October 14, 2002
Volvo gasoline engine meets world’s toughest emissions standards
Volvo Car Corporation is producing a new gasoline engine that complies with
California’s 2003 PZEV (Partial Zero Emission Vehicles) standard – the
toughest in the world – and will allow several Volvo models to be sold in
the state in the same category as zero-emission electric vehicles.
Starting next year, all auto manufacturers selling cars in California must
include a specified percentage of zero-emission vehicles in their lineups.
Legislators first envisioned that these would be electric vehicles (ZEVs
or Zero Emission Vehicles), but they subsequently decided to permit other
technologies – such as ‘ordinary’ gasoline engines, hybrids and natural gas
– provided emission levels are as low as those of electric cars, including
production of the electricity. These cars are described as Partial Zero
Emission Vehicles or PZEVs.
Volvo’s new technology, which earned Volvo’s development team the 2002 Henry
Ford Technology Award, produces emissions that are lower in hydrocarbons
and nitrogen oxide than the air going into the engine. In other words, the
car actually purifies the air, ridding it of these pollutants.
In production since September, the new 2.4-litre, five-cylinder engine will
be installed in Volvo V70 and S60 models sold in California.
Emissions of toxic hydrocarbons from Volvo’s PZEV vehicles have been
reduced to less than a thousandth of the levels from cars produced 30 years
The keys to the Volvo PZEV’s performance include a method of quickly
heating the car’s catalytic converter after cold starts and a modified fuel
system and fuel tank that reduce evaporative emissions to almost zero.
At least 90 percent of all emissions from a car are emitted from the
exhaust pipe within the first minute of starting. Once the catalytic
converter is hot, the emissions basically drop to zero.
To solve the cold-starting problem, Volvo engineers developed VVT (Variable
Valve Timing), which enables the car to be started with excess air – in
other words, with a lean mixture, or ‘negative choke.’ This enables large
quantities of air to be heated, bringing the catalytic converter to working
temperature very quickly. New software has also been developed to control
the starting sequence with a high degree of precision.
Volvos with PZEV have two catalytic converters, the first of which is
installed close to the engine, immediately downstream of the exhaust
manifold. This also contributes to rapid activation of the unit.
Performance and fuel consumption are not adversely affected by PZEV.
Evaporative emissions are largely hydrocarbons that evaporate not only from
the fuel system, but also from the tires, body and air-conditioning system.
As a result of Volvo’s development work, evaporation from the Volvo PZEV
has been reduced to almost zero.
All components are manufactured to ensure long durability in view of the
length of the guarantee. VCC has been conducting comprehensive, accelerated
endurance tests to assure the operation of the complete emission
purification system for as long as 15 years or 240,000 kilometres (150,000
For the moment, only Volvo cars sold in California will be equipped with
the PZEV system, but several engines currently under development will also
be equipped with the technology. Volvo expects to widen its availability as
more units are produced and the costs drop accordingly.