US3394889A

US3394889A - Spray nozzles having elliptical swirl chambers

Info

Publication number: US3394889A
Application number: US566282A
Authority: US
Inventors: Macguire-Cooper Richar Terence
Original assignee: Oxford Industrial Research and Development Co
Current assignee: Oxford Industrial Research and Development Co
Priority date: 1965-08-06
Filing date: 1966-07-19
Publication date: 1968-07-30
Anticipated expiration: 1985-07-30
Also published as: GB1160113A

Description

SPRAY NOZZLES HAVING ELLIPTICAL SWIRL CHAMBERS Filed July 19, 1966 Richard T. Mac Gu\r6CooPe.v

ATTORNEY United States Patent 3,394,889 SPRAY NOZZLES HAVING ELLIPTICAL SWIRL CHAMBERS Richard Terence Macguire-Cooper, Boars Hill, Oxford, England, assignor to The Oxford Industrial Research and Development Company, Boars Hill, Oxford, England, a partnership Filed July 19, 1966, Ser. No. 566,282 Claims priority, application Great Britain, Aug. 6, 1965, 33,668/65; Aug. 8, 1965, 35,374/65; Oct. 27, 1965, 45,455/65; Feb. 16, 1966, 6,744/66 9 Claims. (Cl. 239468) ABSTRACT OF THE DISCLOSURE This invention relates to a new and improved nozzle, useful in conjunction with the dispensing of fluids contained within pressurized cans or the like. In particular, this invention is directed to an elliptical swirl chamber having at least two foci, discharge means coupled to said chamber, and means for providing material to be dispensed to said swirl chamber.

This invention relates to the design and construction of a nozzle which may with advantage serve as an actuation or operating button in addition to its main function as a device for producing a fine spray when connected to the tubular stem of a valve fitted to a container of a pressurized fluid or material.

The invention is principally concerned with those types of spray nozzles or buttons used on what are often known as pressure packaging or aerosol systems, and the invention refers to the type of nozzle known as mechanical break-up spray nozzles.

Such nozzles are at the present time produced in large numbers and are designed with such a configuration that a spray of very fine particles is produced from fluids which are substantially non-volatile at ordinary ambient room temperatures, by the use of relatively low container pressures. Such devices at present produced may incorporate a simple system wherein a pressure is produced inside the container by means of a low boiling point liquid which volatilises at room temperatures, or by the introduction of a compressed gas charge into the container by suitable mechanical means, and in this way can exert a pressure inside the container thus acting as a simple propellent for the discharge of the contents of the container through a simple valve control system into the atmosphere.

In the mechanical break-up nozzles in current use, the spray is produced by both mechanical and physical forces, often assisted by the simultaneous vapourisation and expansion of any liquid propellent or gas which may pass into the nozzle.

The mechanism of the production of the spray production is one wherein the contents of the container under the control of the discharge valve system are passed into the body of the nozzle and there enter a circular or cylindrical chamber by means of a feed passage system in which one or more fluid feed passages merge substantially at a tangent to the circular chamber, in a swirl chamber system.

In this manner the fluid entering the swirl chamber is given a swirling or circular motion within the chamber.

A fine spray is produced by the discharge of the swirl chamber into a simple orifice in the wall of the swirl chamber, or a passage leading to such an orifice.

In this action a combination of the centrifugal and forward axial movement of the discharging fluid in the swirl chamber or associated discharge passage will on passing "ice through the discharge orifice serve to produce a very fine spray of fluid particles, due to a mechanical shearing effect and/or the break-down of a fine film of fluid under surface tension physical effects.

It has been noted that in such systems in current use the swirl chamber is circular in section, this being on first sight the most obvious shape to produce a simple swirling motion.

The main object of the present invention is to produce an improved design and construction of nozzle, which will allow greater ranges of spray production to be effected at low cost, and without the need to depart from the simple production methods at present employed in the systems now utilized.

Thus according to the invention the use of swirl chambers of different shapes will serve to promote different spray characteristics, and the use of certain specified swirl chamber configurations will produce a range of spray characteristics which may be matched to formulation requirements, thus allowing a range of nozzles to 'be produced without departing from a common outside shape, or departing from common orifice and passage or channel dimensions.

The swirl chamber shape to which this patent relates is that which may be generally described as compound elliptical in shape, and an illustration of such a swirl chamber is shown in the accompanying drawings.

Such a swirl chamber may be moulded in one piece in a complex moulding or may with advantage be produced by the assembly of one or more suitable components, or may be formed in any suitable manufacturing process.

The walls of the swirl chamber need not be regular in dimension, and as a rule it should be possible to accommodate a circular shape inside the chamber in such a way that the area of the space so taken up will be the greater part of the tot-a1 area.

The passages or channels which serve to feed the swirl chamber should with advantage be so disposed that they are tangential to the circular area of the swirl chamber.

Two of the walls of the swirl chamber should with advantage be flat, and these walls will be those which contain and face the discharge orifice or passage.

It has been proved that any reduction in the energy required to produce a fine spray can be a factor which will allow the container to work at a lower and therefore safer pressure, irrespective of the saving in the cost of the propellent system, and this fact applies in particular to sprays produced by mechanical break-up spray nozzles.

According to the present invention, a swirl chamber will present a compound elliptical form which serves to minimise the laminar impingement of currents moving in circular motion in the swirl chamber and would also serve to minimise the friction between the fluid in motion and the Walls of the swirl chamber, and thus reduce energy losses absorbed in the swirling process.

It is also important in reducing energy loss at the point where the fluid stream from the feed passages or channels enter the swirl chamber by providing expansion space which will serve to limit interference between streams of fluid already in motion within the chamber and the stream of fluid entering the chamber.

It is found that the walls of the chamber may with advantage taper towards the wall containing the orifice or discharge passage, as this reduction in effective diameter of the swirl chamber serves to increase the velocity of the fluid as it moves towards the discharge orifice or passage.

It has also been found that the conditions producing the droplet formation are improved by a uniform degree or turbulence at the orifice area immediately inside the swirl chamber, and the production of this regular turbulent condition is assisted by the use of the elliptical chamber. It has also been established that the use of regular elliptical swirl chambers will have advantages in cases where two feed passages are used to feed the swirl chamber, and the degree of irregularity or compounding of the swirl chamber shape can range over a wide variety of elliptical shapes. According to the formulation of the contents of the container, the use of elliptical swirl chambers will serve to reduce kinetic energy loss in the nozzle, and will thus serve to promote greater fluid stream momentum, leading to the production of greater spray particle velocities without pressure increases in the formulation.

The use of the elliptical swirl chamber will reduce those factors leading to the production of a vortex in the swirl chamber, and will assist in the promotion of regular uniform turbulent conditions and thus uniform spray patterns.

A further advantage of the use of the elliptical swirl chamber is that their use will delay propellent fluidgaseous changes of state in the swirl chamber and will thus release energy due to these changes of state at the period of the droplet formation and film break-down when it can have the greatest effect in producing a fine spray.

The effective diameter of an elliptical swirl chamber can be made smaller than that of a normal circular swirl chamber due to the provision of expansion spaces within the area immediate to the entry of the tangential streams, and this design factor can be used to limit the centrifugal component and thus produce a spray which will have a greater and more uniform mass flow per unit area, i.e. a spray with a less hollow centre.

It has also been found that the use of the elliptical swirl chamber will limit the production of hydrodynamic shock waves, and thus produce a smoother more uniform circular motion within the swirl chamber.

The use of this swirl chamber configuration has also certain advantages in allowing the production of the nozzle when produced as a one-piece plastic moulding, in that the swirl chamber forming tool core which is often a projection of the tool core forming the tangential feed passages, may be removed more easily, from the surrounding warm and soft, resilient plastic body of the nozzle body due to the elliptical and tapering configuration of the tool core forming the swirl chamber during the moulding process, and this removal process is of great advantage in such difficult mouldings as those incorporating a feed passage leading off-centre into a swirl chamber.

From a consideration of the above factors it may be seen that there are both utilisation and production engineering advantages in the use of the elliptical or compound elliptical swirl chamber as applied to both onepiece end assembled spray nozzles, and it is a factor in this invention that the use of variations on the configuration and dimensions of the swirl chamber can be used to produce different spray patterns, velocities, or particle momentum without reference to alterations in other features of the nozzle, valve or formulation of the fluid to be sprayed.

The invention will now be illustrated in the accompanying drawings, with various swirl chamber shapes and one embodiment of a one piece nozzle type in current use.

FIG. 1 is an outline illustration of a normal orthodox circulate, or circulate cylindrical swirl chamber with the feed passages 1 merging at a tangent to the circular shaped swirl chamber cavity 2. A discharge orifice 3 being formed in the centre.

FIG. 2 is an outline illustration of a compound elliptical swirl chamber with two feed passages 4 leading initially into the expansion area of the swirl chamber 5 and then into the main body of the swirl chamber which contains the usual discharge orifice 7. Fluid entering the main area of the swirl chamber 6 will not interfere greatly with the fluid already in circular swirling motion, and it is important to note in the context of this invention that limited swirling motion does start in the expansion area 5. Thus :more uniform turbulent conditions are established in the main swirling cavity area 6.

FIG. 3 is an illustration of a normal one-piece nozzle at present in common use whichmay be improved by the use of an elliptical swirl chamber the illustration shown being with or without the elliptical chamber.

In this illustration the main nozzle body 8 contains a central cavity 10. which fits in sealing engagement with the hollow valve stem 9.

A swirl chamber is formed inside the nozzle body at 14 with an off centre passage leading tangentially into the swirl chamber from the projection of the hollow nozzle cavity.

The swirl chamber 14 discharges to the outside of the nozzle by means of a discharge passage and orifice 13. The whole being contained in a cavity in the outer wall of the nozzle body 15.

FIG. 4 illustrates a compound elliptical swirl chamber which may with advantage be used in the previous example nozzle, with the feed passage leading off centre and tangentially into the initial expansion area 17 and then into the main chamber cavity area 18. prior to establishing a discharge outlet in the orifice 19.

FIG. 5 illustrates a section through the valve stem and nozzle body in the area of the swirl chamber with the off-centre feed passage 22 leading to the compound elliptical swirl chamber at a substantially tangential angle 20 being a section of the nozzle body containing the swirl chamber, 21 being the elliptical swirl chamber, 22 being the off centre feed passage, whilst 23 represents the valve stem.

FIG. 6 illustrates a plan view of the nozzle shown in FIG. 3. 24 represents the valve stem feed passage, which is continued in feed effect with a passage leading into the off-centre tangential feed passage leading into the swirl chamber 26 from which the chamber discharges through a passage and then through the discharge orifice 28, which is in a recess 29 formed in the outer surface of the nozzle body.

In the previous detailed description of the invention several different ways of utilising the invention have been described, but in all cases the object of the invention is accomplished by the use of an elliptical or compound elliptical swirl chamber with sides that taper towards the face containing the discharge passage or orifice.

The invention relates to in the main, the construction of one piece nozzles as used for the discharge of pressure packages or aerosols and allows the more efficient production of a fine spray or mist.

This invention has many advantages over established practice, and allows the simple and convenient production of the nozzle by pressure moulding and ensures that a more efiicient production of a spray or mist may be carried out, without the use of ultra-high container pressures.

What we claim is:

1. An assembly for use with a pressurized container or the like, having a valve with a valve stem having a liquid conveying passage, characterized in that a nozzle body is provided with a cavity which fits in sealing engagement with the valve stem, an elliptically shaped swirl chamber having at least two distinct foci formed in the body, discharge means extending from said chamber to discharge material from said body, and a feed passage formed in said body and communicating with said swirl chamber and said passage in said stem.

2. An assembly according to claim 1, in which an expansion area is provided in said body between said feed passage and said swirl. chamber.

3. An assembly according to claim 1, in which a plurality of feed passages are provided which communicate with said swirl chamber and said passage in said stem.

4. An assembly according to claim 3, in which expansion areas are provided between said feed passages and said swirl chamber.

5. In a device for use in a dispensing mechanism for a pressurized container or the like, and elliptical swirl chamber having at least two distinct foci, discharge means coupled to said swirl chamber, and feed passage means for providing material to said swirl chamber.

6. In a device according to claim 5, in which is provided one feed passage means.

7. In a device according to claim 5, in which is provided a plurality of feed passages for directing material into the swirl chamber.

8. In a device according to claim 6, in which is provided an expansion area between said swirl chamber and said feed passage.

9. In a device according to claim 7, in which expansion areas are provided between said swirl chamber and said feed passages.

References Cited UNITED STATES PATENTS 1,716,174 6/1929 Klein 239468 X 2,161,016 6/1939 Carr 239468 2,904,263 9/1959 Tate et al. 239468 X 3,008,654 11/1961 Abplanalp et a1. 239468 3,075,708 1/1963 Cooprider 239468 X 3,083,917 4/1963 Abplanalp et a1 239468 3,118,612 1/1964 Abplanalp 239468 X 3,223,332 12/1965 .Nyden 239-579 X 3,236,031 2/ 1966 Bennett et al. 239463 X M. HENSON WOOD, IR., Primary Examiner.

V. M. WIGMAN, Assistant Examiner.