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The system has the advantage that it is continuously variable rather than switching in at a set speed. Its disadvantage is the complexity of the system and corresponding price. Other systems will achieve similar results with less cost and simpler design (electronic control).
A helical camshaft is a type of mechanical variable valve actuation (VVA) system. More specifically, it is a camshaft that allows the valve opening duration to be varied over a wide, continuous, step-less range, with all of the added duration being at full valve lift.
The timing, duration and lift of these valve events has a significant impact on engine performance. Without variable valve timing or variable valve lift, the valve timing is the same for all engine speeds and conditions, therefore compromises are necessary to achieve the desired result in intake and exhaust efficiency . This has been described ...
There are many systems for VVT, which involve changing either the relative timing, duration or opening of the engine's inlet and exhaust valves. One of the first practical VVT systems used a variator to change the phase [note 1] of the camshaft and valves. This simple system cannot change the duration of the valve opening, or their lift.
For twin-cam or DOHC engines, VCT was used on either the intake or exhaust camshaft. (Engines that have VCT on both camshafts are now designated as Ti-VCT.↓) The use of variable camshaft timing on the exhaust camshaft is for improved emissions, and vehicles with VCT on the exhaust camshaft do not require exhaust gas recirculation (EGR) as retarding the exhaust cam timing achieves the same ...
High Redundancy Actuation (HRA), a new approach to fault tolerant control in the area of mechanical actuation; Variable valve actuation, any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine; Actuation, a type of self-realization referred to in Aristotle's philosophy of entelechy.
The blue valve body is visible in-line with the pipe. The valve actuator opens or closes the butterfly disc of the valve based on electrical signals sent to the actuator. Another valve actuator is visible in the background, with windows to indicate the valve position. A valve actuator is the mechanism for opening and closing a valve. Manually ...
The solenoid valve regulates the amount of oil pumped by the cam action to either the valve or a bypass reservoir. When pressurized, the hydraulic line behaves like a solid body and transmits the lift schedule imparted by the intake cam directly to the intake valve. When the solenoid is disengaged, a spring takes over valve actuation duties.