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Last time we learned how pneumatic actuators impart linear motion to machines. Now, let’s see how the pneumatic actuator is connected to the depositor’s pump. The connection imparts linear motion to the pump so it draws in jelly filling from the supply hopper and sends it streaming out of the nozzle onto a passing pastry. On the depositor, the pneumatic actuator’s piston rod is connected to the pump’s piston. As such, the pistons in the actuator and pump move together. When compressed air is admitted to the right side of the pneumatic actuator, the pistons in actuator and pump move to the left. As the pump’s piston moves to the left, a vacuum is formed in the pump. This vacuum sucks the jelly out of the hopper, through the diverter valve, and into the pump as shown below. The Depositor’s Pneumatically Actuated Pump
Once the pump is full of jelly, compressed air is admitted to the left side of the actuator piston. The pistons in actuator and pump move to the right as the compressed air expands and presses against the piston in the actuator. As the pump’s piston moves to the right, pressure builds up on the jelly in the pump. The pressure empties the jelly from the pump. The jelly is forced from the pump, back through the diverter valve, and it streams out of the nozzle as shown below. The Depositor’s Pneumatic Actuator Empties the Pump
For the pumping process to take place, the diverter valve must be rotated to first allow jelly to flow from the hopper. The diverter valve must be rotated again to allow jelly to flow through the nozzle. Next time, we’ll see how a pneumatic actuator is attached to a mechanical linkage that rotates the diverter valve. Copyright 2018 – Philip J. O’Keefe, PE Engineering Expert Witness Blog ____________________________________ |
