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Apr 12, 2007



Nissan Motor Co., Ltd. recently introduced an engine-valve-control technology that “delivers a balance of responsiveness and power, fuel efficiency and low emissions.” The new system combines Nissan’s Variable Valve Event and Lift (VVEL) and continuous valve-timing control (C-VTC).

The first product to feature the VVEL technology is the Infiniti G37 coupe, scheduled to be unveiled at the 2007 New York International Auto Show. The new technology will be available to customers worldwide through both the Nissan and Infiniti product lines. Whereas conventional engines control air intake using a throttle valve, VVEL-equipped engines do this directly at the intake valves. Valve events and lifts are thereby continuously controlled. C-VTC and VVEL together control the valve phases and valve events and lifts, allowing free control of the valve timing and lift. This will result in more efficient air flow through the cylinder and will significantly improve responsiveness.

In low- and medium-rpm ranges, intake-valve lift is kept low in order to reduce camshaft friction and improve fuel efficiency. Controlling air intake at the intake valves improves acceleration response by allowing more dense air into the cylinders from the start of acceleration. In the high-rpm range, greater intake-valve lift allows increased air intake to deliver greater torque inputs. Intake-valve timing is optimized when the motor starts up in order to quickly raise the temperature of exhaust gases and more quickly activate the catalytic converter. Because hydrocarbon emissions are reduced in the low-to-medium range by keeping intake-valve lift low and dispersing fuel into a fine mist, more efficient full combustion is achieved. Fuel efficiency is improved most effectively in the low-to-medium operating range.

Source: “Nissan introduces innovative engine valve control technology,” Nissan Motor Co.

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