AUTOMATIC TRANSAXLE SYSTEM

Line Pressure Optimal Control

• The line pressure is controlled using shift solenoid valve SLT.

• Through the use of shift solenoid valve SLT, the line pressure is optimally controlled in accordance with the engine torque information, as well as with the internal operating conditions of the torque converter and the transaxle.

• Accordingly, the line pressure can be accurately controlled in accordance with the engine output, traveling condition and the ATF temperature, thus achieving smooth shift characteristics and regulating the workload of the oil pump (reducing unnecessary parasitic losses).

  

Powertrain Cooperative Control

1. Throttle Control at Starting

   
   

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

     

2. Deceleration Force Control

   
   

   • The ECM determines the gear that is to be selected when the accelerator pedal is released (released completely) in accordance with the way the accelerator pedal is released (suddenly or slowly) during deceleration. In this way, unnecessary upshifts are prevented during deceleration, matching the driver's intentions. In addition, unintended downshifts are prevented when accelerating the vehicle again, achieving smooth acceleration.

     

3. Transient Shifting Control

   
   

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

     

Artificial Intelligence Shift Control (AI-shift Control)

• The automatic transaxle gear is determined by the shift pattern, which uses the vehicle speed and accelerator pedal depression angle.

• Additionally, AI-shift control enables the ECM to estimate the road conditions and the driver's intention in order to automatically control the shift pattern in an optimal manner. As a result, a comfortable ride has been achieved.

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

• AI-shift control determines optimal transaxle control based on input signals and automatically changes the shift pattern.

  

1. Road Condition Support Control

   
   

   • Under road condition support control, the ECM determines from the accelerator pedal depressing angle and the vehicle speed whether the vehicle is being driven uphill or downhill. To achieve the optimal drive force while driving uphill, this control prevents unnecessary upshifts. To achieve the optimal engine brake effect while driving downhill, this control automatically performs downshifts.

     

2. Driver's Intention Support Control

   
   

   • The driver's intention is estimated based on the accelerator pedal depression angle and vehicle condition to switch to a shift pattern that is well-suited to the driver.

     

3. Quick Brake Downshift Control

   
   

   • When sudden braking is applied in Sport mode, the quick brake downshift control improves re-acceleration response and engine brake force by downshifting.

     

Deceleration Downshift Control

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

• When the vehicle is in 6th gear and starts decelerating, the transaxle downshifts from 6th to 5th, 5th to 4th and 4th to 3rd* before fuel cut control ends so that the fuel cut control can continue operating.

  Tech Tips

  *: The operation of 4th to 3rd downshift control is limited when the air conditioning is off.

  

Direct Downshift Control

• For conventional downshift control, when shifting from 6th to 3rd or 5th to 2nd, downshifts use an intermediate gear in order to achieve smooth acceleration response. In addition to conventional control, direct downshift control is used for this model. This control skips unnecessary shifts, enabling the vehicle to downshift directly from 6th to 3rd or from 5th to 2nd.

• When the accelerator pedal is depressed quickly, direct downshift control enables direct downshifts with a quick shift response, skipping unnecessary shifts. Direct downshift control places the emphasis on reducing the time required to achieve the target gear. Conventional downshift control is used when the accelerator pedal is depressed slowly, providing smooth acceleration response. As a result, this logic achieves downshift responsiveness in accordance with the driver's intentions.

  

Lock-up Timing Control

• The ECM uses lock-up timing control in order to improve fuel consumption performance in 2nd or higher when the shift lever is in D, or when the S6, S5 or S4 range is selected.

  

Flex Lock-up Clutch Control

• During acceleration, partial control of the power transmission between the lock-up clutch and torque converter greatly boosts transmission efficiency in accordance with the driving conditions, improving fuel economy.

• Even when the vehicle is decelerating (the accelerator pedal is released), flex lock-up clutch control operates. As a result, the fuel-cut area is expanded and fuel economy is improved.

• By allowing flex lock-up clutch control to continue operating during gearshifts, smooth torque transmission is obtained. As a result, fuel economy and driveability are improved.

• For flex lock-up clutch control, H infinity (H∞) control theory is used to achieve a high level of system stability and response to various characteristic changes.

  

  

Multi-mode Automatic Transmission

• The multi-mode automatic transmission is designed to allow the driver to switch between gear ranges. By moving the shift lever to S and then moving the shift lever toward "+" (forward) or to "-" (backward), the driver can select the desired shift range. Thus, the driver is able to shift gears with a manual-like feel.

• This multi-mode automatic transmission is designed to allow the driver to switch gear ranges; it is not for manually selecting single gears.

• When the vehicle is being driven at a speed that is higher than the maximum safe speed for a downshift, any attempt to shift to a lower range by operating the shift lever will not be performed. This is done in order to protect the automatic transaxle. In this case, the ECM sounds the buzzer in the combination meter assembly twice to alert the driver.

  

• The driver can select S mode by moving the shift lever to S. At this time, the 4th or 5th shift range will be selected according to the vehicle speed (during AI-shift control, however, the 3rd shift range may be selected).

• Under this control, the ECM performs shift control within the usable gear range that the driver selects. As with an ordinary automatic transaxle, the ECM shifts to 1st gear when the vehicle is stopped.

• The shift lever position and the shift range are indicated by the shift indicator light in the combination meter assembly (the shift range is shown only when the shift lever is in S, and it is not shown when the shift lever is in P, R, N or D).

• When the shift lever is in S, the S mode indicator light in the combination meter assembly illuminates. The shift indicator light indicates the shift range that the driver has selected.

• Holding the shift lever toward "+" with the shift lever in S changes the shift range to the S6 range regardless of the current range (S1 to S5).

• In order to prevent an excessive engine speed, a function is used that automatically selects a higher shift range before the engine speed becomes excessive.

• In order to protect the automatic transaxle, a function is used that automatically selects a higher shift range when the fluid temperature is high.

  

  *a	Transition of Shift Ranges	*b	Shift Pattern
  	Default Shift Range	-	-

High Response Upshift Control

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

• When the shift lever is in D or S, the high response upshift control activates when Sport mode is selected.

  

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 proper engine brake force. In this way, a smooth and quick downshift is achieved.

• The blipping downshift control activates by downshifting with the shift lever in S when Sport mode is selected.