AUTOMATIC TRANSMISSION SYSTEM

Clutch Pressure Optimal Control

• The TCM monitors the signals from various types of sensors, such as the transmission revolution sensor (NT) and transmission revolution sensor (NC3), allowing shift solenoid valve SL1, SL2, SL3, SL4, SL5, SLT (line pressure control solenoid assembly) and shift solenoid valve SLU (lock up control solenoid assembly) to minutely control the clutch pressure in accordance with engine output and driving conditions. As a result, smooth shift characteristics are achieved.

  

Clutch to Clutch Pressure Control

• Clutch to clutch pressure control is used for shift control. As a result, shift control in the 2nd gear or above is possible without using the 1-way clutch, and the automatic transmission has been made lightweight and compact.

• Using the fluid pressure circuit, which enables the clutches and brakes (C1, C2, C3, C4 and B1) to be controlled independently, and the high flow SL1, SL2, SL3, SL4 and SL5 shift solenoid valves, which directly control the line pressure, the TCM controls each clutch and brake accordingly with the optimum fluid pressures and timings in accordance with the information transmitted by the sensors, and then shifts the gears. As a result, highly responsive and excellent shift characteristics have been achieved.

  

Powertrain Cooperative Control

• Driving Response and Acceleration Management System (DRAMS) is used for this vehicle. This system integrally controls the engine, transmission and other driving related controls. By integrally controlling the engine and automatic transmission using this system, quick response and a high quality driving feel in accordance with the driver's intentions are achieved, such as when accelerating or decelerating or during gear shifts.

  

1. Throttle Control at Launch

   
   

   • The engine output is optimally controlled with Electronic Throttle Control System intelligent (ETCS-i) in real-time in accordance with the transient force from the torque converter when the vehicle is launched. This achieves a "suppressed sense of lurchingforward", "tire slippage suppression" and "improved responsiveness", ensuring excellent launch performance.

     

2. Deceleration Force Control

   
   

   • The TCM determines the gear position when the accelerator pedal is off (released completely) in accordance with the way the accelerator pedal is released (suddenly or slowly) during deceleration. In this way, unnecessary upshifts and downshifts are prevented when the accelerator pedal is off and subsequent smooth acceleration is ensured, matching the driver's intentions.

     

3. Transient Shifting Control

   
   

   • Through integrated control with Electronic Throttle Control System-intelligent (ETCS-i), Electronic Spark Advance (ESA), and electronic control of the engagement and release speed of clutch and brake hydraulic pressures, excellent response and shift shock reduction have been achieved.

     

Coast Downshift Control

• The TCM performs downshift control to prevent the engine speed from decreasing, thus keeping fuel cut control operating for as long as possible. In this way, the fuel economy is improved.

• In this control, the transmission downshifts from 8th to 7th, 7th to 6th and then 6th to 5th before fuel cut control ends when the vehicle is decelerated in the 8th gear, so that fuel cut control continues operating. In addition, the TCM performs downshifting when the vehicle is decelerated both in the 6th and 7th gears.

  

Multi-mode Transmission

• The driver can select the desired gear range by moving the shift lever to "+" (forward) or to "-" (backward) while the shift lever is in M. Also, the shift paddle switch (transmission shift switch assembly) can be used to change the gear range while the driver is holding the steering wheel. Thus, the driver is able to shift gears with a manual-like feel.

• When the shift lever is in D, the driver can momentarily select a desired shift range by operating the shift paddle switch (transmission shift switch assembly). Automatic shifting will be reinstated under the following conditions:

  - The vehicle has stopped.

  - The driver continues to push the shift paddle switch (transmission shift switch assembly) in the "+" direction longer than 1 second.

  - The driver depresses the accelerator pedal longer than a predetermined length of time.

• When the vehicle is being driven at a prescribed speed or higher, any attempt to shift to a lower range by operating the shift lever will not be executed, in order to protect the automatic transmission. In this case, the ECM sounds the multi buzzer in the combination meter assembly twice to alert the driver.

  

• When the shift lever is in M, the gear hold control, lock-up control, high response upshift control and blipping downshift control are used in order to improve response in accordance with the driver's operation of the accelerator pedal, shift lever or transmission shift switch, and to improve gear shift feeling.

  

1. Gear Hold Control

   
   

   • Gear shifting will not be performed under gear hold control as long as the shift lever or shift paddle switch (transmission shift switch assembly) is not operated. This makes it possible to make efficient use of highest engine speeds. However, in the following cases, operation of gear hold control is limited.

   Automatic shifting when the shift lever is in M

   When the ATF or engine coolant temperature is low, gear shifting will be performed automatically. When the ATF temperature is high, gear shifting will be performed automatically.

2. Lock-up Control

   
   

   • While the shift lever is in M, lock-up control operates from 2nd gear, transmitting the changes in engine power directly to the output shaft, the same way as with a manual transmission, and thus, direct response to the accelerator operation is achieved.

3. High Response Upshift Control

   
   

   • The high response upshift control achieves highly responsive upshift operation using the clutch to clutch pressure control, which regulates each clutch and brake quickly and precisely, and by the powertrain cooperative control, which optimally regulates engine torque during shifting.

   

4. Blipping Downshift Control

   
   

   • The blipping downshift control regulates each clutch and brake using the clutch to clutch pressure control, allowing them to be engaged smoothly and disengaged quickly. In addition, fuel injection volume is increased and engine speed is boosted by the powertrain cooperative control, thus ensuring engine brake force. In this way, a smooth and quick downshift is achieved.

   

Artificial Intelligence Shift Control (AI-shift Control)

• The AI-shift control determines optimal transmission control based on input signals and automatically changes the shift pattern. As a result, a high caliber of transmission operation is achieved.

• The AI-shift control includes a road condition support control and a driver's intention support.

• The AI-shift control is effected with the shift lever in D, based on the accelerator pedal and brake operation data. The AI-shift control will be canceled when the shift lever is moved to a position other than D.

  

1. Road Condition Support Control

   
   

   • The TCM identifies the throttle valve opening angle, accelerator pedal opening angle and vehicle speed to determine whether the vehicle is being driven uphill or downhill. Unnecessary upshift is restrained to automatically achieve optimal drive force at all times while driving uphill. Downshift is automatically conducted to achieve optimal engine brake force, while driving downhill.

     

2. Driver's Intention Support Control

   
   

   • The driver's intention support control is estimated based on the accelerator pedal operation, vehicle condition and a shift pattern that is well-suited to the driver is selected without operating the switch.

   
   

   1. Sudden Accelerator Pedal Release Control

   
   

   • When the accelerator pedal is released suddenly, the transmission is kept in gear as long as possible, which improves engine braking force.

     

   2. Sudden Accelerator Pedal Depress Control

   
   

   • When the accelerator pedal is depressed suddenly, downshifting occurs earlier providing for improved acceleration response.

     

   3. Downshifting control during hard braking

   
   

   • High engine braking force and good re-acceleration response have been achieved by actively downshifting during deceleration when hard braking is made.

     

   4. G AI-shift Control

   
   

   • When the vehicle enters a corner, this system assesses the overall vehicle condition based on signal from the G sensor signal and the driver's intention, and downshifts to the appropriate gear to obtain necessary driving force for coming out of a corner.

   • Controllability during cornering is ensured by suppressing gear shifting.

     

Linear feel improving control

• Conventionally, drive force was dependent on the accelerator pedal operation (throttle opening) and the gear position.

• With the linear feel improving control, optimum engine torque (throttle opening) for the gear position is achieved, reducing the frequency of downshifting.

• Continuous drive force has been achieved by reducing the variations in drive force when downshifting, improving controllability of the vehicle during accelerator pedal operation.