What Is a Valve Actuator?

Video Transcript

"Next question is, what is a valve actuator? Have a simple one right here. We have a choke butterfly valve right here at the top of this carburetor, right in the air horn. The choke is used to start the vehicle when it's cold. So, what has to happen is that this choke which is actually partially closed has to close off this passageway and basically has a choke effect. What happens is that it causes fuel to be flooded into the engine into the intake, and you can start the engine when it's cold. Once the engine starts, this has to open up and let air in. We have a bi-metal spring right in here, that's temperature controlled, that senses the temperature of the engine because it has a heat stove that comes up to it and it can actually open and close the choke diaphragm that's one type of actuator. We have other types of valve actuators and anti lock brake systems, that actually open and close hydraulic passages, again these are controlled electronically, and actually actuated by solenoids, a solenoid is an actuator that is controlled electrically, but actually does mechanical work. They all put some type of mechanical aspect. We have an actuators on starter motors where we have starter solenoids on top. We have again vacuum actuators, heating ventilation and air conditioning systems and we have all different types on vehicles. So again just depends specifically what type of actuator you want to focus on. The other thing in the engine if you are going to talk about valves, the cam shaft actually opens the engine valves at the correct time so the cam shaft is nothing more then an eccentric globe that actually pushes up against the cam follower or valve lifter and that either via a push rod or directly will push open the valve and hold the valve open for a certain duration and then it will close as the cam shaft rotates and the cam follower lifter comes back down on the base circle of the cam shaft. The spring on the valve also helps close it so a lot of times when an actuator opens a valve it maybe closed by a spring tension and not by a the actuator itself in some situations depending upon the system, the actuator can close the valve too as well as open it."