CVT SYSTEM

Pulley Ratio Control

• The ECM judges the driving conditions through each input signal and selects the optimal control to achieve driving which meets the driver's intentions.

  

• The ECM calculates the target primary pulley speed in accordance with the accelerator pedal position signal, vehicle speed signal and stop light switch signal, in order to attain an optimal pulley ratio and shifting speed. To allow the actual primary pulley speed (acquired from the primary speed sensor) to match the target primary pulley speed, the ECM actuates the shift solenoid valves DS1 and DS2 in order to control the inflow and outflow volume of the line pressure to and from the primary pulley. As a result, optimal pulley ratio and shifting speed have been achieved.

1. Automatic Shift Control

   
   

   • When the shift lever is in D, the system performs engine integrated control to optimize fuel economy characteristics and driving performance.

   • Through the wide shifting range and lock-up control, which can be regulated by low vehicle speed, quietness and low fuel consumption are achieved by decreasing the engine speed as far as possible.

   • Throttle characteristics and shifting characteristics are utilized to flexibly control driving speed in response to the acceleration operation, thus achieving smooth driving without shifting shock.

     

   • The Sport mode limits the gear step for the acceleration side and maintains the primary pulley speed at high speeds. This produces a moderate engine braking force and provides an excellent shift response.

     

2. Acceleration Improvement Control

   
   

   • The system determines the driver's acceleration request based on the vehicle speed and the changes in the accelerator pedal position. When the system determines this request, it changes the shift characteristic into one in which the engine speed and vehicle speed increase linearly. This improves the acceleration feeling.

     

   • When Sport mode is on, upshifting time is shortened and engine speed increase rate is improved, thus giving a sportier setting compared to when Sport mode is off.

     

3. Deceleration Improvement Control

   
   

   • During deceleration, the pulley ratio is determined and a high engine speed is maintained, thus ensuring adequate engine braking.

   • Engine control, which generates driving force quickly, is conducted during re-acceleration.

     

   • When decelerating with Sport mode on, the pulley ratio is fixed in the lower ratio side to achieve a quicker deceleration response and stronger engine braking force compared to when Sport mode is off. In addition, a higher brake pedal force is caused by increasing engine speed when braking hard, and braking downshift control which generates a quick drive force during re-acceleration is used.

     

4. 7-speed Sport Sequential Shiftmatic

   
   

   • The 7-speed sport sequential shiftmatic is designed to allow the driver to switch the gear step. After moving the shift lever to M, the driver can select the desired gear step by moving the shift lever to "+" (forward) or "-" (backward). Thus, the driver is able to shift gears with a manual-like feel.

   • Through the engine-CVT integrated control, pulley ratio and engine torque which corresponds to shifting speed are finely controlled, thus improving shifting response and achieving a reduction in shifting shock.

     

   • When the shift lever is in M, this system automatically upshifts or downshifts under the following conditions:

     Condition	System Control
     Engine is under-revving.	1 step downshift
     Engine is over-revving.	1 step upshift

   • When the vehicle is stopped while the shift lever is in M, the transaxle automatically downshifts to M1.

   • When the accelerator pedal is fully depressed and a kickdown operation is performed, a downshift to a gear step determined according to the vehicle speed is performed.

   • The ECM will restrict the changing of the gear step if it detects a malfunction in the CVT system.

   • If the vehicle speed and engine speed exceed or go below a preset level in response to the driver's downshift operation request, changing the gear step will be prohibited. In this case, the buzzer in the combination meter will sound to alert the driver.

   
   

   High Response Sequential Shiftmatic Control

   • High response sequential shiftmatic control is used for shift shock reduction and improved shifting response during shift operation. The control cooperates with Electronic Throttle Control System-intelligent (ETCS-i) and Electronic Spark Advance (ESA) to finely regulate engine torque in accordance with the pulley ratio and shifting speed. As a result, shifting performance with smooth and sharp response has been achieved to shorten the time of shifting considerably.

     

5. Shift Control in Uphill/Downhill Traveling

   
   

   • The ECM determines that the vehicle is driving uphill or downhill based on the accelerator pedal position sensor signal and the vehicle speed signal. During uphill driving, the ECM limits upshift to achieve smooth driving. During downhill driving, the ECM downshifts upon detecting brake pedal operation, in order to provide moderate engine braking.

     

     *a	Without Control	*b	With Control
     *c	Downshift	*d	Upshift
     *e	Restrict Upshift	*f	Brake Operation

   • The actual acceleration calculated from the vehicle speed signal is compared with the reference acceleration (based on level road travel) stored in the ECM to determine uphill or downhill travel.

     

     *a	Smaller	*b	Greater
     *c	Uphill	*d	Downhill
     	Actual Acceleration		Reference Acceleration

Lock-up Control

• The lock-up operation range has been expanded from that of the previous automatic transaxle, thus enabling control to start from low speeds.

• The lock-up operation range during deceleration has been expanded to the low-speed range. This expands the fuel cut range and achieves excellent fuel economy.

  

  *1	Lock-up on
  *2	Throttle Opening Angle
  *3	Vehicle Speed