Introduction
The
concept of the Selespeed transmission system for Alfa Romeo
147 follows the aim already developed on the Alfa Romeo 156
from which it originates. The aim is to improve performance
of the manual gearbox transmission components.
To avoid
that the driver has to check the clutch pedal and the gear
control lever but at the same time ensuring the driving
pleasure that comes from direct control of transmission.
To
improve driving safety by a direct control that foresees
the errors of the driver
and prevents an incorrect control
of the transmission system. Offer the driver a more
advanced car interface.
It should be remembered that the
system essentially consists of a mechanical transmission,
with dry monodisk clutch and synchronised mechanical gear,
moved by hydraulic power steering.
As previously with the
Alfa Romeo 156, neither the clutch nor the gearbox is
changed to install the hydraulic actuators that control the
stroke of the clutch and the gear engagement and
selection.
An electronic control unit manages a complex
functioning logic that permits the use of the gearbox:
• in "semi-automatic" conditions,
where the driver controls the gear engagement by the lever
on the tunnel or with two push-buttons.
• In "automatic" mode, called "City"
that assigns the decision to change gear to the electronic
system. The clutch pedal has been eliminated , the
traditional "H" gear lever of manual transmission has been
replaced by a specific "Joystick" lever and two "UP-DOWN"
buttons on the steering wheel.
General overview with the main components of the Selespeed
system
Key
1. Control unit
2. Electro-hydraulic group with electric pump
3. Engine control unit (Bosch M7.3.1)
4. Motorised throttle case (D.V.E.)
5. Gear selection display
6. Down-gear button (Down)
7. Up-gear button (Up)
8. "City" mode button
9. Gear control selection lever
10. Accelerator
11. Switch on brake pedal
Power
steering system that
essentially consists of an electro-hydraulic group (2)
mounted directly onto the gearbox. By means of two pistons
it manages the gear selection and engagement.
The two
pistons are controlled by a group of solenoid valves, to
which an electric pump and an accumulator supply the
required hydraulic power.
An electronic control unit (1)
having identified the requirements of the driver from the
lever (9) or from buttons (6) and (7) autonomously manages
the gear change, directly controlling clutch, gearbox and
engine torque. During the gear shift the engine control is
subordinated to the gear control.
The
gear - engine interface considerably
improves the system performance and relieves the driver of
any need to synchronise the clutch-accelerator movements
during the gear change, that can be effected with the
accelerator always fully pressed down.
Furthermore, the
system inhibits incorrect requests to change gear and
avoids engine stalling.
In terms of aid to driving it also
ensures: immediate availability of first gear when the
vehicle stops; automatic downward gear change n the case of
a strong deceleration.
The gear engaged is shown on a
display built into the panel on board (central display),
whereas indications of faults or driving conditions
critical for the vehicle or for transmission components are
indicated directly on the display highlighting the text:
Selespeed system fault, and, on the right of the panel the
gearbox fault symbol is shown.
Selespeed system components
Key
1. gear selection lever
2. "City" button
3. Selespeed control unit (assembled in passenger
compartment under the dashboard, passenger side)
4. Gear selection buttons on steering wheel
5. Electro-hydraulic group
6. Electric pump
7. Hydraulic oil pump
8. Speed sensor on gearbox
9. Gear selection display
10. Fault warning light