US3520477A - Pneumatically powered water cannon - Google Patents

Description

July 14, 1970 w. c. COOLEY 3,520,477

I PNEUMATICALLY POWERED WATER CANNON Filed Feb. 23. 1968 FIGI FIGZ

INVENTOR WILLIAM C. COOLEY ATTORNEY United States Patent 3,520,477 PNEUMATICALLY POWERED WATER CANNON William C. Cooley, Bethesda, Md., assignor to Exotech Incorporated, Rockville, Md.

Continuation-impart of application Ser. No. 612,945, Jan. 31, 1967. This application Feb. 23, 1968, Ser.

Int. Cl. Bb N08 US. Cl. 239-101 3 Claims ABSTRACT OF THE DISCLOSURE A device for compressing liquid to extremely high pressures and discharging it in the form of pulsed jets from a nozzle by means of a reciprocating piston in a cylinder. Liquid is supplied under constant pressure to a separate extrusion chamber which communicates with an end face of the cylinder. The free piston is provided with a cylindrical rod having an impact surface. The rod extends through one of the end faces of the cylinder apertured for this purpose and communicates with the extrusion chamber to which the liquid is supplied. Pneumatic means is provided to actuate the free piston driving the same to cause the extension rod to impact the liquid in the extrusion chamber and thereby force a pulsed jet from a nozzle located therein.

This application is a continuation-in-part of application Ser. No. 612,945, entitled Hydraulic Pulse Jet Device, filed Jan. 31, 1967.

This invention relates to devices for producing pulsed jets of liquid from a nozzle under extremely high pressures in the order of 50,000 to 200,000 p.s.i or higher which is particularly useful for rock-breaking, rock-tunneling, mining, breaking of concrete and a wide variety of other applications.

In the past, systems for producing pulsed jets of liquid have utilized such methods as piston expulsion or the cumulation or shaped-charge principle. The piston expulsion theory, utilized in fuel injection techniques, offers difficulties with piston sealing and leakage at pressures greater than 3,000 atm. The cumulation principle, that is, the theory of explosive-shaped charges, has been used for production of metallic jets but has not, as yet, been extensively applied for production of liquid jets because of the complexity, expense and hazards in using explosive materials.

Accordingly, it is an object of this invention to provide a pneumatically powered hydraulic pulsed jet device for producing repetitive pulsed jets of liquid with stagnation pressures greater than 100,000 p.s.i.

Another object of this invention is to provide a jet pulsing device employing a reciprocating pnematic actuator in conjunction with a high pressure liquid extrusion housing.

Still another object of this invention is to provide a jet pulsing device in which a pneumatic actuator cooperates with a high pressure liquid cylindrical housing for ejecting pulsed liquid jets from the cylinder and utilizes only a single valve control for the pneumatic actuator.

It is a further object of this invention to provide a jet pulsing device employing a minimum of parts and which can be constructed in a simple and economic manner for producing a reliable and continuous operation.

It is still another object of this invention to provide a pulsed jet device utilizing a reciprocating pneumatic actuator in combination with a high pressure liquid extrusion housing which is constantly supplied and kept filled with a liquid independent of the operation of the actuator and wherein the actuator cooperates with the high pressure liquid extrusion cylinder for producing repetitive jet pulses of liquid in the order of 50,000 to 200,000 p.s.i.

According to one embodiment employing the principles of this invention there is provided a reciprocating pneumatic actuator comprising a cylinder with a reciprocating piston therein. A gas inlet is provided on one side of the piston and a gas outlet on hte other side of the piston. With a valve timer control on the gas inlet and a spring means provided at one end of the cylinder, reciprocation of the piston can be controlled. The piston is provided with a rod having an impact surface extending through an aperture provided in the cylindrical casing. Adjacent this aperture there is provided a high pressure liquid extrusion housing comprising a high pressure cylinder and an end closure with a nozzle. A suitable liquid inlet means and a liquid drain are provided to keep the cylinder filled with liquid. When the extension ar mof the piston enters the high pressure cylinder filled with liquid, a shock wave is generated which moves back and forth in the liquid between the nozzle end and the impact face of the extension arm thereby raising the pressure of the liquid therein to a range between 50,000 and 200,000 p.s.i. or higher, and, consequently, ejecting a pulsed jet of liquid through the nozzle for each stroke of the piston.

Other objects and advantages will become apparent from the following detailed study of the specification and drawings, in which:

FIG. 1 is a partial cross-sectional and partial elevational view of the liquid jet pulsing device according to the principles of this invention; and

FIG. 2 illustrates an alternate embodiment of the impact face of the extension rod of the piston.

Referring now to FIG. 1, there is shown a cylindrical housing 2 for the pneumatic actuator. Slida-bly mounted by suitable means, such as gaskets or the like, is a piston member 4 having a centrally extending rod 6. The rod 6 extends through an aperture 8 at one end of the casing 2 and a suitable seal 10 positioned on the periphery of the aperture surrounds the rod 6 providing a sealing engagement. To the left of the piston 4 there is provided in the casing wall a gas inlet port 12. A suitable valve control 14 is provided therein for regulating the gas flow into the chamber of the cylindrical housing 2. The valve 14 may be controlled to open and close by a suitable timing means 14a. To the right of the piston member 4 there is provided a gas outlet port 16. Also to the right of the piston member 4 there is provided a spring 18 of the coil type, as shown, which is held in place to the right end face of the housing 2 by an annular recess. The spring 18 coacts with the piston member 4 for effecting a return stroke thereto which will be more fully described below.

Adjacent the right end face of the housing 2 there is positioned a high pressure liquid extrusion housing 20 generally of cylindrical configuration. The housing 20 consists of an interior chamber 22 communicating with a coaxially aligned reduced cross-sectional liquid extrusion chamber 24, the latter having an outlet nozzle 26. The en tire housing 20 may be bolted by suitable means 28, as shown, to the apertured end face of the pneumatic actuator chamber 2. One or more liquid inlet ports 30 supply liquid to the extrusion chamber 24 and one or more liquid drain ports 32 are provided at the periphery of the chamber 22.

The entire device may be reciprocably supported by a support frame which includes at one end a suitably perforated encircling annular ring 34 provided with two or more bearing means 36 and at the other end a pedestal 38 surmounted by a suitable bearing means 40. The encircling annular ring 34 and the pedestal 38 are connected by a support frame structure 42 which is arranged to be slidably and rigidly supported on a rigid support bed plate 44 as shown. Plate 44 may have axially aligned guideways to permit axial recoil motion. Frictional or hydraulic damping means may be provided between the support frame structure 42 and the support bed plate 44. The device may be provided at one end by suitable means integrally or otherwise with a perforated flange 48 thereby providing means by which plural hydraulic damping devices 50, 52 may be aflixed between the annular ring 34 and the flange 48, respectively.

The operation of the device is as follows. A flow of com ressed gas, for example, compressed air, at 50 to 1,000 p.s.i. is supplied to the gas inlet port 12 and hence into the chamber of the housing 2. The piston 4 will then accelerate to a velocity of at least 30 ft. per second by the time the extension rod member 6 reaches the liquid extrusion chamber 24. A liquid, for example, water, is continuously supplied through the inlet port 30 communicating with the extrusion chamber 24 thus filling the chamber 22 and the chamber 24 until an overflow occurs through both the nozzle 26 and the drain port 32. When the extension rod 6 of the piston 4 enters the chamber 24, a shock wave is generated which moves back and forth in the liquid between the impact face of the extension rod 6 and the nozzle. This reaction raises the pressure within the chamber 24 to a range between 50,000 and 200,000 p.s.i. or higher, and thus acts to eject a pulsed jet of liquid through the nozzle 26 while at the same time the piston 4 is decelerating by its coaction with the liquid. The piston then comes to rest and by virtue of its engagement with the spring 18 it then effects a return stroke within the bore of the housing 2. The piston is stopped and the return stroke is initiated prior to extrusion of all the liquid from the chamber 24, while at the same time the inlet port 30 is constantly supplying liquid. At approximately the time of piston impact on the liquid, the gas to the left of the piston member 4 will be allowed to escape through the gas outlet port 16, the piston 4 being positioned to the right of the gas outlet port at this particular instance. At this point the valve 14 for the gas inlet 12 is closed by the timer control means 14a. With the gas inlet port 12 closed, the piston, upon its return stroke, will encounter very little resistance and will therefore return to a position just in front of the gas inlet port 12, at which time the timer control means 14a opens the valve 14 to initiate another actuating stroke of the piston 4.

As previously mentioned, during the return and the power stroke of the piston 4, liquid is continually injected into the chambers 24 and 22 in order that the liquid completely fills the available volume with the excess draining through the outlet port 32 as well as the nozzle 26. With the chamber 22 continuously filled with liquid, there is no danger of the piston 4 damaging the device, especially the extrusion housing 20, by virtue of impact damage in the absence of any liquid pressure in the chamber 22 to absorb the shock of the power stroke of piston 4. To this end the spring 18 will absorb the shock of the power stroke in the absence of any liquid in the extrusion housing 20.

In FIG. 2 there is shown an alternate embodiment of the impact face of the extension rod 6 of piston 4. Here, the impact face 6a of the extension rod 6 is concave. The concave shape provides focusing of the liquid shock waves in order to achieve higher jet stagnation pressures than that ordinarily achieved from the actual pressures acting on the cylinder wall of the chamber 24. It also is contemplated that a suitable gel material may be used as a liquid medium in the manner above described.

Although several embodiments of the invention have been depicted and described, it will be apparent that these embodiments are illustrative in nature and that a number of modifications in the apparatus and variations in its end use may be effected.

That which is claimed is:

1. In a device for discharging pulsed liquid jets, the combination comprising: a first cylindrical low-pressure casing having end faces and an axial bore, a reciprocable free piston in said bore, one of said end faces of said casing having means defining an aperture, said aperture having a healing means, said piston having an extension rod defining an impact surface and extending through said aperture, a second cylindrical housing having a highpressure chamber coaxial with said bore of said first housing and having an open face adjacent said apertured end face of said first housing, the other end face of said second housing having means defining a nozzle communicating with said chamber, means for supplying liquid to said chamber, and pneumatic means connected to said first cylinder housing for driving said piston, whereby said impact surface of said extension rod impacts said liquid in said chamber for raising the pressure of said liquid and extruding said liquid from said nozzle in the form of a pulsed jet having high stagnation pressures.

2. A device for discharging pulsed liquid jets, the combination comprising: a first cylindrical low-pressure housing having end faces ad an axial bore, a reciprocable free piston in said bore, one of said end faces having means defining an aperture, said aperture having a sealing means, said poston having an extension member defining an impact surface and extending through said aperature, a second cylindrical housing having an open face adjacent said apertured end face of said first housing, said second housing having a cylindrical high-pressure chamber therein coaxial with said bore of said first housing, the other face of said second housing having means defining a nozzle communicating with said chamber therein, means supplying liquid to said chamber, and pneumatic means connected to said first housing for driving said piston, whereby said impact surface of said extension member impacts said liquid in said chamber and extrudes said liquid from said nozzle in the form of a pulsed jet having high stagnation pressures.

3. In a device for discharging pulsed liquid jets, the combination comprising: a first cylindrical low-pressure housing having end faces and an axial bore, a reciprocable free piston in said bore, one of said end faces having means defining an aperture therein, said piston having an extension rod defining an impact surface and extending through said aperture, a second cylindrical high-presence housing having an open face adjacent said apertured end face of said first cylindrical housing, said second cylindrical housing having a first chamber adjacent said apertured end face, said first chamber having substantially the same diameter as said bore of said first cylindrical housing, a second chamber in said second cylindrical housing communicating with said first chamber and having diametrical dimensions substantially corresponding to the diametrical dimensions of said extension rod, the other end face of said second cylindrical housing having means defining a nozzle communicating with said second chamber, means supplying liquid to said first and second chambers, and pneumatic means connected to said first cylindrical housing for driving said piston, whereby said impact surface of said extension rod impacts said liquid in said second chamber and forces said liquid through said nozzle in the form of a pulsed jet.

References Cited UNITED STATES PATENTS 3,412,554 11/1968 Voitsekhovsky et a1. 6054.5

M. H. WOOD 1a., Primary Examiner B. BELKIN, Assistant Examiner US. Cl. X.R.

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