1. The continuously variable valve timing mechanism CVVT
CVVT Continue Variable Valve Timing is the English acronym, translated into Chinese is continuously variable valve timing mechanism, which is being increasingly used in recent years many variable valve timing on modern cars in a technology. For example: BMW is called Vanos, Toyota called the VVTI, called the Honda VTEC, but no matter what is their purpose is to work under different conditions of the engine matches the best valve overlap angle (valve timing), but implemented the method is different.
Shape Characteristics
Hyundai car developed CVVT a camshaft changes by an electronic-hydraulic control system of the intake valve is opened sooner or later, so that a desired valve overlap control angle . This technology focuses on the first letter C (Continue continuous), auspicious CVVT engine stressed continuously varied according to the operating condition of the engine, always control the size of the valve overlap angle, thereby changing the cylinder intake air quantity. When the engine low speed low load operation (idling state), this time should be delayed intake valve opening time, the valve overlap angle is reduced, a stable combustion state; when the low speed and high engine load operation (start, acceleration, climbing), should the intake valve opening time is advanced, the valve overlap angle is increased to obtain a greater torque; high speed and large when the engine load operation (high speed), and the intake valve opening time should be delayed, the valve overlap angle is reduced, thereby improving engine efficiency; when the engine operating condition is in the middle (with uniform speed), will be relatively CVVT intake valve opening delay time, reducing the valve overlap angle, in this case the aim of reducing fuel consumption and pollution.
Interior Design
CVVT system includes the following components: oil pressure control valve, the intake cam tooth plate, crankshaft position sensor, cam shaft position sensor, the pump, the engine electronic control unit (ECU ).
Kia CVVT engine intake cam tooth plate comprising: an outer gear by the Timing Belt driven, the internal gear connected to the intake cam can be controlled with a piston movable between the inner and outer gears. When the piston moves the piston of the helical gear position of the external gear change, thereby changing the positive effect. The displacement of the piston by the hydraulic pressure control valve is determined, the hydraulic control valve is an electronically controlled valve which is controlled by the oil pressure pump. When the computer (ECU) receives input signals, such as the engine speed, the intake air amount, throttle position, engine temperature, etc. to determine the operation of the hydraulic control valve. The computer will use the cam position sensor and the crankshaft position sensor to determine the actual timing of the intake valve cam.
When the engine is started or closed position by changing the hydraulic control valve, so that the intake cam timing for delay state. When the engine is idling or low load, the timing is also delayed position than the engine promote stable operation. When the intake cam that meet at an advanced position, which when the low speed high load at an increased torque output advanced angle position. In line with the high-speed position in order to facilitate high speed operation delay. When the engine temperature is low in the retarded position of the cam position, stable idle reduce fuel consumption.