Liquid distribution device

A liquid distribution device having preferred utility as a lawn sprinkler head consists of a hollow chamber having continuously curved interior walls and having a series of exit ports disposed therein. The interior chamber walls are structured to create a rapidly rotating turbulent mass of fluid in the chamber, producing a rapidly directionally unstable flow of discrete drops from each exit port. The chamber is preferably ellipsoidal in shape, and has a total exit-port cross-sectional area greater than that of the fluid inlet to the chamber.

BACKGROUND OF THE INVENTION 
This invention relates generally to irrigation systems, and specifically to 
a device for distributing liquid uniformly over a desired area. More 
particularly, the invention provides a lawn sprinkler nozzle having no 
moving parts which distributes a plurality of bursts of discrete drops 
which oscillate in both horizontal and vertical planes. 
The problems associated with the development of a low-cost, effective 
sprinkler or spray head, particularly for lawn or turf irrigation, have 
proven to be a technically fascinating but frustrating chore. Several 
different varieties are commercially available, and the literature is 
replete with many dozens of designs. In the past, systems have used such 
designs as a plurality of nozzles delivering a fixed irrigation pattern, 
mechanically rotated or oscillated nozzles delivering a generally narrow 
stream of water in an angular sweep, and various nozzle designs to provide 
generally dispersed jets of water. Most of these systems suffer from one 
or more shortcomings; for example, spray heads often produce a mist or fog 
rather than discrete droplets, thereby causing high evaporation losses and 
very poor distribution patterns particularly if a breeze exists, or, 
because of the fixed angle of stream exit, water is distributed 
non-uniformly over the area desired to be covered. Most small spray heads 
used in permanent lawn installations have narrow passageways which plug 
easily. Mechanically rotated units are cumbersome and expensive. Units 
having moving parts, such as are shown in Krynicki, U.S. Pat. No. 
3,747,858, are subject to jamming or clogging from corrosion, traffic, 
dirt, or grass clippings. 
Descriptions of several spray heads having pulsating or oscillating 
discharges formed without moving parts exist in the prior art. A nozzle 
having a flow-splitting "wedge" in a jet stream producing a very rapid 
oscillation in one plane is shown in Stauffer, U.S. Pat. No. 4,151,955. 
Frempter, U.S. Pat. No. 3,301,493 discloses a sprinkler head having an 
elongate cylindrical chamber and a single horizontal slotted discharge 
which produces a "fluttering" discharge apparently produced by interaction 
of water and air at the top of the cylindrical chamber. Hruby, U.S. Pat. 
No. 3,684,176 has a large chamber with an oblique inlet and a single long 
outlet duct at the top of the chamber to produce a pulsating spray. An 
oscillating spray is also produced in Hruby, U.S. Pat. No. 4,055,302 in a 
nozzle having a tortuous fluid path terminating in a single flared conical 
nozzle. 
Non-oscillating sprinkler heads having a plurality of discharge apertures 
communicating with an interior chamber of vertically decreasing 
cross-section are shown in Svet, U.S. Pat. No. 2,311,266, and Garabedian, 
U.S. Pat. No. 2,493,719. The Svet patent shows a head having a plurality 
of bores in the hemi-ellipsoidal chamber wall. A large fastener extending 
vertically through the chamber, along with the ;arge discontinuity in the 
chamber wall at the bottom of the hemi-ellipsoid, and the large inlet 
channels at the sides of the chamber would all preclude this device from 
establishing a fluid-flow pattern necessary to produce oscillation. The 
Garabedian patent has an inverted conical head having a cap thereover; the 
cap is rotatable to permit holes in the cap to register with holes in the 
head to provide flow control. The Garabedian head, having a large inlet 
and ledge formed by the base of the conical cap and straight chamber side 
walls, again will not produce an oscillating spray. 
It has been discovered in accord with the present invention that particular 
interior chamber geometries coupled with a critical ratio of chamber 
outlet to chamber inlet areas provides directionally unstable discharge of 
a series of discontinuous streams of discrete drops of varying velocities. 
Each stream of drops thus oscillates in both a vertical and horizontal 
plane. Stop-action photographs of the oscillating streams show that while 
the basic pattern of oscillation is random, control of vertical 
oscillatory frequency can be superimposed by proper alignment of the inlet 
relative to the output orifice array. Oscillation from each discharge 
orifice occurs through vertical angles of as much as 
45.degree.-50.degree., and horizontal angles of up to about 20.degree., 
resulting in a very uniform distribution pattern. Sprinkler heads made in 
accord with the invention produce almost no misting even at high line 
pressures, thus reducing evaporation loss and imparting wind resistance to 
the liquid discharge of drops. 
The oscillatory potential of the liquid discharge is a function of the 
design of the nozzle chamber. The chamber has a plurality of sharp-edged 
discharge ports in the chamber wall which extend to various extents 
(depending on whether full-, half-, quarter-head, or some other watering 
pattern is desired) around the periphery of the head. The chamber is 
entirely hollow and unobstructed, and has an upper wall portion which is 
curvilinear in both horizontal and vertical cross-sections. The upper 
chamber portion is preferably symmetrical about its vertical axis, having 
a circular or elliptic horizontal cross-section continuously decreasing in 
radius toward its uppermost portion (e.g., ellipsoidal, elliptic 
paraboloidal, or spherical). The lower portion of the chamber is 
curvilinear, preferably circular in horizontal cross-section, and may be 
straight or curvilinear in vertical cross-section. The width of the 
interior of the lower portion of the chamber either remains constant or 
decreases downwardly. An inlet port is located at the bottom of the 
chamber; for typical residential scale turf irrigation the area of the 
inlet port is importantly equal to or smaller than the total area of the 
outlet ports. The head functions as described herein because the jet of 
water exiting the inlet port interacts with the surrounding fluid and the 
chamber geometry to induce formation of a rapidly rotating, turbulent mass 
of water which travels along the chamber wall towards the discharge 
orifices. The aforesaid jet interaction with the ambient fluid and chamber 
geometry creates vortex-like cells of varying velocities within the main 
mass of rotating fluid. The differential velocities of the cells thus 
created cause the direction of the jet relative to the chamber walls to 
change periodically, thereby producing changes in direction of the 
turbulent rotating mass of fluid therein. Over a given time period the 
fluid mass thus approaches the discharge orifices from many different 
directions, thereby causing oscillations of the liquid discharge. 
Accordingly, it is an object of the invention to provide liquid 
distribution apparatus which distributes discrete drops of liquid in a 
generally uniform distribution pattern. It is a further object of the 
invention to provide a sprinkler head which produces discontinuous streams 
of discrete drops which oscillate in multiple planes. It is yet a further 
object of the invention to provide a lawn sprinkler head having no moving 
parts, which is easily and inexpensively manufactured, and which provides 
relatively even ground coverage without production of aerosols. These and 
other objects of the invention will be evident from the following detailed 
description of preferred embodiments of the invention. 
SUMMARY OF THE INVENTION 
Liquid distribution apparatus comprises an unobstructed hollow chamber 
defined by one or more walls, the interior chamber walls being 
substantially continuously curved, and an upper portion of the chamber 
walls having curvilinear horizontal and vertical cross-sections. The upper 
portion of the chamber wall has a plurality of discharge ports, and a 
lower portion of a chamber wall has inlet means; the total effective 
cross-sectional area of the discharge ports is equal to or greater than, 
and preferably at least 1.4 times greater than, the cross-sectional area 
of the inlet means.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring first to FIG. 1, a pop-up lawn sprinkler half head 2 fabrication 
in accord with the invention is shown in perspective in the elevated, or 
operating, position. The terms "full head", "half head", and "quarter 
head" as used herein mean spray heads providing circular, semi-circular, 
and quarter-circular distribution patterns, respectively; in each case, 
the head is located at the center of the circle. Other distribution 
patterns may be realized by differing placements and sizes of the outlet 
orifices on the chamber wall surface. The head consists of a egg-shaped or 
ellipsoidal discharge portion 10 having a series of horizontally aligned 
discharge ports 14 mounted on a riser tube 16. The long axis of the 
ellipsoid is oriented vertically. The shaft is mounted on a base 18 having 
a ledge 19 which abuts the lower portion of ring 20 when the head is 
raised into operating position. Guides (not shown) in the ledge 19 prevent 
rotation of the shaft in the ring. When the water pressure to the head is 
turned off, the shaft drops by gravity or spring pressure (spring not 
shown) to a resting position in which the uppermost tip of discharge head 
10 is below the upper surface of ring 20. The particular method of 
mounting the distribution apparatus of the invention forms no part of the 
invention, and it will be readily apparent to those skilled in the art 
that any conventional support for this apparatus may be used. 
The half head shown in FIG. 1 is shown in side elevational view in FIG. 2 
and in side section in FIG. 3. The discharge head 10 of spray apparatus 2 
has an interior discharge chamber 11 formed by chamber wall 13. The 
chamber is ellipsoidal in shape, with the longitudinal axis being 
vertical. The chamber wall has an aperture 9 at the bottom portion thereof 
which forms the discharge end of inlet duct 12. The inlet duct 
communicates with a chamber 17 at the lower portion of the shaft; this 
chamber is simply a portion of the water feed line and its size and shape 
are not critical, although its cross-sectional area is desirably 
significantly greater than that of the inlet duct such that unnecessary 
pressure drops do not result. 
A top view of the half head is shown in FIG. 4. The discharge ports 14 are 
of uniform size and are located in a horizontal plane around an upper 
portion of the spray head. The ports extend around about 165.degree. of 
the periphery; extension to a full 180.degree. to obtain semicircular 
coverage is not necessary because of the oscillation of the droplet 
streams in the horizontal plane. A top view of a similarly mounted quarter 
head 3 is shown in FIG. 7, discharge ports 23 extend slightly less than 
90.degree. around the periphery of the head. A full head 4 having ports 24 
extending completely around the periphery is shown in FIG. 8; the circular 
inlet 28 is shown in phantom. 
A section view of the lower portion of shaft 16 showing the upper wall 21 
of chamber 17 and the end of inlet duct 12 is shown in FIG. 5. The inlet 
duct is also shown in bottom view of the device of FIG. 6. The half-head 
inlet duct is of uniform rectangular cross-section, with a long side of 
the rectangle aligned perpendicular to the center of the array of 
discharge ports (see FIGS. 4-6). Other alignments may be used to create 
different drop distribution patterns. 
FIG. 9 shows a partial section of a portion of the discharge chamber and 
one of the discharge ports. The discharge port is a countersunk aperture 
having inwardly sloped walls 25 and 26 forming an angle "A" of 90.degree.. 
This angle may be greater or smaller but to realize maximum oscillation 
must equal the potential angle of escape of the fluid eject from the 
chamber. Potential angle of escape is a function of wall curvature, 
orifice diameter, inlet placement and outlet inlet ratio. These walls form 
sharp edges with the curved interior wall 13, which allows a greater angle 
of escape of the discharge of water drops. While a sharp-edged aperture is 
preferred, wide cylindrical countersinks with very short narrow ducts have 
been used with success, though angles of potential oscillation are 
reduced. Countersinking may be achieved of course in any manner, e.g., by 
molding, the result of having an aperture through the chamber wall having 
an outwardly increasing size being more important than the method of 
formation. 
For typical residential scale lawn watering, circular discharge ports are 
preferably from about 0.05" to about 0.08" in diameter at the inside wall, 
but need not be uniform in size. Multiple non-circular ports may also be 
used provided their individual areas are approximately the same as 
circular one, i.e., from about 0.002 sq.in. to about 0.005 sq.in. Larger 
ports tend to produce drops which are too large, promoting soil 
compaction, and smaller orifices tend to produce undesirably small 
droplets or mists. While a single horizontal row of discharge ports is 
shown in the half, quarter, and full heads of FIGS. 4, 7, and 8, several 
rows may be used, and different sizes ports may be used on different rows 
or on the same row. Additionally, the ports need not be arranged in rows, 
as can be seen in FIG. 18, which shows a top view of an ellipsoidal full 
head 27 which produces a generally rectangular elongated watering pattern. 
The particular number, size, orientation, and shape of discharge ports 
will depend upon the type of distribution pattern desired. While multiple 
ports, preferably at least 3, are preferred, a single slit orifice (in a 
one-half or one-quarter head for example) can be used but at typical water 
line pressures for turf irrigation would have to be quite narrow to 
preserve chamber pressure and consequently the radius of water 
distribution. This is undesirable as very narrow orifices of any shape 
will tend to produce aerosols even at normal operating pressures. Multiple 
ports also result in a mechanically stronger nozzle assembly. The ports 
may be of a variety of shapes, such as a series of horizontal or vertical 
slits, square, triangular, oval, etc. While the area ratio of the ports to 
the inlet is very important, to produce maximum oscillation of the 
discharge, the shape does not appear to be critical. 
In addition to the type and placement of discharge ports, many variations 
can be made within the scope of the invention to obtain specific desired 
results. In general, exterior configuration of the heads is not critical 
to their performance. Exterior configuration may depend on such variables 
as cost, ease of manufacture, and durability. A particularly preferred and 
easily manufactured embodiment is shown in FIGS. 10 and 11; in this mode, 
a screw-in head 30 having male threads 31 for connection to conventional 
pipe fittings or to the upper portion of a tubular sprinkler pop-up riser 
has a cylindrical exterior surface 32 which is attractive, easily molded 
from plastic, and sturdy. The head contains discharge ports 33 of the type 
previously discussed. The head contains an ellipsoidal discharge chamber 
34 as shown in FIG. 11. The device is molded from an upper portion 36 and 
lower portion 37, which fit together as shown and can be either glued or 
sonic welded along the seam to provide a unitary structure. The inlet is 
rectangular with a short edge of the rectangular facing the center of the 
array; this results in a somewhat rectangular distribution pattern. 
The particular shape of the interior chamber is very important, but may be 
varied considerably within the parameters believed important. The chamber 
must be a substantially unobstructed hollow chamber having a horizontal 
cross-section which is a continuous curve. The chamber is preferably 
symmetrical about a vertical plane extending through its vertical axis, 
and is more preferably symmetrical about any plane in which its vertical 
axis is contained. The horizontal cross-section is preferably circular or 
elliptic with an upwardly decreasing radius at its upper portion toward 
its top. An upper portion of the chamber, which generally carries the 
discharge ports, has walls which are curvilinear in both horizontal and 
vertical cross-sections; the lower portion of the chamber must be 
curvilinear in horizontal cross-section but may be straight in vertical 
cross-section. For effective vertical oscillation, the chamber length must 
exceed its width. Examples of configurations of heads within the scope of 
the invention are shown in the cross-sectional views of FIGS. 12-17. FIG. 
12 shows a head 40 having a paraboloidal upper portion and a cylindrical 
lower portion. FIG. 13 shows head 41 having a hemispherical upper section 
and a cylindrical lower portion. FIG. 14 shows an ellipsoidal section 
mounted over a hemispherical lower portion on head 42; this head also has 
two parallel rows of discharge ports 43 and 44 in the upper chamber 
portion. FIG. 15 shows a head 45 comprising a hemispherical upper portion 
and an ellipsoidal lower portion. FIG. 16 shows a half head 46 having an 
ellipsoidal upper portion and a frusto-conical lower portion, and FIG. 17 
depicts a head 47 having a hemispherical upper portion and a conical lower 
portion. Each of FIGS. 12-17 shows a half head with a rectangular inlet, 
with the long side of the rectangle shown aligned approximately parallel 
to the row of discharge ports. 
Both the size and shape of the inlet to the operating chamber are 
important, although considerable variation in shape may exist. Inlets 
having circular and rectangular cross-sections have been successfully 
used, and oval, semi-circular, and other geometric cross-sections, such as 
annular rings, can be used. Circular inlets are preferred for 
three-quarter and full heads, whereas rectangular or oval inlets are 
preferred for half or quarter heads. The inlet is preferably centrally 
located at a bottom portion of the discharge chamber, although the inlet 
can be moved off center or canted to create variations in oscillatory 
frequency (and hence different precipitation patterns). The inlet size, 
and its relationship to the area of the discharge ports is, however, 
critical. It is absolutely essential that the cross-sectional area of the 
total of the discharge ports for a full or 3/4 pattern head be at least 
equal to or greater than, and preferably at least 1.4 times greater than, 
the cross-sectional area of the inlet. Half heads and quarter heads need 
even greater ratios, preferably at least 2:1, to oscillate maximally. If 
the discharge ports have a cross-sectional area substantially smaller than 
that of the inlet, the discharge chamber functions simply as a sudden 
enlargement in the line, and non-oscillating streams of water are produced 
from the head. 
The invention contemplates that the discharge chamber interior is 
substantially unobstructed and has sidewalls which are substantially 
continuously curved. By "substantially continuously curved" is meant a 
wall which has a cross-section having substantially no straight lines; 
while is it possible to construct an interior wall from a series of very 
short straight segments, the wall is substantially curvilinear if the 
water flow around the interior wall follows a relatively smooth, 
continuous path. By "substantially unobstructed" is meant that the 
interior is hollow without flow obstructing members extending into the 
interior; i.e., the interior surface must be continuous, without any 
substantial ledges, protrusions, or other discontinuities which would 
obstruct flow. 
While the theory of operation of the devices of the invention is not 
completely understood and forms no part of the invention, an understanding 
of the principles of operation is helpful to appreciate both its 
simplicity of ultimate structure and the complexity of the reasons for 
successful operation. The flow pattern of a preferred ellipsoidal design 
of the head is illustrated in FIGS. 19 and 20. 
As shown in FIGS. 19, the fluid stream 50 entering the inlet 51 of 
discharge chamber 49 jets upwardly toward the concave upper walls of the 
chamber, distributing downwardly in an umbrella-like pattern. Because of 
the interaction of the inlet jet with the surrounding fluid medium and the 
interior chamber shape, internal cells of varying velocities are formed 
around the jet, many of which can coexist at any given time. A cell 
composed of a high velocity rotating mass of fluid shown as cell 53 in 
FIG. 20, will tend to have a lower internal pressure across its boundaries 
than that of the lower velocity ambient fluid. The inlet jet 50 will bend 
toward the wall over the cell with the lowest internal pressure as shown 
in FIG. 20; the tendency of the jet to bend towards the wall beyond the 
upper-limit of a low pressure cell is known as the Coanda effect. Because 
of the continuously curved horizontal cross-section of the "3 dimensional" 
chamber, the inlet jet cannot seal off the low pressure cell from the 
remainder of the chamber. Therefore, fluid from other parts of the chamber 
migrates to the cell, changing local velocities and pressures, causing the 
cell to shift rapidly from side to side (or to extinguish and be created 
elsewhere). As the jet "follows" the minor shifts of the low pressure 
cell, rapid horizontal oscillation of about 18.degree. in the output of 
each discharge port results. When major movements of a low pressure cell 
occur, the jet, in response to the large pressure differential across it, 
will make major movements such as a 180.degree. shift from one wall to the 
opposite wall. These major changes in jet orientation create reversals in 
the rotational direction of the fluid mass in the chamber. Such reversals 
are responsible for the vertical oscillatory component of the output of 
drops. 
The formation of true cohesive streams of liquid output is prohibited by 
the highly convoluted stream tubes formed in the turbulent fluid within 
the chamber. Such "tubes" cause each unit of fluid particles to exit the 
nozzle at different velocities. 
The frequency and degree of oscillation of the output is controlled by the 
position and attitude of the inlet relative to the outlet array, the 
inlet/outlet area ratio, the chambers internal volume and line pressure 
feeding the chamber. 
If the jet is bent across a low-pressure cell toward the wall on an upward 
path as shown in FIG. 20, the discharge profile of the drops 55 will be in 
an upwardly direction. As the water follows the chamber contour past the 
uppermost portion of the chamber, water flows down the opposite wall, 
causing a downward ejection profile 56 from the opposite discharge ports. 
When the jet is bent toward the opposite wall, the fluid mass rotation is 
reversed, as is the drop ejection profile, as shown in FIG. 20. 
While the invention has been described having utility for lawn and 
agricultural sprinklers, in principle it has utility for other devices 
such as fire sprinklers, dental irrigation devices, fountain nozzles, 
shower heads, therapy tub jets, and the like. In addition, various 
modifications to the invention will be obvious to those skilled in the 
art, and the invention should not be considered limited to the specific 
embodiments described herein.