Ducati Diavel Service Manual: Operating principle and characteristics of the ride-by-wire system

The engine control system of the diavel uses a ride-by-wire system with motorised throttle valves. This eliminates all direct connection with metal cables between the throttle grip and the throttle valves themselves. Cables are used to rotate the aps potentiometer, which generates an electric signal that is sent to the engine control unit. The engine control unit uses this signal to determine the throttle grip position and the throttle opening dynamics, in other terms, the torque demand made by the rider. The ride-by-wire system enables the following:

• Smooth torque delivery, as the ecu filters the signal received from the aps. As there is no direct connection with metal cables between the throttle grip and the throttle valve, any spurious movement of the throttle grip itself due, for example, to unevenness in the road surface straining the arms and hands of the rider, have no direct or immediate effect on engine delivery.
• Improved management of different engine operating states. As the ecu controls the aperture of the throttle valves, the ecu itself can determine the air flow into the engine independently of the actual throttle grip position set by the rider.

  This strategy defines three different regimens for throttle valve aperture (150 hp hard, 150 hp soft and 100 hp) that may be selected by the user without modifying the calibration of the engine control unit (in other terms, the quantity of fuel injected and the ignition advance, which are defined solely in relation to the 150 hp hard throttle valve aperture regimen).

The three curves show the relationship between the throttle valve aperture regimens and the angle of the throttle grip.

Different curves for different engine speed bands are stored in the engine control unit. Each one of these is activated by the rider in relation to the selected riding mode. On a conventional mechanical system there is only one throttle valve aperture regimen, which is determined by the profile of the control roller mounted on the spindle of the valves themselves and actuated by a metal cable that moves as the throttle grip is twisted. With the 150 hp hard setting selected (red curve with maximum power of 150 hp available), with the exception of the initial zone, the relationship between percentage throttle grip aperture and percentage throttle valve aperture is practically linear (direct). Therefore, high throttle grip aperture angles correspond to identical high throttle valve aperture angles. This linear relationship, however, does not apply at small throttle grip aperture angled (a small throttle valve aperture angle is achieved with a slightly higher throttle grip rotation angle). With the 150 hp soft setting (purple curve with maximum power of 150 hp available), throttle valve opening is "softer". Therefore, a given aperture angle of the throttle grip corresponds to a lower throttle valve aperture angle. However, this setting still allows the maximum throttle valve opening to be attained when the throttle grip is fully rotated (100% throttle grip rotation corresponds to a throttle valve opening angle á equal to 90). With the 100 hp setting (green curve with maximum power restricted to 100 hp), throttle valve aperture is significantly attenuated, and rotating the throttle grip fully (100%) does not achieve full throttle valve aperture (throttle valves reach a maximum angle of less than 90. Restricting maximum power). The blue line represents a direct relationship between throttle grip opening angle and throttle valve opening angle, whereby a given throttle grip rotation angle corresponds to an identical opening of the throttle valves.

Tps

The position of the throttle valves is monitored by the engine control unit via a sensor (tps) integrated into the electric motor, fixed onto the spindle of the vertical cylinder throttle valve.

For maximum reliability, the sensor consists of two integrated hall effect sensing elements (main and sub), which measure the position of the throttle valve.

The tps uses a single power supply voltage and a single ground.

The two signals generated, also denominated main and sub, are monitored using a diagnostic algorithm by the ecu (engine control unit), which constantly compares the signals against each other and verifies their consistency. In the event of inconsistency or a fault, the error is indicated and the throttle valve actuator motor is disabled.

Aps

The position of the throttle grip is measured by a sensor (aps) mounted on the throttle body and consisting of two resistance potentiometers (main and sub), integrated into a single element.

Each of the two resistance potentiometers has its own dedicated power supply and ground.

The two signals generated, also denominated main and sub, are monitored using a diagnostic algorithm by the ecu (Engine control unit), which constantly compares the signals against each other and verifies their consistency. In the event of inconsistency or a fault, the error is indicated and the throttle valve actuator motor is disabled.

The information provided by the aps is used by the engine control unit to determine what is known as the "torque request" made by the rider - in other terms, the performance required of the engine by the rider.

The two diagrams illustrate the operating principle of the ride-by-wire system and the monitoring and control functions performed by the internal ecu circuits. As can be seen, the aps consists of a potentiometer with two elements (main and sub), with independent power supply and ground. The tps also has a potentiometer with two elements (also main and sub), but with common power supply and ground. The cpu is the processing core of the control unit, the ipd (integralproportional- derivative controller) is the control circuit and the lsi is a large scale integrated circuit that controls the power relay on the exterior of the actuator. When necessary (in the event of malfunction), this circuit and the cpu generate a signal that inhibits the electric throttle valve actuator motor. In this case, the throttle valves are returned to the closed position by a spring on the throttle body.

The image shows the throttle body seen from the intake side. The accelerator sensor (aps) is visible on the left, while the electric actuator (motor driving the throttle valves), which also incorporates the throttle valve sensor (tps), is on the right. The electric actuator operates the vertical cylinder throttle valve directly, and operates the horizontal cylinder throttle valve via a link rod.

When removing the airbox, the throttle body remains fixed to the bottom of the air box itself.

The throttle body is fastened to the rubber intake pipes with metal clamps.

Important

In the event of a fault of the electric throttle valve actuator motor, the tps throttle valve position sensor (integrated into the electric motor) or the aps accelerator position sensor, the entire throttle body must be replaced.

Never alter the setting of the throttle valve synchronisation screw