Green Engine Technology - Petrol Engines

[R-34]

Honda ULEV and ZLEV
California's ULEV requirements
The US State of California is the leader in the field of emission legislation. Its "LEV" (Low Emission Vehicles) requirement, roughly equals to Euro 2000, will be effective in 2000. 3 years later, "ULEV" (Ultra Low Emission Vehicles) requirement will restrict the pollution level to 30% of today's standard, that is similar to the Euro 2005.

At the focus of attention is the so-called "non-methane organic gases" (NMOG) - organic hydrocarbon compounds such as aldehydes, alcohols, alkanes, aromatic compounds and esters found in car exhaust, and which experts consider to be responsible for the increase in the concentration of ozone in the atmosphere. All car makers are required to ensure that the passenger cars which they sell in California do not exceed a certain annual NMOG fleet average.

Honda's leading ULEV and ZLEV technology

Honda is currently leading LEV and ULEV technology. Back in 1995, it created the first ULEV engine in the world and installed to Accord. Today, while other car makers are working hard on their ULEV engines, Honda once again lead this field by introducing an even cleaner ZLEV ( "Zero" Low Emission Vehicles ) engine.

Basically, ZLEV based on ULEV but improves the catalytic converter arrangement. Since I only got the pictures of ZLEV, let me explain its theory first and by the way tell you ULEV.

[R-34]

ZLEV achieves extremely low emission by three stages :


During start up, its VTEC system lifts one of the intake valves higher than the other (refer to the diagram in Honda's 3 stages VTEC page). Because of unbalance pressure, swirl will be created in the air, thus leads to better mixing of fuel and air. As a result, leaner fuel / air ratio (16 : 1, compare with conventional's 14 : 1) can be achieved. This not only save fuel, but also allows more complete burning.
As usual, when the engine has started, the catalytic converter are still too cold to be effective. Therefore a close-coupled high efficiency converter, locating just at the exhaust port, is employed for the benefit of faster heat up. Anyway, many pollutant still escape from it. Therefore a newly developed hydrocabonate-asbsorbing catalyst is used to absorb the HC temporarily. At the same time, another converter is pre-heating for later use.
HC particles begin to loose out from the HC-absorbing catalyst, but then they will be converted by the pre-heated catalytic converter which has been brought up to operating temperature.
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As a result, ZLEV engine deals comfortably with cold start emission. ULEV engine is similar but without the HC-absorbing catalyst, therefore its NMOG level is much higher, although NOx is not much different.


Mark Wan

[MuonChoi]

what is this? So the more the converter put close in the engine, the more power it produce. is this right?

[R-34]

it not about h/p alone but it about consuming gas too