This invention relates to an air injection system operative during deceleration of an automobile engine.
In the conventional secondary air injection (SAI) system, additional air is supplied at the exhaust port to dilute the exhaust gas which In turn reduces the emission levels but cannot reduce fuel consumption.
During deceleration of the vehicle the throttle is closed and high vacuum is created at the intake manifold / intake pipe. This will make more fuel to flow into the combustion chamber which will be wasted as exhaust emissions. Since there is no power requirement during deceleration there is no need for extra fuel supply. Also as there is no airflow during deceleration / throttle closed condition the combustion will be poor due to rich air fuel mixture.

The air injection system proposed herein reduces exhaust emission with the benefit of Improved fuel economy by reducing fuel supply during deceleration.
The air injection system operative during deceleration of an automobile engine, comprising an air control valve, the diaphragm of which senses the manifold vacuum and causes the air filter and intake pipe to connect to each other directly, bypassing the carburetor, thereby allowing more air to flow to the intake pipe and nullify the vacuum inside the manifold during deceleration and simultaneously reduce the fuel supply to the engine.
The air injection system will now be described with reference to the accompanying drawings which illustrate, by way of example, and not by way of limitation, one of possible embodiments of this invention.

In this invention fuel saving during deceleration is done by nullifying the vacuum created during throttle closed condition. This is done by a separate air supply system which operates on intake manifold vacuum. The manifold vacuum is sensed by an air control valve A which results In supply of air to the intake pipe P from air filter F, such that carburetor C Is bypassed and fuel supply Is substantially reduced.
As soon as the throttle is closed a sudden vacuum is created in the intake manifold which will be sensed by a diaphragm in the air control valve which allows the air filter and intake pipe to connect to each other directly, bypassing the carburetor. This will allow more air to flow to the intake pipe and thereby nullify the vacuum inside the manifold during deceleration.
Once the vacuum level is minimized, the fuel drawn from the carburetor also will be less.

It will be appreciated that other embodiments of the air injection system proposed herein are possible without departing from the scope and ambit of this invention.

We Claim:
1. An air injection system operative during deceleration of an automobile engine, comprising an air control valve the diaphragm of which senses the manifold vacuum and causes-the air filter and intake pipe to connect to each other directly, bypassing the carburetor, thereby allowing more air to flow to the intake pipe and nullify the vacuum inside the manifold during deceleration and simultaneously reduce the fuel supply to the engine.
2. An air injection system operative during deceleration of an automobile engine substantially as herein described and illustrated in the accompanying drawings.