Air suction valve


Air suction valve

An air suction valve (SAV ) is a subsystem used to reduce emissions in the exhaust gases of internal combustion engines.

Working principle

When an engine exhaust valve is open, the pressure in the exhaust manifold is higher than atmospheric pressure. The exhaust manifold is configured in such a way that positive and negative pulses are produced during the operation of the cycle by designing it as a diffuser.

The SAV has three openings: one is connected to the manifold vacuum, another is connected to the exhaust pipe and the third is open to the atmosphere. When a negative pulse is induced in the exhaust, air from the atmosphere enters the exhaust manifold through a one-way reed valve and serves to oxidize the carbon monoxide and hydrocarbons in the exhaust.

Air cut valve system

This system consists of a spring-loaded diaphragm, and a shaft which is attached to the bottom. A manifold vacuum is applied over the diaphragm where the shaft end is towards the opening of the atmosphere.

During deceleration, the engine vacuum rises and acts against the spring to push the shaft downwards, thereby blocking the opening through which atmospheric air is passed to the exhaust.

Though there is a negative pulse during deceleration, the manifold vacuum blocks and cuts off the air to the exhaust manifold.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Suction valve — Suction Suc tion, n. [L. sugere, suctum, to suck; cf. OF. suction. See {Suck}, v. t.] The act or process of sucking; the act of drawing, as fluids, by exhausting the air. [1913 Webster] {Suction chamber}, the chamber of a pump into which the… …   The Collaborative International Dictionary of English

  • Suction — Suc tion, n. [L. sugere, suctum, to suck; cf. OF. suction. See {Suck}, v. t.] The act or process of sucking; the act of drawing, as fluids, by exhausting the air. [1913 Webster] {Suction chamber}, the chamber of a pump into which the suction pipe …   The Collaborative International Dictionary of English

  • Suction chamber — Suction Suc tion, n. [L. sugere, suctum, to suck; cf. OF. suction. See {Suck}, v. t.] The act or process of sucking; the act of drawing, as fluids, by exhausting the air. [1913 Webster] {Suction chamber}, the chamber of a pump into which the… …   The Collaborative International Dictionary of English

  • Suction pipe — Suction Suc tion, n. [L. sugere, suctum, to suck; cf. OF. suction. See {Suck}, v. t.] The act or process of sucking; the act of drawing, as fluids, by exhausting the air. [1913 Webster] {Suction chamber}, the chamber of a pump into which the… …   The Collaborative International Dictionary of English

  • Suction pump — Suction Suc tion, n. [L. sugere, suctum, to suck; cf. OF. suction. See {Suck}, v. t.] The act or process of sucking; the act of drawing, as fluids, by exhausting the air. [1913 Webster] {Suction chamber}, the chamber of a pump into which the… …   The Collaborative International Dictionary of English

  • valve — A device used to either open or close an opening to allow or prevent the flow of a liquid or gas from one place to another. There are many different types. See ABS relay valve accumultor valve air valve carburetor air control valve air gulp valve …   Dictionary of automotive terms

  • Valve — This article is about the flow control device. For the game developer, see Valve Corporation. For the electronic component, see Vacuum tube. For other uses, see Valve (disambiguation). These water valves are operated by handles. A valve is a… …   Wikipedia

  • suction relief valve — A control valve that provides constant negative pressure by opening the system to the outside air when the vacuum rises above the preset value. Some gyro instruments (air driven direction indicator, or DI, artificial horizons, etc.) are operated… …   Aviation dictionary

  • suction throttling valve — (STV) A backpressure regualted valve on some Ford and GM systems placed between the air conditioning evaporator and compressor which controls evaporator pressure to provide maximum cooling without icing evaporator core. See POA suction throttling …   Dictionary of automotive terms

  • suction side — [1] The side of a pumping system or pump at which the liquid to be pumped enters the suction line or pump casing [2] The low pressure part of the air conditioning system between the orifice/expansion tube, or expansion valve outlet, and the… …   Dictionary of automotive terms


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.