Variable Valve Timing System 气门调节的认识，图片+video

ckerz

气门扬程和开启时间技术，最喜欢的还是VANOS。谢谢分享。

vin_jovin

全部红毛字。。。

3-SGTE

Nissan VVL engines
Nissan SR20VE engineDisplacement2.0LPower:187 hp (139 kW)Torque:145 lb·ft (197 N·m)Production:1997-2001Vehicle:Nissan Primera
Nissan Bluebird
Nissan Wingroad
Nissan SR16VE engineDisplacement1.6LPower:173 hp (129 kW)Torque:119 lb·ft (161 N·m)Production:1997-2001Vehicle:Nissan Sunny VZ-R
Nissan Lucino VZ-R
Nissan Pulsar VZ-R
Nissan SR20VE '20V' engineDisplacement2.0LPower:204 hp (152 kW)Torque:152 lb·ft (206 N·m)Production:2001-PresentVehicle:Nissan Primera 20V
Nissan SR20VET engineDisplacement2.0LPower:276 hp (206 kW)Torque:228 lb·ft (309 N·m)Production:2001-presentVehicle:Nissan X-Trail GTNissan Ecology Oriented Variable Valve Lift and Timing (commonly known as VVL) is an automobile variable valve timing technology developed by Nissan. VVL varies the timing, duration, and lift of valves by using hydraulic pressure switch between two different sets of camshaft lobes. It functions similarly to Honda's VTEC system.
The SR20VE is the most common engine with NEO VVL. There have been two main versions of this engine. The first version made 187 hp (139 kW) and 145 lb·ft (197 N·m) torque. This engine was used by Nissan from 1997 to 2001. It is found in the Nissan Primera, Nissan Bluebird, and the Nissan Wingroad.
The second variant of the SR20VE is found only in the 2001 and up, P12 Nissan Primera. This version of the SR20VE makes 204 hp (152 kW), and 152 lb/ft torque. This engine is commonly known as the SR20VE '20V'. Although, in automotive terms, '20V' would normally be interpreted as having twenty valves, this is incorrect. The name '20V' is the name of the trim level of the Nissan Primera that it is found in. It is also a shortened version of the name SR20VE. This engine has 16 valves like the rest of the SR20 engines. This newer '20V' engine, is the only SR20 engine to get a restyled valve cover. It also has an upgraded intake manifold, which has longer runners and a larger 70 mm (2.8 in) throttle body (earlier SR20VE has 60 mm).
Another version of the VVL SR engines, is the 1.6L SR16VE. The engine block for the SR16VE is the same as the SR20VE, it also has the same cylinder bore. The crankshaft has a shorter stroke, which lowers the displacement, but allows the engine to safely rev to higher RPM. Although this engine has 1.6L of displacement, it has more aggressive camshaft specifications. It manages to make 173 hp (129 kW). The camshafts from this engine are considered to be an upgrade for SR20VE owners.
From 1997 to 1998, Nissan produced 500 limited edition SR16VE N1 engines. These engines made 197 hp (147 kW). They had further upgraded camshafts, upgraded intake manifold untilising 8 injectors and a larger 70 mm (2.8 in) throttle body. These engines were found in the limited edition Nissan Pulsar VZ-R N1. They were only sold in Japan.
The most powerful VVL engine so far, is the SR20VET. The SR20VET is a turbocharged '20V' SR20VE. It uses a Garrett GT2560R turbo charger, and makes 280 PS (206 kW; 276 hp) . Nissan's technical information about this engine states that it is 9:1 compression ratio, but it really adds up to 8.8:1.[citation needed] Compaired to the SR20DET (used in the Nissan Silvia, and Bluebird), the SR20VET (aside from having VVL technology) has improved airflow in the cylinder head, higher compression, and also improved coolant passages.
One difference from Honda's VTEC system, is that NEO VVL engages the change of intake and exhaust cams independently for a flatter, more consistent power band. On the SR20VE the intake camshaft is switched at 5000 rpm, and the exhaust at 6500 rpm. However this trait was not included on the newer '20V' version, as both camshafts

[ 本帖最后由 3-SGTE 于 2009-7-12 12:44 AM 编辑 ]

3-SGTE

SUBARU (AVCS)

A balance between increasing engine performance, improving fuel economy, reducing emissions and stabilizing idle is difficult to achieve. In its 3.0-liter 6-cylinder and turbocharged 2.5-liter 4-cylinder engines, Subaru strikes that balance using the Active Valve Control System (AVCS). What AVCS Does and Its Effects Pulling the connecting rod, the crankshaft pulls the piston toward the center of the engine, drawing in air and fuel from the intake system. The air and fuel enters the cylinder through the intake ports opened by the intake valves. This is like a person taking a breath – inhaling. AVCS adjusts exactly when intake valves begin to open. With both valves closed, the turning crankshaft forces up the piston, compressing the air/fuel mixture. The spark plug ignites this compressed mixture, causing an explosion that forces down the piston and connecting rod, which, in turn, rotates the crankshaft. These explosions within the cylinders provide the engine’s power. The crankshaft forces the piston to the top of the cylinder again, this time pushing leftover gases out of the combustion chamber past the opened exhaust valves and into the exhaust system. This is similar to a person exhaling. The camshaft is a very precise engine component, with lobes that open and close the intake and exhaust valves with the critical timing required for the 4-stroke cycle. AVCS changes the timing of the intake valves by adjusting the positions of the camshafts based on inputs from various sensors in the powertrain. The system varies when the camshaft lobes open and close the intake valves during the 4-stroke cycle. The effects of variable valve control include greater power through a wider range of engine speeds, improved fuel economy and reduced emissions. But to better understand how it works, let’s start with engine basics – the 4-stroke engine cycle. The 4-Stroke Cycle Most of today’s automotive gasoline engines function via a 4-stroke cycle. Engine components continuously cycle through four strokes, named for their functions of intake, compression, power and exhaust. AVCS affects the roles of the camshafts in this process. Actuation is mechanical, by direct contact or through a combination of lifters, tappets and/or pushrods, depending on engine design. How the camshafts are designed essentially gives engines their personalities. Camshafts in Subaru engines are belt-driven (4-cylinder) or chain-driven (6-cylinder) by the crankshaft. Intake valves open to let the air into the combustion chamber, and exhaust valves open to let out the exhaust gases. AVCS operation affects the intake valve timing or at exactly what point each valve opens and closes. Overall, intake- and exhaust-valve operation during the 4-stroke cycle follows this pattern: However, there are nuances in operation, and that’s where AVCS plays a part. In the 4-stroke sequence, the exhaust cycle immediately precedes the intake cycle. Overlapping the timing of the closing of the exhaust valves and the opening of the intake valves can help the engine perform better under heavy loads, but not under light loads. AVCS continuously varies this overlap through an infinite number of positions. Overlap ranges between a slight overlap (“retard” position) through as much as 35 degrees of the crankshaft rotation (“advance” position). AVCS Components Variable valve timing is controlled through a hydraulic system that takes instruction from a system of electronic controls. Engine management computer: Electronic control is by the engine management computer, which uses input from a number of engine sensors to determine the ideal position for the camshafts. The sensors include those that measure airflow into the intake system, coolant temperature, throttle position and camshaft position. Oil control valve: The control unit then actuates changes through an oil control valve positioned at each intake camshaft sprocket. The oil control valve uses oil pressure from the engine to advance and retard the intake camshafts via the AVCS actuator. Actuator: Mounted in the chain- or belt-driven drive sprocket, the actuator is fitted directly to the camshaft. Chambers in the actuator allow oil pressure to advance or retard it within the timing-belt sprocket. The oil fills the chambers and pushes against three lobes to turn the actuator and the camshaft on its axis. AVCS – Bringing It All Together At idle: The intake valves open just after the piston reaches the top of the cylinder (called “top dead center” or TDC; BDC refers to “bottom dead center”) at the end of the exhaust stroke, as the piston begins the intake stroke. The exhaust stroke creates negative pressure within the chamber, and intake air enters the cylinder with positive pressure “to fill the void.” There is very little or no overlap between the exhaust and the intake strokes. Retarding valve timing improves the smoothness of engine operation at idle, which tends to be a problem area in high-performance engines without variable valve control. (If you remember the muscle cars of the 1960s and 1970s, you may recall how roughly they idled.)

[ 本帖最后由 3-SGTE 于 2009-7-12 12:57 AM 编辑 ]

ckerz

VANOS工作构造省略，不如其它技术复杂，但可变扬程时间多。搭载这个技术的V12（如mclaren f1）和V8（如M3 GTR），它们的实力应该不需要说了吧...em0012

3-SGTE

At light-to-medium engine loads: From idle through medium engine loads, AVCS advances the intake valves to begin opening during the last part of the exhaust stroke, when the exhaust valves are still slightly open. Some of the pressure created during the exhaust stroke flows into the intake manifold, having the effect of exhaust gas recirculation (EGR). The intake valves also close earlier during the intake stroke. Advancing valve timing for some overlap helps reduce the level of harmful oxides of nitrogen in the exhaust. It also improves volumetric efficiency, which is an indication of how well air flows through the engine. The greater the efficiency, the stronger the engine’s performance. At heavy engine loads: When the engine is used aggressively for greatest performance, AVCS advances the intake valves further to open even sooner during the exhaust stroke. This produces a scavenging effect – that is, intake airflow helps clear the cylinder of exhaust gas. It also closes the intake valves sooner on the compression stroke. This results in improved volumetric efficiency and helps to generate higher power output. Overall, varying valve timing helps the engine to develop power more evenly between low and high speeds. At the same time, it improves engine idle and lowers exhaust emissions. Thoroughly Modern AVCS AVCS contributes to the driveability and performance of many Subaru engines. It provides greater power, smoother operation and fewer harmful emissions through a thoroughly modern engine technology.

[ 本帖最后由 3-SGTE 于 2009-7-12 12:58 AM 编辑 ]

ckerz

过奖了，大家互相学习。em0001

3-SGTE

原帖由 ckerz 于 2009-7-7 06:05 PM 发表
过奖了，大家互相学习。em0001

我想放video可是放不到。你会吗em0010

ckerz

youtube的吗？

3-SGTE

原帖由 ckerz 于 2009-7-7 06:14 PM 发表
youtube的吗？

对咯。。。不会玩