System Description

SYSTEM DIAGRAM








SYSTEM DESCRIPTION

1. GENERAL DESCRIPTION
(a) Under the control of the HV control ECU, this system uses an MGR (Motor Generator Rear) in the rear transaxle to directly drive the rear wheels.
According to the driving conditions of the vehicle, the HV control ECU linearly effects distribution control to attain an optimal front-rear torque distribution that provides the drive force required by the vehicle as a whole. Thus, this system realizes a high level of fuel economy and traction performance under various conditions, achieving excellent driving stability.

Operation of Axle System:

2. OPERATION DESCRIPTION
(a) Start-off
^ The HV control ECU calculates the required motive force based on the amount of effort applied to the accelerator pedal by the driver and the signals from the sensors. Then, the HV control ECU transmits the required motive force and the shift position signal to the skid control ECU.
^ The skid control ECU determines that the vehicle is in the start-off state based on the signals from the speed sensors, steering angle sensor, and the yawrate & deceleration sensor. Then, the skid control ECU calculates the torque distribution between the front and rear wheels based on the foregoing signals, the required motive force and the shift position signal from the HV control ECU, and transmits them to the HV control ECU.
^ Upon receiving the signals from the skid control ECU, the HV control ECU controls the motive forces of MG2 and MGR, in order to achieve traction performance while ensuring driving stability.
^ The HV control ECU constantly monitors the SOC (state of charge) of the HV battery. Thus, it decides whether to use the electrical power of the HV battery to drive MG2 and MGR, to use the electrical power generated by MG1 to drive MG2 and MGR, or to use both electrical powers.





(b) Normal Driving
^ The system stops the driving of the rear wheels during normal driving, to ensure fuel economy performance.
^ If the vehicle is being driven on a slippery road surface, accelerating, or making a tight turn, the skid control ECU detects the conditions of the vehicle based on the signals provided by the speed sensors, steering angle sensor, and the yawrate & deceleration sensor. Then, the skid control ECU calculates the torque distribution between the front and rear wheels, and transmits the signals to the HV control ECU.
^ Upon receiving the signals from the skid control ECU, the HV control ECU controls the motive forces of the engine, MG2, and MGR, in order to achieve traction performance while ensuring driving stability.
^ The HV control ECU constantly monitors the SOC (state of charge) of the HV battery. Thus, it decides whether to use the electrical power of the HV battery to drive MG2 and MGR, to use the electrical power generated by MG1 to drive MG2 and MGR, or to use both types of electrical power.





(c) Decelerating
^ The HV control ECU determines that the vehicle is decelerating by the required motive force and the shift position signal, and calculates the torque distribution for the front and rear wheels.
^ Based on the front and rear wheel torque distribution values that have been calculated, the HV control ECU determines the ratio for operating the regenerative brakes of the MG2 and MGR. According to this ratio, the MG2 and MGR charge the HV battery. By converting the kinetic energy of the vehicle into electrical energy and recharging it in the HV battery, this system contributes to enhancing fuel economy.








3. FAIL-SAFE FUNCTION
If 4WD driving is prohibited due to a malfunction in the vehicle system, "CHECK AWD SYSTEM" will be displayed on the multi-information display in the combination meter assembly, and operations of the rear transaxle will be prohibited.

4. DATA LIST
By referring to the DATA LIST displayed on the intelligent tester, the value and status of the switch, sensor, ECU, etc. can be read without removing parts. Reading DATA LIST as the first step in troubleshooting is one way to shorten labor time.

5. ACTIVE TEST
Performing the ACTIVE TEST using the intelligent tester allows the relay, actuator, etc. to operate without removing parts removal. Performing the ACTIVE TEST as the first step in troubleshooting is one way to shorten labor time. It is possible to display the DATA LIST during the ACTIVE TEST.

6. FUNCTION OF COMPONENTS
The table below describes the functions of the main components of the axle system.