|
AVCS
The active valve control system (AVCS) is an automobile variable valve timing technology used by Subaru. It varies the timing of the valves by using hydraulic oil pressure to rotate the camshaft, known as "phasing", in order to provide optimal valve timing for engine load conditions. The system is closed loop using the camshaft sensors, crankshaft sensors, air flow meter, throttle position as well as oxygen sensors and/or Air-Fuel ratio sensors in order to calculate engine load. The ECU is programmed to operate control valves that adjust the delivery of the hydraulic pressure in order to move the camshaft into the position that will provide the engine with the best performance while meeting emissions standards. AVCS is used on the Version 7 and up EJ207 engines, the EJ204, EJ254, EJ255, EJ257, the second generation EZ30D (2005+ in the USA market) found in the Legacy Outback, Legacy 2.0R, 3.0R and the B9 Tribeca. A dual AVCS system phases both the intake and exhaust camshafts on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Valve Timing
In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with variable valve lift systems. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems. Increasingly strict emissions regulations are causing many automotive manufacturers to use VVT systems. Two-stroke engines use a power valve system to get similar results to VVT. Background theory The valves within an internal combustion engine are used to control the flow of the intake and exhaust gases into and out of the combustion chamber. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
