AUTOMATIC TRANSAXLE SYSTEM

Line Pressure Control

1. The line pressure is controlled using the shift solenoid valve SLT.

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

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

   

Lock-up Timing Control

1. The ECM uses lock-up timing control in order to improve the fuel economy in 3rd gear or higher when the shift lever is in D, or when the S6, S5, S4 or S3 range has been selected.

   Figure 1. Lock-up Operating Range in Each Gear

   

   Lock-up Operation

   Gear	Shift Lever Position or Range
   	D or S6	S5	S4	S3
   1st	X	X	X	X
   2nd	X	X	X	X
   3rd	○	○	○	○
   4th	○	○	○	-
   5th	○	○	-	-
   6th	○	-	-	-

   ○: Operates

   X: Does not operate

   -: Not applicable

Flex Lock-up Clutch Control

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

2. Even when the vehicle is decelerating (the accelerator pedal is released), flex lock-up clutch control operates. Therefore, the fuel-cut area of the engine has been expanded and fuel-economy has been improved.

3. By allowing flex lock-up clutch control to continue operating during gearshifts, smooth torque transmission has been obtained. As a result, fuel economy and drivability have been improved.

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

   

5. The flex lock-up operating range has been expanded. Flex lock-up begins operating once the vehicle starts moving to lower engine speed and improve fuel economy.

   Figure 2. Flex Lock-up Operating Range

   

   Flex Lock-up Operation

   Gear	Shift Lever Position or Range
   	D or S6	S5	S4	S3
   1st	X	X	X	X
   2nd	○	○	○	○
   3rd	○*	○*	○*	○
   4th	○*	○*	○*	-
   5th	○*	○*	-	-
   6th	○*	-	-	-

   ○: Operates

   X: Does not operate

   -: Not applicable

   *: Flex lock-up clutch control also operates when the vehicle decelerates.

Powertrain Cooperative Control

1. The engine output is appropriately controlled with the Electronic Throttle Control System-intelligent (ETCS-i) in real-time according to the transient force from the torque converter when the vehicle is launched. This achieves a high response and smooth acceleration, ensuring excellent launch performance.

   

2. 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 (quickly 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. 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.

   

Coast Downshift Control

1. 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.

2. For this control, 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 fuel cut continues operating. (The operation of 4th to 3rd downshift control is only available when the air conditioning system is off.)

   

Direct Downshift Control

1. 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 vehicle. This control skips unnecessary shifts, enabling the vehicle to downshift directly from 6th to 3rd or from 5th to 2nd.

2. 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.

   

Artificial Intelligence Shift Control (AI-shift Control)

1. The automatic transmission gear is determined by the shift pattern, which uses the vehicle speed and throttle valve opening angle.

2. 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 the manner. As a result, a comfortable ride has been achieved.

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

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

   

5. Under road condition support control, the ECM determines the throttle opening angle and the vehicle speed in addition to whether the vehicle is being driven uphill or downhill. To achieve the drive force required while driving uphill, this control prevents unnecessary upshifts. To achieve engine braking while driving downhill, this control automatically performs downshifts.

   

6. The ECM estimates the driver's intention based on the accelerator pedal operation and vehicle operating conditions to select a shift pattern that is well-suited to each driver, without the need to operate the shift pattern select switch used on conventional models.

Multi-mode Automatic Transmission

1. A 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 "-" (backward), the driver can select the desired shift range. Thus, the driver is able to shift gears with a manual-like feel.

2. This Multi-mode Automatic Transmission is designed to allow the driver to switch gear ranges; it is not for manually selecting single gears.

3. 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.

   

4. 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).

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

6. The shift lever position and the shift range are indicated by the shift indicator 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).

7. 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.

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

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

10. In order to protect the automatic transmission, a function is adopted that automatically selects a higher shift range when the fluid temperature is high.

    Usable Gear Chart

    Shift Range	Shift Indicator Light	Usable Gear
    S6	6	1st to 6th
    S5	5	1st to 5th
    S4	4	1st to 4th
    S3	3	1st to 3rd
    S2	2	1st to 2nd
    S1	1	1st

11. 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.

    • The high response upshift control activates when the shift lever is in S.

    • Engine torque reduction via engine integrated control is precisely controlled to the optimal state according to the driving conditions from the fuel cut to normal control.

      Tech Tips

      During D-range paddle active control, high response upshift control is not performed.

      Figure 3. Upshift from 2nd to 3rd Gear

      

12. 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 D or S.

      Figure 4. Downshift from 3rd to 2nd Gear