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An
electronically controlled manual gearbox, the SensoDrive features
electronically managed clutch and gear-shift functions. As a result,
the car has no clutch pedal and the gear lever - which remains present
- has no mechanical link with the gearbox.
The
SensoDrive gearbox is managed by a control unit, which controls two
actuators. One actuator changes gears while the other, which is
equipped with a facing wear compensation system, opens and closes the
clutch. The gearbox control unit also dialogues with the engine control
unit.
Linked to the C3's multiplex electrics (CAN network), the
gearbox control unit manages all the functions linked to the SensoDrive
gearbox: start-up, automatic mode, safety functions, instrument cluster
display. It diagnoses any operating failures and switches to degraded
operation where necessary.
This
sophisticated electronic management system takes into account all the
parameters necessary for efficient gear-changing: gear lever,
accelerator, brake, engine and gearbox rpm, vehicle speed, ABS, ESP,
engine torque and temperature.
In
this way, when the gearbox control unit receives an order - in either
operating mode - to change speeds, it briefly cuts off the engine's
power flow, disengages the clutch, changes gears, engages the clutch
and authorises power to be restored. These operations are sequenced as
quickly as possible to minimise the break in acceleration.
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For
vehicle start-up, the gearbox control unit closes the clutch in
accordance with the accelerator position and the engine speed. With
this high-precision servo system, the driver remains in full control of
the car in the most difficult situations [reverse parking, hill starts)
as well as on fast starts.
In
automatic mode, gears are selected by the computer on the basis of the
auto-adaptive shift patterns. The control unit analyses the driver's
behaviour and the type of route (rising, falling, corner) as well as
the vehicle load and surface grip in order to define the most
appropriate gear speed. The SensoDrive gearbox reaps the benefits of
the experience acquired by PSA Peugeot Citroen with the auto-adaptive
gearbox.
To avoid changing
gears too frequently, gear shifts are conducted at different speeds
during acceleration and deceleration.
On
C3 models equipped with ESP, the SensoDrive gearbox takes account of
the ESP to initiate gear shifts and ensure optimised vehicle operation
in all situations.
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