An improved and tunable ultrahigh-pressure nozzle for use in generating ultrahigh-pressure fluid jets is shown and described. In a preferred embodiment, a nozzle body is provided with a first conical bore that extends from an entrance orifice to an exit orifice, the bore transitioning into a second conical bore that is formed in a seal. The seal is formed to capture a nozzle orifice and position it in the nozzle body adjacent the exit orifice. By selecting the geometry of the nozzle, namely the diameter of the entrance orifice, and an included angle of the first and second conical bores, it is possible to optimize performance of a fluid jet generated by the nozzle for a selected task and operating parameters.

TECHNICAL FIELD 
This invention relates to nozzles, and more particularly, to nozzles for 
generating ultrahigh-pressure fluid jets. 
BACKGROUND OF THE INVENTION 
Numerous tasks, for example, cutting, cleaning and surface preparation, may 
be accomplished through the use of a stream of pressurized fluid, 
typically water, generated by high-pressure, positive displacement pumps 
or other suitable means. Such pumps pressurize a fluid by having a 
reciprocating plunger that draws a volume of fluid from an inlet area into 
a pressurization chamber during an intake stroke, and acts against the 
fluid during a pumping stroke, thereby forcing pressurized fluid to pass 
from the pressurization chamber into an outlet chamber, from which it is 
collected into a manifold. The pressurized fluid is then directed through 
a nozzle of a tool, thereby creating an ultrahigh-pressure fluid jet that 
may be used to perform a particular task, for example, cutting a variety 
of materials or cleaning a surface. Such jets may reach pressures up to 
and beyond 55,000 psi. 
It is desirable to maximize the effectiveness of the fluid jet in its 
performance of a selected task. Although currently available nozzles 
produce good results, applicants believe that it is possible and desirable 
to provide an improved nozzle. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide an improved nozzle 
for generating an ultrahigh-pressure fluid jet. 
It is another object of this invention to provide a nozzle that may be 
tuned to maximize its performance for a given set of operating conditions. 
It is another object of this invention to provide an ultrahigh-pressure 
nozzle that is more simple to use than currently available systems. 
These and other objects of the invention, as will be apparent herein, are 
accomplished by providing an improved ultrahigh-pressure nozzle. In a 
preferred embodiment, a nozzle body is provided having an entrance orifice 
and an exit orifice, and a bore extending from the entrance orifice to the 
exit orifice. A seal is provided in the bore adjacent the exit orifice, 
the seal having a first conical bore at a first upstream end and a second 
bore at a second downstream end, the first and second bores being adjacent 
to each other. The second bore of the seal is sized to accommodate a 
nozzle orifice that is held in place in the assembly by the seal. As a 
result, when the nozzle is used, a volume of pressurized fluid flows 
through the entrance orifice of the nozzle body, through the bore of the 
nozzle body and through the conical bore of the seal, prior to flowing 
through the nozzle orifice to exit the nozzle body as an 
ultrahigh-pressure fluid jet. 
In a preferred embodiment, a diameter of the entrance orifice is 0.1-0.75 
inch, an included angle of the bore of the nozzle body is 
0.degree.-20.degree., and an included angle of the first conical bore of 
the seal is 30.degree.-170.degree.. By adjusting these three parameters 
within the given ranges, it is possible to tune the nozzle to optimize its 
performance at a selected stand-off distance. 
More particularly, it is believed that a fluid jet transitions from a 
coherent state near the exit of a nozzle into high velocity, large 
droplets at some distance from the orifice, and that the droplets then 
slow down and break up at some greater distance from the exit orifice. A 
fluid jet may therefore be thought of as transitioning through three zones 
after it exits a nozzle, namely, a coherent zone, a high velocity, large 
droplet zone, and a low velocity, small droplet zone. It is believed that 
the contact stresses are greater in the second zone, and that superior 
surface preparation results are therefore achieved by placing a surface to 
be treated in the second zone. 
However, the stand-off distance, or distance between the exit orifice of a 
nozzle and a surface to be treated, may be dictated by operating 
conditions. For example, if a nozzle is used in a hand-held tool, the 
stand-off distance will vary, and may average approximately 4 inches. In a 
different context, given space constraints or other considerations, it may 
be necessary to operate at a specified stand-off distance. Applicants 
believe that by providing a nozzle in accordance with a preferred 
embodiment of the present invention, they may alter the turbulence in the 
fluid jet generated by the nozzle by adjusting the three parameters 
identified above, namely, the diameter of the entrance orifice of the 
nozzle, the included angle of the bore of the nozzle body, and the 
included angle of a second conical bore. In this manner, the distance from 
the exit nozzle at which the ultrahigh-pressure fluid jet begins to 
transition from a zone 1 coherent jet to a zone 2 jet having a coherent 
core and large velocity droplets may be set at a desired value, thereby 
ensuring that performance of the fluid jet is optimized at a pre-selected 
stand-off distance. 
In a preferred embodiment, a smallest diameter of the bore of the nozzle 
body and a smallest diameter of the conical bore of the seal are both at 
least as large as an outer diameter of the nozzle orifice, such that the 
nozzle orifice may be easily pushed out of the nozzle body and replaced as 
necessary. 
Furthermore, in a preferred embodiment, an exterior surface of the nozzle 
body is formed to have at least one flat surface. As a result, any cracks 
that may result from the cycling of pressure through the nozzle body will 
propagate to the flat surface, causing the nozzle to leak, rather than 
break. Applicant further believes that preferable results are achieved 
when the exterior surface of the nozzle body is formed into a hexagon 
measuring at least 3/8 inch in width between two parallel faces.

DETAILED DESCRIPTION OF THE INVENTION 
Numerous tasks such as curing, cleaning or preparing a surface may be 
accomplished through use of an ultrahigh-pressure fluid jet, generated by 
forcing a volume of pressurized fluid through a nozzle. The nozzle may be 
provided in a machine operated tool or in a hand-held tool. This 
condition, as well as operating considerations such as space constraints 
or safety issues, may dictate an operating stand-off distance, namely, the 
distance between an exit of a nozzle and the surface to be treated. 
An improved ultrahigh-pressure nozzle 10 is provided in accordance with a 
preferred embodiment of the present invention. As illustrated in FIG. 1, a 
volume of pressurized fluid from a source of ultrahigh-pressure fluid 14 
is provided to the nozzle 10 via supply tube 12. The nozzle 10 is 
comprised of a nozzle body 16 having an entrance orifice 18 and an exit 
orifice 20. As illustrated in FIGS. 1 and 2, a bore 22 is provided in the 
nozzle body 16, extending from the entrance orifice 18 to the exit orifice 
20. 
As illustrated in FIGS. 1 and 3, a seal 24 is provided having a first 
conical bore 26 at a first upstream end 30, and a second bore 28 at a 
second downstream end 32. A nozzle orifice element 34 having an aperture 
extending therethrough and referred to hereinafter as a nozzle orifice is 
positioned in the second bore 28 of the seal 24, the seal 24 and nozzle 
orifice 34 being positioned in the bore 22 of the nozzle body 16 such that 
the bore 22 of the nozzle body is adjacent the first conical bore 26 of 
the seal, and the nozzle orifice 34 is adjacent the exit orifice 20. In a 
preferred embodiment, the second bore 28 of the seal 24 is cylindrical, 
and is sized according to an outer diameter 50 of the nozzle orifice 34, 
as illustrated in FIG. 4. Although a variety of materials may be used, in 
a preferred embodiment, seal 24 is made of Delrin, and the seal captures 
the nozzle orifice and holds it in position in the nozzle 10. 
An ultrahigh-pressure fluid jet 11 is therefore generated in accordance 
with a preferred embodiment of the present invention by forcing a volume 
of pressurized fluid through the entrance orifice 18 of nozzle body 16 via 
supply tube 12. The pressurized fluid flows through first conical bore 22 
and a second conical bore formed by the first bore of the seal 24, the 
pressurized fluid flowing through nozzle orifice 34 to exit the nozzle 
body 16 via exit orifice 20 as an ultrahigh-pressure fluid jet 11. 
Although applicants do not intend for the scope of their invention to be 
bound by any theoretical basis for the improved results, it is believed 
that the fluid jet 11 transitions from a coherent and transparent state 
near the exit orifice 20 into a jet having a coherent core surrounded by 
high velocity large droplets at some distance from the exit orifice 20. It 
is further believed that the droplets then slow down and break up at some 
greater distance from the exit orifice, such that the fluid jet 11 may be 
thought of as transitioning through three zones after it exits the nozzle 
10. The fluid jet 11 is most effective at cutting materials of low yield 
strength, such as plastics, paper, cardboard, etc., in zone 1, while 
increased contact stresses and a water hammer effect caused by the impact 
of droplets on a surface make the second zone more effective in cutting 
granular materials such as rock and in surface cleaning and preparation. 
Given a particular task, therefore, it is desirable to ensure that the 
surface to be treated is impacted by the zone of the fluid jet that is 
most effective for the given task. As noted above, however, the stand-off 
distance may be set, given operating conditions. However, by providing a 
nozzle in accordance with a preferred embodiment of the present invention, 
the nozzle may be tuned such that the resulting high-pressure fluid jet 
will transition from zone 1 to zone 2 at a desired distance from the exit 
orifice, thereby ensuring that a selected portion of the fluid jet 
performs the given task, thereby optimizing the performance of the fluid 
jet. 
This tuning of the nozzle is accomplished in accordance with the preferred 
embodiment of the present invention, by selecting a diameter 36 of the 
entrance orifice 18, and by selecting an included angle 38 of bore 22 and 
an included angle 40 of bore 26. In a preferred embodiment, the diameter 
36 of entrance orifice 18 is 0.1-0.75 inch, the included angle 38 of bore 
22 is 0.degree.-20.degree., and the included angle 40 of bore 26 is 
30.degree.-170.degree., with superior results being achieved when the 
diameter 36 is 0.18-0.22 inch, angle 38 is 5.degree.-11.degree. and angle 
40 is 40.degree.-80.degree.. 
A series of tests were carried out to evaluate the relative effectiveness 
of several ultrahigh-pressure fluid jets generated by nozzles having 
different geometries, in eroding an aluminum target. For example, with a 
stand-off distance of 2 inches, a nozzle provided in accordance with the 
present invention having an entrance orifice diameter of 0.25 inch, an 
included angle 38 of bore 22 of 0.degree. and an included angle 40 of bore 
26 of 90.degree., outperformed all other geometries tested, thereby 
optimizing performance for the selected stand-off. In contrast, when the 
stand-off distance was set at 4 inches, a nozzle having an entrance 
orifice diameter of 0.2 inch, an included angle 38 of bore 22 of 
8.degree., and an included angle 40 of bore 26 of 60.degree. outperformed 
the other geometries tested, including prior art nozzles. (It should be 
noted that these results were achieved through use of a supply tube having 
a standard inner diameter 13 of 0.141 inch.) 
It is therefore possible to tone the nozzle of the present invention by 
providing a nozzle body 16 as described above, step 52, and providing a 
nozzle orifice 34 that is sized for the selected task, step 54. Once the 
desired stand-off distance is selected, step 56, it is possible to size 
the diameter of the entrance orifice and select and form included angles 
for the bore 22 and bore 28, step 58, such that an ultrahigh-pressure 
fluid jet formed by the nozzle will begin to break up into high velocity 
droplets prior to or upon reaching the surface to be treated, thereby 
optimizing the performance of the nozzle. Conventional methods of 
manufacture and milling may be used to create the desired entrance 
diameter and included angles in the nozzle. 
As further illustrated in FIGS. 1-3, in a preferred embodiment, a smallest 
diameter 46 of bore 22 and a smallest diameter 48 of bore 26 are both at 
least as large as outer diameter 50 of nozzle orifice 34, such that the 
nozzle orifice 34 may be easily removed from the nozzle body 16 and 
replaced, without removing seal 24. The nozzle orifice 34 is therefore 
easily replaceable, in contrast to currently available systems. Although 
the outer diameter 50 of nozzle orifice 34 may vary, in a preferred 
embodiment, a standard nozzle orifice having an outer diameter of 0.078 
inch is used. For applications requiring more horsepower, a larger nozzle 
orifice having an outer diameter of 3/16 inch is used. 
As illustrated in FIG. 5, an outer surface 42 of nozzle body 16 is formed 
into a hexagon, having a width 44 of at least 3/8 inch between two 
parallel faces. In operation, the nozzle is typically subjected to 
numerous pressure cycles, which may result in cracks that propagate 
through the nozzle body. By providing the outer surface 42 in the form of 
a hexagon, a crack will not uniformly reach the outer boundary of the 
nozzle body, but rather will reach a flat face of the hexagon causing the 
nozzle body 16 to leak while the tips of the hexagon hold the structure 
together. This leakage may be observed and will cause a pressure drop in 
the system, thereby signaling the operator to change the nozzle. This 
benefit is also achieved by forming the outer surface 42 of the nozzle 
body 16 to have at least one flat surface. 
In a preferred embodiment, as illustrated in FIG. 1, the diameter 36 of 
entrance orifice 18 is larger than the inner diameter 13 of supply tube 
12, thereby resulting in superior fluid jet performance. Again, although 
applicants' invention is not dependent on any theory, applicants believe 
that by generating turbulence at the step between the supply tube 12 and 
the bore 22 of nozzle body 16, and then damping the turbulence via the 
internal geometry of nozzle 10, that superior results are achieved. In a 
preferred embodiment, however, the ratio of the supply tube inner diameter 
13 to the nozzle entrance diameter 36 is 0.5-1. 
An improved and tunable ultrahigh-pressure nozzle, and a method for making 
such a nozzle, is shown and described. From the foregoing, it will be 
appreciated that although embodiments of the invention have been described 
herein for purposes of illustration, various modifications may be made 
without deviating from the spirit and scope of the invention. Thus, the 
present invention is not limited to the embodiments described herein, but 
rather as defined by the claims which follow.