AUTOMATIC TRANSAXLE SYSTEM

Clutch-to-Clutch Pressure Control

1. Clutch-to-Clutch pressure control is used for shift control. As a result, shift control in 2nd gear or above is possible without using a one-way clutch, making the automatic transaxle lightweight and compact.

2. Using the fluid pressure circuit, which enables the clutches and brakes (C1, C2, C3, C4, B1 and B2) to be controlled independently, and the high flow SL1, SL2, SL3, SL4, SL5, and SL6 linear solenoid valves, which directly control the clutch pressure, the ECM 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, the transmission has highly responsive and excellent shift characteristics.

   

Line Pressure Control

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

2. 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 clutch assembly and the automatic transaxle assembly.

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 optimizing the workload of the oil pump (reducing parasitic losses).

   

All Range Lock-up

1. Compared to the previous model, the UA80E performs lock-up control at lower speeds as well as at higher opening angles, enabling direct transmission of power similar to a manual transmission. Furthermore, the increased rate of engagement contributes to improved fuel efficiency.

2. By increasing the lock-up range, and suppressing engine revving, smooth driving with high responsiveness and linearity is realized.

   

   *1	UA80E L/U Range
   *2	Accelerator Pedal Angle
   *3	Conventional A/T
   *4	Vehicle Speed

   

3. Previously, lock-up was cancelled when downshifting to avoid shift shock, but with a torque converter adopting a multiple disc lock-up clutch as well as precision control taking into account transient characteristics of engine torque and hydraulic pressure, it has become possible to maintain lock-up continuously.

4. In 1st gear and the low engine speed regions of 2nd and higher gears, lock-up is not performed, and the torque converter function is employed to realize smooth driving.

   Gear Position	Shift Lever Position
   	D,S
   1st	X
   2nd	○*(During acceleration)
   3rd	○*(During acceleration)
   4th	○*
   5th	○*
   6th	○*
   7th	○*
   8th	○*

   ○: Operates

   X: Does not operate

   *: Except at low engine speed range

Powertrain Cooperative Control

1. At low accelerator opening angles, the highly efficient low engine speed ranges are aggressively employed, contributing to improved fuel efficiency and reduced noise.

2. Previous driving force characteristics were dependent on the torque characteristics of the engine electronic throttle opening angle and the gear ratio at each gear speed level. To achieve the driver's target driving force, the new control system uses an independent engine torque request for each gear, realizing increased fuel efficiency and driveability.

3. At low accelerator opening angle ranges, highly efficient engine ranges are aggressively employed, realizing increased fuel efficiency. At the same time the differences between target driving forces at each gear level are small, enabling smooth downshift without noticeable driving force change.

4. When the accelerator is deeply depressed to accelerate, the target driving force is set to be directly linked to the engine speed change, resulting in a direct and energetic feeling of acceleration, with the goal of achieving high balance of fuel efficiency and driveability.

   

   *1	Drive Force
   *2	Engine Speed
   *3	Accelerator Pedal Angle

Deceleration 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. In this control, the transmission downshifts from 7th to 4th before fuel cut control ends when the vehicle is decelerated in the 8th gear, so that fuel cut control continues operating.

   

Direct Connected Downshift

1. Smooth vehicle acceleration changes and linear changes in engine speed during downshifting were realized.

2. By precisely controlling hydraulic pressure, downshifting from a high gear to a low gear is accomplished with a smooth shift through the intermediate gears without any unevenness of engine speed or drive force.

   

   *1	Conventional A/T
   *2	Accelerator Pedal Angle
   *3	Engine Speed
   *4	Vehicle's Acceleration Forces

Artificial Intelligence Shift Control (AI-shift Control)

1. The automatic transaxle 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 optimal manner. As a result, a comfortable ride has been achieved.

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

4. The AI-shift control determines optimal 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 optimal drive force while driving uphill, this control prevents unnecessary upshifts. To achieve the optimal engine braking while driving downhill, this control automatically performs downshifts.

   

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

Multi-mode Automatic Transmission

1. 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 "+" or "-", 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 or 6th 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 optimal 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 position 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 in the combination meter illuminates. The shift position indicator indicate 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 S8 range regardless of the current range (S1 to S7).

9. In order to prevent excessive engine speed, a function was adopted that automatically selects a higher shift range before engine speed becomes too high.

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 Position Indicator	Usable Gear
    S8	8	1st to 8th
    S7	7	1st to 7th
    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