CVCC

CVCC ( Compound Vortex Controlled Combustion ) is the name of a technology from Honda to reduce pollutant emissions in car exhaust. Further CVCC is a registered trademark of Honda and a shape of a stratified charge engine.

Trigger

Since 1969, Honda experimented with a stratified charge engine, which should meet the expected stringent emission regulations. 1972, a corresponding experimental engine was introduced to the public. 1974 was such a motor in series. The CVCC technology allowed Honda to comply with the strict U.S. emissions laws for car exhaust, without having to use a catalyst. For the first time the CVCC technology was in 1975 at 1.5 l / 53 hp engine ( ED1 ) of the Civic used in the U.S. market.

Namesake

The acronym CVCC was the namesake for the model Civic.

Design and function

The essential features of the Honda CVCC engine over a conventional engine are:

• Modified cylinder head with the main combustion chamber and precombustion chamber with an additional small intake valve is approximately synchronized with the main intake valve is operated
• 3- flutiger carburetor with additional complex load and engine speed-dependent control
• Trained as exhaust manifold thermal reactor
• Abgasvorheizung the main combustion chamber mixture

The size of the pre-chamber amounts to approximately 10 % of total compression chamber; it is provided with a thimble-shaped insert made of high-alloy steel in order to increase the wall temperature, and thus to improve mixture preparation.

The intake stroke the front chamber via the first stage of the carburetor is supplied with a rich mixture, at the same time the main combustion chamber through the second stage, at higher loads by the third, with a lean mixture. As a multiple of the prechamber is sucked in during the intake process, it comes to the overflow of the fuel-rich mixture in the main combustion chamber. During the compression stroke, this is partially pushed back into the prechamber. This then forms at the ignition three zones of varying mixture composition out: rich mixture in the prechamber, lean in the main combustion chamber and form a mixture of medium composition in the vicinity of the overflow. The ignited in the prechamber mixture flows through this overflow into the main combustion chamber and ignited there the lean mixture ( torch ignition), it is a controlled combustion with greater than stoichiometric air ratio while largely avoiding relevant for the formation of nitrogen oxide peak temperatures of over 1100 ° C instead. The emitted fumes can in the downstream as a thermal reactor ( reactor skimmed ) afterreact trained exhaust manifold and thus mainly but also lower the hydrocarbon emissions (conversion of over 90 %) the carbon monoxide emissions. The reactor itself consists of a voluminous cast iron housing with internal reactor chamber from heat-resistant chromium-nickel steel.

At the same time the intake pipe firmly connected to the exhaust manifold below the carburetor heated ( hot spot ), taking it to an optimum mixture preparation and distribution.

The Honda CVCC engine was the only stratified charge engine of that time, the standard was built and sold in U.S. and Japan. With the tightening emission limits, the limits of such an approach showed. For heavier vehicles, especially prepared for the lowering of emissions of nitrogen oxides difficulties.

The CVCC engine was later fitted with a catalyst, he then disappeared, however, after a relatively short time from the market. Meanwhile, the controlled three -way catalytic converter had prevailed.

Only recently, however, the layer charge used again, this time as an air-compressing direct injection engines. Became known for the VW FSI engine.