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IDLING DEVICES OF AUTOMOBILE | IDLING DEVICES IN CARBURETOR | ANTI-DIESELING DEVICE

Idling devices in carburetor

During idling, the throttle plate is almost in the closed position. Then the mass rate of air flow through the venture is small. Hence, the vacuum or depression produced at the venture is also small. With this small depression, no fuel can issue from the fuel orifice. Hence, an idling device is incorporated in the carburetor unit.
he engine idling device can be seen in the picture. This device utilizes the large vacuum that prevails at the edge of the throttle plate for effecting fuel supply, when the throttle plate is almost in the closed position.

The required idling mixture strength can be obtained by adjusting the idling air screw. The quantity of the mixture supplied to the engine is controlled by the throttle plate setting. This setting decides the extent of closure of the inlet passage by the throttle plate.

The idling device operates at maximum capacity when the throttle plate is almost in the closed position. The effectiveness of the idling device gradually diminishes, as the throttle plate is being opened.

When the throttle plate is wide open, the depression felt at the idling get is extremely small. This small depression is not capable of raising the fuel through the large height in the idling jet upto the discharge point. Now the maximum depression shifts to the venture throat. As such the main orifice starts supplying the fuel.







Anti-dieseling device

A spark ignition engine sometime continues to run for a very small period, even after the ignition is switched off. This phenomena is called dieseling or after running. This causes wastage of fuel and pollution.

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