Spray head

Abstract

A spray head is provided comprising a driver section and a nozzle section. The driver section has a central hub carrying helical vanes mounted in the bore of a generally tubular housing. The liquid to be atomized enters the housing bore, flows over the hub to form an annular sheet, and is caused by the vanes to rotate helically. The nozzle is connected to the housing at its downstream end. It comprises a generally tubular body whose bore communicates with the housing bore. A circumferential row of axially extending ridge-like members extend into the nozzle bore from the bore surface at the nozzle outlet. Individual portions of the annular sheet of liquid each contact a face of one of the ridge-like members and are deflected to form a sheet of liquid egressing from the nozzle outlet. These latter sheets spread and form spray.

Description

BACKGROUND OF THE INVENTION

This invention relates to a hydraulic spray head for atomizing a liquid flow.

A hydraulic spray head is here defined as one which requires only the hydraulic power in the liquid stream being atomized to accomplish atomization; it does not require another power source such as compressed air or a motor-driven impellor.

Hydraulic spray heads of the prior art have deficiencies that limit their usefulness in some applications, such as in burners. If designed to finely atomize and disperse throughout a solid angle, then multiple small ports are frequently used; these ports tend to plug up easily. If a single large port is used, as in the typical vortex-type spray head, then only a wide-angle hollow cone spray will yield fine atomization. If the spray head is constructed to vary the flow rate by varying the outlet orifice area, then a moving part in the head is required; this may be undesirable in a burner. If the spray head is constructed without moving parts, then the spray velocity decreases as the flow rate decreases, causing the droplet size to increase; this severely limits the range of flow within which the desired spray characteristics can be produced.

The prior art in this area is exemplified by the following U.S. Pat. No. 1381095, issued to F. C. Starr; 2000792, issued to V. E. Schmiedeknecht; 2044720, issued to J. Fletcher; 3324891, issued to J. M. Rhoades; 3351080, issued to W. F. Datwyler, Jr., et al; and 3424182, issued to E. A. Mayer.

SUMMARY OF THE INVENTION

With the foregoing in mind, it is one object of this invention to provide a spray head capable of producing a finely atomized spray dispersed throughout a relatively small solid angle.

It is another object to provide such a spray head having no moving parts and relatively large orifices, with reduce plugging.

It is a further object to provide a spray head which is adapted to operate over a relatively wide range of feed rates.

In accordance with the invention, a spray head is provided which combines two principal sections, i.e. a driver and a nozzle. The driver accepts the liquid that is to be atomized and forms it into a helically flowing annular sheet. The nozzle receives this sheet and utilizes a series of spaced deflecting faces, which intercept the flow, to deflect individual portions thereof to form individual sheets of spray. The pattern of the spray which is formed can be controlled by the attitude and/or shape of the deflecting faces. A third section, called a modifier, is sometimes included between the driver and the nozzle. The modifier changes the direction of flow of the liquid in the helically flowing annular sheet, helping to produce the desired spray pattern.

The spray head produces a finely atomized liquid spray dispersed throughout a small solid angle. The device is relatively free of plugging and is capable of performing through a relatively wide range of flow.

DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a longitudinal cutaway view of a spray head in accordance with the invention;

FIG. 2 is a cross section of the nozzle of the spray head taken along the line AA of FIG. 1;

FIG. 3 is an illustration of a deflecting face, such as appear in FIG. 2, in use with a stream of liquid contacting it;

FIG. 4 is a longitudinal cutaway view of an alternative embodiment of the spray head;

FIG. 5 is a cross section of the modifier, taken along the line BB in FIG. 4;

FIG. 6 is a cross section of the vortex mixer portion of the spray head shown in FIG. 4, and illustrates the disposition of the primary inlet ports;

FIG. 7 is a cross section along the line DD of the Vortex mixer shown in FIG. 4, and illustrates the disposition of the secondary inlet ports;

FIG. 8 is a longitudinal cutaway view of a second embodiment of the spray head;

FIG. 9 is a cross section along the line EE of FIG. 8;

FIG. 10 is a cross section taken along the line FF of FIG. 8;

FIG. 11 is a diagram of a typical piping arrangement for use in association with the vortex-mixer type spray head shown in FIGS. 4 and 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, there is shown a spray head or body 1 comprising a driver 1a and nozzle 1b. The driver 1a includes a housing 1c defining a bore or inlet chamber 2. One or more fixed, twist-inducing, helical vanes 6 are positioned within the bore 2; a hub 7 is centrally positioned within the vanes 6. The bore 2 extends to and communicates with the throat 3, which leads into the nozzle bore 4. The surface 4a of the nozzle bore is preferably outwardly flared. A plurality of ridge-like members 5a, each having a deflecting face 5, are disposed in a circumferential row at or near the outlet 30 of the nozzle 1b. The deflecting faces 5 project inwardly from the nozzle bore surface 4a. Pipe thread 8 and wrench flats 9 are provided for convenience in installing the spray head.

In operation, the incoming fluid entering the inlet chamber 2 flows around the hub 7 to form an annular sheet which is directed into helical motion by the fixed vanes 6. The rotating sheet moves through the throat 3 into the nozzle bore 4; individual portions of the sheet each then contact a deflecting face 5 and are deflected, as depicted in FIG. 3. As these deflected sheets leave the nozzle 1b, they spread and form sheets of spray.

An alternative embodiment of the invention is illustrated in FIG. 4. In this case, a body 1, consisting of two parts screwed together, comprises driver, nozzle and modifier. The driver is a vortex mixer and comprises a vortex chamber 14 having primary inlet ports 10 communicating tangentially therewith through the wall 40 of the body 1. A secondary inlet system, comprising tangential secondary inlet ports 11, secondary inlet chamber 12, and annular passageway 13, also leads through the wall 40 and communicates with the vortex chamber 14. The chamber 14 has ends 14a, 14b and a periphery 14c between the ends. An axial opening 41 leads from the chamber 14 into the throadt 3 and nozzle bore 4. The nozzle 1b is identical to that of FIG. 1. A modifier is provided, comprising helical vanes 6 extending inwardly from the surface of the throat 3. A fluid, such as air or steam or natural gas, other than the spray fluid, may be injected through axial port 15 to mix with the spray. Wrench holes 16 facilitate disassembly.

Another alternative embodiment of the invention is shown in FIG. 8. In this version, each feature of the spray head that affects spray head performance is contained in a separate part. The nozzle is identical with the nozzle 1, but is removable. The modifier is identical with the modifier of FIG. 4, but is also removable. The driver is of the vortex-mixer type and functions like the driver of FIG. 4, but is constructed differently. Primary inlet ports 10 lead into vortex chamber 14 through primary insert sleeve 22. Secondary inlet ports 11 are angled slots leading into annular passageway 13 through secondary insert 23. Body 1 contains pipe connections 24 and 25 for primary and secondary inlets. Threaded cap 18 holds sealing gasket in place and clamps the spray head together.

In the drivers of FIGS. 4 and 8, the incoming fluid to be atomized enters vortex chamber 14 tangentially, spirals towards center in an inwardly-flowing vortex, and exits into throat 3 as a helically flowing annular sheet. Part of this fluid enters through primary inlet ports 10, which are relatively small, and the rest of the fluid enters through secondary ports 11, which are relatively large. The small primary inlet ports 10 allow only a small flow with a given fluid supply pressure. The larger inlet ports 11 allow a larger flow with the same fluid supply pressure. The spray head may be hooked up as shown in FIG. 11, with the fluid supply going directly to the small primary inlet ports 10 (pipe connection 24) and passing through a flow controlling valve 26 to the larger secondary inlet ports 11 (pipe connection 25). Total flow at constant supply pressure may then be varied by varying the opening of flow-controlling valve 26, and outlet spray velocity will remain substantially constant.

It is usually desirable that outlet spray velocity be as high as possible for a given fluid supply pressure, since the higher the velocity the finer the spray. Vortex mixers, as used in the drivers of FIGS. 4 and 8, are not very efficient at accomplishing this, because of mechanical energy losses through friction and turbulence in the vortex. In order to achieve reasonably good performance in this respect, some constraints are necessary on the proportions used in the vortex mixer. Vortex chamber 14 should be relatively short and wide, smooth walled, and free of any projections or openings that interfere with the vortex fluid flow. Primary inlet ports 10 should not be relatively too small. Throat 3 should not be relatively too small. Annular passageway 13 for the secondary fluid inlet is necessary and should be relatively narrow. Drivers in proportions as drawn in FIGS. 4 through 9 give reasonably good performance and have a flow range of about six to one at constant supply pressure, when hooked up as shown in FIG. 11.

The direction of flow of the helically flowing annular sheet of fluid issuing from a vortex mixer type driver varies as the ratio of secondary inlet flow to primary inlet flow is varied. This will cause the spray pattern to vary, which may or may not be wanted. If a constant spray pattern is desired, the direction of flow of the helically flowing annular sheet should be kept from changing; this may be accomplished by the small vanes 6 in throat 3, as shown in FIGS. 4, 5 and 8.

The inner surface 4 of the nozzle is usually flared and should lie inside the trajectory that liquid from the driver or modifier would follow if the nozzle were removed. Otherwise irregularities in the helically flowing annular sheet of liquid tend to build up rather than smooth out, which may affect the spray character adversely. Inner surface 4 should be smooth and as short as possible in order to minimize drag on the fluid and keep the outlet spray velocity high.

Deflecting faces 5 are disposed according to the spray pattern desired. In order to produce a spray pattern that has no empty center, deflecting faces 5 must be parallel to the nozzle's axis of rotation. Deflecting faces 5 may be flat or curved, regular or irregular, as the desired spray pattern dictates.

It will be apparent to those skilled in the art that forms of this invention differing from those specifically described and illustrated herein may be made without departing from the spirit of the invention. It is intended that the scope of this invention be limited only by the scope of the claims.

Claims

What is claimed is:

1. A spray head comprising:

a nozzle section and a driver section connected together;

said nozzle section having a bore formed therethrough of substantially circular cross-section, said nozzle bore having an inlet and an outlet, the outlet end of said nozzle bore being outwardly flared;

said driver section having a bore formed therethrough, said driver bore having an inlet and outlet, said driver section outlet communicating with the nozzle section inlet;

means associated with the driver section for forming liquid and moving said liquid through the driver bore and into the nozzle bore, into a helically flowing annular sheet; and

a plurality of members associated with the nozzle section and disposed in a circumferential row at the outlet of the nozzle bore, said members projecting inwardly from the bore surface, each said member having a deflecting face, parallel to the longitudinal axis of the nozzle bore, for deflecting a portion of the helically flowing annular sheet to form an individual sheet of fluid spray;

whereby a finely atomized, conical liquid spray dispersed throughout a small solid angle is obtained.

2. The spray head as set forth in claim 1 wherein:

said driver section forms a bore comprising a chamber having ends and a periphery between said ends;

said driver section further forms an outlet in one of said ends remote from said periphery for transmitting fluid from the chamber into the nozzle bore; and

said driver section further forms a primary inlet, for admitting liquid into the chamber adjacent to said periphery and in a direction more parallel than perpendicular to said periphery, and a secondary inlet, comprising one or more passageways for the admission of additional liquid to said chamber, at least one of said passageways being located adjacent said periphery.