Rotating air valve simplifies designs

By Claire S. Goodwin, Scott Rotary Seals, Inc., Hinsdale, N.Y.

All controls engineers seek solutions to application problems that are simple, reliable, and economical. In pneumatic applications that involve rotary or indexing tables, there might be a number of devices that must be actuated at different times during the 360° cycle of rotation. Examples include holding fixtures, push rods, locating devices, air motors, etc. Arranging to deliver compressed air to these devices at the proper time can be a complex problem, particularly as the number of work positions increases.

A single rotating valve that can supply and control single or multiple devices at each workstation might be the solution. The Rotary Timing Valve (RTV), built by Scott Rotary Seals, has stationary inlet ports that are connected internally to predetermined sequence slots. These slots distribute air through a manifolded rotating base to the workstation ports. The timing pattern on the interface between the stationary and dynamic sections of the valve defines the circuit. The angular relationship of the workstation ports to the slotting arrangement automatically provides the on/off control required - no other control device or operator action is needed.

If a function must occur at only one station, Scott can provide for external control by installing a special inlet port for the function. This eliminates the need for multiple-station control devices, and also channels all control through the RTV. As a result, piping arrangements are greatly simplified. Inlet connections can easily be brought into the machinery. The manifolded rotating ports direct compressed air from the valve to the proper workstations.

Reduction of complexity, elimination of expensive multiple controls, and the minimizing of system interfacing are achieved by this one component. This adds up to substantial cost savings - savings that can be 50% or more when compared to electromechanical control systems. And these savings increase as the job grows more complex.

The Rotary Timing Valve's simplicity also can reduce the time needed to fine-tune equipment performance after start-up. The valve arrangement provides controls engineers with a mechanical solution to automation in rotating pneumatic machinery.