CVCC is a trademark

Trademark

A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...

 by the Honda Motor Company

Honda

is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...

 for an engine with reduced automotive emissions

Pollution

Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

, which stood for "Compound Vortex Controlled Combustion". This technology allowed Honda's cars to meet United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 emission standard

Emission standard

Emission standards are requirements that set specific limits to the amount of pollutants that can be released into the environment. Many emissions standards focus on regulating pollutants released by automobiles and other powered vehicles but they can also regulate emissions from industry, power...

s in the 1970s without a catalytic converter

Catalytic converter

A catalytic converter is a device used to convert toxic exhaust emissions from an internal combustion engine into non-toxic substances. Inside a catalytic converter, a catalyst stimulates a chemical reaction in which noxious byproducts of combustion are converted to less toxic substances by dint...

. A type of stratified charge engine

Stratified charge engine

In a stratified charge engine, the fuel is injected into the cylinder just before ignition. This allows for higher compression ratios without "knock," and leaner air/fuel mixtures than in conventional internal combustion engines....

, it first appeared on the 1975 ED1 engine.

In 2007, the Honda CVCC technology was added to the Mechanical Engineering Heritage

Mechanical Engineering Heritage (Japan)

The is a list of sites, landmarks, machines, and documents that made significant contributions to the development of mechanical engineering in Japan. Items in the list are certified by the .- Overview :...

 of Japan.

Construction and operation

Honda CVCC engines

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

 have normal inlet and exhaust valves, plus a small auxiliary inlet valve which provides a relatively rich air–fuel mixture to a volume near the spark plug

Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by...

. The remaining air–fuel charge, drawn into the cylinder through the main inlet valve, is leaner than normal. The volume near the spark plug is contained by a small perforated metal plate. Upon ignition flame fronts emerge from the perforations and ignite the remainder of the air–fuel charge. The remaining engine cycle is as per a standard four stroke engine.

This combination of a rich mixture near the spark plug, and a lean mixture in the cylinder allowed stable running, yet complete combustion of fuel, thus reducing CO (carbon monoxide

Carbon monoxide

Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

) and hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 emissions.

Advantages over previous stratified charge engines

Honda's big advancement with CVCC was that they were able to use carburettors and they did not rely on intake swirl. Previous versions of stratified charge engine

Stratified charge engine

In a stratified charge engine, the fuel is injected into the cylinder just before ignition. This allows for higher compression ratios without "knock," and leaner air/fuel mixtures than in conventional internal combustion engines....

s needed costly fuel injection

Fuel injection

Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....

 systems. Additionally, previous engines tried to increase the velocity and swirl of the intake charge in keeping the rich and lean mixtures separated. Honda was able to keep the charges adequately separated by combustion chamber shape.

Early design flaw

Some of the early CVCC engines had a problem with the auxiliary valves retaining collars vibrating loose. Once unscrewed, engine oil would leak from the valvetrain into the pre-combustion chamber, causing a sudden loss of power and massive amounts of smoke to emanate from the exhaust pipe. The condition simulated a blown engine, even though the needed repair was quite simple. Honda eventually came up with a fix involving metal retaining rings that slipped over the collars and prevented them from backing out of their threads.

CVCC-II

The 1983 Honda Prelude

Honda Prelude

The Honda Prelude was a sports coupe produced by Japanese automaker Honda from 1978 until 2001. It replaced the Honda S800, a front-engined, front wheel drive sports car...

 (the first year of the second generation of Preludes) used a CVCC design and a catalytic converter to reduce emissions, called CVCC-II, along with 2 separate sidedraught carburettors (instead of a single progressive twin choke carburettor). The following year a standard cylinder head design was used and the centre carburettor (providing the rich mixture) was dropped. The Honda City AA, introduced in November 1981, also used a CVCC-II engine called the ER.