Control valve assembly

BACKGROUND OF THE INVENTION
The field of this invention is control valves, particularly of the type used for mixing abrasive particles with high pressure fluid for abrasive blasting operations.
Abrasive blasting systems have long been and are well known in the art, such as generally disclosed in U.S. Pat. Nos. 3,834,082 and 3,543,444. Typically, such systems require some mechanism for introducing an abrasive from a reservoir into a high pressure fluid line to provide such abrasive particles under high pressure remote from the abrasive reservoir. Some systems utilized a valving structure wherein the flow of sand entering the high pressure fluid source is regulated by a sliding valve adjacent the base of the abrasive reservoir, such as shown in U.S. Pat. No. 3,182,425 or British Pat. No. 1,394,483, or using a gate-type valve as used with the Clemco Model FSV "Sand Miser Control Valve" as manufactured by the Clemco Manufacturing Company, or having a rotatable blocking valve element as shown in U.S. Pat. No. 3,476,440.
In U.S. Pat. No. 3,618,263, a pinchtype valve is used wherein high pressure fluid flow is regulated by adjusting the amount of air flow through the abrasive line rather than the metering of the abrasive by "pinching" the line closed. However, problems with the pinch-type valve systems include difficulty in obtaining complete shut off of abrasive and/or fluid as well as having high abrasive wear adjacent the valve point with a consequent short life span of the abrasive line adjacent thereto.
U.S. Pat. No. 3,924,657 discloses the use of a opposed-piston arrangement mixing valve whereas in U.S. Pat. No. 3,557,498, a rotatable valving plate is incorporated for controlling mixing of the abrasive and high pressure fluid. The prior art as far as known, has further encountered problems due to abrasives plugging up the valving structure with such abrasives becoming lodged therein. Many prior art devices not only require complete system shut downs to cure this defect but also may require complete disassembly of the control valve to remove such foreign particles.
The prior art also includes an abrasive mixing system wherein a closed pressurized tank having abrasive particles therein mixes with high pressure fluid adjacent a nozzle, directing the same upwardly through a stand pipe through the center portion of the abrasive tank with air bleeding outwardly from the stand pipe for further pressurizing the abrasive tank. Pressurized fluid within the stand pipe mixes with the abrasive and the fluid-entrained abrasive is directed outwardly from the top of the pressurized tank for use downstream in abrasive blasting operations. However, such prior art systems require depressurizing the tank, hence the entire system for cut off of the fluid-entrained abrasive flow while further requiring fill-time to repressurize the tank and system. Furthermore, such systems are not practical for multiple user operations as any user can deactivate the entire system by "dumping" the abrasive tank pressure. Further, all operators must have their remote control system in an "on" position for such a unit to operate properly. Additionally, failure of any component of such a system would result in shutting down all operations thereof.
SUMMARY OF THE INVENTION
The present invention relates to a new and improved control valve assembly for regulating the mixing of abrasive with high pressure fluid for abrasive blasting operations, having a control valve housing with a mixing chamber therein and a tubular abrasive flow pipe mounted therewith, an abrasive control nozzle disposed within the abrasive flow pipe, and means for moving the abrasive control nozzle and the tubular abrasive flow pipe relative to each other to and from an open abrasive fluid mixing position from and to a sealed, closed position, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation of the control valve assembly of the present invention with an abrasive blasting system;
FIG. 2 is a sectional view, partly in elevation, of the first embodiment of the control valve assembly of the present invention, in a closed position;
FIG. 2A is a sectional view, partly in elevation, of the control valve assembly of FIG. 1 in an open position;
FIG. 3 is a sectional view, partly in elevation, of the second embodiment of the control valve assembly of the present invention, in a closed position;
FIG. 3A is a sectional view, partly in elevation, of the control valve assembly of FIG. 3, in an open position; and
FIG. 4 is a sectional view, partly in elevation of the third embodiment of the control valve assembly of the present invention, in a closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, the letter A designates generally the control valve assembly of one embodiment of this invention which is illustrated in FIGS. 2 and 2A. The control valve assembly A includes a control valve housing H, a tubular abrasive flow pipe P, an abrasive control nozzle N, moving means M and seal means S. Unless otherwise noted, the components of this invention are preferably made of steel or other high-strength materials capable of taking abrasive-wear as well as high stresses and strains typical for pressurized systems.
As shown in FIG. 1, the control valve assembly A of the present invention is adapted to be used with an abrasive blasting system 10 which is commonly utilized to clean or otherwise treat surfaces of building stone, brick work, metal castings, and the like. Such abrasive blasting system 10 typically includes an abrasive reservoir, which may or may not be pressurized, but preferably includes large pressurized tank 12 for holding abrasive particles such as sand, glass beads or the like. Further, the system includes a source of high pressure fluid (not shown) for providing high pressure fluid, such as air, entering the system in the direction of arrow 14 which is adapted to be mixed with abrasive particles in the control valve assembly A of the present invention and directed outwardly therefrom into a tubular conduit such as high pressure abrasive hose 16. Typically, the tubular conduit or abrasive hose 16 may be quite long to enable the operator to get into places too small for the pressurized tank 12 to fit into or enable the operator to cover large working areas without requiring the constant movement of the pressurized tank 12.
A remote control valve 18 may be mounted adjacent the end of the tubular conduit or abrasive hose 16, which terminates with outlet nozzle 20 which directs the high pressure fluid-entrained abrasive outwardly thereof in the direction of arrow 22. The remote control valve 18 may be of the "dead man" type of remote control valve wherein the manually operative mechanism in the remote control valve 18 is biased in such a manner that in order to operate the control valve assembly A of the present invention, the operator must maintain the mechanism in a certain position, and upon the release thereof, it returns to its "off" position for deactivating the abrasive blasting system 10. Fluid control lines 24, 26, 28 communicate with metering valve 30, control valve assembly A of the present invention, and remote control valve 18 for control of the abrasive blasting system 10 as described more fully hereinbelow.
As shown in FIGS. 2 and 2A, the control valve assembly A of the present invention includes a control valve housing H. The control valve housing H includes housing 36 having a fluid inlet end portion 36a and a discharge outlet end portion 36b. An abrasive inlet 36c is formed between the fluid inlet end portion 36a and discharge outlet end portion 36b. A mixing chamber 36d is formed within the housing 36 in communication with abrasive inlet 36c.
The fluid inlet end portion 36a includes end plate 36e, flange plate 36f and tubular member 36g. End plate 36e is affixed to flange plate 36f by suitable fasteners 38, such as bolts, screws or the like and flange plate 36f is preferably rigidly affixed to tubular member 36g by weldment 40. Outer diaphragm flange 36h is mounted with the tubular member 36g by weldment 42 adjacent the end opposing the flange plate 36f. Outer diaphragm flange 36h is affixed to central body member 36i by fasteners 44 such as bolt 44a or the like.
The central body member 36i is formed having the mixing chamber 36d therein. The central body member 36i has a top opening 36j, a bottom opening 36k and a side opening 36l, all in communication with and adjacent to the mixing chamber 36d. Abrasive inlet member 36m is mounted with the top opening 36j of central body member 36i by weldments 46 with the abrasive inlet member 36m having the abrasive inlet 36c formed therein and communicating with the mixing chamber 36d. The abrasive inlet member 36m is adapted to be mounted with the neck portion 12a adjacent the lowermost end of pressurized tank 12 in any suitable manner having an appropriate seal 48 disposed therebetween for preventing fluid or particle leakage therebetween. Thus, the control valve housing H is mounted with the pressurized tank 12 above the abrasive inlet 36c. It will be appreciated that the abrasive inlet 36c communicates with the interior portion (not numbered) of the pressurized tank 12 for receiving abrasive particles therein. Preferably, the pressurized tank 12 has a conically-shaped base 12b adjacent to and above the neck portion 12a for directing abrasive particles within the pressurized tank 12 thereinto neck portion 12b and into the abrasive inlet 36c within abrasive inlet member 36m.
An abrasive pipe sleeve 36n is preferably mounted with the central body member 36i having end portion 36o adapted to be disposed within side opening 36l of the central body member 36i and rigidly affixed thereto, preferably by weldments 50. Abrasive pipe sleeve 36n is formed having interior threads 36p which are adapted to receive corresponding exterior threads 36r formed on the exterior surface of adjusting ring 36q with the adjusting ring 36q being rotatable within the interior threads 36p. A suitable detent 36s is formed in the adjusting ring 36q to receive an appropriate tool (not shown) for rotating the adjusting ring 36q with respect to the abrasive pipe sleeve 36n. Locking ring 36t is formed having internal threads 36u which threadedly engage exterior threads 36r of the adjusting ring 36q. By threaded rotation of the locking ring 36t such that end surface 36v thereof engages end surface 36w of the abrasive pipe sleeve 36n, relative movement of the adjusting ring 36q with respect to the abrasive pipe sleeve 36n and locking ring 36t is prevented.
The control valve assembly A of the present invention further includes a tubular abrasive flow pipe P adapted to be mounted with the discharge outlet end portion 36b of the housing 36. The tubular abrasive flow pipe P includes flow pipe 60 being of a substantially tubular configuration having a bore 60a therethrough. The flow pipe 60 has a first end 60b extending into the mixing chamber 36d of housing 36 and a second end 60c extending beyond the discharge outlet end portion 36b of the housing 36. The flow pipe 60 is adapted to be disposed within bore 36x formed in abrasive pipe sleeve 36n with seal 62 preventing any fluid migration between the exterior surface 60d of flow pipe 60 and the bore 36x of the abrasive pipe sleeve 36n. The flow pipe 60 has detents 60e, 60f formed on exterior portion thereof for receiving retaining rings 64, 66, respectively. The flow pipe 60 is further adapted to be disposed within bore 36y formed in adjusting ring 36q with the outside diameter of exterior surface 60d being slightly smaller in diameter than bore 36y. Counterbore 36z formed in adjusting ring 36q allows disposition of the retaining ring 66 in the counterbore 36z and properly positioned within detent 60f while detent 60e receives retaining ring 64. The retaining rings 64, 66 locate the adjusting ring 36q with respect to the flow pipe 60 while allowing relative rotation of the adjusting ring 36q with respect to the exterior surface 60d of the flow pipe 60. Rotation of the adjusting ring 36q in threads 36p results in longitudinal movement of the flow pipe 60 with respect to bore 36x and further regulates the extension of the first end 60b of flow pipe 60 into the mixing chamber 36d of the housing 36.
Flow pipe 60 is further formed having exterior threads 60g adjacent second end 60c to threadedly receive abrasive hose coupling 68. The abrasive hose coupling 68 is threaded onto exterior threads 60g at one end thereof and is adapted to receive the tubular conduit/abrasive hose 16 adjacent the other end thereof for use in the abrasive blasting system 10.
The control valve assembly A of the present invention further includes an abrasive control nozzle N mounted in substantial longitudinal alignment with the tubular abrasive flow pipe P with the abrasive control nozzle N being disposed within the tubular abrasive flow pipe P. The abrasive control nozzle N includes nozzle 70 having a bore 70a therethrough, an exterior conically-shaped end portion 70b, a flat annular surface 70c, an attachment flange 70d, and an abutting surface 70e. The exterior conically-shaped end portion 70b is preferably disposed within the tubular abrasive flow pipe P adjacent the similarly formed, conically-shaped end portion 60h. Seal means S is preferably disposed on the flat annular surface 70c as discussed more fully hereinbelow. Mounting ring 72 is adapted to engage attachment flange 70d of the nozzle 70 for securing the nozzle 70 to the mandrel 80 adjacent second end 80b as discussed more fully hereinbelow while further locating and securing the seal means S with the nozzle 70.
The control valve assembly A of the present invention further includes seal means S for sealing between the first end 60b of flow pipe 60 and nozzle 70 when the flow pipe 60 and nozzle 70 are in the closed position as shown in FIG. 2. Preferably, the seal means S includes seal 76 having an inner bore 76a adapted to engage annular surface 70c of nozzle 70. Surface 76b of nozzle 76 is adapted to fit in an abutting relation with the attachment flange 70d. The seal 76 further includes a conical exterior surface 76c adapted to abut conical interior surface 72a of mounting ring 72. As such, when the mounting ring 72 is fastened with the nozzle 70 and the mandrel 80, the seal 76 is held in position on the annular surface 70c and attachment flange 70d of nozzle 70 by the conical interior surface 72a of the mounting ring 72 so engaging the conical exterior surface 76c of seal 76. The seal 76 may be of any suitable sealing material such as butyl rubber, leather, "Teflon", polyvinyl chloride, or any other suitable sealing material.
The control valve assembly A of the present invention further includes a mandrel 80 adapted to be movably mounted with the control valve housing H in substantial longitudinal alignment with the tubular abrasive flow pipe P. The mandrel 80 has a first end 80a adapted to be connected to the high pressure source (not shown) adjacent the fluid inlet end portion 36a of housing 36 and has a second end 80b extending into the mixing chamber 36d of housing 36. The mandrel 80 further includes a bore 80c extending therethrough, with the exterior surfaces of the mandrel 80 including a neck portion 80d adjacent first end 80a, a radial lip 80e adjacent the second end 80b and radial lip 80f substantially intermediate of first end 80a and second end 80b. Outer annular surfaces 80g, 80h of radial lips 80e, 80f, respectively, correspond to and are adapted to be disposed in tubular member 36g of the housing 36 for longitudinal movement therein. Exterior threads 80i are formed adjacent first end 80a for threadedly connecting the control valve assembly A of the present invention with the high pressure fluid flowing in the direction of arrow 14 having passed through metering valve 30 thereinto member 32 for connection therewith mandrel 80.
The neck portion 80d of mandrel 80 has an outside diameter corresponding substantially to that of opening 90 formed in end plate 36e of the fluid inlet end portion 36a. A recess 92 is formed intermediate of opening 90 in the end plate 36e for receiving a suitable seal 94 for allowing movement of the mandrel 80 longitudinally with respect to opening 90 adjacent neck portion 80d without fluid migration therebetween the neck portion 80d and opening 90.
The control valve assembly A of the present invention further includes moving means M for moving the abrasive control nozzle N and the tubular abrasive flow pipe P relative to each other to and from an open abrasive fluid mixing position (FIG. 2A) and from and to a closed position (FIG. 2), respectively. The moving means M includes diaphragm means D mounted with the control valve housing H and the mandrel 80 for allowing fluid pressure responsive movement of the mandrel 80 to and from the closed position from and to the open position, respectively, as discussed more fully hereinbelow.
The diaphragm means D includes a first diaphragm 96 mounted with the radial lip 80f and the control valve housing H. The outer portion 96a of the first diaphragm 96 is preferably secured with the control valve housing H therebetween end plate 36e and flange plate 36f by fasteners 38, in an abutting, fluid-tight relation. The inner portion 96b of the first diaphragm 96 is secured to the mandrel 80 therebetween radial lip 80f and mounting ring 82 by suitable fasteners 84 extending through mounting ring 82, first diaphragm 96 and thereinto radial lip 80f.
A closure chamber 86 is formed therebetween the first diaphragm 96 and the end plate 36e of fluid inlet end portion 36a of housing 36 within the control valve housing H. Threaded opening 88 formed in end plate 36e is adapted to threadedly receive fluid control line 26 which is in communication with closure chamber 86. As such, the closure chamber 86 communicates with the fluid source through fluid control line 26 such that in response to fluid moving in the direction of arrow 78 through fluid control line 26, fluid pressure in closure chamber 86 urges against first diaphragm 96 such that mandrel 80 moves from the open position (FIG. 2A) to the closed position (FIG. 2) as discussed more fully hereinbelow.
The diaphragm means D further includes a second diaphragm 98 mounted with the control valve housing H and between the second end 80b of the mandrel 80 and the abrasive control nozzle N. The abrasive control nozzle N is preferably mounted with the second end 80b of mandrel 80 in substantial longitudinal alignment with the tubular abrasive flow pipe P. Inner portion 98a of second diaphragm 98 is preferably disposed between the attachment flange 70d of nozzle 70 and second end 80b of mandrel 80 and secured thereto by fasteners 74 extending through mounting ring 72, attachment flange 70d, inner portion 98a of second diaphragm 98, and thereinto the mandrel 80 adjacent second end 80b, resulting in a fluid-tight, abutting relation therebetween. The outer portion 98b of the second diaphragm 98 is secured with the control valve housing H by being disposed therebetween the central body member 36i and outer diaphragm flange 36h and secured therebetween by fasteners 44 extending through outer diaphragm flange 36h, outer portion 98b of second diaphragm 98 and into central body member 36i, resulting in an abutting, fluid-tight relation.
In the use or operation of the control valve assembly A of the present invention as shown in FIGS. 1, 2 and 2A, the control valve assembly A is in a closed position as shown in FIG. 2. As such, the first end 60b of flow pipe 60 is in a sealing, abutting relation with the seal 76 of seal means S. This sealing relationship is maintained because of positive fluid pressure entering into closure chamber 86 in the direction of arrow 78 from fluid control line 26 as controlled by the metering valve 30 and remote control valve 18. The fluid pressure acting upon first diaphragm 96 urges the mandrel 80 having the nozzle 70 mounted therewith longitudinally towards the first end 60b of the flow pipe 60 to insure a sealable relation therebetween seal 76 and first end 60b of flow pipe 60. Seal 94 engaging neck portion 80d prevents any fluid leakage outwardly from closure chamber 86. Any fluid escaping from the closure chamber 86 into the recess 92 of opening 90 will coact with the interior portion of seal 94 to further force the seal 94 into sealing engagement with recess 92 and the neck portion 80d of mandrel 80 to insure a fluid-tight arrangement. It should be noted that in this closed position, the fluid pressure entering in the direction of arrow 78 into closure chamber 86 may be equal to or greater than that exerted by the pressurized abrasive particles being stored within the pressurized tank 12 under fluid pressure to be directed into abrasive inlet 36 into mixing chamber 36d due to the larger effective area of diaphragm 96 than that of diaphragm 98.
Actuation of remote control valve 18 of the abrasive blasting system 10 results in actuation of metering valve 30 wherein fluid pressure acting in the direction of arrow 78 (FIG. 1) is released, reversing the direction thereof outwardly in the direction of arrow 79 as shown in FIG. 2A while permitting high pressure fluid flow through bore 80c of mandrel 80 from metering valve 30 through flexible member 32. Reduction in pressure in the closure chamber 86 allows the fluid pressure urging the abrasive particles from pressurized tank 12 into the abrasive inlet 36c and mixing chamber 36d to urge the second diaphragm 98, mandrel 80, and nozzle 70 out of engagement with the first end 60b of the flow pipe 60. When the first end 60b of the flow pipe 60 moves out of contact with the seal 76, mixing of the abrasive from the pressurized tank 12 with high pressure fluid is permitted in an orifice 99 formed adjacent to and between the abrasive control nozzle N and the tubular abrasive flow pipe P. The abrasive flows from within the mixing chamber 36d into orifice 99 between conical end portion 70b and nozzle 70 and, preferably, a similarly shaped conical interior surface 60h of flow pipe 60 adjacent first end 60b. High pressure fluid flowing in the direction of arrow 14 enters into bore 80c of mandrel 80 adjacent first end 80a, thereafter flowing into bore 70a of nozzle 70 having a reduced cross-sectional area resulting in venturi-action across the nozzle 70. This venturi-action in addition to fluid pressure on the abrasive particles within mixing chamber 36d from pressurized tank 12 results in abrasive particles flowing through orifice 99 into flow pipe 60 adjacent position 97 where the abrasive is entrained within the high pressure fluid. The thus highly fluid-pressurized abrasive is directed through the bore 60a of flow pipe 60 and outwardly therefrom into a tubular conductor such as high pressure abrasive hose 16 to thereafter be discharged in the direction of arrow 22 from outlet nozzle 20 for use in abrasive blasting operations. Upon release of the remote control valve 18, positive fluid pressure is again directed in the direction of arrow 78 into fluid control line 26, then into closure chamber 86 for closing the control valve assembly A of the present invention for preventing mixing of high pressure fluid and abrasive in the closed position. It should be noted that when the control valve assembly A is in the closed position, metering valve 30 prevents the directing of high pressure fluid in the direction of arrow 14 through the bore 80c of mandrel 80 to effectively stop the flow of fluid and abrasive through the control valve assembly A.
The control valve assembly A of the present invention further includes clean-out means C in communication with the mixing chamber 36d for cleaning abrasive particles therefrom during non-blasting periods. The clean-out means C preferably includes a cleanout plug 52 having threads 52a to be threadedly received in threaded bottom opening 36k of central body member 36i of housing 36. Preferably, threaded opening 36k is in substantial longitudinal alignment with abrasive inlet 36c. Should abrasive particles clog within the mixing chamber 36d, orifice 99, between end portion 60b and seal 76, or in abrasive inlet 36c, the cleanout plug 52 need merely be removed from the central body member 36i of housing 36 and suitable means, such as air pressure or the like may be used to dislodge the clogging particles therefrom so that blasting operations may thereafter proceed unencumbered with such blockage. Thereafter, the cleanout plug 52 is replaced and further blasting operations may ensue without requiring disassembly of the control valve assembly A.
The control valve assembly A of the present invention further includes a second embodiment as shown in FIGS. 3 and 3A. The structure that is substantially identical to the control valve assembly A as shown in FIGS. 2 and 2A will be referenced with the same numerals as used in FIGS. 2 and 2A but being preceded by the numeral "1", using the exact alpha-numeric digits thereafter. Differing structure will be signified by the use of 200-299 series numbers.
The control valve assembly A of the embodiment of FIGS. 3 and 3A includes a control valve housing H including housing 210 having a fluid inlet end portion 210a and a discharge outlet end portion 210b. An abrasive inlet 210c is formed between fluid inlet end portion 210a and discharge outlet end portion 210b. A mixing chamber 210d is formed within the housing 210 in communication with abrasive inlet 210c. Preferably, the housing 210 is formed having a central body member 210e having an opening 210f formed adjacent the upper portion thereof and adapted to receive abrasive inlet member 210g which is suitably affixed thereto by weldments 212. The abrasive inlet member 210g is suitably affixed to neck portion 112a of pressurized tank 112 having an appropriate seal 148 between the upper end of the abrasive inlet member 210g and the neck portion 112a of abrasive tank 112 to prevent any fluid leakage therebetween. The abrasive inlet 210c within abrasive inlet member 210g is in communication with the interior portion (not numbered) of the pressurized tank 112 such that abrasive particles within the pressurized tank 112 may flow into the abrasive inlet member 210c and thereafter into the mixing chamber 210d.
The housing 210 is further formed having interior threads 210h adjacent fluid inlet end portion 210a, having a stepped surface 210i adjacent interior threads 210h and further having bore 210j formed adjacent stepped surface 210i, with radial flange 210k adjacent bore 210j. Radial surface 210l with radial flange 210k abuts counterbore 210m adjacent discharge outlet end portion 210b, with interior threads 210n between counterbore 210m and the discharge outlet end portion 210b. Cleanout plug 152 of clean-out means C is preferably threadebly mounted with a suitable threaded opening 210o formed in the lower portion of the central body member 210e. It should be noted that preferably, the threaded opening 210o is longitudinally aligned with the longitudinal axis of the abrasive inlet member 210g to enhance proper cleanout thereof during maintenance operations.
The control valve assembly A of the present invention further includes a mandrel 214 adapted to be mounted with the fluid inlet end portion 210a of the housing 210. The mandrel 214 is preferably formed having a tool receiving surface 214a adjacent end 214b on the exterior surface thereof. Exterior threads 214c are preferably formed adjacent to tool receiving surface 214a and compatible with interior threads 210h of housing 210. Radial surface 214d is formed adjacent to thread 214c with sleeve receiving surface 214e abutting radial surface 214d. Sleeve receiving surface 214e extends between radial surface 214d and end 214f. Bore 214g extends from end 214f therethrough mandrel 214 further having threaded counterbore 214h formed in axial alignment with bore 214g adjacent end 214b.
The abrasive control nozzle N includes nozzle 216 adapted to be mounted with the mandrel 214 adjacent and 214f. The nozzle 216 includes a bore 216a, a preferably conically-shaped end portion 216b, a flat annular surface 216c, an attachment flange 216d, and abutting surface 216e. The bore 216a of nozzle 216 is adapted to be longitudinally aligned with the bore 214g of mandrel 214. Seal 176 of seal means S is adapted to be disposed on flat annular surface 216c of nozzle 216 with surface 176 a engaging same while surface 176b abuts the attachement flange 216d.
Seal means S is secured in position by sleeve 218 having conical end surface 218a for engaging conical surface 176c of seal 176. Conical end surface 218a is formed adjacent end 218b of sleeve 218. Sleeve 218 has a bore 218c, an outer annular surface 218d, and stepped annular surface 218e. Preferably, a recess 218f is formed on outer annular surface 218d and adapted to receive a seal 220 which sealably engages stepped surface 210i of housing 210. The sleeve 218 not only positions seal 176 appropriately on the nozzle 216 but further engages attachment flange 216d of nozzle 216 for securing the nozzle 216 with the mandrel 214. A seal 222 of any suitable material is disposed between attachment flange 216d of nozzle 216 and end 214f of mandrel 214 to prevent fluid leakage therebetween such surfaces and the bore 218c of sleeve 218. In assembly, mandrel 214 is threaded by exterior threads 214c into interior threads 210h of housing 210, end 214f of mandrel 214 engages seal 222 and attachment flange 216d of nozzle 216 with end 218b of sleeve 218 constraining the attachment flange 216d from movement with the sleeve 218 having shoulder 218g engaging shoulder 210p of housing 210 in an abutting relation to secure the nozzle 216 snugly between sleeve 218 and mandrel 214.
The control valve assembly A of the present invention further includes a tubular abrasive flow pipe P including flow pipe 224. The flow pipe 224 has a bore 224a, a first end 224b extending into the mixing chamber 210d, a second end 224c extending outwardly from the discharge outlet end portion 210b and an exterior surface 224d. The flow pipe 224 is adapted to be disposed within the discharge outlet end portion 210b of housing 210. The flow pipe 224 is movably disposed within the housing 210 and mounted therewith by means of seal retainer 226.
The seal retainer 226 has exterior threads 226a for engaging interior threads 210n on housing 210 and further includes a bore 226b for disposing the flow pipe 224 therein such that the external surface 224d thereof has an outside diameter slightly smaller than the bore 226b of seal retainer 226. An inner recess 226c is formed in bore 226b for receiving gasket 228 for sealably engaging the exterior surface 224c of flow pipe 224. Recess 226d is preferably formed adjacent exterior threads 226a for receiving a suitable seal 230, such as an O-ring or the like for sealably engaging counterbore 210m of housing 210. End portion 226e of seal retainer 226 is adapted to engage packing gland gasket 232 between end portion 226e and radial surface 210l and radial flange 210k of housing 210. Rotation of the seal retainer 226 by engagement of the tool receiving surfaces 226f of the seal retainer 226 with a tool (not shown) results in rotation of the seal retainer 226 within threads 210n for appropriately packing the packing gland gasket 232 in position such that the packing gland gasket 232 engages end portion 226e, radial surface 210l, radial surface 210l, radial flange 210k, and exterior surface 224c of flow pipe 224 in a sealing relation.
The flow pipe 224 has threads 224e formed adjacent second end 224c for threadedly receiving hose coupling 234. Preferably, house coupling 234 is formed having a collar 234a for receiving pin 236 as described more fully hereinbelow. Hose coupling 234 is adated to secure the abrasive hose 116 with the control valve assembly A of the present invention.
The control valve assembly A further includes moving means M for moving the abrasive control nozzle N and the tubular abrasive flow pipe P relative to one another to and from an open abrasive fluid mixing position as shown in FIG. 3A and from and to a closed position, as shown in FIG. 3, respectively. The moving means M includes lever means L that is pivotally mounted with the second end 224c of the flow pipe 224 for moving the flow pipe 224 to and from the closed position and from and to the open position, respectively. The lever means L preferably includes lever 238, preferably of a right-angular configuration having arms 238a , 238b preferably substantially perpendicular to each other. The lever 238 is preferably supported by support bracket 240 which is secured by fasteners 242 to support tab 244 mounted with the control valve housing H in any suitable fashion. The support bracket 240 may parallel the exterior surface of pressurized tank 112 and is preferably formed having a central opening 240a formed therein and adapted to receive pin 246 for pivotally mounting the lever 238 therewith adjacent arm juncture 238d. Lever arm 238a of lever 238 is preferably pinned to hose coupling 234 by pin 236.
The lever means L further includes a pneumatic cylinder 247 including pneumatic cylinder housing 248 adapted to be mounted with support bracket 240. Cylinder mount 240b secured to end 240c of support bracket 240 mounts the pneumatic cylinder housing 248 with support bracket 240 by fasteners 250, which may be of a bolt and nut configuration 250a, 250b, as shown, or any other suitable fastening device, for securing housing tabs 248g with cylinder mount 240b. The pneumatic cylinder 247 preferably includes a piston, schematically shown as 248a having an upper piston surface 248b and a lower piston surface 248c. The pneumatic cylinder 248 further includes a lower inner surface 248d such that a spring 248e may be appropriately disposed between the lower inner surface 248d and the lower piston surface 248c of piston 248c. Piston rod 248f is connected with lower piston surface 248c of piston 248a and extends outwardly therefrom pneumatic cylinder housing 248 having an adjusting rod 252 threadedly attached thereto. Clevis 254 is adapted to threadedly receive adjusting rod 252, with the clevis 254 being appropriately pinned to lever arm 238b by pin 256. Adjusting screw 258 is preferably mounted with lever arm 238b by threads 258a of adjusting screw 258 engaging threads 238c formed in arm 238b. Further, the adjusting screw 258 has an end portion 258b which is adapted to engage surface 240d of bracket 240 as described more fully hereinbelow.
In the use or operation of the control valve assembly A as shown in FIGS. 3 and 3A, fluid pressure in the direction of arrow 78 from metering valve 30 (FIG. 1) through fluid control line 126 acts upon the upper piston surface 248b of piston 248a of pneumatic cylinder 247 resulting in downward urging of piston rod 248f, adjusting and 252, and clevis 254. This downward movement acts through pins 256, 246 and 236 resulting in longitudinal movement of the flow pipe 224 such that first end 224b of flow pipe 224 sealably engages seal 176 of seal means S. As such, the control valve assembly A of the present invention is in a closed position wherein no mixing of abrasive and high pressure fluid occurs. Release of fluid pressure in fluid control line 126 by actuation of remote control valve 18 and thus, metering valve 30 results in removal of the fluid pressure on upper piston surface 248b. Spring 248e acts upon lower piston surface 248c of piston 248a with the piston 248a moving upwardly within the pneumatic cylinder housing 248. The upward movement of the piston 248a is translated by lever means L and pins 256, 246, 236 to the hose coupling 234 for withdrawing the flow pipe 224 from engagement with the seal means S. As such, abrasive particles under pressure from pressurized tank 112 within mixing chamber 210d are allowed to flow into the bore 224a of flow pipe 224 to mix with high pressure fluid entering the control valve assembly A as regulated by metering valve 30. The high pressure fluid flows through bore 214g of mandrel 214, through bore 216a of nozzle 216 into bore 224a of flow pipe 224. An orifice 199 is formed adjacent adjacent and between the end 224b of flow pipe 224 and the nozzle 216 of the abrasive control nozzle N. A combination of venturiaction across the nozzle 216 and the pressurized flow of abrasive particles from pressurized tank 112 results in dispersion and entrainment of the abrasive particles in the high pressure fluid within the bore 224a of the flow pipe to thereafter be directed outwardly through hose coupling 234 to the tubular conduit or abrasive hose 116 for use as described above. Rotation of adjusting screw 258 controls the relative size of orifice 199 available for introducing the abrasive into the high pressure fluid flow. Gaskets 228, 232 prevent any fluid-particle leakage between flow pipe 224 and the seal retainer 226 upon the sliding, longitudinal movement of the flow pipe 224 within the control valve housing H of the present invention. Upon release of the remote control valve 18, the pneumatic cylinder 147 is again pressurized for returning the control valve assembly to its closed position. It will be appreciated that the pneumatic cylinder 247 could alternatively be of a "double-acting" type having fluid responsive movement to fluid pressure acting on lower piston surface 248c by appropriate porting and removal of spring 248e. Further, the spring 248e may be alternatively disposed between the upper piston surface 248b of piston 248a and upper inner surface 248m of the pneumatic cylinder housing 248 as shown as 248e' for resiliently urging the tubular abrasive flow pipe P into the closed position when no fluid pressure is imposed in the pneumatic cylinder housing 248. In this instance, fluid control line 126 would necessarily communicate with the chamber between lower piston surface 248c and lower inner surface 248d of housing 248.
The control valve assembly A of the present invention further includes a third embodiment as shown in FIG. 4. This structure is similar in many respects to that of FIGS. 2 and 2A. That structure that is substantially identical to the control valve assembly A as shown in FIGS. 2 and 2A will be referenced with the same numerals as used in FIGS. 2 and 2A, but preceded by the numeral "3" using the exact alpha-numeric digits thereafter. Differing structure will be signified by the use of 400-499 series numbers.
As shown in FIG. 4, the control valve assembly A of the present invention includes a control valve housing H. The control valve housing H includes housing 436 having a fluid inlet end portion 436a and a discharge outlet end portion 436b. An abrasive inlet 436c is formed between the fluid inlet end portion 436a and discharge outlet end portion 436b. A mixing chamber 436d is formed within the housing 436 in communication with the abrasive inlet 436c.
The fluid inlet end portion 436a includes end plate 436e and flange plate 436f. End plate 436e is affixed to flange plate 436f by suitable fasteners 438, such as bolts, screws or the like, and the flange plate 436f is preferably formed having a tubular member 436g and outer flange 436h formed therewith with flange 436h at the end opposing the flange plate 436f. Preferably, flange plate 436f, tubular member 436g and flange 436h are formed of a one-piece construction. Flange 436h is affixed to central body member 436i by fasteners 444 such as bolts 444a or the like.
The central body member 436i is formed having the mixing chamber 436d therein. The central body member 436i has a top opening 436j, a bottom opening 436k, and a side opening 436y, all in communication with and adjacent to the mixing chamber 436d. Abrasive inlet member 436m is mounted with the top opening 436j of the central body member 436i by suitable weldments 446 with the abrasive inlet member 436m having the abrasive inlet 436c formed therein and communicating with the mixing chamber 436d. The abrasive inlet member 436m is adapted to be mounted with the neck portion 312a adjacent the lowermost end of the pressurized tank 312 in any suitable manner having an appropriate seal 348 disposed therebetween for preventing fluid or particle leakage therebetween. Thus, the control valve housing H is mounted with the pressurized tank 312 above the abrasive inlet 436c. The abrasive inlet 436c communicates with the interior portion (not numbered) of the pressurized tank 312 for receiving abrasive particles therein. The conically-shaped base 312b of the pressurized tank 312, adjacent to and above the neck portion 312a, directs abrasive particles within the pressurized tank 312 thereinto the neck portion 312b and into the abrasive inlet 436c within abrasive inlet member 436m.
Preferably, the central body member 436i is formed having an abrasive pipe sleeve 436n therewith, having interior threads 436p formed therein which are adapted to receive corresponding exterior threads 336r formed on the exterior surface of adjusting ring 336q, with the adjusting ring 336q being rotatable within the interior threads 436p. A suitable detent 336s is formed in the adjusting ring 336q to receive an appropriate tool (not shown) for rotating adjusting ring 336q with respect to the abrasive pipe sleeve 436n. Locking ring 336t is formed having internal threads 336u which threadedly engage exterior threads 336r of the adjusting ring 336q. By threaded rotation of the locking ring 336t, such that the end surface 336v thereof engages end surface 436w of the abrasive pipe sleeve 436n, relative movement of the adjusting ring 336q with respect to the abrasive pipe sleeve 436n and locking ring 336t is prevented.
The control valve assembly A of the present invention further includes a tubular abrasive flow pipe P adapted to be mounted with the discharge outlet end portion 436b of the housing 436. The tubular abrasive flow pipe P includes flow pipe 360 which is substantially identical with flow pipe 60 of FIGS. 2, 2A and described fully hereinabove. The flow pipe 360 has a bore 360a extending therethrough, further having a first end 360b extending into the mixing chamber 436d of the housing 436, and a second end 360c extending beyond the discharge outlet end portion 436b of the housing 436. The flow pipe 360 is adapted to be disposed within the opening 436y formed in the central body member 436i with seal 362 preventing any fluid migration between the exterior surface 360d of the flow pipe 360 and the opening 436y of the central body member 436i. The flow pipe 360 has detents 360e, 360f formed on the exterior surface 360 thereof for receiving retaining rings 364, 366, respectively. The flow pipe 360 is further adapted to be disposed within the bore 336y formed in adjusting ring 336q with the outside diameter of exterior surface 360d being slightly smaller in diameter than bore 336y. Counterbore 336z formed in adjusting ring 336q allows disposition of the retaining ring 366 in the counterbore 336z and properly positioned within detent 360f while detent 360e receives retaining ring 364. The retaining rings 364, 366 locate the adjusting ring 336q with respect to the flow pipe 360 while allowing relative rotation of adjusting ring 336q with respect to the exterior surface 360d of the flow pipe 360. Rotation of adjusting ring 336q in threads 336p results in longitudinal movement of the flow pipe 360 with respect to opening 336k and further regulates the extension of the first end 360b of the flow pipe 360 into the mixing chamber 436b of the housing 436.
Flow pipe 360 is further formed having exterior threads 360g adjacent second end 360c to threadedly receive abrasive hose coupling 368. The abrasive hose coupling 368 is threaded onto exterior threads 360g at one end thereof and is adapted to receive the tubular conduit abrasive hose 316 adjacent the other end thereof for use in the abrasive blasting system 10.
The control valve assembly A of the present invention further includes an abrasive control nozzle N mounted in substantial longitudinal alignment with the tubular abrasive flow pipe P with the abrasive control nozzle N being disposed within the tubular abrasive flow pipe P. The abrasive control nozzle N includes nozzle 370 having a bore 370a therethrough, an exterior conically-shaped end portion 370b, a flat annular surface 370c, an attachment flange 370d, and an abutting surface 370e. The exterior conically-shaped end portion 370b is preferably disposed within the tubular abrasive flow pipe P adjacent the similarly formed, conically-shaped end portion 360h. Seal means S is preferably disposed on the flat annular surface 370c as discussed more fully hereinbelow. Mounting ring 372 is adapted to engage attachment flange 370d of the nozzle 370 for securing the nozzle 370 to the mandrel 480 adjacent second end 480d as discussed more fully hereinbelow while further locating and securing the seal means as with the nozzle 370.
The control valve assembly A of the present invention further includes seal means S for sealing between the first end 360b of the flow pipe 360 and nozzle 370 when the flow pipe 360 and nozzle 370 are in a closed position as shown in FIG. 4. Preferably, the seal means S includes seal 376 having an inner bore 376a adapted to engage annular surface 370c of nozzle 370. Surface 376b of nozzle 376 is adapted to fit in abutting relation with the attachment flange 370d. The seal 376 further includes a conical, exterior surface 376c adapted to abut conical interior surface 372a of mounting ring 372. As such, when the mounting ring 372 is fastened with the nozzle 370 and mandrel 480, the seal 376 is held in position on the annular surface 370c and attachment flange 370d of nozzle 370 by the conical interior surface 372a of the mounting ring 372 so engaging the conical exterior surface 376c of seal 376. The seal 376 may be of any suitable sealing material such as butyl rubber, leather, "Teflon", polyvinyl chloride, or any other suitable sealing material.
The control valve assembly A of the present invention further includes a mandrel 480 adapted to be movably mounted with the control valve housing H in substantial longitudinal alignment with the tubular abrasive flow pipe P. The mandrel 480 has a first end 480a adapted to be movably disposed adjacent the fluid inlet end portion 436a of housing 436 and has a second end 480b extending into the mixing chamber 436d of the housing 436. The mandrel 480 further includes a bore 480c extending therethrough, with the exterior surfaces of the mandrel 480 including spring mounting surface 480d adjacent first end 480a, a radial lip 480e adjacent the second end 480b, engaging surface 480f adjacent radial lip 480e, with radial surface 480g therebetween engaging surface 480f and spring mounting surface 480d. Engaging surface 480f is adapted to be disposed in tubular member 436g of the housing 436 for longitudinal movement therein. Similarly, spring mounting surface 480d is adapted to be disposed in bore 413a of spring retainer 413. Spring retainer 413 is adapted to be mounted with the end plate 436e of the housing 436 in threaded opening 436o formed in the end plate 436e by suitable threads 413b engaging such threaded opening 436o. Interior threads 413c are formed adjacent the bore 413a for threadedly connecting the control valve assembly A of the present invention with the high pressure fluid flowing in the direction of arrow 14 (FIG. 1) having passed through metering valve 30 thereinto member 32 for connection therewith spring retainer 413 by fluid line 415.
Appropriate sealing members such as seals 417, 419 formed of a suitable sealing material provide for sealable movement of surfaces 480d, 480f of the mandrel 480 within bore 413a, tubular member 436g, respectively. The spring mounting portion 480d of mandrel 480 has an outside diameter corresponding substantially to that of bore 413a formed in spring retainer 413 and mounted adjacent fluid inlet end portion 436a. The seal 417 mounted within the bore 413a allows for movement of the mandrel 480 longitudinally with respect to the bore 413a adjacent spring mounting surface 480d without fluid migration therebetween the spring mounting portion 480d and the bore 413a.
The control valve assembly A of the present invention further includes moving means M for moving the abrasive control nozzle N and the tubular abrasive flow pipe P relative to each other between an open abrasive fluid mixing position and the closed position as shown in FIG. 4. The moving means M includes diaphragm means D mounted with the control valve housing H and the mandrel 480 for allowing fluid pressure responsive movement of the mandrel 480 to and from the closed position from and to the open position, respectively, as discussed more fully hereinbelow.
The diaphragm means D includes a first diaphragm 496 mounted with the control valve housing H and mandrel 480. The outer portion 496a of the first diaphragm 496 is preferably secured with the control valve housing H therebetween end plate 436e and flange plate 436f by fasteners 438, in an abutting, fluid-tight relation. The inner portion 496b of the first diaphragm 496 is disposed between diaphragm mounting rings 421, 423 and is secured therewith by fasteners 425. The bores 421a, 423a are of slightly larger diameter than the spring mounting surface 480d of the mandrel 480 and adapted to be positioned thereon with diaphragm mounting ring 421 abutting radial surface 480g of the mandrel 480. Retaining ring 425 locates the diaphragm mounting rings 421, 423--diaphragm 496 assembly therebetween the radial surface 480g and the retaining ring 425, being mountable in a suitable detent 480h formed in the spring mounting surface 480d. Further, preferably a suitable seal 427 is mounted with the mandrel 480 adjacent detent 480h for engaging bore 423a of diaphragm mounting ring 423 to prevent any fluid migration therebetween.
A closure chamber 486 is formed therebetween the first diaphragm 496, the end plate 436 of fluid inlet end portion 436a of housing 436 and spring retainer 413 within the control valve housing H. Opening 488 formed in end plate 436e is adapted to threadedly receive fluid line 429 which is in communication with closure chamber 86 for venting of the same as discussed more fully hereinbelow. A spring 431 is preferably mounted in the closure chamber 486, being disposed about the spring mounting surface 480d and therebetween diaphragm mounting ring 423 and counterbore 413d formed in spring retainer 413 for resiliently urging the mandrel 480-abrasive control nozzle N-seal means S into engagement with tubular abrasive flow pipe P.
An opening chamber 487 is formed therebetween flange plate 436f of housing 436, first diaphragm 496, diaphragm mounting ring 421, and engaging surface 480f of mandrel 480. Threaded opening 489 formed in flange plate 436f is adapted to threadedly receive fluid control line 426 which is in communication with opening chamber 487. As such, the opening chamber 487 communicates with the fluid source through fluid control line 426 such that in response to fluid moving in the direction of arrow 478 through fluid control line 426, fluid pressure in opening chamber 487 urges against the first diaphragm 496 such that the mandrel 480 moves from the closed position of FIG. 4 to an open position (not shown).
The diaphragm means D further includes a second diaphragm 498 mounted with the control valve housing H and between the second end 480b of the mandrel 480 and the abrasive control nozzle N. The abrasive control nozzle N is preferably mounted with the second end 480b of the mandrel 480 in substantial longitudinal alignment with the tubular abrasive flow pipe P. Inner portion 498a of the second diaphragm 498 is preferably disposed between the attachment flange 370d of the nozzle 370 and the second end 480b of the mandrel 480 and secured thereto by fasteners 374 extending through mounting ring 372, attachment flange 370d, inner portion 498a of second diaphragm 498, and thereinto mandrel 480 adjacent second end 480b, resulting in a fluid-tight, abutting relation therebetween. The outer portion 498b of the second diaphragm 498 is secured with the control valve housing H by being disposed therebetween the central body member 436i and flange 436h and secured therebetween by fasteners 444 extending through flange 436h, outer portion 498b of second diaphragm 498 and into central body member 436i, resulting in an abutting fluid-tight relation.
A balancing chamber 491 is formed therebetween the second diaphragm 498, radial lip 480e of mandrel 480 and flange 436h of housing 436. Threaded opening 493 formed in tubular member 436g of housing 436 is adapted to threadedly receive fluid line 433 which is in communication with balancing chamber 491. Sleeve 435 is adapted to be disposed within tubular member 436g with the bore 435a of sleeve 435 being of substantially the same diameter as that of engaging surface 480f of the mandrel 480. The sleeve 435 is preferably disposed within the tubular member 436g in counterbore 436z, formed adjacent thereto. The sleeve 435 has a suitable reduced neck portion 435b having a smaller outside diameter than the inside diameter of counterbore 436z for providing an annular passageway 437 therebetween neck portion 435 and counterbore 436z for communication therebetween threaded opening 493 and balancing chamber 491.
The control valve assembly A of the present invention further includes cleanout means C in communication with the mixing chamber 436b for cleaning abrasive particles therefrom during non-blasting periods. Cleanout means C preferably includes a cleanout plug 352 having threads 352a to be threadedly received in threaded bottom opening 436k of the central body member 436i of housing 436. Preferably, threaded opening 436k is in substantial longitudinal alignment with abrasive inlet 436c to provide ease in cleaning-dislodging clogging particles therein the mixing chamber 436d as described fully hereinabove.
In the use or operation of the control valve assembly A of the present invention as shown in FIG. 4, the control valve assembly A is in a closed position. As such, the first end 360b of flow pipe 360 is in a sealing, abutting relation with the seal 76 of seal means S. This sealing relationship is maintained because of the positive, resilient urging of the spring 431 therebetween spring retainer 413 and diaphragm mounting ring 423, longitudinally towards the first end 360b of the flow pipe 360 to insure a sealable relation therebetween seal 376 and first end 360b of flow pipe 360. Actuation of the remote control valve 18 (FIG. 1) of the abrasive blasting system 10 results in actuation of metering valve 30 wherein fluid pressure acting in the direction of arrow 478 (FIG. 4) is directed into the opening chamber 487. Fluid pressure in opening chamber 487 acts upon first diaphragm 496 to result in longitudinal movement of the mandrel 480 towards the spring retainer 413 once the resilient spring force of spring 431 is overcome. Any unwanted pressure buildup in closure chamber 486 is vented outwardly therefrom through opening 488 and fluid line 429 to prevent any back pressure upon the diaphragm 496. Fluid pressure in opening chamber 487 moves the mandrel 480 having the nozzle 370 therewith out of engagement with the first end 360b of the flow pipe 360.
When the first end 360b of the flow pipe 360 moves out of contact with the seal 376, mixing of the abrasive from the pressurized tank 312 with high pressure fluid flowing through fluid line 415, and therethrough bore 480c of mandrel 480 is permitted in orifice 499 formed adjacent to and between the abrasive control nozzle N and the tubular abrasive flow pipe P. As discussed hereinabove, the abrasive flows from within the mixing chamber 436d into orifice 499 between conical end portion 370b of the nozzle 370 and preferably, a similarly shaped conical interior surface 360h of flow pipe 360 adjacent first end 360b. High pressure fluid flowing in the direction of arrow 14 enters into bore 480c of mandrel 480 adjacent first end 480a, thereafter flowing into bore 370a of nozzle 370 having a reduced cross-sectional area resulting in Venturi-action across the nozzle 370. This Venturi-action in addition to fluid pressure on the abrasive particles within the mixing chamber 436d from pressurized tank 312 results in abrasive particles flowing through orifice 499 into flow pipe 360 adjacent position 497, where the abrasive is entrained within the high pressure fluid.
The highly fluid-pressurized abrasive is directed through the bore 360a of flow pipe 360 and outwardly therefrom into a tubular conductor such as the high pressure abrasive hose 316 to thereafter be discharged in the direction of arrow 22 (FIG. 1) from outlet nozzle 20 for use in abrasive blasting operations. Upon release of the remote control valve 18, positive fluid pressure in the direction of arrow 478 into opening chamber 387 is terminated for closing control valve assembly of the present invention for preventing mixing of high pressure fluid and abrasive in the closed position. This release of pressure results in the spring 431 resiliently closing the control valve assembly A.
It should be noted that fluid line 433 is preferably mounted with the top (not shown) of the pressurized tank 312 for receiving filtered air therefrom. As is discussed hereinabove, the pressurized tank 312 is pressurized and accordingly, it is desirable that filtered air from the pressurized tank 312 be directed therefrom pressurized tank 312 through fluid line 433 therethrough passage 437 into balancing chamber 491 so that no pressure differential acts across the diaphragm 498 inasmuch as the mixing chamber 436d is in communication with the pressurized abrasive within the pressurized tank 312. The diaphragm 498 prevents the abrasive particles from damaging the moving surfaces of the mandrel 480. However, due to the resilient spring action of spring 431, it is desirable that no pressure differential be experienced across the diaphragm 498, hence the balancing chamber 491 and mixing chamber 436b, inlet chamber 436c and pressurized tank 312 are all at substantially the same fluid pressure levels.
It will be appreciated that the embodiment of FIG. 4 is of a "fail-safe" design inasmuch as it utilizes spring 431 to close the control valve assembly and fluid pressure applied to diaphragm 496 through opening chamber 487 to open to the control valve assembly A. This is a very desirable mode of operation inasmuch as the control valve assembly A will automatically close in the event that fluid pressure in the direction of arrow 478 is lost. Furthermore, this "fail-safe" feature may furthermore be incorporated with the embodiment of FIGS. 3, 3A by altering the spring location of spring 248e (FIG. 3) and fluid control line 126 by mounting the spring 148e therebetween upper piston surface 248b and upper inner surface 248m with control line 126 being mounted with the lower inner surface 248d of pneumatic cylinder 248. In such a configuration, the control valve assembly A would be maintained in its closed position due to spring 248e acting on upper piston surface 248b. The control valve assembly A will open upon fluid pressure acting in the direction of arrow 78 acting upon lower piston surface 248c once the resilient force of spring 248e is overcome to thereafter open the control valve assembly A.
Thus, the control valve assembly A of the present invention provides a new and improved control valve for use with abrasive blasting systems wherein positive on-off control may be maintained at the pressurized tank without requiring the dumping of tank pressure to deactivate the abrasive system. Further, the control valve assembly A while having multiple built-in safety features is easily maintainable and adapted to be used with a wide variety of abrasive particles for various blasting procedures.
The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

Number	Name	Date
RE21275	Pletcher	Nov 1939
509992	Wood	Dec 1893
2608801	Ridley	Sep 1952
3102368	Smith	Sep 1963
3359024	Morgan	Dec 1967
3970280	Kunz	Jul 1976

Control valve assembly

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CPC

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Abstract

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