Vacuum generator is a new type of vacuum component which produces negative pressure by positive pressure air source. It is efficient, clean, economical and small. This makes it very easy and convenient to obtain negative pressure in the place where compressed air exists or where positive and negative pressure is needed in a pneumatic system at the same time. Vacuum generator is widely used in industrial automation. In the fields of machinery, electronics, packaging, printing, plastics and robots, the traditional use of vacuum generators is suction cup matching to absorb and transport various materials, especially for adsorbing fragile, soft, thin non-ferrous, non-metallic or spherical objects. It is also suitable for adsorbing and transporting various materials, especially for adsorbing fragile, soft, thin non-ferrous and non-ferrous objects. Metal material or spherical object. In this kind of application, a common characteristic is that the required pumping capacity is small, the vacuum requirement is not high and it works intermittently. The author believes that the analysis and study of the pumping mechanism of vacuum generator and the factors affecting its working performance are of great practical significance for the design and selection of positive and negative pressure air circuit.
The diagram above shows the working principle of the vacuum generator, which consists of a nozzle, a receiving chamber, a mixing chamber and a diffusion chamber. After the compressed air is injected through the contracted jet, the flow of a stream of fluid ejected from the nozzle is called a jet. Jets can entrap the stationary fluid around them and flow forward together, which is called entrainment of jets. The flow of free jet in the receiving chamber will restrict the contact between the jet and the outside world, but the main jet from the nozzle still needs to absorb a part of the surrounding fluid to move forward, thus forming a low-pressure zone around the jet, and the fluid in the receiving chamber will be sucked in, after mixing with the main jet, through the other end of the receiving chamber. Flow out. This phenomenon is called ejection when one high-speed fluid is used to suck in another (static or low-speed flow) and the super-flow after mixing with each other is called ejection phenomenon. If the pressure difference between the two ends of the nozzle reaches a certain value, the airflow reaches the sonic or subsonic velocity, then a certain negative pressure can be obtained at the nozzle outlet, that is, in the receiving chamber.