
- A guide rail is provided to both the tension side and the releasing side, which reduce the string vibration of the chain and resultant noises.
Scheme 47
Forward/Reverse Changeover Mechanism
The mechanism is located between the pulley and the AWD system.
The structure is composed of an forward clutch, a reverse brake, single pinion planetary gears, and an aluminum planetary carrier.
Scheme 48
Scheme 49
ADVANCING
The gears rotate together as the result of the engagement of forward clutch and the release of reverse brake, making the torque input from the ring gear rotate the sun gear directly as the output.
Scheme 50
REVERSING
The planetary carrier is fixed as the result of the release of forward clutch and the engagement of reverse brake, making the torque input from the ring gear rotate the sun gear in the reverse direction due to the function of pinion gears.
Scheme 51
Control Valve
| No. | Contents | Remarks | |
|---|---|---|---|
| 1 | Torque converter lockup control | Lockup ON/OFF solenoid | Changes over the supply pressure to the torque converter between the lubrication pressure and the lockup pressure. |
| 2 | Lockup duty solenoid | Adjusts the torque converter lockup pressure. | |
| 3 | Speed change control | Primary UP duty solenoid | Performs an upshift. |
| 4 | Primary DOWN duty solenoid | Performs a downshift. | |
| 5 | F&R clutch pressure control | F&R clutch linear solenoid | Adjusts the F&R clutch pressure. |
| 6 | Manual valve | Changes over the forward/reverse travel directions. | |
| 7 | Transfer pressure control | AWD duty solenoid | Adjusts the transfer clutch pressure. |
| 8 | Line pressure control | Secondary linear solenoid | Adjusts the line pressure. |
Scheme 52
Sensors and Switches
| No. | Contents | Remarks | Position |
|---|---|---|---|
| 1 | Secondary hydraulic pressure sensor | Detects the pressure of the secondary hydraulic circuit. | Center on right side of converter case |
| 2 | Front wheel speed sensor | Detects the front wheel speed. | Bottom of extension case |
| 3 | Secondary speed sensor | Detects the secondary pulley rotation speed. | Center of left side of transmission case |
| 4 | Primary speed sensor | Detects the primary pulley rotation speed. | Upper right of converter case |
| 5 | ATF oil temperature sensor | Detects the ATF temperature. | In the harness for the control valve |
| 6 | Inhibitor switch | Enables engine start when the select lever is set at P or N. Detects the shift position. | Right side of transmission case |
Scheme 53
Scheme 54
LINE PRESSURE CONTROL
With the chain type CVT, the line pressure is optimized and the oil pump loss is reduced by making the most of the characteristic that the clamping force necessary for torque transmission is low, improving the torque estimate accuracy, and performing the optimal control according to driving conditions.
ENGINE COOPERATION CONTROL
While the optimal line for the engine fuel economy is used, the torque and speed change are controlled cooperatively so that the driving power change against acceleration becomes linear, thus achieving both high fuel economy performance and drivability.
In addition to smooth speed change that is a feature of Lineartronic™, driving pleasure, such as excellent fuel economy, ease of control and comfortable acceleration feel, is realized. Also, by increasing the engine revolution speed linearly against accelerator depression amount and vehicle speed increase, driving power controllability is improved, thus achieving drivability without discomfort even compared to the existing multistage AT.
Furthermore, the drivability improvement control that has been achieved from the past Subaru vehicles is refined for the Lineartronic™, and various controls to support the following driving pleasure are performed.
MANUAL SHIFT CONTROL
The manual mode of the Lineartronic™ provides 6 speed ranges.
Various road conditions are simulated with an intent of providing driving feel and driving power controllability equivalent to manual transmission, and the 6 speed configuration has been adopted. This creates an easy-to-use manual shifting which, for example, can provide appropriate engine brake effect or acceleration as intended just with one shift down operation. (Example: With a 7-speed or 8-speed system, the driver must perform two or three downshift operations to obtain an intended traction power because the gear ratio steps are smaller)
Scheme 55
- Normal manual shift mode In the D range, tilting the select lever to the manual side triggers the manual mode. In the manual mode, the inherently continuous speed change range of Lineartronic™ is divided into 6 gear ratios to allow the driver to select a desirable gear by operating the paddle switch on the steering wheel.
- Temporary manual shift mode When the paddle switch integrated in the steering wheel is operated during a travel at D range, the system enters the manual mode temporarily. This mode is cancelled automatically and the normal D range control is restored if no further paddle switch operation takes place and the accelerator pedal is depressed.
- Manual 2nd vehicle start mode
During a vehicle stop, the manual 2nd gear vehicle start mode can be selected by tilting the select lever to the manual side and operating the paddle switch +. This mode allows a vehicle start with a traction power equivalent to the 2nd speed range, making it easy to control the traction on a slippery road.
UPHILL/DOWN HILL CONTROL
This control helps the driver running on a uphill and downhill by estimating the road gradient during driving, then optimizing the traction and the engine brake force.
On-Board Diagnosis System
The on-board diagnosis system detects a trouble and generates/displays a code corresponding to the trouble point. The AT OIL TEMP light on the combination meter flashes to indicate the occurrence of a trouble or malfunction.
The AT OIL TEMP light flashes as the result of trouble detection by the control module, and the diagnostic trouble code (DTC) corresponding to that trouble is stored in the control module.
Before checking a DTC, you must connect the Subaru Select Monitor III (SSM III) to the data link connector. To facilitate various functions and diagnosis operations, a SSM III-ready diagnosis system is adopted.
The on-board diagnosis system detects troubles in the electric system or abnormal system conditions as listed below.
| Lockup duty solenoid | AWD duty solenoid |
|---|---|
| Lockup ON/OFF solenoid | ATF oil temperature sensor |
| Primary speed sensor | Inhibitor switch |
| Secondary speed sensor | Manual switch |
| Front wheel speed sensor | Speed change control function |
| Secondary hydraulic pressure sensor | High-speed CAN communication |
| Secondary linear solenoid | Self-shut relay |
| F&R clutch linear solenoid | Brake switch |
| Primary UP duty solenoid | AT shift lock solenoid |
| Primary DOWN duty solenoid |
Fail-Safe Function
The Lineartronic™ performs diagnoses to the following devices in order to secure safety and minimum drivability upon a trouble.
If a trouble is detected, it makes the AT OIL TEMP light flash at 2 Hz cycles and allows the user to retrieve DTC by SSM III and identify the trouble point easily.
PRIMARY SPEED SENSOR
If a trouble occurs with the primary speed sensor, the Lineartronic™ continues the control according to the engine speed value during a lockup or the secondary speed sensor value when the lockup is OFF.
SECONDARY SPEED SENSOR
If a trouble occurs with the secondary speed sensor, the Lineartronic™ continues the control according to the front wheel speed sensor value.
FRONT WHEEL SPEED SENSOR
If a trouble occurs with the front speed sensor, the Lineartronic™ continues the control according to the secondary speed sensor value.
SECONDARY HYDRAULIC PRESSURE SENSOR
If a trouble occurs with the secondary hydraulic pressure sensor, the Lineartronic™ stops the pressure feedback control and performs an open loop control.
SECONDARY LINEAR SOLENOID
If a trouble occurs with the secondary linear solenoid, the Lineartronic™ stops the solenoid driving current supply, providing a mechanical maximum hydraulic pressure for the secondary pressure.
F&R CLUTCH LINEAR SOLENOID
If a trouble occurs with the F&R clutch linear solenoid, the Lineartronic™ stops the solenoid driving current supply, providing a maximum hydraulic pressure corresponding to the secondary pressure for the F&R clutch pressure.
PRIMARY UP AND DOWN DUTY SOLENOIDS
If a trouble occurs with the primary UP or DOWN duty solenoid, the Lineartronic™ stops the driving control for each solenoid sequentially to provide a speed change ratio that allows vehicle travel at minimum.
LOCKUP DUTY SOLENOID
If a trouble occurs with the lockup duty solenoid, the Lineartronic™ stops the solenoid driving control and inhibits any lockup.
LOCKUP ON/OFF SOLENOID
If a trouble occurs with the lockup ON/OFF solenoid, the Lineartronic™ stops the solenoid driving control and inhibits any lockup.
AWD DUTY SOLENOID
If a trouble occurs with the AWD duty solenoid, the Lineartronic™ stops the solenoid driving control and creates a front wheel drive status.
ATF OIL TEMPERATURE SENSOR
If a trouble occurs with the ATF oil temperature sensor, the Lineartronic™ continues the control by assuming the specified oil temperature.
INHIBITOR SWITCH
If no input or multiple input occur consecutively in the TCM input circuit, the Lineartronic™ continues the control by selecting a range according to the following priority order.
D --> R --> N --> P
MANUAL SWITCH
If an ON failure is detected for the manual switch, the Lineartronic™ inhibits the manual mode.
HIGH-SPEED CAN COMMUNICATION
The Lineartronic™ exchanges information with various control modules including the engine control system via. the high-speed CAN communication and constantly checks the reliability of communication by monitoring the incoming information mutually. If TCM detects a CAN communication error in the CAN communication line or any system, it continues the control by replacing the data necessary for transmission control with the appropriate backup values.
SELF-SHUT RELAY
If the TCM self-shut relay is not activated due to a malfunction even when the ignition switch is ON, the transmission falls in a no-control state because it cannot supply power to each solenoid. Even in this case, TCM makes the AT OIL TEMP light flash via the CAN communication to alert the driver to the malfunction.
SSM III Support Controls
The Lineartronic™ adopts the following new convenience functions in the SSM III "AT related learning&inspection mode".
AWD ON/OFF CHANGEOVER FUNCTION
The AWD fuse in the fuse box, which was used to disable the AWD mechanism, has been abolished and the same function is now available from SSM III.
SIMPLIFIED LEARNING CONTROL
The solenoid learning promotion process carried out before delivery is now executable on-board in the market by using SSM III as is the case with the conventional 4AT and 5AT transmissions. Because of this, an equivalent quality level to that attained at the factory can be secured even after the transmission assembly or TCM is replaced.