Note: Descriptions are shown in the official language in which they were submitted.
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WATER HAMMER DRIVEN VIBRATOR
FIELD OF THE INVENTION
This application relates to devices used for shaking industrial devices or
structures. The structure may be the wall of a hopper bin, a screen for separating finer
particles from coarser particles, a fin for agitating or stirring a liquid, vibrating cont~inPrs,
shaker tables or the like.
BACKGROUND OF THE ~VENTION
Vibrators are used in many industrial applications where it is nPcess~ry to shake a
structure or device with high ~mplihl~le vibrations. For example, vibrators are used to:
shake screens for separating particles, such as crushed rock, by size; to vibrate bins and
hoppers to prevent gr~n~ r particles from "bridging" and to help granular particles flow;
and to vibrate pieces of machinery, such as steam rollers. Various types of vibrators are
currently available. All of these vibrators have disadvantages.
Many prior art vibrators cause vibration by turning an unbalanced rotor with an
electric or hydraulic motor or by compressed air. These vibrators tend to be expensive
because they require precision heavy duty bearings and/or are inefficient at converting
input energy into vibration energy. Another characteristic of the prior art vibrators is that
amplitude versus time generated force is following sinusoidal curve.
Water h~mmPr is a phenomenon by which high intensity pressure pulses are
produced in a confined body of flowing fluid when the flow of the fluid is suddenly
blocked. Water hammer is generally undesirable, and can be destructive. Much effort is
spent in the design of hydraulic circuits to avoid water hammer. The mathematics of
water h~mmPr are discussed in various texts on fluid mechanics including Fluid
Mechanics (7th Edi~ion) Victor L. Streeter and E. Benjamin Wylie, McGraw-Hill Book
Company, 1979 and R.L. Daugherty and J. B. Franzini, Fluid Mechanics With
Engineering Applications, pages 425-431 McGraw-Hill Book Company, 1977.
Water hzlmmPr has been used to generate acoustic pulses for use in marine seismic
exploration. For example, Baker et al., US Pat. No. 3,376,949, Anstey, U.S. Pat. No.
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3,536,157, Burg U.S. Pat. No. 4,271,926, Bricout, U.S. Pat. No. 3,36g,519 and Davis,
U.S. Pat. No. 3,690,403 disclose underwater acoustic generators, also for use inunderwater seismic exploration. Each of these devices use a deliberately created water
hzlm me.r to produce a one shot high amplitude burst of acoustic signals appropriate for
geophysical seismic exploration. Akimoff, German Patent No. 620,483 discloses a siren
for broadcasting noise into air wherein the noise is generated by series of water hammers
in a pipe.
Bayhi, U.S. Pat. No. 4,396,088 discloses a generator of low power, low frequencyacoustic waves for seismic exploration. The Byhi apparatus modulates the flow of fluid
flowing into an array of flexible sleeves at the frequency of the desired sound. Bayhi
does not disclose the use of water h~m m~r and is not designed for or adapted to shake
industrial machinery or structures.
Walter, U.S. Pat. No. 5,467,322 discloses a system for shaking structures such as
fins in a fluid agitator, sh~king screens, tables, bins of hoppers or the like. Disclosed
apparatus transfers repeatedly generated water hammer pressure pulse to the vibrated
structure via expanding rubber conduit or through an actuator.
Walter, U.S. Pat. No. 5,626,016 shows vibrating of members by transferring waterhammer generated pulses into a deformable element which is attached to the vibrated
member.
SUMMARY OF THE INVENTION
This invention provides a vibrator suitable for use in industrial settings which uses
water h~m mer pressure pulses to shake a member.
The vibrator comprises a hydraulic circuit where the working conduit is connected
to the hydraulic driving system by flexible conduits or by conduits allowing free
movement of the working conduit.
Working conduit can be formed as a single loop or it can be formed into a coil.
This working conduit is directly attached to the member that is to be vibrated. Each
closure of the interrupting valve provides multiple vibrating forces acting on the working
conduit.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying
drawings which illustrate specific embo-lim~,nt.c of the invention, but which should not be
construed as restricting the spirit or scope of the invention in any way:
FIG, 1 is a partially cut-away schematic view of a system according to the
invention for ~git~ting fluid,
FIG . 2 is a graph showing water hammer generated forces acting on the working
conduit in time,
FIG, 3 is a schematic view of a working conduit formed in a coil for ~git~3ting
fluids.
FIG, 4 is a graph showing water h~mme,r generated forces acting on the working
conduit that is formed in a coil in time.
FIG, 5 is a partially cut-away schematic view of a system according to the
invention for agitating fluid. Shape of the working conduit allows for axial agitation in
this arrangement,
FIG. 6 is a partially cut-away schematic view through a hopper with the working
conduit formed into a coil that is attached to the hoppers wall,
DETAILED DESCRIPTION OF THE PREFERRED EM~ODIMENT
FIG. 1 Shows a liquid agitation device 10 which incorporates apparatus
according to the invention for shaking fluid agitation fins 11 to agitate and stir fluid 12.
Agitation device 10 comprises a hydraulic driving system 14 which drives agitation
device 10. Agitation device 10 may include a tank 15 containing a fluid 12 which may
for example be a cleaning fluid or tar sands slurry,
Liquid agitation device 10 further includes working conduit 16 on which are
fastened or welded fins 11. Working conduit 16 is attached to the hydraulic driving
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system by flexible conduits 17 and 18. This connection can also be secured by designing
pivotal rigid conduits that would allow free movement of the working conduit.
Working conduit 16 is suspended by movable supporting means 19. This
supporting means 19 can be in a form of a steel cable, chain or springs, or in any
configuration that would allow for the free movement of the working conduit 16.
Hydraulic driving system 14 produces a series of high pressure pulses by
deliberately creating a series of water hammers in the hydraulic circuit 20.
Hydraulic circuit 20 comprises of a tank 21, conduit 24, fluid 25, hydraulic pump
22 which can be replaced by any other means of delivering pressurized fluid, driving
motor 23, conduit 26, conduit 18, working conduit 16, conduit 17, conduit 27, valve 28,
valve actuator 29 and conduit 30.
Hydraulic pump 22 is driven by preferably electric motor 23. The output pressureof the pump is typically in the range of 30 - 300 psi, although it is possible to practice
invention outside of this range. Exiting pump 22 fluid 25 flows trough conduit 26 to
enter flexible pressure conduit 18. This conduit and conduit 17 can be designed in many
dirr~ l ways, however preferred way would be to use a flexible rubber pressure hose
that is currently being used in high pressure hydraulic systems.
Fluid 25 flows through the working conduit 16, through conduit 17 into conduit
27, through the valve 28 through the conduit 30 into the tank 21.
Driving hydraulic system 14 can also comprise a system where pump 22 and
motor 23 is replaced by supply of fluid flow from a reservoir under pressure or a tank
sufficiently elevated above the working conduit 16 to provide pressure head required for
adequate velocity V of the fluid 25.
In some instances conduits 24 and 30 can be connected through the wall of tank
15 and use fluid 12 as a working fluid. Valve 28 is provided between conduit 27 and
conduit 30. When the valve 28 is open working fluid 25 will circulate through the entire
hydraulic circuit 20 and through the valve 28 substantially unintell upl~d. When valve 28
is closed it substantially blocks the flow of working fluid through hydraulic circuit 20.
Valve 28 is operated by a suitable actuator 29 which is capable of suddenly moving valve
28 from its open state to its closed state. Valve 28 must be of a type which can be opened
and closed at the desired frequency of operation of the hydraulic driving system 14. For
example, valve 28 may be a solenoid activated spool or needle valve, a self actuating-
valve operated by the flow of working fluid 25 or a cam operated valve as described on
FIG. 15, FIG. 16 and FIG. 17 in my U.S. Patent No. 5,459,699 issued October 17,
1995.
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Another arrangement for the valve operation is shown in FIG. 8 of my U.S.
Patent 5,549,252 issued Aug. 27, 1996. In this arrangement the valve is being closed by
the effect of the flow of the working fluid and the valve is opened by the generated water
hammer pressure.
Hydraulic driving system 14 functions as follows. With valve 28 open, pump 22
pumps working fluid 25 at a high velocity V through hydraulic circuit 20. Valve 28 is
than suddenly closed by actuator 29. The sudden closure of valve 28 causes a water
hammer within hydraulic circuit 20. In general, valve 28 need not completely block the
flow of working fluid 25 in hydraulic circuit 20 to create a water hammer but a more
intense water hammer is created if valve 28 is closed completely and suddenly. The
water hammer results in a high pressure pulse prop~g~ting upstream through the conduit
27, flexible conduit 17, through the working conduit 16, through the flexible conduit 18,
through the conduit 26, pump 22, conduit 24 and into the tank 21.
In a typical application the pressure of the water h~mm~r pulse is in the range of
500 psi to 2000 psi. The pressure of the water hammer pressure pulse is determined by
the velocity V, the comprescihility of the working fluid 25, the speed at which valve 28 is
closed, the degree of closure of valve 28 and the speed of sound in the working fluid 25,
among the other factors. Under ideal circumstances, when valve 28 closes fully, the
magnitude of the water hammer pressure is given by:
Ph=Q Cp V
Where Ph is the pressure of the water hammer pulse, Q is the specific density ofthe working fluid 25, and Cp is the velocity at which the water hammer pulse travels in
hydraulic circuit 20. By increasing the velocity V of working fluid 25 in hydraulic circuit
20, making the walls of conduit 27 and conduit 16 rigid, and closing the valve 28
completely and very quickly the pressure of the water hammer pulses generated byhydraulic driving system 14 may be m~imi7~d
Actuator 29 continuously opens valve 28, retains valve 28 open for a time
sufficient for working fluid 25 to attain a significant velocity through valve 28 and
suddenly closes valve 28 to create a continuous series of water hammer pressure pulses
within hydraulic circuit 20.
When valve 28 closes suddenly, fluid 25 which flows at velocity V is suddenly
stooped. Kinetic energy of the flowing fluid 25 is suddenly converted into a pressure.
This raise in pressure - water hammer pulse travels upstream through the conduit 27 and
into a conduit 17 at the speed of sound in the particular conduit. Stiffness of the conduit
wall is determining factor in the velocity Cp of sound in the fluid 25. When raise in
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pressure enters working conduit in the location marked 31 the water h~m m~r pressure
acting on the projected area marked Al creates a force Fl acting in the direction of Fl.
This force Fl will accelerate working conduit with fins 11 in the direction of Fl. This
acceleration will stir and agitate fluid 12. Time during which force Fl will aet on the
working conduit 16 is obtained by dividing length Ll/Cp. When raise in pressure due to
water hammer reaehes position marked 32 foree Fl will stop to aet on the workingeonduit 16.
When water hammer pulse passes position marked 32 a new foree F2 aeting in the
direetion of F2 will act on the working conduit 16 and fins 11. Force F2 will aecelerate
working conduit 16 and fins 11 in the direetion of F2 eausing effeetive agitation of the
fluid 12. Time during whieh foree F2 will aet on the working eonduit 16 ean be obtained
by dividing length L2/Cp.
After passing loeation 33 pressure pulse eontinues upstream through eonduit 18,
eonduit 26, pump 22 and eonduit 24 into the tank 21. To reduee effect of the water
h~m mer pressure pulse on the pump 22 we can place a pulsation dampener in front of the
pump 22 ( not shown).
Movement of the working eonduit 16 and fins 11 is allowed by suspending
working eonduit 16 by ehains or eables 19 and by eonneeting the working eonduit 16 to
the hydraulie driving system 14 by flexible eonduits 17 and 18. Flexible eonduits 17
and 18 ean be substituted by a pivotal arranged rigid eonduits, however a flexible
eonduit sueh as a hydraulie pressure rubber reinforeed hose would be most practical for
water h~m m~r pressure in the range of 500 to 2000 psi.
FIG. 2 shows a graph describing action of the forces Fl and F2 acting in time onthe working conduit 16.
FIG. 3 shows a working conduit 33 on which are attached fins 11. This working
conduit is formed in a coil. In this particular case eoil consist of two turns.
Working conduit 33 is suspended by cables 19 and is connected to conduits 26
and 27 by flexible pressure conduits 17 and 18. When hydraulic driving system 14produces water hammer pressure pulse, this pulse travels upstream from the valve 28 and
enters the working conduit 33 at the position marked 34. For the duration of time Ll/Cp
resulting force Fl acts on the working conduit 33 and fins 11 in the direction Fl . After
water hammer pulse passes location marked 35 a force Fl stops and Force F2 starts
acting in the direction of F2 for the time duration L3/Cp. Working conduit 33 and fins 11
are accelerated in the direction F2 and effectively stirring and agitating fluid 12. After
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water h~m m~r pulse passes location marked 36 Force F2 stops and force Fl starts acting
on the working conduit in the direction of Fl for the duration of time L3/Cp. Working
conduit 33 is now accelerated in the direction of Fl and it is stirring the fluid 12. After
water hammer pulse passes location marked 35 force Fl stops and force F2 acts in the
direction of F2 for the time L2/Cp. Working conduit 33 and fins 11 are accelerated in the
direction F2 and are actively stirring and agitating fluid 12. By creating a coil of more
turns we would create additional forces that would accelerate working conduit and fins at
higher frequency than is the frequency of the hydraulic driving system 14. Therefore the
frequency of the hydraulic driving system 14 is multiplied by a single loop by two For
each additional turn of the coil we will multiply the frequency of the hydraulic driving
system 14 by two.
FIG 4 shows a graph describing action of the water hammer generated forces Fl
and F2 acting in time on the working conduit 33.
FIG. 5 shows a liquid agitation device 10 that was shown on FIG. 1 with the
exception that working conduit 16 shown on FIG. 1 is replaced by working conduit 37.
Suspending cables 19 shown on FIG. 1 are replaced by springs 38.
Movement of the working conduit 37 is caused by water hammer generated forces
that are generated as described in FIG. 1 and FIG. 3 and these forces act in the direction
Fl, F2, and F3. It follows that a great versatility of arrangement is possible.
FIG. 6 shows hydraulic driving system 14, vibrator 41 and hopper 42. Hydraulic
driving system 14 is connected to the working conduit 43 by flexible pressure hoses 17
and 18. Working conduit 43 is connected to the wall 40 of the hopper 42 by a bracket 39.
When valve 28 is suddenly closed water hammer pressure pulse travels upstream inconduit 27, 17 and enters working conduit 43 at location marked 44. Water hammerpressure pulse acting on the inside projected area of the working conduit 43 creates force
Fl that is acting in the direction Fl. When the water hammer pulse reaches the location
marked 45 force Fl stops and force F2 acting in the direction F2 on the working conduit
43. The effect of the water hammer pulse on the working conduit 43 is the same as the
effect of the water hammer generated forces acting on the working conduit 33 as shown
in FIG. 3.
It is clear that we can vibrate numerous industrial members by a wide variety ofconfiguration of working conduit. The big advantage of this system is that we can
increase the effective frequency of the vibrated member beyond the frequencies of the
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hydraulic driving system 14. In some instances we could also fasten the hydraulic
driving system to the vibrated member.
Working conduits 16, 33, 37 and 43 should be made from material that is strong
and light for the best acceleration of the working conduit. High strength steel or carbon
fiber filament wound composite material would allow for the lightest working conduit
that would allow for maximum acceleration. High strength would also provide minimum
expansion of the conduit wall and therefore allow for the maximum Cp in the fluid 25
which will produce maximum water hammer pressure pulse.
As is shown on all drawing it is preferable that the working conduit incorporates
longer section of the straight portion which will provide sufficient length and therefore
time during which the water hammer generated force will have time to accelerate
working conduit to stir fluid more efficiently.
As will be apparent ~o the skilled in the art in light of the foregoing disclosure,
many alterations and modifications are possible in the practice of this invention without
departing from the spirit or scope thereof.
