Catalytic Converters - Gasoline
The trend in catalytic converter design is to locate the converter closer to the
engine in order to meet increasingly stringent emissions regulations. When
converters are located closer to the engine, engine-out gases lose less heat
through the exhaust pipe before reaching the catalytic converter, so the unit
reaches temperature in less time. This allows the catalyst to light off more
quickly after start-up. However, the increased temperatures and vibration near
the engine place greater demands on the durability of the converter.
So
called Close Coupled Converters (CCC – pre-converters or light off converters)
are connected directly to the engine manifold with the aim of reducing gaseous
emissions. The converter operates at high gas temperatures directly from the
engine at approx. 900 – 1050°C.
The majority of gaseous emissions occur in
the first 2 minutes after starting the engine. As the converter is attached
directly to the engine manifold, it will need to withstand the associated
vibration forces. Higher gas temperature means the outer shell will also get
hotter and thus expand more and contract back to the original canned gap. The
mat needs to act like a spring (resiliency) to absorb this change.
Under
body Converters (UBC or UFC for Under Floor Converters) are situated underneath
the main body of the car and operate at lower temperatures (approx. 700 – 750°C)
and lower vibration forces.
Ecoflex® products are currently used with CC
as well as UB converters and are an enabling technology for thin (600/3) and
ultra thin (900/2) wall substrates.
| Feature: | Non Intumescent | High Temperature Durability & Low Thermal
Conductivity | Constant Holding Force with Temperature &
Excellent Exhaust Gas Erosion Properties |
| Benefit: | Holding pressure does not exceed Isostatic Strength
of Substrate | Reduced Outer Shell Temperatures | Reduced System Cost with Ecoflex Converter
Systems |
| Enables: | | • | Increased goemetric surface area which
increases catalyst efficiency | | • | Reduced precious metal content | | • | Faster light-off due to lower thermal
mass | | • | Reduced package
space | | | • | Reduced Canned Gap Change Due to
Temperature | | • | Increased Mat lifetime & Holding
Force | | • | Vibration resistance in CCC
positions | | | • | Removal of Converter pre-baking during
manufacture | | • | No requirement for Edge Seals
| |