CVT SYSTEM

Automatic Shift Control (Speed Ratio Control)

1. 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 adjust the actual primary pulley (acquired from the primary speed sensor) to match the target primary pulley speed, the ECM actuates linear solenoid valve SLP (for primary pulley control) and linear solenoid valve SLS (for secondary pulley control) in order to control the pressure of primary pulley and secondary pulley. As a result, the optimal pulley ratio and shifting speed are achieved.

   

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

   

3. When the shift lever is in M, the shift characteristic is as shown below. The system will upshift automatically when the vehicle reaches the set speed during acceleration.

   

4. SPORT mode restricts the variable range of the high gear ratio to ensure a more direct feeling, and provides Deceleration Improvement Control and G AI-shift Control to support vehicle stability during cornering and to ensure responsiveness when exiting a corner by holding the optimal gear ratio. In addition, newly adopted Step Shift Control provides excellent response and linear and powerful acceleration and when driving on winding roads or situations in which gentle acceleration is required.

   Tech Tips

   
   

   • SPORT mode is turned on by pressing the SPORT mode switch (pattern select switch assembly).

   • When SPORT mode is selected, the SPORT mode indicator in the combination meter assembly illuminates.

   • When SPORT mode is operating, SPORT mode is turned off by pressing the SPORT mode switch (pattern select switch assembly).

   • When the engine is stopped with SPORT mode on, SPORT mode is turned off.

   • When the shift lever is in M, or temporary 7-speed sport sequential shiftmatic mode is selected with the shift lever in D, the gear ratio for each gear step is maintained.

   
   

   1. Low gear ratio shift schedule

   
   

   1. The variable range of the low gear ratio is restricted to ensure appropriate engine braking force when decelerating and to enhance engine response when accelerating.

   2. Depending on the accelerator pedal depression amount, the engine can quickly rev to and be maintained in the high speed range, ensuring quick acceleration and responsiveness.

      

   2. G AI-shift control

   
   

   1. G AI-shift control generates an appropriate engine braking force by varying the gear ratio according to the brake pedal depression force.

   2. If a certain amount of lateral G force is detected, G AI-shift control determines that the vehicle is cornering and maintains engine speed by restricting the variable gear range, ensuring excellent throttle control and appropriate driving force.

      

   3. Step Shift Control

   
   

   1. Step Upshift Control

   
   

   1. During acceleration, Step Upshift Control enables the engine speed to increase in proportion to vehicle speed and repeats upshifts to promote unconstrained and powerful acceleration.

   2. During upshift, the throttle valve is electronically controlled to improve shift response and reduce shift shock.

      

Acceleration Improvement Control

1. 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 will change the shift characteristic into one in which the engine speed and vehicle speed increase linearly. This improves the acceleration feeling.

   

Deceleration Improvement Control

1. During deceleration, a pulley ratio which allows high engine speed to be maintained, is calculated, thus ensuring adequate engine braking.

2. During subsequent acceleration, the engine is controlled to generate driving force quickly.

   

Uphill/Downhill Shift Control

1. Uphill/downhill shift control helps perform optimal shifting while driving on a winding uphill or downhill road.

2. When the ECM determines the vehicle is traveling uphill, the control restricts upshifting, thus offering smooth driving.

3. If a signal indicating that the driver has operated the brake pedal is input when the ECM has determined the vehicle is traveling downhill, the control downshifts to generate optimal engine braking force.

   

4. 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	Uphill	*b	Downhill
   *c	Smaller	*d	Greater
   	Reference Acceleration		Actual Acceleration

Lock-up Control

1. The lock-up operation range has been expanded from that of previous continuously variable transaxles, thus enabling control to start from low speeds.

2. 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 Off
   *2	Throttle Opening Angle
   *3	Lock-up On
   *4	Vehicle Speed

Flex Lock-up Control

1. In order to improve the transmission efficiency and also the fuel economy, the linear solenoid valve SLU (for lock-up control) for lock-up engagement pressure control is employed to deliver flex lock-up control that can provide more precise control than that of a conventional lock-up clutch mechanism.

2. The flex lock-up control consists of flex start control and flex lock-up control during deceleration.

3. The flex start control aggressively operates the lock-up clutch during start-off to increase the transmission efficiency, as a result, the engine can run in its most efficient operating range.

   

   

4. Flex lock-up control during deceleration is used to expand the fuel-cut range. It operates the lock-up clutch over the low vehicle speed range when the vehicle decelerates so that minimal speed difference between the engine speed and turbine speed can be maintained.

Neutral Control

1. When the vehicle speed is approximately 10 km/h (6 mph) or less during braking or the vehicle is stopped with the shift lever in D, the engine and CVT are disconnected (the forward clutch is released halfway) to reduce engine load.

   

   

Shift Lock System

1. A shift lock system consisting of a key interlock device* and a shift lock mechanism is used.

2. On the models without the entry and start system, the key interlock device prevents the key from being pulled out after the ignition switch is turned off, unless the shift lever is moved to P. Thus, the driver is urged to park the vehicle with the shift lever in P.

3. The shift lock mechanism prevents the shift lever from being moved to any position other than P, unless the ignition switch is ON and the brake pedal is depressed. This mechanism helps prevent unintentional vehicle movement.

4. The shift lock control ECU sub-assembly uses the P detection switch to detect the shift lever position, and receives input signals from the stop light switch and ignition switch. Upon receiving these signals, the shift lock control ECU sub-assembly turns on the shift lock solenoid and the key interlock solenoid* in order to release the shift lock and key interlock*.

5. A shift lock release button, vehicle manually overrides the shift lock mechanism, is used.

   
   

   • *: Models without entry and start system

   

CVT Fluid Warmer

1. The CVT fluid warmer (transmission oil cooler) uses engine coolant that has been warmed by the engine to warm up the CVT fluid quickly and maintain a high CVT fluid temperature (within limits). Consequently, the friction losses of the CVT are quickly reduced, thus improving fuel economy.

2. After warming up the CVT fluid, the engine coolant continues to flow into the CVT fluid warmer (transmission oil cooler) to cool down the CVT fluid.

   

   *1

   CVT Fluid Warmer (Transmission Oil Cooler)

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   -

Oil Pump Assembly

1. A trochoid gear type oil pump is used.

2. The oil pump assembly has 1 inlet port and 2 discharge ports.

   

   *a	Conventional Type Oil Pump	*b	2 Discharge Port Oil Pump
   *c	Discharge Port	*d	Inlet Port
   *e	Discharge Port 2	*f	Discharge Port 1

3. The 2 discharge port oil pump system enables the selection of 2 oil pressure modes in accordance with the engine operating conditions, reducing the required oil pump drive torque.

   

   *1	Drive Torque of Single Discharge Port Oil Pump
   *2	Drive Torque of Oil Pump
   *3	Drive Torque of 2 Discharge Port Oil Pump
   *4	Engine Speed

CVT Fluid Filling Procedure

1. A specialized CVT fluid filling procedure is used in order to improve the accuracy of the CVT fluid level when the CVT is being repaired or replaced. For details about the CVT fluid filling procedure, refer to the Repair Manual.

2. The CVT fluid filling procedure utilizes the refill plug, overflow plug, CVT fluid temperature sensor and shift position indicator.

   

   *1	Refill Plug	*2	Oil Pan
   *3	Overflow Tube	*4	Overflow Plug

Forward/Reverse Switching Unit

1. The forward/reverse switching unit consists of a planetary gear, a forward clutch and a reverse brake.

2. The forward clutch, which operates during forward movement, connects the input shaft to the sun gear.

3. The reverse brake, which operates during reverse movement, keeps the planetary carrier stationary.

   

   *1	Reverse Brake	*2	Forward Clutch
   *3	Ring Gear	*4	Planetary Gear

Pulley and Steel Belt

1. The widths of the grooves of the pulleys are changed through hydraulic control.

2. During acceleration, the operation of the linear solenoid valve SLP (for primary pulley control) increases the oil pressure of the primary pulley, thus decreasing the width of the pulley groove.

3. During deceleration, the operation of the linear solenoid valve SLP (for primary pulley control) decreases the oil pressure of the primary pulley, thus increasing the width of the pulley groove.

4. The secondary pulley is hydraulically controlled by the linear solenoid valve SLS (for secondary pulley control). The linear solenoid valve SLS (for secondary pulley control) controls the belt clamping pressure to ensure the proper power transmission efficiency.

   

   *1	Primary Pulley	*2	Steel Belt
   *3	Secondary Pulley	-	-
   *a	Pulley Ratio (Low)	*b	Pulley Ratio (High)
   *c	Groove Width (Large)	*d	Groove Width (Small)

5. The primary pulley uses a single piston construction.

   

   *a	Pulley Ratio (Low)	*b	Pulley Ratio (High)
   *c	Chamber	-	-
   	Oil Pressure	-	-

6. The steel belt consists of elements and 2 rows of steel rings. In contrast to chains and V-belts which transmit power through the use of tensile force, this steel belt uses the compressive action (pushing force) of the elements to transmit power.

   

   *1

   Steel Ring

   *2

   Element

Parking Lock Mechanism

1. A parking lock mechanism is used on the secondary pulley. The engagement of the parking lock pawl with the parking lock gear integrated into the secondary pulley locks the transaxle.

   

   *1

   Parking Lock Pawl

   *2

   Parking Lock Gear

Transmission Valve Body Assembly

1. The transmission valve body assembly consists of upper and lower valve bodies and 5 shift solenoid valves.

2. The 5 shift solenoid valves are installed in the lower valve body, ensuring serviceability.

   

   *1	Upper Valve Body	*2	Lower Valve Body
   *3	Linear Solenoid Valve SLP (for Primary Pulley Control)	*4	On-off Solenoid Valve SC (for Clutch)
   *5	Linear Solenoid Valve SLS (for Secondary Pulley Control)	*6	Linear Solenoid Valve SLU (for Lock-up Control)
   *7	On-off Solenoid Valve SL (for Lock-up)	-	-

   

   *1	Transmission Revolution Sensor (NIN)	*2	Transmission Revolution Sensor (NT)
   *3	Primary Pulley	*4	Secondary Pulley
   *5	Transmission Revolution Sensor (NOUT)	*6	Valve Body
   *7	Manual Valve	*8	Linear Solenoid Valve SLP (for Primary Pulley Control)
   *9	Linear Solenoid Valve SLS (for Secondary Pulley Control)	*10	Linear Solenoid Valve SLU (for Lock-up Control)
   *11	On-off Solenoid Valve SL (for Lock-up)	*12	On-off Solenoid Valve SC (for Clutch)
   *13	ECM	-	-
   *a	Vehicle Speed Control	*b	Belt Clamping Pressure Control
   *c	ON-OFF and Back Pressure Control	*d	Clutch Pressure Control

CVT Fluid Temperature Sensor

1. The CVT fluid temperature sensor is installed to the transmission valve body assembly.

2. The CVT fluid temperature sensor detects the fluid temperature, performs pulley ratio control in accordance with the fluid temperature, and is used in performing lock-up clutch pressure control, forward clutch pressure control and belt clamping pressure control.

   

   *1	Thermistor
   *2	Resistance (kΩ)
   *3	CVT Fluid Temperature Sensor
   *4	Fluid Temperature (°C)

Oil Pressure Sensor

1. The oil pressure sensor detects the hydraulic pressure applied to the secondary pulley and is used in performing belt clamping pressure control, which optimally controls the clamping pressure of the steel belt necessary for transmitting torque.

   

   *1	Piezoelectric Element
   *2	Voltage
   *3	Oil Pressure Sensor
   *4	Oil Pressure

Shift Lever

1. A shift control mechanism with a push-pull type transmission control cable assembly is used.

   

   *1	Continuously Variable Transaxle Assembly	*2	Transmission Control Cable Assembly
   *3	Shift Lever Knob	*4	Shift Lock Control Unit Assembly
   *5	Position Indicator Housing	*6	Shift Lock Release Button Cover

Park/Neutral Position Switch Assembly, Transmission Control Switch and Shift Paddle Switch (Transmission Shift Switch Assembly)

1. The park/neutral position switch assembly sends the P, R, N, D and M position signals to the ECM.

2. The transmission control switch detects whether the shift lever is in D or M, and detects the operating conditions of the shift lever ["+" (forwards) or "-" (backwards)] when the 7-speed sport sequential shiftmatic mode is selected, and sends signals to the ECM.

3. The shift paddle switch (transmission shift switch assembly) is installed in the steering wheel. The ECM detects the operation of the shift paddle switch (transmission shift switch assembly) ["+" (right side) or "-" (left side)] when the M mode is selected.

4. The ECM controls the CVT system in accordance with the shift lever position signals.

5. The ECM transmits signals to the combination meter assembly for the shift position and shift range indicator (P, R, N, D and M) in response to the signals received from the switches.

   

CVT Power Flow

1. The changing of the pulley ratio is accomplished in a continuously variable manner by varying the widths of the grooves of the primary and secondary pulleys.

   

   *1	Primary Pulley	*2	Secondary Pulley
   *3	Steel Belt	*4	Reduction Driven Gear
   *5	Reduction Drive Gear	*6	Reverse Brake
   *7	Forward Clutch	*8	Input Shaft
   *9	Differential Ring Gear	*10	Differential Drive Pinion

   Figure 3. Pulley Ratio Low (Shift Lever in D)

   

   *1	Primary Pulley	*2	Secondary Pulley
   *3	Steel Belt	*4	Reduction Driven Gear
   *5	Reduction Drive Gear	*6	Reverse Brake
   *7	Forward Clutch (ON)	*8	Input Shaft
   *a	Groove Width (Large)	*b	Groove Width (Small)

   Figure 4. Pulley Ratio High (Shift Lever in D)

   

   *1	Primary Pulley	*2	Secondary Pulley
   *3	Steel Belt	*4	Reduction Driven Gear
   *5	Reduction Drive Gear	*6	Reverse Brake
   *7	Forward Clutch (ON)	*8	Input Shaft
   *a	Groove Width (Small)	*b	Groove Width (Large)

   Figure 5. Neutral (Shift Lever in N)

   

   *1	Primary Pulley	*2	Secondary Pulley
   *3	Steel Belt	*4	Reduction Driven Gear
   *5	Reduction Drive Gear	*6	Reverse Brake
   *7	Forward Clutch	*8	Input Shaft
   *a	Groove Width (Large)	*b	Groove Width (Small)

   Figure 6. Reverse (Shift Lever in R)

   

   *1	Primary Pulley	*2	Secondary Pulley
   *3	Steel Belt	*4	Reduction Driven Gear
   *5	Reduction Drive Gear	*6	Reverse Brake (ON)
   *7	Forward Clutch	*8	Input Shaft
   *a	Groove Width (Large)	*b	Groove Width (Small)

Steel Belt Clamping Force Control

1. To ensure the proper control of the belt clamping pressure necessary for transmitting torque, the system controls the hydraulic pressure applied to the secondary pulley. The transmission valve body assembly is provided with a dedicated hydraulic pressure circuit for belt clamping pressure control. This circuit optimally controls the hydraulic pressure applied to the secondary pulley, thus achieving superior torque transmission performance.

   

   *1	Oil Pump Assembly	*2	Primary Regulator Valve
   *3	Linear Solenoid Valve SLS (for Secondary Pulley Control)	*4	Linear Solenoid Valve SLP (for Primary Pulley Control)
   *5	No. 1 Line Pressure Modulator Valve	*6	No. 3 Line Pressure Modulator Valve
   *7	Primary Pulley	*8	Secondary Pulley

Speed Ratio Control (Shift Control)

1. Speed ratio control is performed by controlling the hydraulic pressure applied to the primary pulley in order to provide fine-tuned control and a high level of reliability.

   

   *1	Oil Pump Assembly	*2	Primary Regulator Valve
   *3	Linear Solenoid Valve SLS (for Secondary Pulley Control)	*4	Linear Solenoid Valve SLP (for Primary Pulley Control)
   *5	No. 1 Line Pressure Modulator Valve	*6	No. 3 Line Pressure Modulator Valve
   *7	Primary Pulley	*8	Secondary Pulley