Introduction of vacuum generator selection and principle

- Jul 19, 2019-

About vacuum generator selection:


First, single-stage vacuum generator:


A single stage vacuum generator is a single nozzle vacuum generator. There are common single nozzle vacuum generators, linear vacuum generators and integrated vacuum generators. The ordinary single-nozzle vacuum generator is slightly larger than the linear vacuum generator, and the flow rate is also slightly larger, and the flow rate is smaller than that of the multi-stage vacuum generator. The linear vacuum generator has the smallest volume and the smallest flow rate and is usually connected in the middle of the trachea. The integrated vacuum generator was developed to further compress the volume and reduce the failure rate of the air pipe. It generally consists of a single-stage vacuum generator, a vacuum filter, a silencer, a vacuum-generated electromagnetic switch, a compressed air blowback electromagnetic switch, a pressure sensor with a vacuum setting function, a digital signal line with a standard interface, etc. Partial composition. These vacuum generators are widely used in automated assembly lines in the fields of electronics, automobiles and the like.


Features:


1. Medium: air


2. No lubrication required.


3. Supply pressure: 0.4MPa~0.6MPa


4. Working temperature: 0 ° C ~ 60 ° C




Second, multi-stage vacuum generator:


Generally, a three-nozzle series-parallel vacuum generator is used. It is characterized by the saving of compressed air, and the multi-stage vacuum generator with reasonable structure has a ratio of air consumption to vacuum pumping up to 1:3.




Features of a single three-stage nozzle:


1. The initial vacuum flow rate can reach 354 liters / minute.


2. The maximum supply pressure is 0.7 MPa.


3. The maximum vacuum is -950 mbar.


4. When 1 liter of air is drawn, the time to reach the maximum vacuum is 2.4 seconds.


5. The normal operating temperature range is -10 ° C ~ 80 ° C.


6. The field of application is very wide.


Vacuum generator principle introduction:


The vacuum generator is driven by compressed air (4-6 bar) produced by an air compressor to produce a vacuum of up to -100.8 kPa. Widely used in vacuum systems, bringing revolution to the field of vacuum automation.


Vacuum generator working principle:


真空发生器的选型和原理的介绍


As shown in the above figure, the working principle is that after the compressed air enters from the port 1, it is discharged from the exhaust port 3 through more than one vacuum chamber. The venturi phenomenon created between the nozzles creates a vacuum in each chamber. When the vacuum chambers are integrated into the port 2, air is drawn in from the port 2.


The method of selecting the vacuum generator:


1. The flow rate of the vacuum generator refers to the amount of air intake when the vacuum port is completely open under a standard atmospheric pressure.


2. The suction flow at this time is also called displacement flow or volume flow. Units are expressed in standard liters per minute, standard cubic feet per minute, or standard cubic meters per hour.


3. Select the three elements of the vacuum generator: vacuum flow (L / min), vacuum (bar) and actual use.


4. The flow calculation formula of the vacuum generator:


S = 2.303*(V/T)*Log(P1/P2)


S: vacuum flow rate (L/min)


V: total volume of the vacuum generator at the inlet of the suction cup (L)


T: Time to reach maximum vacuum (Min)


P1: initial atmospheric pressure (Bar)


P2: maximum vacuum (Bar)


Advantages of the vacuum generator:


1. Use a compressed air drive to create a vacuum. It can be used in explosion-proof areas without electricity.


2. No fever. The normal operating temperature is -20 ° C ~ +120 ° C.


3. Save energy. The ratio of compressed air consumption to vacuum pumping can be up to 1:3. When the throttle is installed, it saves compressed air and reduces vacuum.


4. Small size and light weight. Easy to install in tight spaces.


5. Low noise. The noise is only 53dB to 56dB compared to a vacuum pump of the same flow rate.


6. No vibration. Widely used in spaces where vibration is to be avoided.


7. No lubrication, no hidden troubles. This eliminates the need for maintenance and does not require regular maintenance like a motor-driven vacuum pump.


8. The reaction speed is fast, suitable for occasions with frequent startup. The response speed of the corresponding vacuum pump is very slow.