Venturi Nozzle for Air Guns

A venturi nozzle for air guns includes an elongated, cylindrically shaped tube having a restricted orifice in a compressed air receiving end thereof through which compressed air is passed into a discharge end thereof. The air flow area of the discharge end of the tube is greater than the air flow area of the orifice to allow expansion of the air exiting the orifice in a region of the discharge end of the tube adjacent the orifice. Apertures formed through the tube in the discharge end thereof adjacent the orifice permit ambient air to be drawn by venturi effect into the tube and to be discharged with the expanded air out of the discharge end of the tube. It has been discovered that when the apertures are positioned around the circumference of the tube at nondiametrically opposed positions, and have a length along the axis of the tube which is greater than the width of the apertures around the circumference of the tube, the volume of air output from the discharge end of the nozzle is maximized for a given volume of compressed air input to the receiving end of the nozzle. Furthermore, it has also been found that when the ends of the apertures along the lengths thereof are tapered at an acute angle relative to the axis of the tube toward the receiving end thereof, the volume of air output from the discharge end of the nozzle is further maximized and the noise generated by air passing through the nozzle is minimized.

1. Field

The passage relates to nozzles for air guns, and in particular to a venturi nozzle for an air gun which maximizes the volume of air discharged from the nozzle for a given volume of compressed air input thereto, and which minimizes the noise generated by the nozzle upon the passage of air therethrough.

2. Description of the Prior Art

In the manufacture and maintenance of various types of equipment, air guns are often employed to blow dust and other debris from the equipment. Air guns ordinarily operate with an input air pressure greater than 40 psi. However, as a result of one standard promulgated under the Occupational Safety and Health Act (OSHA), the maximum pressure generated at an air gun nozzle discharge tip when the nozzle is dead ended, such as by being placed against an operator's hand or a flat surface, must be less than 30 psi.

A known nozzle for alleviating the problem of dead ended pressure build up includes a restricted orifice within a central bore of the nozzle through which compressed air passes into a discharge end of the nozzle, and a plurality of circular apertures formed through the nozzle in the discharge end thereof. When the discharge end of the nozzle is dead ended, the compressed air therewithin passes through the circular apertures, or vent holes, to limit build up of pressure within the discharge end of the nozzle.

Moreover, in many instances, the compressors available to supply compressed air to guns are limited in capacity, resulting either in the inability to supply air continuously to any one air gun, or in the inability to simultaneously operate several air guns. While previous venturi nozzles have operated to increase the volume of air discharged from the exhaust hole of the nozzle for a given volume of compressed air input to the nozzle from the air gun, the increase obtained has not been of sufficient magnitude to permit satisfactory and efficient use of limited capacity compressors. It is, therefore, desirable that the design of the vented nozzle be such as to maximize the volume of air discharged therefrom for a given volume of compressed air input thereto.

SUMMARY

In accordance with the present invention, a venturi fluid discharge nozzle includes an elongated, cylindrically shaped tube having a restricted orifice formed adjacent a fluid receiving end thereof through which a compressed gaseous fluid is passed into a fluid discharge end thereof. The fluid flow area of the discharge end of the tube is greater than the fluid flow area of the orifice to allow expansion of the fluid passed through the orifice in a region of the discharge end of the tube adjacent the orifice, and a plurality of nondiametrically opposed elongated apertures (i.e., a plurality of apertures each having a length along the axis of the tube which is greater than the width of the aperture along the circumference of the tube) are formed through the tube along the length thereof from a point adjacent the restricted orifice to a point toward the discharge end of the tube to permit ambient gaseous fluid adjacent the exterior of the tube to be drawn by venturi effect through the aperture into the tube and discharged with the expanded fluid out of the discharge end of the tube.

Preferably, three elongated apertures are formed through the tube at 120° increments around the periphery of the tube which is in reality a venturi tube defined by a pair of internal truncated conical surfaces which have their small ends joined by a short cylindrical surface or venturi throat. The elongated apertures are located adjacent the dischage end of the venturi throat and extend into the truncated surfaces on the discharge side of the throat. Both end surfaces are tapered in the same general direction so as to extend from the internal surface of the tube back toward the receiving end of the tube.

The discharge nozzle of this invention is particularly suitable for use in a gas discharge system having a source of limited capacity, e.g., a portable air compressor, in view of the fact that the nozzle substantially increases the volume of air output for a given volume of compressed air input to the nozzle relative to prior nozzles having circular apertures therein.