Electronic Controls

Electronic Controls



The ECVT is based on a standard CVT unit with electronic components fitted to control the gear ratios, the secondary pressure and the clutch pressure. The location of the components that form the steptronic transmission vary depending upon vehicle installation.

All of the control methods associated with the transmission are run as part of the EMS2000 software. The EMS2000 receives inputs from the main sensors of this system, communicates with the gearbox interface unit (GIU) to control the transmission, accepts driver inputs and provides information to the driver via the instrument cluster.

The control of the transmission is integrated with the EMS2000 and a GIU enables this integration, acting as a slave/interpreter for the EMS.

EMS2000 can control the transmission so that the input shaft speed, relative to the output shaft speed, is fixed in one of six ratios. This gives the effect that the vehicle has a six speed manual transmission with a sequential gear change.

The system protects the transmission, while in manual mode, against shifts that could be potentially dangerous or could damage the engine, for example, shifting to first gear at 90 mph, or shifting to top gear at 10 mph. In addition, if the driver does not shift up, the next gear will be automatically selected when the engine revolutions reach approximately 6000 rpm. Equally, if the driver does not shift down when reducing vehicle speed, the system performs the down-change automatically thus ensuring the transmission is in the appropriate gear when throttle is applied. This prevents excessive clutch slip should the throttle pedal be reapplied.

Driving and ambient conditions can influence the pulley positions, these conditions include:
- Oil temperature
- Clutch slip
- Hydraulic balancing of the controlling cylinders
- Hydraulic pressure within the control lines

The primary and secondary pulleys alter their position to maintain the commanded transmission input/output ratio.

All inputs and outputs of the ECVT control system pass through the EMS2000 and the GIU The EMS2000 monitors the speed of the transmission output shaft and communicates with the GIU to select the correct gear ratio to suit the current driving conditions. The GIU drives the park, reverse, neutral, drive and sport LED module to display the selected gear next to the gear selector lever and the EMS drives the instrument cluster display.