Dual-clutch for Alfa Romeo MiTo
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Alfa Romeo
25th February, 2010
Sales of the Alfa Romeo MiTo are set to make an advance with the
launch of new Alfa Romeo Twin Clutch Transmission (Alfa TCT) at the Geneva Motor Show next week (4th March 2010)
and its arrival in Australia in the third quarter of this year.
“While the Alfa Romeo MiTo has put in a solid performance for us in Australia since its launch last year,
its lack of an automatic gearbox has held back sales,” says Andrei Zaitzev, General Manager for Alfa Romeo
in Australia. ”This new gearbox will transform this situation. We will have a state of the art gearbox with
the performance and fuel economy advantages of a manual and, thanks to the new twin clutch technology, the
refinement and ease of operation of full automatic. This intelligent technology fits seamlessly with the MiTo
and we fully expect it to double Alfa Romeo MiTo sales in Australia.”
The arrival of the Alfa TCT gearbox will also mark the launch of the first engine in Australia to use the
revolutionary MultiAir technology that dramatically cuts fuel consumption and emissions while also boosting
performance. The TCT transmission will be matched to the 99 kW 1.4 litre MultiAir engine and, in another first
for Australia, this new version of the Alfa Romeo MiTo will be fitted with the Stop&Start technology that turns
off the engine when it is not required, further saving fuel and cutting emissions.
“This advanced technology combines to provide excellent performance on the road, at the fuel bowser and
from the exhaust pipe,” says Mr Zaitzev. “The Alfa Romeo Mito 1.4 MultiAir zips to 100 km/h in just
8.4 seconds, yet, at the same time, offers an open road fuel consumption of just 4.5 litres 100 km and CO2
emissions of just 129 g/km. Despite this advanced technology and the benefits it offers, we expect pricing to
be comparable with a conventional automatic gearbox.”
“This means that the Alfa Romeo Mito MultiAir has a unique blend of Alfa Romeo style, performance, fuel
economy and low emissions and it explains why we are certain it will transform sales of the MiTo in
Australia,” says Mr Zaitzev.
The Alfa Romeo MiTo MultiAir and TCT Gearbox will arrive in Australia in the third quarter of 2010, when
local specifications and prices will be announced.
The Alfa TCT Gearbox
Developed and produced by FPT - Fiat Powertrain Technologies - the new gearbox belongs to a modern family
of six-speed gearboxes (C635), which saw their debut in the manual form in the Alfa Romeo MiTo 1.4 Turbo
MultiAir last year.
With the launch of the TCT version, Alfa Romeo is the first company to combine a double clutch gearbox with
Stop&Start technology fitted to a MultiAir engine. Fiat has no less than 23 patents on this new technology.
The new gearbox uses two gear sets, each with its own clutch, which allows the gearbox to select the next
required gear while the previous gear is still engaged. This allows a virtually seamless gearshift and a
continuous supply of torque and power to the driving wheels.
To ensure smooth and efficient operation, the Alfa TCT interacts with more systems than any other gearbox
of its type on the market, including the steering, brake and accelerator controls, the Alfa DNA switch, the
Start&Stop system, ABS and the body inclinometer which is the slope detector for Hill Holder system. The use
of a dry clutch allows for a more compact mechanism and further cuts power losses removing the friction losses
associated with a wet clutch. Further savings are made by the dry clutch requiring less oil in the gearbox –
4.8 litres less than a wet system – and there is no requirement for an oil cooling system, all cutting weight
and maintenance costs, a total saving of 6.0 per cent over a wet system.
The Alfa Romeo MultiAir System
The MultiAir system represents as significant and larger improvement in efficient and emissions for petrol
engines over non-MultiAir engines as did Common Rail/Direct Injection with diesel engines. With MultiAir fuel
consumption is improved by 10 per cent, power by 10 per cent, torque by 15 per cent, carbon dioxide is cut by
10 per cent, particulates by 40 per cent and NOx is slashed by 60 per cent.
The heart of the MultiAir is a new electro-hydraulic valve management system that allows a reduction in
fuel consumption (by controlling air directly via the engine intake valves, without using the throttle) and
polluting emissions (via combustion control). As befits a flag-bearer for the downsizing concept, the MultiAir
is a versatile system that is easily applicable to all petrol engines that may potentially be developed for
diesel engines in the future.
Load management by means of the intake valves also means that combustion can also optimised even during
motorway use. The area within which the mixture is made richer has been greatly limited by exploiting system
characteristics: the fuel-air mixture is still stoichiometric at 150 km/h, for example with particularly low
specific consumption.
The new generation of MultiAir power units has also been designed to enhance the car set-up options
available via the Alfa DNA selector to ensure the most effective response to the driver's expectations and
the different road conditions.
How the MultiAir system works
The project aim was ambitious: to allow the intake valves to be controlled without their strict dependency
on the camshaft, which has nearly always represented the only way to ensure their operation over more than
100 years of technological development.
Achieving this goal was possible by using the wealth of technological and human experience built up over
the years by the Alfa Romeo brand and Fiat Powertrain Technologies on ordinary roads and race tracks.
It is therefore no exaggeration to claim that MultiAir is a distillation of the exceptional technological
pathway that allowed the Italian motoring industry to make its name on roads and racetracks throughout the
world. It is yet another Alfa Romeo milestone in the history of the motor car: production of the first
aluminium twin shaft engine on a mass produced car (Alfa Romeo Giulia), the use of twin variable valve
timing and the Twin Spark (Alfa Romeo 75), the first modular engine (Alfetta) and the Common Rail system
(Alfa Romeo 156). And now the Alfa Romeo MiTo extends this extraordinary list of achievements with the
MultiAir system, a versatile technology that is easily applicable to all petrol engines that may potentially
be developed for diesel engines in the future.
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In conventional petrol engines, load is controlled by modulating the density of air taken into the
cylinders by means of the throttle valve. This determines an efficiency loss known as "pumping work". The
MultiAir system does away with this loss. The load is controlled by adjusting the volume of air added at
constant density temperature due to direct and extremely flexible control of the intake valves.
The system controls the intake valves by means of an electro-hydraulic system: a piston operated by a
mechanical cam is connected to the intake valve by means of a hydraulic chamber controlled by a normally
open solenoid valve.
Two situations may arise: when the solenoid valve is closed, the fluid in the hydraulic chamber acts as
a solid body and transmits the lift law imposed by the mechanical intake cam to the intake valves. In the
second case, however, when the solenoid valve is open, fluid in the hydraulic chamber can flow out toward
a low-pressure circuit: as a consequence, the intake valves no longer follow the mechanical cam profile
and close under the effect of the two intake spring force. The final part of the valve closure travel is
managed by a dedicated hydraulic brake that ensures a controlled approach stage under all service
conditions.
It is therefore possible to obtain innumerable intake valve opening profiles with ease by adjusting the
solenoid valve opening and closure times. In this way, engine load is controlled directly via the intake
valves and no longer via the throttle valve. The behaviour of the MultiAir in three different situations
is described below.
1) Maximum power delivery stage: the solenoid valve is permanently closed and the valves are fully
opened by following the entire profile of the mechanical cam, which is specifically optimised for power
at high speeds (long intake valve opening intervals).
2) At low rpm and full load: the solenoid valve opens ahead of the theoretical cam profile, closing
the intake valve prematurely. This does away with undesirable flow back into the manifold, maximising the
air mass trapped in the cylinders.
3) Under partial engine load conditions: the solenoid valve opens during the intake travel to partly
open the valves and control the incoming air mass on the basis of the torque requirement. Alternatively,
the valves may be partly opened to close the solenoid valve with a delay in relation to the beginning of
the theoretical profile guaranteed by the mechanical cam. In this case, the speed of the air flow
entering the cylinders is higher and generates a particularly high level of swirl in the cylinders. It is
also possible to combine these two operating modes for the same intake event: this gives rise to the
“Multilift” effect, which increases swirl and combustion speed at very low loads and speeds.
To sum up, the flexibility and speed of response guaranteed by the MultiAir system make it possible to
manage engine load by means of the intake valves, eliminating the use of the throttle valve to benefit
combustion efficiency at partial loads and hence fuel consumption.
Alfa Romeo Start&Stop
Debuting on the Alfa Romeo Mito MultiAir, the Start&Stop system controls temporary engine cut-off
and subsequent restarting when the engine is idling at a standstill. In these situations, which are
typical of heavy traffic in urban areas and when halted at traffic lights, and when the control strategy
permits, the system automatically cuts out the engine in order to reduce fuel consumption and emissions
up to 10% for an urban route and 3.5% over an NEDC type approval cycle.
As soon as the brake pedal is released or a gear engaged, the system then quickly restarts the engine
to ensure the user an immediate response to controls. If the engine is turned off by mistake (stalls),
when setting off from a traffic light, it can be restarted by simply pressing the clutch.
The Start&Stop system offers further advantages in terms of passenger compartment comfort because
there are no vibrations or noises. The driver is also informed about the use of the device by means of
messages on the control panel and can always turn it off using a control on the panel near the steering
wheel.
Gear Shift Indicator (GSI)
The Gear Shift Indicator (GSI) linked to the “Start&Stop” is a kind of co-pilot that discreetly
suggests to drivers when they should change gear, leading to more efficient use of the power unit in
terms of fuel consumption. For example, the GSI may suggest shifting to a higher gear by means of a
message on the control panel in order to allow the engine to guarantee combustion with a leaner mixture,
i.e. containing less fuel, or to shift down a gear to make the best use of the available torque.
The device is permanently active when the Alfa DNA selector is set to “Normal” or “All Weather” in
order to ensure a smooth and comfortable drive while also aiming to save fuel and slash emissions.
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