Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.

Tech Briefs
Renault research


Renault's camless valve operation has each valve operated by an electromagnetic actuator.


Renault's twin-scroll turbocharger design is aimed at enhanced performance and reduced fuel consumption.


Multistroke operation would be possible in a camless design.

Is the camshaft one day to be consigned to the parts trashcan? Renault thinks it may be. It is exploring the possibility of introducing camless valve operation, with each valve operated by an electromagnetic actuator, independently of the other valves. Renault regards the system, which is now an important element of its advanced technology research programs, as a route to complete freedom-of-action to time the opening and closing of valves according to the engine's operating condition, with the potential of increasing torque at low speeds by between 10 and 20%.

"This allows the gearing to be raised and, therefore, the consumption to be reduced, without any effect on performance," stated a company spokesperson at a recent technology seminar near Paris. A camless design would result in a reduction of moving parts that in turn would reduce friction losses. Pumping losses would also be reduced. Cylinder deactivation or valve deactivation would be relatively straightforward and a complex "multistroke" operation would be feasible. A six-stroke operation, for example, would be possible instead of a conventional four-stroke, by adding a "dead" two-stroke phase, including a compression and expansion stroke without igniting the mixture. This would provide the best means of controlling operation of the engine and its combustion in an operating zone in which the specific fuel consumption would be as low as possible. Renault claims that the camless system would allow possible gains in reduced fuel consumption and lower emissions on the order of 15 to 20%.

Renault also discussed a new turbocharger design aimed at both enhancing performance and reducing fuel consumption. It is described as a new type of twin-scroll configuration that it says allows efficiency to be increased while limiting "chuffing" in the exhaust by connecting the exhausts from cylinders 1 and 4 to the first turbine scroll, and cylinders 2 and 3 to the second. The conventional problem of "cylinder exhaust interaction" (for example, the drawing into cylinder 1 — which has almost finished its exhaust stroke — of exhaust gas from cylinder 3 as it begins its exhaust stroke) is therefore eliminated to the benefit of the cylinder, which fills with air and, therefore, gains in efficiency.

Reducing exhaust emissions seems to be an endless mission and Renault is heavily committed to it. Renault plans to offer a new particulate filter starting in 2002 for its diesel engines — well ahead of scheduled regulations for 2005. Although diesel-engine emissions have been radically reduced in recent years, NOx and particulate emissions remain a challenge. Within the engine itself, there exists the paradox that formation of NOx and particulates can depend, for example, on the use of exhaust gas recirculation (EGR). The greater the EGR ratio, the more the formation of NOx diminishes, but particulate formation increases. Conversely, the lower the EGR ratio, fewer particulates are formed, but formation of NOx increases.

Existing solutions are compromises, so Renault believes the future lies with reducing NOx to a minimum within the combustion chamber, while particulate emissions are dealt with via exhaust aftertreatment in the form of a filter. Regeneration of the filter is reliable only from 550C (1022F). "Our goals can be achieved by precisely controlling increases in temperature using the heat released by combustion and additional electric heating, together with the use of an additive that reduces the regeneration temperature," said the company's spokesperson. The company revealed that it is developing a particulate filter for emissions control to meet Euro 2005 regulations for "all pollutants and not only for particulates as is the case for certain existing solutions."

Stuart Birch

AEI March 2000

Error 404--Not Found

Error 404--Not Found

From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:

10.4.5 404 Not Found

The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.

If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.