Apparatus for generating a high-speed pulsed fluid jet

An apparatus and method for generating a high-speed pulsed fluid jet wherein the apparatus has a valve cylinder that forms a valve cavity. A piston is slidably mounted within the valve cavity. A plunger with an internal chamber is fixed with respect to the piston. The internal chamber communicates with the valve cavity. An end plug is sealably mounted with respect the plunger. The end plug has a bore through which a valve stem is sealably and slidably mounted. The valve stem is mounted to slide within the internal chamber, the bore of the end plug and a valve chamber of a cylinder. The valve chamber communicates with a pressurized fluid source. A valve poppet is attached to the valve stem. A spring or compressed gas is used to exert a bias force which normally urges the valve poppet into a releasable seated position within a valve port of an end plug which is sealably mounted with respect to a fluid cylinder that forms the valve chamber.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a valve apparatus and method for pressurizing 
fluids, such as gas or liquid, which can then be quickly released or 
dumped when over-pressurized, to transform continuous fluid flow into 
pulsed waterjets without significant energy losses. This invention is 
particularly suitable for use with liquids, such as water, that operate at 
relatively high pressures and generate high-speed pulsed fluid jets which 
have high impact energy levels and which travel great distances. 
2. Description of Prior Art 
The utility of high-speed fluid jets, such as waterjets, is well known. 
Continuous waterjets having various flow rates and velocities are used in 
a wide range of applications. One basic process for generating a 
continuous waterjet is relatively simple, wherein water is transported to 
a suitable pump to raise the operating pressure, the pressurized water is 
then communicated through tubes or hoses to a suitable nozzle, and the 
pressurized water is ejected through the nozzle to form a coherent 
waterjet. The particular type of conventional system can vary depending 
upon the different complexities associated with an intended application. 
The discharge velocity and the energy content of the waterjet can vary 
among different conventional systems, and are often a function of the 
pressure and the power input of the system. 
Conventional waterjets are used in different civil, commercial and 
industrial applications. One common use is for firefighting processes, in 
which relatively large diesel engine-driven crankshaft pumps are used to 
pressurize water at moderately high pressures, such as at several hundred 
pounds per square inch (psi), and at relatively high flow rates. In 
firefighting operations, it is important for a nozzle, such as a long and 
smooth nozzle, to generate a coherent waterjet capable of traveling a 
significantly long distance. High-speed waterjets are also created by 
relatively compact hand-held jetting lances, for cleaning and blasting 
industrial structures and equipment at water pressures up to about 35,000 
psi. Water can be pressurized to pressures up to about 60,000 psi, and 
discharged at supersonic velocities, with pressure intensifiers. Such 
waterjets are used in factories, normally with automated robots, to cut a 
wide variety of materials such as paper products, leathers, fabrics, food 
items and many other industrial products. 
Conventional systems also mix selected particulate materials, such as 
industrial abrasives, to a high-speed waterjet to generate what is known 
as an abrasive waterjet (AWJ) for cutting relatively hard material such as 
glass, plastics, laminates, composite, alloys, metals, rock and concrete. 
Experiments are now being conducted with water-based abrasive slurries, 
for generating abrasive waterjets; such processes involve direct or 
indirect pressurization of abrasive slurries and discharging pressurized 
slurries through a nozzle, to form a high-speed slurry jet. The relatively 
high velocities achieved by the abrasive particles offer a slurry jet with 
unmatched cutting capabilities. 
Waterjet systems can be characterized by two basic system parameters: 
system pressure and energy output. In firefighting applications, a 
waterjet system pressure is relatively low but the mass flow rate is 
relatively high, and thus the emphasis of the system is directed toward 
delivery distance of the waterjet. In waterjet material-cutting 
applications, the system has quite opposite requirements wherein the mass 
flow rate is relatively low but the system pressure is relatively high. In 
both applications, the waterjet energy is basically defined as a product 
of mass flow rate and system pressure. The system equipment delivers 
energy at a relatively steady rate, which is a common characteristic of 
continuous waterjet systems. Such continuous waterjet systems can be 
modeled as electrical systems wherein electrons are equivalent to water, 
voltage is equivalent to water pressure, current is equivalent to flow 
rate, electrical conductors are equivalent to hoses or conduits, 
electrodes are equivalent to water nozzles, and an electrical discharge at 
an electrode is equivalent to a waterjet. 
Relatively powerful electrical discharge can be produced by raising a 
voltage across two electrodes, particularly if relatively large capacitors 
are used to store a large amount of energy and then quickly discharge the 
energy. A similar situation exists in waterjet systems. In many waterjet 
applications, it is very desirable and advantageous if the waterjet energy 
can be stored and ejected through a nozzle in a pulsed jet rather than a 
continuous jet. It is quite desirable in many applications to deliver a 
relatively large amount of waterjet energy to a target material, in a 
concentrated fashion and within a relatively short time duration. This is 
the realm of pulsed waterjet (PWJ) technology. 
The benefits of relatively high-speed PWJ have been recognized and 
appreciated in mining applications, due to the particular nature of rock 
and minerals. Such porous materials are known to have relatively high 
compressive strength but relatively low tensile strength, so that the 
water can produce fractures in such materials. Continuous waterjets 
applied in a conventional fashion, even at relatively high pressures, 
result in localized failure, such as formation of slots and kerfs. On the 
other hand, pulsed waterjets can caused rocks and minerals to fail in a 
more pronounced manner as compared to that possible with continuous 
waterjets operating at a same energy level. If a sufficiently large slug 
of relatively high-speed waterjet is delivered to rock material in a 
relatively short time, the rock material can fail catastrophically, in a 
manner similar to explosive forces. Even in ordinary waterjet cleaning and 
blasting operations, discrete waterjets are preferred over continuous 
waterjets, for efficiently and effectively removing contaminants. 
Other lesser known applications exist where suitable pulsed waterjets could 
significantly impact the operation, for example, pulsed waterjets may be 
quite suitable for injecting materials into the ground for applications 
such as in situ bioremediation. However, pulsed waterjet processes are 
often quite involved and many have been only laboratory curiosities, never 
reduced to practice. 
Pulsed waterjet processes can be characterized by other system parameters, 
such as pulsation factors which define the pulse length, spacing and other 
features. Such pulsation factors may be relatively important in many 
applications and are governed by the particular system application and 
type of pulsed waterjet generated. 
Many different methods can be used to generate pulsed fluid jets. A 
relatively simple method is to use a pump with an unbalanced pressure 
discharge, such that a jet discharged from a nozzle has a naturally 
fluctuating velocity, if the distance between the pump and the nozzle is 
not too great. Another conventional method employs a nozzle that segments 
a continuous stream fluid jet into discrete slugs. Impact extrusion, 
pressure extrusion and cumulation methods for waterjetting have been 
conventionally used to generate relatively high-power pulsed waterjets, 
for applications such as fracturing rock and concrete. 
U.S. Pat. No. 4,074,858 teaches a pressure extrusion process for generating 
relatively high-power and relatively high-pressure pulsed waterjets 
capable of fracturing concrete pavement. Compressed gas, such as nitrogen, 
is used to store energy. Two sets of pistons are used to cock and drive a 
plunger for transferring the stored energy to the fluid, such as water. 
Hydraulic fluid is often the working fluid for the required power input. A 
fast-acting valve is used to fire an oil port in a controlled fashion and 
thus the water is discharged from a nozzle by a fast-traveling plunger 
within a high-pressure cylinder. U.S. Pat. No. 4,074,858 discloses a 
plunger that must first pressurize water prior to forming a waterjet at a 
nozzle, even though the pressure within a cylinder may not be steady 
during plunger travel and may not even be critical to the end result. Such 
process works relatively well but is rather limited in usefulness. One 
limitation relates to the speed of the plunger which inherently depends 
upon working fluid flow, which is situated between the compressed gas and 
a power piston. Oil is inherently slower than gas in similar flow 
conditions and oil velocity is affected by different viscosities. Another 
limitation relates to an absence of a water valve at an outlet, to prevent 
leakage through the nozzle while charging. Water leakage can be quite 
substantial in vertical, downward applications of pulsed waterjet 
processes, and partial filling of the chamber can result in undesirable 
shocks and performance losses. 
U.S. Pat. No. 4,190,202 teaches a process for generating high-power and 
high-pressure pulsed waterjets, wherein a restrictive oil port is 
eliminated and a cocking piston is moved into a same chamber with a power 
piston, to increase the piston and plunger speed, and to improve firing 
control, a relatively difficult task in high-power pulsed-jet processes. 
Such process also allows the cocking gas to be evacuated prior to firing, 
thus improving energy transfer from gas to water. However, there is still 
a need for a suitable water valve that prevents nozzle leakage prior to 
firing, and there is still the need for eliminating premature firing. 
U.S. Pat. No. 4,607,792 teaches a pulsed waterjet produced by impacting 
water with a reciprocating piston within a reciprocating cylinder equipped 
with a cumulation nozzle. Pressurized gas supplies necessary energy to 
power the piston and inertia of the piston along with reciprocating motion 
of the nozzle cylinder produces oscillating action. It is possible to 
produce rates of up to several pulses per second with such process. U.S. 
Pat. No. 4,607,792 is a good example of one of many processes for 
generating pulsed waterjets that have relatively low mass per pulse but 
relatively high repetitive rates. Such process can produce pulse jets at 
relatively high velocities, if the power input is high and the cumulation 
nozzle is adequately constructed in terms of internal profile and 
smoothness, which are two relatively difficult manufacturing tasks. In 
order to accelerate a piston of significant mass to a relatively high 
velocity within a relatively short time and distance, explosives or 
detonation of a fuel-air mixture is used, neither of which is desirable in 
many applications. If compressed gas is used, only compressed air is 
practical and only when delivered at relatively low pressures, due to cost 
considerations. As a result, the pulsed waterjet generated with air 
compressors has relatively low velocity and cannot generate impact forces 
necessary to fracture rock and concrete, for example. Furthermore, the 
absence of a restricting valve to minimize leakage at the nozzle can be a 
disadvantage with the invention taught by U.S. Pat. No. 4,607,792. 
U.S. Pat. No. 4,573,637 teaches a pulsed-jet process which uses energy 
stored in a high-pressure fluid to generate a high-speed jet through a 
cumulation nozzle and an oscillating self-actuating valve. Liquid such as 
water is relatively incompressible, even at high-pressures, and the amount 
of energy available which can be released to generate and sustain 
high-speed jet pulses is limited. Even when using a cumulation nozzle, 
energy contained in each pulsed waterjet is not high enough to adequately 
fracture or damage material such as rock and concrete. 
Other conventional pulsed waterjet devices and processes are available, 
which use cumulation nozzles that have hyperbolic or other internal fluid 
passages for accelerating fluid flow velocities. The valves for such 
nozzles are relatively difficult and expensive to manufacture and there is 
no particular design to which manufacturers conform. Many conventional 
cumulation nozzles used in pulsed waterjet processes lack scientific 
evidence to substantiate their virtues, thus, a survey of conventional 
devices and processes show that many high-powered pulsed waterjet 
processes only exist as laboratory projects. Many unresolved difficulties 
are associated with the equipment design. Practical devices are not 
commercially available for particular jobs, such as fracturing rock and 
concrete. There is an apparent need for an apparatus and method for 
producing a high-powered pulsed waterjet with a relatively inexpensive and 
practical device that is easy to manufacture. 
SUMMARY OF THE INVENTION 
It is one object of this invention to provide a rapid-acting, quick-release 
on-off valve for controlling a fluid passage operating under a relatively 
high fluid pressure, so that the fluid passage can be constructed straight 
and devoid of obstacles that could otherwise interfere with fluid flow and 
thereby cause flow turbulence. 
It is another object of this invention to provide a rapid-acting, 
quick-release on-off valve that can be operated in an automatic, a 
semi-automatic or a manual mode, to open and close a fluid passage 
operating under a relatively high pressure and at a particular frequency. 
It is another object of this invention to provide a pulsed fluid-jet 
generator that produces a relatively high-speed fluid jet at a wide range 
of pressures, power outputs and pulsation frequencies. 
It is still another object of this invention to provide a process for 
generating a high-power, high-speed, pulsed fluid jet that can be altered 
to perform a wide variety of tasks which are not possible with 
conventionally available equipment and/or processes. 
It is still another object of this invention to provide a fluid-powered 
apparatus and process that can be used to power other tools or to drive or 
launch projectiles.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The apparatus according to this invention comprises subsystems that can be 
used in part, in whole or in combination with other subsystems. The 
subsystems include: a valve cylinder that receives system fluid; a 
potential energy storage system, such as compression spring or springs or 
compressed gas; an energy transfer system, such as a piston-plunger set; a 
fluid-actuated valve poppet assembly; a fluid discharge with or without a 
nozzle; and a valve system for regulating the fluid inlet. When used as 
individual components, the subsystems of this invention can act as a 
fluid-actuated manual-reset dump valve or a fluid actuated on-off valve. 
When a plurality of the subsystems are integrated with respect to each 
other, the apparatus of this invention can act as a pulsed fluid jet 
generator. 
Referring to FIG. 1, self-actuating relief valve 100 is used to convert a 
preferably steady, continuous fluid flow to a discontinuous fluid flow 
while maintaining fluid pressures by energy storage devices or other 
energy storage means, such as one or more compression springs or 
compressed gas. Self-actuating relief valve 100 comprises valve cylinder 
101 having end plug 102 preferably attached at one end portion of valve 
cylinder 101 and end block 103 preferably sealably secured or otherwise 
attached at an opposite end portion of valve cylinder 101. 
Valve cylinder 101 forms a valve cavity that houses compression spring 104 
and power piston 105, which is slidably mounted within the valve cavity of 
valve cylinder 101. Valve spring 104 preferably abuts or is otherwise 
mounted or fixed with respect to end plug 102 on one end and an opposite 
end of valve spring 104 abuts or is otherwise mounted or fixed with 
respect to power piston 105. Power piston 105 comprises plunger 106 
extending through central passage 107 or another suitable block bore of 
end block 103. Plunger 106 is slidably and sealably mounted within central 
passage 107 of end block 103. In one preferred embodiment, one end portion 
of plunger 106 is fixed with respect to power piston 105. Plunger end plug 
117 is sealably mounted with respect to an opposite end portion of plunger 
106, such as shown in FIG. 1. Plunger end plug 117 is preferably attached 
to an end portion of plunger 106 which is housed within valve chamber 121. 
One end portion of end block 103 is fixed or otherwise attached with 
respect to valve cylinder 101 and an opposite end portion of end block 103 
is fixed or otherwise attached with respect to fluid cylinder 108. Outlet 
plug 109 is sealably attached to or mounted with respect to an end portion 
of fluid cylinder 108, which is opposite the end portion of fluid cylinder 
108 that is attached with respect to end block 103. Seal 110 prevents 
leakage between outlet plug 109 and fluid cylinder 108. Seal 110 is 
preferably constructed of a material that is capable of handling the 
particular pressurized fluid within the system. Outlet plug 109 comprises 
discharge passage 111 which is in communication with valve chamber 121, 
when valve 100 is in an open condition. 
Internal chamber 112 of plunger 106 houses valve stem 113 which is slidably 
mounted to slide with respect to plunger 106. In one preferred embodiment, 
valve stem 113 is slidably mounted within internal chamber 112, a plug 
bore within plunger end plug 117, and valve chamber 121. Internal chamber 
112 communicates with the valve cavity of valve cylinder 101, such as 
through fluid passage 140, as shown in FIG. 1. Valve stem 113 has shoulder 
114 on one end portion and valve poppet 116 on an opposite end portion, as 
shown in FIG. 1. Shoulder 114 is preferably housed within internal chamber 
112. Spring 115 is mounted about valve stem 113 and has one end portion 
that directly or indirectly abuts valve poppet 116 and an opposite end 
portion that directly or indirectly abuts plunger end plug 117. As shown 
in FIG. 1, valve stem 113 straddles through a bore within plunger end plug 
117. Valve stem seal 118 is positioned about the hole within plunger end 
plug 117. 
End block 103 accommodates plunger seal 120. Plunger 106 is positioned 
within high-pressure valve chamber 121 of fluid cylinder 108. Inlet means 
are used to form communication between a pressurized fluid source, such as 
a compressor discharge, a vessel outlet or the like, and valve chamber 
121. In one preferred embodiment, the inlet means comprise fluid inlet 119 
of end block 103. However, it is apparent that the inlet means may also 
comprise any other conduit, bore, valve, control system or other 
mechanical device known to those skilled in the art, which continuously or 
intermittently introduces a working fluid into valve chamber 121. Valve 
chamber 121 preferably but not necessarily has a circular cross section. 
Valve cylinder 101 preferably forms vent 122 at one or more locations. 
Still referring to FIG. 1, pulsating or self-actuating relief valve 100 of 
this invention is shown in a normally closed position when there is no 
operating fluid flow. Bias means are used to indirectly or directly urge 
valve poppet 116 into a releasable seated position within discharge 
passage 111. Power piston 105 is normally urged downward, relative to the 
direction shown in FIG. 1, by a bias force F.sub.s within compression 
spring 104. Compression spring 104 may be a coil spring, as shown in FIG. 
1, a leaf spring or any other spring or bias element that provides bias 
force F.sub.s. In FIG. 1, valve stem 113 is shown at a lowest or 
bottom-out position and valve poppet 116 is seated within valve port 123 
and thereby closes discharge passage 111, when the valve is in a normally 
closed position. Spring 115 preferably exerts a moderate closure bias 
force that urges valve poppet 116 in a seated position within valve port 
123. 
When pressurized fluid, such as water, enters valve chamber 121, the 
pressurized fluid exerts fluidic forces on valve plunger 106 and thereby 
forces valve plunger 106 upward, relative to the direction shown in FIG. 
1, against spring bias force F.sub.s. The magnitude of fluid force F.sub.f 
is governed by the equation F.sub.f =P(A.sub.p -A.sub.s), where P is the 
fluidic pressure, A.sub.p is the cross-sectional area of plunger 106, and 
A.sub.s is the cross-sectional area of valve stem 113. If F.sub.f is 
greater than F.sub.s, plunger 106 will move upward against power piston 
105 and compression spring 104 while valve stem 113 remains fixed and 
thereby seats valve poppet 116 within valve port 123. As compression 
spring 104 is compressed, spring bias force F.sub.s increases in 
magnitude. 
To ensure that valve port 123 remains closed while valve chamber 121 is 
filled, the contact area of valve poppet 116 and valve port 123 is 
preferably designed to be greater than the cross-sectional area of valve 
stem 113. Thus, the pressurized fluid exerts a net poppet hold-down force 
on valve poppet 116 which is in addition to spring force. 
Still referring to FIG. 1, as long as fluid force F.sub.f continues to 
exceed spring force F.sub.s, plunger 106 can be pushed further and 
eventually end plug 117 will engage shoulder 114 and raise valve stem 113, 
relative to the orientation shown in FIG. 1. During such motion, once 
valve poppet 116 becomes unseated from valve port 123, discharge passage 
111 opens. When valve poppet 116 is raised and exposed to the pressurized 
fluid, the pressurized fluid exerts force on valve stem 113 and pushes it 
upward into internal chamber 112. The magnitude of the force necessary to 
accomplish such motion is a product of the fluid pressure P and the 
cross-sectional area A.sub.s of valve stem 113. Ultimately, valve poppet 
116 contacts plunger end plug 117 and stops. However, as soon as discharge 
passage 111 opens, fluid within valve chamber 121 discharges outward and a 
pressure drop occurs. Consequently, fluid force F.sub.f drops rapidly and 
causes plunger 106 to move downward with valve stem 113 and valve poppet 
116. When valve poppet 116 contacts valve port 123, discharge passage 111 
again closes and thereby completes one cycle of valve operation. The cycle 
of valve operation is repeated as long as pressurized fluid is supplied to 
valve 100. The cycling rate is preferably governed by design of valve 100 
and by the flow rate of the fluid. Increasing the flow rate increases the 
cycling frequency. 
The operating sequence of valve 100 of this invention can be better 
understood by referring to FIGS. 2A-2D, which show different positions of 
internal valve ports during one cycle of operation. As shown in FIG. 2A, 
compressed gas P.sub.1 is used as energy storage for the bias means, in 
lieu of compression spring 104 as shown in FIG. 1. FIG. 2A shows valve 100 
in a closed position, which represents a start point or an end point of an 
operating cycle. FIG. 2B shows a position wherein valve chamber 121 is 
filled with a system fluid and plunger 106 is pushed upward, relative to 
the orientation shown in FIGS. 2A-2D, and is about to engage shoulder 114 
of valve stem 113. FIG. 2C shows valve 100 in a position wherein valve 
poppet 116 is forced all of the way upward and is about to begin travel 
downward along with plunger 106. The compressed gas at pressure P.sub.3 is 
at a minimum volume and exerts a bias force upon power piston 105 pushing 
power piston 105 downward. FIG. 2D shows plunger 106 and the assembly of 
valve stem 113 near a bottom of travel and valve port 123 about to be 
closed by valve poppet 116. 
Once valve poppet 116 contacts valve port 123, valve poppet 116 can quickly 
close valve port 123 and another operating cycle of valve 100 will be 
repeated. In such operating mode, valve 100 becomes a fluid-actuated 
automatic on-off valve, transforming continuous fluid flow to 
discontinuous pulsed fluid flow. However, in other cases, once valve 
poppet 116 moves to close valve port 123, if valve poppet 116 does not 
completely seal valve port 123 and the system fluid reaches equilibrium 
with the spring bias force or gas bias force and then the system fluid 
leaks through valve port 123. To close valve port 123 completely requires 
an external force applied to valve poppet 116. Reset rod 124, as shown in 
FIG. 1, can be used to provide such external force. By pushing power 
piston 105 with reset rod 124, the fluid equilibrium can be broken at 
valve port 123, in order to close discharge passage 111. Thus, this 
invention can operate as a pressure relief valve with a manual reset. 
Valve 100 of this invention can be set with compression spring 104 or a 
compressed gas at a force level below that applied to plunger 106 from 
pressurized system fluid that operates to close valve port 123. When the 
system fluid is over-pressurized beyond a set value, a pressure relief 
valve opens automatically to release the system fluid and thus reduce the 
system pressure. Valve 100 can then remain open until manually reset with 
reset rod 124. However, manual reset can also be accomplished locally or 
remotely by other reset means, such as a solenoid, an air actuator, or 
another suitable manual or automatic motion-generating apparatus known to 
those skilled in the art. 
When valve 100 of this invention is used with fluid at relatively high 
pressures, such as in waterjetting applications, the use of compressed gas 
is normally preferred over compression spring 104 to generate a bias 
force. If manual reset is desired, the reset is preferably accomplished 
with high-power actuators, such as a hydraulic actuator. By using 
compressed gas and a valve system that regulates the inlet flow of system 
fluid, valve 100 of this invention can be used as a pulsed-jet generator 
suitable for generating relatively high-speed pulsed fluid jets. By 
regulating the system fluid inlet, valve port 123 can be accurately closed 
in a controlled fashion. 
Referring to FIG. 3, valve 100 is shown as a high-pressure pulsed-jet 
generator 200 through which relatively high-speed fluid jets can be 
generated, one pulse at a time, under manual control or repeatedly in an 
automatic mode. Pulsed-jet generator 200 of this invention comprises valve 
cylinder 201. End plug 202 abuts or is fixed or otherwise attached with 
respect to one end portion of cylinder 201, and end block 203 abuts or is 
fixed or otherwise attached to an opposite end portion of cylinder 201, as 
shown in FIG. 3. Fluid cylinder 204 abuts end block 203 on one end portion 
and has outlet end plug 205 abutting an opposite end portion of fluid 
cylinder 204. Power piston 206 is housed within a valve cavity formed by 
valve cylinder 201 and divides the valve cavity into gas chamber 207 and 
ambient chamber 208, such as with piston seal 209. Plunger 210 is 
preferably a hollow assembly that is attached to power piston 206, for 
example with threads, anchor bolt 211 or any other suitable mechanical 
attachment means. Plunger 210 preferably has a generally cylindrical 
external surface and a cylindrical internal surface that at least 
partially forms internal chamber 216. Plunger end plug 212 is fixed or 
otherwise attached to plunger 210, such as with a threaded connection. 
Valve stem 213 straddles across plunger end plug 212, through a central 
hole and through seal 214 assembly. One end portion of valve stem 213 
extends into internal chamber 216 of hollow plunger 210 and another end 
portion of valve stem 213 extends into internal chamber 215 of fluid 
cylinder 204. Jet nozzle 217 abuts or is mounted within or with respect to 
outlet plug 205. The inlet means may also comprise external flow control 
valve assembly 250, which regulates flow of system fluid from an external 
pump to pulse-jet generator 200 of this invention. 
Still referring to FIG. 3, end plug 202 is connected to valve cylinder 201, 
preferably but not necessarily with a threaded connection as shown in FIG. 
3, or by seals or any other suitable mechanical means to form a gas-tight 
or hermetic seal between valve cylinder 201 and end plug 202. End plug 202 
comprises inlet means, such as inlet passage 218 or any other conduit, 
passageway, channel or other suitable void that forms communication with 
gas chamber 207, for filling gas chamber 207 with a suitable fluid or gas, 
such as nitrogen. Pressure gauge 219 and valve 220 can be used to monitor 
and control fluid flow through inlet passage 218. 
Anchor bolt 211 is one preferred embodiment for attaching plunger 210 to 
power piston 206. Anchor bolt 211 preferably comprises fluid passage 221 
which is in communication with gas chamber 207 and internal chamber 216 of 
plunger 210. Pressurized fluid within internal chamber 216 acts upon 
shoulder 225 of valve stem 213. Plunger 210 straddles across end block 
203, through central passage 222 and seal assembly 223, and extends into 
internal chamber 215 of fluid cylinder 204, and is also free to slide up 
and down with power piston 206. Valve stem 213 is preferably but not 
necessarily relatively elongated. Shoulder 225 is formed as part of or 
attached to an end portion of valve stem 213, as shown in FIG. 3. Shoulder 
225 is housed within internal chamber 216 of plunger 210. Valve poppet 226 
is attached to an end portion of valve stem 213 which is opposite shoulder 
225. 
Valve stem 213 is free to slide across seal 214. Valve poppet 226 is 
preferably constructed to seat within valve port 227 of outlet plug 205. 
Fluid cylinder 204 is attached or otherwise secured with respect to end 
block 203, such as with a threaded connection, tie rods or any other 
suitable mechanical means sufficient to form a fluid-tight or hermetic 
seal between fluid cylinder 204 and end block 203. Seal assembly 228 also 
forms a fluid-tight or hermetic seal between outlet plug 205 and fluid 
cylinder 204. 
Outlet plug 205 comprises fluid passage 229 that is preferably located in a 
central position of outlet plug 205. Fluid passage 229 is in communication 
with valve port 227 and the bore within jet nozzle 217. Fluid passage 230 
is in communication with fluid passage 229 and external tube 231, which is 
in communication with control valve assembly 250. End block 203 comprises 
fluid inlet 232 that is in communication with outlet 252 of control valve 
250. Fluid passage 232 can be located in other elements of this invention 
as long as the result of introducing fluid into internal chamber 215 is 
accomplished. 
Valve cylinder 201 comprises vent 233 at one or more locations. It is 
apparent that vent 233 can also be positioned within end block 203. Valve 
cylinder 201 is preferably attached to end block 203 by a threaded 
connection, anchor bolts, tie rods or any other suitable means known to 
those skilled in the art. 
Still referring to FIG. 3, control valve assembly 250 comprises: fluid 
inlet 251 in communication with a discharge from a pump; fluid outlet 252; 
and sidelet 253 which receives fluid from tube 231. Control valve assembly 
250 functions on controlling the flow of system fluid from a pump to a 
pulse-jet generator. In a condition where no fluid flows through tube 231, 
control valve assembly 250 is in an open condition. When fluid flows 
through tube 231, control valve assembly 250 is in a closed condition. 
Many different ways exist to construct a valve that functions in such 
manner. A particularly suitable stem valve is shown in FIG. 3. 
The stem valve shown in FIG. 3 comprises valve body 254 having four 
integrated or connected chambers: a spring or reset chamber 255; upstream 
chamber 256; downstream chamber 257; and actuating chamber 258. Elongated 
valve stem 259 preferably straddles across all four chambers and is 
slidably mounted within a preferably central passage that houses three 
sets of seal assemblies. Stem seal assembly 260 separates reset chamber 
255 from upstream chamber 256. Valve port seal assembly 261 separates 
upstream chamber 256 from downstream chamber 257. Stem seal assembly 262 
separates downstream chamber 257 from actuating chamber 258. 
Valve stem 259 preferably comprises machined-out fluid passage 263 in a 
middle portion of valve stem 259 that straddles valve port seal assembly 
261. Reset spring 264 and spring disk 265 are housed within reset chamber 
255 and are used as bias means to exert a predetermined force against one 
end of valve stem 259, as shown in FIG. 3. It is apparent that other 
springs, bias elements or pressurized gas can be used as bias means to 
apply a force directly or indirectly upon valve stem 259. An opposite end 
portion of valve stem 259 is exposed to the system fluid within tube 231. 
Reset spring 264 is primarily used for automatic operations and can also 
be replaced with compressed gas, such as shown in FIGS. 2A-2D. For manual 
operation, reset spring 264 or the compressed gas can be replaced by or 
assisted with reset rod 266 or any other suitable mechanical means for 
resetting valve stem 259, as previously discussed in relation to the 
embodiment shown in FIG. 1. 
In operation, control valve assembly 250 is normally open and allows the 
pressurized fluid from a pump to enter upstream chamber 256 at pressure 
P.sub.f, and then to flow through the valve port between upstream chamber 
256 and downstream chamber 257, and then into high-pressure pulsed 
generator 200, as shown in FIG. 3. During such fluid flow, no fluid flows 
through tube 231 because high-pressure pulsed generator 200 is in a 
filling stage or a filling mode. As soon as valve port 227 opens, tube 231 
fills with pressurized system fluid that forces valve stem 259 upward, 
with respect to the orientation shown in FIG. 3, resulting in closure of 
the valve port as fluid passage 263 is moved upward and beyond valve port 
seal assembly 261. The open position of the valve is restored when flow of 
system fluid within tube 231 stops and reset spring 264 pushes valve stem 
259 downward, or as manual reset rod 266 is used. 
Still referring to FIG. 3, high-pressure pulsed generator 200 of this 
invention is intended for generating a relatively high-speed pulsed 
waterjet with relatively high impact energy. High-pressure pulsed 
generator 200 of this invention functions as an energy storage device and 
a fast-actuating quick-release dump valve which is capable of repeated or 
cyclic operation. Although high-pressure pulsed generator 200 has not been 
precisely described as a pump or a pressure intensifier, high-pressure 
pulsed generator 200 of this invention could act as either a pump or a 
pressure intensifier. According to this invention, high-pressure pulsed 
generator 200 is preferably a valve which is equipped with an energy 
storage mechanism designed according to the pressure of the system. 
During operation, system fluid such as water enters generator 200 through 
control valve 250, at pressure P.sub.f and thereby fills internal chamber 
215. Then, valve poppet 226 closes valve port 227 and gas within chamber 
207 exerts a force which pushes valve poppet 226 against valve port 227. 
The magnitude of such pushing force is determined by the gas pressure 
P.sub.g and the diameter of valve stem 213. The initial gas pressure 
P.sub.g within gas chamber 207 is determined by several factors, including 
the operating pressure of system fluid P.sub.f and the design of 
high-pressure pulsed generator 200. However, the gas pressure P.sub.g 
should not be greater than the system fluid pressure P.sub.f. 
Still referring to FIG. 3, as the system fluid fills internal chamber 215, 
the pressurized fluid exerts force F.sub.f, which is a product of the 
system fluid pressure P.sub.f and the cross-sectional area of plunger 210, 
upon plunger end plug 212 and forces plunger 210 upward as valve poppet 
226 closes valve port 227. As internal chamber 215 is filled, power piston 
206 moves upward with plunger 210 and thereby compresses gas within gas 
chamber 207 and raises gas pressure P.sub.g. The pressurized gas exerts 
force F.sub.g on power piston 206 and the magnitude of the force F.sub.g 
is equal to a product of gas pressure P.sub.g and the cross-sectional area 
of power piston 206. The two forces F.sub.f and F.sub.g are at 
equilibrium. As plunger 210 moves upward, end plug 212 eventually engages 
shoulder 225 of valve stem 224 and thereby causes valve poppet 226 to 
unseat from valve port 227, thereby exposing valve poppet 226 to the 
system fluid. 
As pressure P.sub.f of the system fluid is considerably greater than gas 
pressure P.sub.g, valve poppet 226 quickly moves up toward plunger 210. 
The system fluid simultaneously flows into fluid passage 229 and 
discharges through jet nozzle 217, preferably in the form of a relatively 
high-speed jet. The system fluid also simultaneously flows into tube 231 
and into actuating chamber 258 and control valve 250, resulting in closure 
of control valve 250 and stopping the system fluid from flowing into 
high-pressure pulsed generator 200, thus allowing all fluid within 
internal chamber 215 to be discharged by plunger 210. As plunger 210 moves 
downward to discharge the system fluid through jet nozzle 217, forces from 
the gas pressure P.sub.g also act upon and assist power piston 206, and 
thus the pressure of the system fluid is maintained generally constant. 
Finally, valve poppet 226 again seats within valve port 227 and forms a 
seal. Fluid within fluid passage 229 and external tube 231 stops flowing 
and control valve assembly 250 is again ready for the next pulse. In a 
manual operation mode, control valve assembly 250 is reset with reset rod 
266 which acts upon and pushes downward valve stem 259. In an automatic 
operation mode, reset spring 264 automatically reopens control valve 
assembly 250 and allows high-pressure pulsed generator 200 to issue the 
next cyclic pulse. 
For high-pressure pulsed generator 200 according to this invention to 
function smoothly, it is important for several aspects of different 
components of this invention to be correctly designed. For example, it is 
important that valve poppet 226 properly seat against valve port 227, for 
reliable operation. The sealing area should be greater than the 
cross-sectional area of valve stem 224, for the system fluid to properly 
seat valve poppet 226, and yet the total valve seating force should be 
smaller than the force the system fluid exerts upon plunger 210. 
Otherwise, valve poppet 226 cannot be unseated. Thus, another important 
design aspect is for the gas pressure P.sub.g to be high enough to match 
the system fluid pressure and yet be within the operating limit for 
high-pressure pulsed generator 200. The gas must occupy a reasonably large 
volume so that the gas pressure P.sub.g does not drop excessively during 
expansion, which would affect power or energy of the pulsed jet. Another 
important design aspect relates to control valve assembly 250, which 
should be designed to react quickly and accurately to demands of 
high-pressure pulsed generator 200. Still another important design aspect 
relates to the assembly of valve stem 213 which should be designed to 
withstand high stresses from impact forces and repeated impact cycles. 
Referring now to FIG. 4, according to another preferred embodiment of this 
invention, stem valve assembly 300 is shown in a normally closed position 
and is well-suited for use in a pulse-jet generator, such as high-pressure 
pulsed generator 200 shown in FIG. 3. Valve assembly 300 is preferably 
housed within interior chamber 312 of plunger 311. End plug 313 is 
sealably secured or otherwise attached with respect to plunger 311, 
preferably but not necessarily with a threaded connection. Stem seal 314 
is mounted with seal cage 315 and forms a seal about valve stem 316. 
As shown in FIG. 4, stem valve assembly 300 comprises elongated valve stem 
316 with shoulder 317 positioned within interior chamber 312 and shoulder 
318 and head 319 at an opposite end portion of valve stem 316. Valve 
poppet 320 is preferably but not necessarily detachable with respect to 
collar 321 which forms a cavity within which head 319 is mounted. Collar 
321 straddles across head 319 and is connected to valve poppet 320 by a 
threaded connection or any other suitable mechanical connection. 
Compression spring 322 urges valve poppet 320 into a seated position with 
respect to valve seat 327. Compression spring 322 also absorbs initial 
impact forces when valve poppet 320 contacts valve seat 327. Collar 321 is 
slidably mounted to travel along shoulder 318, within cavity 323 of end 
plug 313 but is otherwise trapped by head 319 and valve poppet 320. 
Compression spring 322 is preferably mounted about shoulder 318 and 
trapped by collar 321 and end plug 313. 
In operation, plunger 311 is housed within chamber 326 of fluid cylinder 
304. End plug 305 comprises fluid passage 329, preferably but not 
necessarily in a centrally located position. Seal 328 forms a fluid-tight 
or hermetic seal between end plug 305 and fluid cylinder 304. End plug 305 
is attached with respect to fluid cylinder 304, preferably but not 
necessarily with a threaded connection. Valve seat 327 is positioned near 
a top of fluid passage 329, with respect to the orientation shown in FIG. 
4. When no fluid flows through fluid passage 329, valve stem 316 is at a 
lowest position and is forced into a seated positioned by pressurized gas 
within interior chamber 312. When valve assembly 300 is installed within 
chamber 326 and pressurized system fluid is introduced into chamber 326, 
fluidic forces act upon shoulder 318 and force valve stem 316 into a 
position wherein shoulder 318 abuts end plug 313, as shown in FIG. 4. In 
such position, head 319 does not contact valve poppet 320 or collar 321. 
The cavity of collar 321 is relatively important for absorbing impact 
forces when valve poppet 320 hits valve seat 327. As shown in FIG. 4, 
valve poppet 320 closes valve seat 327, due to forces of compression 
spring 322. 
FIG. 5 shows stem valve assembly 300, according to the embodiment described 
in FIG. 4, but with valve poppet 320 in an unseated position with respect 
to valve seat 327, which thereby allows the system fluid within chamber 
326 to quickly force stem valve assembly 300 upward to engage end plug 313 
and plunger 311. Such components move together downward, with respect to 
the orientation shown in FIG. 5, in a rapid fashion along with the flow of 
system fluid. As shown in FIG. 5, compression spring 322 extends valve 
poppet 320 so that there is space between head 319 and valve poppet 320. 
As valve poppet 320 engages valve seat 327, impact forces cause valve 
poppet 320 to move upward within cavity 323 of end plug 313. Impact forces 
are absorbed by fluid within cavity 323 and by the forces of compression 
spring 322. Because valve seat 327 is sealed, the system fluid within 
chamber 326 has no outlet and thus also assists in decelerating plunger 
311. With such energy-absorbing valve design, valve seat 327 can be opened 
and closed repeatedly without damaging valve poppet 320 or valve seat 327. 
During operation, valve poppet 320 does not contact head 319. 
Stem valve assembly 300 according to invention is unique in several 
aspects. Stem valve assembly 300 is fluid actuated and the actuation point 
can be precisely designed. Stem valve assembly 300 can be used as a manual 
valve which requires a manual reset or can be used as an automatic valve 
with repeated cyclic valve action. Stem valve assembly 300 can be a 
fast-reacting dump valve through which fluid can flow with virtually no 
obstructions, because the valve elements quickly move away from the fluid 
flow. Such quick-release action is particularly important when using the 
valve of this invention for generating relatively high-speed fluid jets. 
If the valve poppet or any other part of the valve is positioned in a path 
of the high-speed flow of system fluid, the fluid jet coherence is 
destroyed, rendering the fluid jet useless for many applications. With the 
valve according to this invention, the fluid path to the nozzle is 
completely open and thus a very high-quality fluid jet is achieved. The 
valve poppet assembly of this invention can also be used in constructing 
on-off valves that are not fluid actuated. In such valves, an external 
lifting force is applied to the valve stem to dislodge the valve poppet. 
FIG. 6 shows another preferred embodiment of this invention wherein the 
valve acts as pulse-jet generator 400 with remote control valve 450. As 
shown in FIG. 6, pulse-jet generator 400 is somewhat similar to the 
preferred embodiment shown in FIG. 3. Pulse-jet generator 400 preferably 
comprises fluid inlet 432 and fluid outlet 429. Fluid inlet 432 is in 
communication with an outlet of remote control valve 450, which is 
preferably an on-off type valve. Pulse-jet generator 400 also comprises 
sidelet 430 which is in communication with fluid outlet 429 and pressure 
transducer 431, which has electrical cable connection 432 routed to 
solenoid valve 433 that directly or indirectly operates the on-off action 
of remote control valve 450. 
Pressure transducer 431 senses fluid pressure within sidelet 430 and emits 
an electrical signal to solenoid valve 433 to close remote control valve 
450. When fluid pressure in sidelet 430 dissipates, pressure transducer 
431 emits a signal to remote control valve 450 to reopen and to resume 
flow of high-pressure fluid from a pump to pulse-jet generator 400. Thus, 
remote control valve 450 can be located a distance away from pulse-jet 
generator 400. 
FIG. 7 shows another preferred embodiment of this invention wherein 
pulse-jet generator 500 is a powered apparatus that can be designed to 
perform a wide range of work tasks, such as creating fluid pressure high 
enough to fracture or break concrete, to drive piles, to drill rock, to 
bore soil, and to launch projectiles. Pulse-jet generator 500 is somewhat 
similar to the preferred embodiment shown in FIGS. 3 and 6. High-pressure 
end plug 505 is attached to tool cylinder 580 which houses a particular 
tool, such as chisel 581. Retaining spring 582 or another suitable 
tool-retaining device can be used to provide return action for chisel 581. 
Chisel 581 preferably has head 583 that forms a relatively tight fit 
within tool cylinder 580 but yet is mounted with enough tolerance to slide 
up and down within tool cylinder 580. 
When a pulse jet, such as a pulsed waterjet is generated, the high-speed 
water enters tool cylinder 580 and drives chisel 581 downward in a rapid 
fashion, thus providing work to break concrete, for example. Because the 
pulsed waterjet is at a very high velocity, power transferred to chisel 
581 is relatively high. For example, with a water input pressure of about 
30,000 psi, chisel 581 of this invention can have a power output which 
exceeds power output offered by conventional hydraulic or pneumatic 
chisels or breakers. If chisel 581 is replaced with a reciprocating 
piston, the piston can be used to drive piles or anchors in construction 
applications. The piston can be constructed to rotate as well as to drive, 
such as to form a rotating drill. In such applications, the waterjet can 
lose power after driving the tool and can then discharge through port 584, 
and then be either discarded or recycled. The water can also be routed 
through a hollow tool, such as to the front of the tool for lubrication 
purposes, dust control purposes and other general purposes. Such 
embodiment of this invention is particularly useful in mining and 
construction operations. 
FIG. 8 shows another preferred embodiment of this invention which relates 
to a pulse-jet powered projectile launcher 600. As shown in FIG. 8, 
launcher 600 comprises a pulse-jet generator similar to the embodiments 
shown in FIGS. 3 and 6, but having launch tube 680 connected to outlet 
plug 605. The high-speed pulsed fluid jet, such as a waterjet, can be used 
to launch projectile 681, for performing various tasks. 
Launcher 600 may be a part of a tool or can simply provide the working 
fluid for driving projectile 681. Because the pulse jet issued by launcher 
600 is at very high velocity, a driving force for launching projectile 681 
can be comparable to forces derived from explosives. Thus, the embodiment 
shown in FIG. 8 may have applications where explosives or detonation of 
fuel-air mixtures are not possible, such as in refineries or natural gas 
facilities. In some applications, projectile 681 can be a simple cone 
which is used to shield water from air resistance to thereby improve a 
delivery distance of pulsed waterjets. The cones can be used to increase 
the power of a pulse waterjet, for example, when fracturing materials. 
Launcher 600 can also be used to launch anchors, nails, capsules or any 
other relatively hard or even soft projectile. 
FIG. 9 shows yet another preferred embodiment of this invention wherein 
pulse-jet generator 700 comprises internal valving components that can be 
easily removed from an outlet end of pulse-jet generator 700. As shown in 
FIG. 9, pulse-jet generator 700 comprises plunger 710 that forms a cavity. 
Plunger 710 is preferably mounted within cavity 721 of power piston 706. 
Plunger 710 can be easily removed from cavity 721. At an opposite end of 
plunger 710, end plug 712 is detachably mounted to plunger 710 for 
relatively easy removal. Seal 723 contacts an interior surface of 
high-pressure cylinder 704. When high-pressure fluid enters chamber 713, 
the pressurized fluid retains valve poppet 726 in a seated position and 
forces end plug 712 upward until end plug 712 forces plunger 710 and power 
piston 706 upward, relative to the orientation shown in FIG. 9, thereby 
compressing gas within gas chamber 707. 
When end plug 712 reaches shoulder 725 of valve stem 724, valve poppet 726 
becomes unseated and thus eliminates a fluid hold-down force which urges 
valve stem 724 upward. Simultaneously, the high-pressure fluid flows 
through valve port 727 and then through discharge nozzle 717, to generate 
a pulse jet. The embodiment shown in FIG. 9 provides easy removal of valve 
stem 724, for maintenance and interchangeability purposes. By removing end 
plug 705, valve poppet 726 and a corresponding valve poppet assembly are 
exposed. Pulling valve poppet 726 will pull out end plug 712 and plunger 
710. According to such preferred embodiment, there is no need to 
disassemble cylinder 704 from any other component, thereby greatly 
enhancing and simplifying maintenance procedures. All moving parts, except 
for power piston 706, of pulse-jet generator 700 can be removed with 
plunger 710, so that a new assembly can be quickly inserted, which is 
particularly advantageous on-site. 
It is apparent that many components are interchangeable between the 
preferred embodiments shown in FIGS. 1-9. It is also apparent that 
different combination of components can be used to achieve different 
results. The components described are preferably constructed of relatively 
hard materials, such as hardened metals, stainless steel, hard plastics or 
any other suitable material known to those skilled in the art. 
EXAMPLE OF THE INVENTION 
A pulse-jet generator similar to the embodiment of this invention as shown 
in FIG. 3 was constructed and the remaining discussion of this Example 
will refer to the element reference numerals shown in FIG. 3. Valve 
cylinder 201 was constructed of stainless steel and had an outside 
diameter of 3.5 inches and an inside diameter of 2.5 inches. Power piston 
206 was constructed of bronze. An external accumulator, acting as a gas 
reservoir, communicated with inlet passage 218 of end plug 202. The gas 
accumulator was equipped with valves and a pressure gauge. The gas 
accumulator stored nitrogen at up to 5,000 psi, and to a maximum volume of 
one gallon. 
Power piston 206 had a maximum travel of 6 inches. Plunger 210 was 
constructed of hardened stainless steel and had an outside diameter of 
0.75 inches and an inside diameter of 0.25 inches and housed stem valve 
assembly 300, similar to that as shown in FIG. 4. Fluid cylinder 204 was 
constructed of hardened stainless steel and had an outside diameter of 
2.25 inches and an inside diameter of 0.815 inches. Fluid cylinder 204 was 
capable of handling water up to 45,000 psi. Fluid cylinder 204 was 
attached to end block 203 with a threaded connection. End plug 305 was 
constructed of hardened stainless steel. Seal assemblies formed 
water-tight seals. 
Fluid inlet 232 and fluid passage 229 were both positioned on end plug 305. 
Stem valve assembly 300 was constructed of stainless steel. Valve stem 316 
was 0.125 inches in diameter and valve poppet 320 was 0.350 inches in 
diameter. Fluid passage 329 was 0.125 inches in diameter and valve port 
327 was tapered at an angle of about 60.degree.. 
Control valve assembly 250, similar to that shown in FIG. 3, was 
constructed and used. Valve stem 259 was 0.125 inches in diameter and 
handled water at pressures up to 45,000 psi. Reset spring 264 was used to 
reset valve stem 259 and valve stem 259 was easily moved by fluid at a 
pressure above 2,000 psi. 
High-pressure pulsed generator 200 was designed for use with water and was 
used with a fluid pressure intensifier capable of generating water 
pressures up to 45,000 psi. A ratio of the cross-sectional area of power 
piston 206 to plunger 210 had an area ratio of 11:1. The forces across 
power piston 206 and plunger 210 were equalized by setting the system 
water pressure at 11 times the gas pressure P.sub.g. Nitrogen was used as 
the gas and the accumulator was filled to a pressure of about 2,000 psi. 
Thus, the system water pressure was used at above about 22,000 psi. At 
pressures below 22,000 psi, plunger 210 did not move. 
High-pressure pulsed generator was installed with jet nozzle 217 having a 
0.035 inch diameter sapphire orifice and was fed with water from a 
pressure intensifier at 35,000 psi. Very quickly, a powerful pulsed 
waterjet was issued at jet nozzle 217, repeatedly at a frequency of 
roughly four pulses per second. Such frequency was determined by the 
output of the pressure intensifier and the internal volume of the 
pulsed-jet generator. The pulsed-jet generator stopped when water stopped 
flowing from the pressure intensifier. The static pressure of the water 
within the pulsed-jet generator remained at 35,000 psi, and maintained a 
pressure close to 35,000 psi during discharge as the gas accumulator used 
was reasonably large in view of the internal volume of the pulse-jet 
generator. Jet nozzle 217 issued a water jet which was very coherent and 
packed with considerable energy, capable of fracturing rock and concrete 
even though no effort was spent to design or shape jet nozzle 217 in a 
manner that would enhance the discharge speed of the fluid. 
While in the foregoing specification this invention has been described in 
relation to certain preferred embodiments thereof, and many details have 
been set forth for purpose of illustration, it will be apparent to those 
skilled in the art that the invention is susceptible to additional 
embodiments and that certain of the details described herein can be varied 
considerably without departing from the basic principles of the invention.