Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Pump loss-of prime automatic shut off valve

Pump loss-of prime automatic shut off valve description/claims

The present invention relates to a loss-of-prime automatic shunt off valve for use with air operated pumps of the kind used primarily for oil and grease dispensing equipment in facilities that service motor vehicles, such as quick lube service centers, automobile dealership service departments, truck fleet garages and the like.

When pumps such as compressed-air-driven piston pumps are in operation,they generate a (pumped) fluid pressure at the pump output port. This pressure effect is due to the fact that the pump is pushing fluid from the pump. This pressure is maintained so long as; 1) the pump, is energized with compressed air; 2) the pump is attached to the output load;and 3) the pump is primed so as to continuously induct fluid from the supply reservoir.

If an air leak occurs in the incoming suction line from the reservoir to the pump, or if the pump reservoir level is allowed to deplete and run dry during pump operation, then a loss of prime occurs within the pump. Upon loss of prime, the air-driven pump,attached to an open and pressurized air entry connection, continues to cycle and it thereby pumps air instead of fluid. Because air (instead of fluid) is moving against an attached load in pumps of this kind,a much lower pressure is produced at the pump outport port and the pump responds by accelerating and then cycles at a very rapid and often damaging cycle frequency.Additionally, during loss of prime,piston seals in the fluid pumping chamber of the pump are purged clean of the pumped fluid and are damaged because the fluid also typically serves to lubricate those seals. Specifically,friction heat is generated and the seals which are no longer submerged,and the pump itself, are subjected to damage particularly when allowed to run for a sustained period in an unprimed dry condition. Rapid pump cycling plus dry seal contact leads to unacceptable levels of seal heating and therefore to rapid seal failure from wear or deformation.

It is accordingly desirable to provide a means to protect pumps of this kind,so that they do not continue to cycle whenever a lodd of prime exists, thereby preventing seal damage during such conditions. It is also desirable to create an indication of the unprimed pump condition,alerting the user so that prompt action can be taken to restore prime and remedy the problem.

While prior attempts have been made to alleviate the damage resulting from original damage that occurs to pumps and seals whenfluid in the reservoir is depleted or functionally inadequate,at the present time no known practical and adequate solution has been identified. For example,the device available as ARO STOP® Pump Saver Control Valve of the Ingersoll-Rand Company, described in that company's one page product service brochure designated 23644-400, has been found to lack various requirements. For example,devices of this kind fail to shut off pump operation is and when the pump suddenly draws in compressed air at a more rapid rate. In practice, when a typical pump loses prime,the increased cycle frequency and therefore the increased rate of flow of compressed air into the pump often is insufficient in magnitude to trigger this kind of shut off means.

The reference to “fluid” herein is taken to mean both self-leveling liquids such as oil and non-self-leveling but pumpable materials such as greases.

The present invention provides a novel automatic speed control device for air operated pumps that functions to automatically stop operation of the air-operated pumps whenever loss of prime occurs. The control device utilizes the fluid output pressure of the pump as a feedback element to provide the necessary control.

FIG. 1 illustrates schematically the location of the speed control device of the invention in a typical pump and reservoir system.

FIG. 2 is a side view of the speed control device of the invention shown in a continuous pumping mode.

FIG. 3 is a view similar to that of FIG. 2 with the speed control device of the invention shown in the interrupt pump-off mode.

FIG. 4 is a perspective view of the speed control device of the invention in the interrupt or pump-off mode and with the body of the control device section cut away to reveal the device interior.

While the invention is described primarily with the application of an automatic shut off valve for use with a reciprocating piston air pump, it will be apparent to those skilled in the art that the invention is applicable for use also in conjunction with rotary air operated pumps.

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws