Electronic Control System
ELECTRONIC CONTROL SYSTEMDESCRIPTION
The electronic control system used in the new generation auto transaxle is far superior to the previous systems. This system is able to adopt a variable shift pattern for smooth and problem free shifting.
A solenoid valve is applied to each of the clutches and brakes and is independently controlled. Feedback control and correction control is performed in all gears as well as utilization of mutual control system to increase shift feeling. The torque converter damper clutch uses a partial lock up and full lock-up system. An additional control method called the HIVEC system (neural network) is adopted to increase shift feeling.
BLOCK DIAGRAM (CAN)
BLOCK DIAGRAM (CAN):
ELECTRIC CONTROL LOCATION
The TCM is located below the dashboard. However, in the B-engine vehicles, there is not TCM but PCM.
OPERATING COMPONENTS AND FUNCTIONS
OPERATING COMPONENTS AND FUNCTIONS:
HIVEC
In addition to the variable shift pattern control, the HIVEC system with neural network is also adopted for the first time in HMC. HIVEC uses information from various inputs and feedback adaptation and selects the best appropriate gear position and shift timing under all possible driving conditions.
CONTROL FOR ALL DRIVING CONDITION
This function makes TCM decide optimal gear range under all driving condition. The optimal operation of the manual shift lever by several drivers" and various driving condition is pre-set in the TCM. On the basis of mapping data, TCM decides the driving condition from throttle opening, vehicle speed and brake signal. And then TCM controls the gear position optimally. Optimal gear position is achieved under various driving condition by HIVEC logic.
OPTIMAL CONTROL FOR ALL DRIVING CONDITION
OPTIMAL CONTROL FOR ALL DRIVING CONDITION:
HIVEC INHIBIT CONDITIONS
- ATF temperature below 40°C.
- When standard pattern is not used.
^ Inhibitor switch: P, R, N, L
^ Extremely low temperature mode
^ Lower emission shift pattern
^ ATF control variable shift pattern
- During fail safe mode (3rd gear hold)
- In case of prohibition of intelligent shift
^ TPS faulty (Short: P1 702, Open: 1701)
^ ATF Temperature sensor faulty (P1 712)
^ Stop lamp s/w faulty (P0703)
- TCM faulty (Check engine lamp ON)
- After IG ON until first time stop lamp S/W comes ON-OFF.
SPORTS MODE
SPORTS MODE SWITCH
Sports mode allows the manual up-shift and downshift with the accelerator pedal is depressed. The prompt response and shift would be obtained due to the continuous shifting without cuffing of driving power. The shifting time is also decreased about 0.1 second during up-shift, 0.2 second during downshift. As the selector lever is pushed upward or downward one time, the gear is up shifted or downshifted by one gear.
SIGNALS OF SPORTS MODE SWITCH
SIGNALS OF SPORTS MODE SWITCH:
CLUTCH TO CLUTCH SHIFT CONTROL
As can be seen in the solenoid valve layout, there are major differences between the previous A/T and New A/T.
In previous A/T, there were only two solenoid valves to enable shift and one solenoid valve to control hydraulic pressure which resulted in inaccurate shift and rough ride. In the new A/T which is adopted for the EF and XG-Car, there are solenoid valves for each clutch brake which enable control of both the disengaging and engaging clutch simultaneously for independent control. This system provides a much smoother shift and comfortable ride as well as preventing Engine run-up or clutch interlock. In addition to advanced shift feeling, the 1st gear is selected at the creep state for eliminating the shift shock during 2nd gear - 1stgear.
SKIP SHIFT CONTROL
SKIP SHIFT CONTROL:
FEEDBACK SHIFT CONTROL
The turbine speed is monitored and controlled during shifting to satisfy target turbine speed which is accomplished by feedback control of solenoid valve duty value. Therefore the compensation of torque for the outworn engine or A/T is possible. This has resulted in the ability to control the change in torque during shifting and produce smooth shift and better shift feeling. Feedback shift control is also applicable in N -> D and N ->R.
DAMPER CLUTCH CONTROL
The Lock-up clutch is designed in a torque converter for the fuel economy. The lock-up clutch works in low speed range as minor slip. And it operates in high speed range as Full lock-up. Low fuel consumption and silence can be obtained with combination of Partial lock-up and Full lock-up control. The damper clutch is operated in 3rd and 4th gear in 4-speed ATA, 4th and 5th gear in 5ATA. In addition, Lock-up control is adapted in order to improve the fuel economy, when reducing vehicle speed too.
DAMPER CLUTCH OPERATING RANGE
As all the conditions are satisfied, it locks up. The cross point of throttle opening and turbine rpm is within shadowed area.
- D range (more than 2nd speed), but damper clutch operating in 2nd speed, the ATF temperature must be higher than 125°C.
- The TCM does not control under N - D or N - R. Oil temperature is above 50°C under full lock-up.
- Oil temperature is above 70°C under minor slip. The system is not under Fail - Safe (3rd gear hold) condition. Uphill (above 5%) longer than 1.5 seconds: Reducing speed Lock-up During this control, the vehicle is running uphill (less than 2.5%) for 1 seconds, the partial lock-up control is functioned again.
SERIAL COMMUNICATION INTERFACE (SCI)
This uses an integrated computer which contains both the ECM and the TCM within the same unit. We will refer to this unit as integrated ECM.
Communication Speed: 15.625 Kbit/second
Frequency: 20 ms
If a fault occurs in either ECM or TCM, the entire integrated ECM must be replaced.
CONTROLLER AREA NETWORK (CAN)
Frequency:
Previously, for different computers in the vehicle to share the same information, each signal required a different pin and wiring. However, with the introduction of a CAN system, only two lines are required to achieve the same function. The information is in digital format. This method does not use a integrated ECM.
Frequency: 500 Kbit/sec
Input signals to TCM through "CAN communication"
- Engine rpm, TPS signal
- A/CON signal, Engine coolant temperature
- Quantity of intake airflow, Vehicle speed
- Shift holding signal (FTCS ON)
Output signals from TCM through" CAN communication"
- Request signal for torque reduction
- ATF temperature, TCM type, TCM error or not
- Damper clutch ON, OFF/Gear position