Abstract:
An externally-mounted, quick-acting trigger assembly for firing blast aerators, air cannons, or the like. The trigger assembly is ideal for high temperature applications involving environmental factors such as excessive heat, humidity, and mechanical shock. The trigger comprises a symmetrical, ventilated housing that internally mounts a hollow piston. A plurality of vent orifices are radially disposed about the housing periphery, and normally covered by a resilient band forming a check valve. The trigger piston comprises a generally cylindrical base and an integral, generally conical bottom that is displaced into and out of contact with a mechanical valve seat. An air passageway through the piston is controlled by a deflectable spherical valve element that is captivated within the piston, for selectively blocking air passage through the piston by contacting an internal valve seat. This construction with internal air passageways facilitates trigger function. The base comprises a circumferential groove for seating an appropriate O-ring.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This utility patent application is based upon, and incorporates the teachings and disclosure of previously-filed and pending U.S. Provisional Patent application Serial No. 60/350,250, which was officially filed Jan. 16, 2002, entitled Quick Release Blast Aerator Trigger Valve, and priority based upon said related prior application is hereby claimed. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    I. Field of the Invention  
           [0003]    This invention relates generally to air-accumulator and discharge devices of the type generally known as air blasters, air cannons, or blast aerators. More particularly, the present invention relates to heavy duty blast aerators of the type classified in United States Patent Class 222, Subclasses 2, 3 and 195 and Class 251, Subclass 30.02.  
           [0004]    II. Description of the Prior Art  
           [0005]    As is well known to those with skill in the art, the passage of bulk materials through conventional handling equipment is often degraded or interrupted. Typical bulk materials comprise concrete mixtures, grains, wood chips or other granular materials disposed within large hoppers or storage bins. In conventional, conically shaped hoppers, for example, bridges or arches of bulk materials often form, preventing or minimizing the orderly flow or delivery of granular materials. Often, “rat holes” or funnels build up, and material passage is severely degraded or halted altogether. Particles of bulk material may form cohesive bonds either by adhesion due to chemical or electrostatic attraction, or particles may interlock because of horizontal and vertical compression. Such materials usually tend to cake or congeal during bulk processing. When moisture accumulates, unwanted caking tends to block flow. It is also recognized that friction between bulk material and the walls of a typical bunker or hopper in which the material is confined tends to interfere with proper flow.  
           [0006]    Blast aerators or air cannons have long been employed to dislodge blocked or jammed bulk material. Storage bins or hoppers, for example, are often fitted with one or more high pressure air cannons that periodically blast air into the interior to dislodge caked particles, break funnels and bridges, and destroy rat holes. Bulk flow problems can temporarily be stopped by physically vibrating the hopper or container to shake loose the jammed materials. But not all materials may be dislodged in this manner. For example, large concrete bunkers may be impossible to vibrate. Materials like soft wood chips ordinarily absorb vibratory energy and must be dislodged by other methods.  
           [0007]    Air blasters are preferred over vibrators because of efficiency. The forces outputted by blast aerators are applied directly to the material to be dislodged, rather than to the walls of the structure. Modern air blasters are also preferred over air slides, air wands, and various air screen devices which operate at low pressures. Live bottoms in hoppers or bins are limited in their effectiveness, since they may tend to create bridging or arching of material. Modern air cannons or blast aerators are intended for use as a flow stimulator against materials that are primarily moved by gravity. They are not intended to be the prime movers of such materials, and for safety purposes they should not be used to initiate the flow or movement of bulk materials unless a gravity feed is employed.  
           [0008]    Typical blast aerators comprise a large, rigid holding tank that relatively slowly accumulate air supplied through standard, high pressure air lines available at typical industrial facilities. A special valve assembly associated with the tank includes a high volume discharge opening directed towards or within the target application. External, solenoid-activated valve assemblies are employed to periodically activates the air cannon, whereupon the large volume of air that was slowly accumulated in the holding tank is rapidly, forcibly discharged within a few milliseconds. The volume of compressed air released by a modern blast aerator strikes the bulk material at a rate over 1000 feet per second. Materials exposed to this high volume inrush are forcibly dislodged by impact. The large volume of air outputted by the aerator spreads throughout the bin or hopper, distributing forces throughout the interior that tend to homogenize and dislodge the mixture. After an exhaust blast, the actuator assembly signals the apparatus to return to a “fill” position, wherein the displaceable internal blast piston blocks the aerator blast output path. The cycle repeats as air that has relatively slowly accumulated again within the blaster is subsequently discharged during the next cycle.  
           [0009]    U.S. Pat. No. 4,469,247, issued Sep. 4, 1984, and owned by Global Manufacturing Inc., discloses a blast aerator for dislodging bulk materials. The blast aerator tank has a blast discharge opening coaxially aligned with its longitudinal axis. The blast discharge assembly comprises a rigid, tubular discharge pipe comprising an internal shoulder that forms a valve seat. A resilient piston coaxially, slidably disposed within the pipe abuts the valve seat to seal the tank during the fill cycle. In the fill position the seal is maintained by a chamfered end of the piston that matingly, sealingly contacts a similarly chamfered seat portion of the valve seat assembly. A cavity at the piston rear is pressurized to close the valve by deflecting the piston. During periodic cycles, discharge occurs in response to cavity venting, whereupon the piston is rapidly displaced away from the valve seat, exposing the discharge pipe opening to the pressurized tank interior.  
           [0010]    Similar blast aerators may be seen in U.S. Pat. Nos. 3,651,988; 3,915,339; 4,197,966; 4,346,822; and 5,143,256. Other relevant blast aerator technology may be seen in Great Britain Pat. Nos. 1,426,035 and 1,454,261. Also relevant are West German Patent 2,402,001 and Australian Pat. No. 175,551.  
           [0011]    Global Manufacturing patent No. 4,496,076 teaches a method of employing a plurality of air cannons in a controlled array.  
           [0012]    In some prior art aerator designs, the piston and valve assembly are disposed at a right angle relative to the discharge flow path. In addition, many blast aerators use a valve assembly that is mounted externally of the accumulator tank. The latter design features are seen in U.S. Pat. Nos. 3,942,684; 4,767,024; 4,826,051; 4,817,821; and 5,853,160.  
           [0013]    U.S. Pat. No. 5,441,171 discloses a protrusion on the rear of a slidably captivated piston to help slow the piston after firing. This design does not bleed air off in a controlled fashion and in fact the protrusion does not shut off the flow of air out of the valve body.  
           [0014]    U.S. Pat. No. 5,517,898 discloses a pneumatic cylinder in which coaxially disposed “pistons” include dampening sleeves. In other words, ports are interconnected with internal passageways including stein portions of the cylinder to dampen piston movement by compressed air.  
           [0015]    During the hundreds of thousands of repetitive discharge cycles occurring over the normal life of a typical blast aerator, critical moving parts will inevitably wear and deform. Typical aerator actuating pistons encounter extremely high stresses from heat, friction, and pressure that eventually result in component failure. As the aerator piston deforms or wears, its ability to properly seal during the critical “fill cycle” is impaired. In many prior art designs that portion of the piston utilized to create a seal also functions as the working surface upon which tank pressure acts to force the piston to its rearward “blast” position, further aggravating component stress and shortening valve life. In operation, the blast piston must rapidly travel away from the seal during the discharge cycle. As it deforms over hundreds of thousands of blast cycles however, it may lose its symmetry, and misalignment within the valve tube can slow piston travel, enlarging the blast time period and denigrating the force of the discharge.  
           [0016]    Of course, problems with wear and tear also afflict the exhaust valve or actuator assembly that triggers the blast aerator. A variety of solutions have been proposed in the prior art for controlling blast aerator assemblies. All of the aforementioned patents disclose some means for firing the aerators. Various venting means including electrical solenoids have been provided previously. All of these are intended to periodically vent critical, internal volumes of aerators, ultimately causing a blast discharge. Many of the actuator devices cyclically facilitate subsequent tank filling after a blast. When typical blast aerators are fired, the large blast piston is partially deflected by actuator ventilation, retreating from a sealed, blocking position to open and expose the discharge passageways for a blast. In use, the actuator solenoid assemblies are subject to repetitive, stressful firings, in conditions involving heat, humidity, and constant vibrations.  
         SUMMARY OF THE INVENTION  
         [0017]    The invention comprises an accessory trigger or actuator assembly for detonating blast aerators, and a blast aerator equipped with the improved system. A preferred embodiment is ideal for high temperature applications involving environmental factors such as excessive, heat, humidity, and mechanical shock. The trigger comprises a unique symmetrical and ventilated housing that mounts a miniature internal piston. The trigger piston comprises a generally cylindrical, base and an integral, generally conical head. The base comprises a circumferential groove for seating an appropriate O-ring.  
           [0018]    A rigid, ventilated housing internally mounts a hollow, reciprocating piston. A plurality of vent orifices radially disposed about the housing periphery are normally covered by a resilient band. The band may be deflected away from the orifices in response to sufficient air pressure, thus functioning as a check valve. The captivated, generally cylindrical piston is lightweight and hollow. It&#39;s integral, generally conical bottom is displaced into and out of contact with a mechanical valve seat within a cylinder formed internally of the housing. An air passageway through the piston is controlled by a deflectable ball forming a valve element that is captivated within a tapered chamber inside the piston. The ball valve selectively blocks various air passages through the piston by contacting an internal valve seat. This construction with internal air passageways facilitates trigger function. The base comprises a circumferential groove for seating an appropriate O-ring.  
           [0019]    Thus a major object is to provide a lightweight, high speed trigger mechanism for activating blast aerators, air cannons and the like.  
           [0020]    Of course a related object is to provide a blast aerator equipped with such a trigger.  
           [0021]    A basic object is to provide a highly reliable trigger device for blast aerators or air cannon that resists high temperatures and other stresses encountered in use.  
           [0022]    Another object is to provide a blast aerator trigger of the character described that is of minimal volume and weight.  
           [0023]    A fundamental option is to provide a highly reliable trigger assembly for blast aerators.  
           [0024]    A related object is to speed up control venting systems for blast aerators.  
           [0025]    Another general object of this invention is to provide an aerator trigger assembly whose internal piston is configured for a multiplicity of tasks.  
           [0026]    A still further basic object is to provide a blast aerator trigger of the character described that minimizes the frequency of service calls required in the field.  
           [0027]    A further object is to provide an improved trigger that can be retrofitted to existing blast aerators and air cannons.  
           [0028]    These and other objects and advantages of this invention, long with features of novelty appurtenant thereto, will appear or become apparent in the course of the following descriptive sections.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views:  
         [0030]    [0030]FIG. 1 is a fragmentary, sectional view of a blast aerator equipped with my new, externally mounted quick release trigger valve, with portions thereof shown in section or broken away for clarity;  
         [0031]    [0031]FIG. 2 is a fragmentary, isometric view of a blast aerator equipped with my new, externally mounted quick release trigger valve;  
         [0032]    [0032]FIG. 3 is an exploded isometric view of the blast aerator and trigger valve of FIGS. 1 and 2;  
         [0033]    [0033]FIG. 4 is an enlarged, fragmentary, sectional view of the trigger valve and a portion of the aerator, corresponding generally to circled region  4  in FIG. 1;  
         [0034]    [0034]FIG. 5 is an exploded isometric view of the preferred trigger valve;  
         [0035]    [0035]FIG. 6 is an enlarged, exploded bottom isometric view of the valve cap;  
         [0036]    [0036]FIG. 7 is an enlarged, exploded isometric view of the preferred piston, with portions shown in section for clarity;  
         [0037]    [0037]FIG. 8 is an enlarged, fragmentary sectional view of the preferred piston;  
         [0038]    [0038]FIG. 9 is an enlarged, bottom isometric view the preferred piston;  
         [0039]    [0039]FIG. 10 an enlarged, fragmentary sectional view of circled region  10  seen in FIG. 8;  
         [0040]    [0040]FIG. 11 is an enlarged, sectional and diagrammatic view of the trigger piston and check-valve ball disposed in the aerator filling position;  
         [0041]    [0041]FIG. 12 is an enlarged, isometric and diagrammatic view of the trigger piston and check-valve ball disposed in the aerator filling position, with portions shown in section for clarity;  
         [0042]    [0042]FIG. 13 is an enlarged, sectional diagrammatic view of the valve with the trigger in the aerator-fill position;  
         [0043]    [0043]FIG. 14 is an enlarged, fragmentary, sectional view, with the trigger in the aerator-discharge position;  
         [0044]    [0044]FIG. 15 is an enlarged, fragmentary, isometric view, with the trigger in the aerator-discharge position, showing air paths indicated diagrammatically, and with portions in section for clarity;  
         [0045]    [0045]FIG. 16 is an enlarged, fragmentary, sectional view, with the trigger in the aerator-discharge position, showing air discharge paths diagrammatically;  
         [0046]    [0046]FIG. 17 is an enlarged, fragmentary, isometric view similar to FIG. 15, with the trigger in the aerator-discharge position, showing air discharge paths diagrammatically, and with portions shown in section for clarity; and,  
         [0047]    FIGS.  18 - 21  are sectional views of prior art devices. 
     
    
     DETAILED DESCRIPTION  
       [0048]    With initial reference now directed to FIGS. 1 and 2 of the appended drawings, a blast aerator constructed in accordance with the teachings of this invention is designated generally by the reference numeral  20 . U.S. Pat. No. 6,321,939 issued Nov. 27, 2001 and entitled High Stress Blast Aerator with Dampened Piston, which is owned by Global Manufacturing Inc., the owner of this application, is hereby incorporated by reference for purposes of disclosure.  
         [0049]    Referring initially to FIGS.  1 - 3 , blast aerator  20  comprises a rigid, barrel-like tank  22  of conventional construction that is mounted adjacent or upon a storage bin, hopper or the like. The blast output valve assembly described in U.S. Pat. No. 6,321,939 has been generally designated with the reference numeral  23 . It periodically exhausts compressed air accumulated within the interior  24  (FIG. 1) of the blast aerator tank  22 . Blasts of air are discharged through a standard, twin flange coupling  26  and pipe  27  that extends to the selected bulk material application (i.e., hopper, bin, bulk material storage tank etc.). The valve assembly  23  is coaxially secured within the aerator interior  24  by a rigid, front mounting flange  30  coaxially disposed at the output end  32  of tank  22 , which can be dimensioned in various sizes and shapes.  
         [0050]    My quick exhaust trigger valve assembly  29  is disposed upon tank  22  at the rear or filling end  34  of the tank. Although trigger assembly  29  can be employed with a variety of preexisting blast aerators, in this instance it is coupled in communication with an internal fill tube  36  (FIGS. 1, 3) that leads to valve assembly  23  through tank interior  24 . A conventional source of external, high pressure air is delivered to trigger assembly  29  via pipe  29 A (FIG. 1) in the usual manner, via optional series valve  20 A. A remote electric solenoid valve (not shown) of conventional construction connected to valve  20 A controls the input air flow. Trigger assembly  29  thus allows the blat aerator tank  22  to periodically fill with air, and additionally, it periodically triggers a bast discharge in the manner to be described hereinafter.  
         [0051]    With primary reference directed to FIGS.  4 - 6 , the new trigger assembly  29  comprises a machined, dual diameter steel housing  40  of generally cylindrical proportions. Housing shank portion  80  (FIG. 12) extends downwardly to threaded portion  82  which screws into the aerator tank upon assembly. A tapered, reduced diameter housing discharge end  41  at the bottom of the housing has a central discharge passageway  44  (FIG. 3) in fluid flow communication with internal volume  45 .  
         [0052]    Housing  40  comprises a solid, integral body  46  spaced apart from a preferably circular flange portion  48 , with a reduced diameter central portion  50  (FIG. 4) defined therebetween. Portion  50  comprises a plurality of radially spaced apart orifices  51  that are normally blocked by a resilient, preferably rubber, circumscribing band  54 . This deflectable circumscribing band forms a one-way check valve; it can be deflected outwardly (i.e. in a displacement direction perpendicular to the longitudinal axis of the apparatus) to vent air, but it cannot allow air to enter the interior of the apparatus. Orifices  51  are actually in the form of horizontal passageways oriented perpendicular to the longitudinal axis of the housing. The housing rear end comprises a circular flange  48  that receives an annular cap  52 . Preferably, cap  52  is secured to the flange  48  by a plurality of fasteners  53  that penetrate cap orifices  55  (FIG. 6). These fasteners  53  are threadably received by and registered within aligned, radially spaced apart threaded orifices  57  (FIG. 5) in flange portion  48 . An integral hub  47  coaxially aligned at the center of plate  52  defines a passageway  49 , which is connected to a controlling electric solenoid of conventional construction (not shown) via pipe  29 A (FIG. 1) described previously. A captivated O-ring  58  (FIGS. 5, 6) seals the junction between cap  52  and flange  48 .  
         [0053]    The trigger assembly is preferably screwed unto the aerator tank  22  as in FIG. 3. Tank end  34  (i.e., FIG. 3) has a large, circular, threaded flange  70  (FIG. 4) welded to it. Flange  70  threadably receives the lower threaded portion of body  40  whose passageway  72  communicates with threadably-coupled nipple  76 . Fill pipe  36  previously described mates with nipple  76 . The aligned pipes and bushings provide a fluid flow passageway generally designated by the reference numeral  65  (FIG. 3) that connects the tank interior  24  (FIG. 1) with the trigger assembly interior  45  (FIG. 3).  
         [0054]    Referencing primarily FIGS.  4 - 7 , the trigger piston  60  is slidably disposed within the housing interior  45  (FIG. 4) between cap  52  and body  46 . The cylindrical interior  45  forms a “cylinder” in which piston  60  is dynamically disposed for reciprocal motion. Piston  60  is displaceable between the “fill” position of FIGS. 11, 12, nesting against and within passageway  44 , and a retracted actuating position (i.e., FIGS. 16,17). In the fill position the piston conical bottom  92  (FIG. 8) bears against valve seat  122  (FIG. 12). When disposed in the actuating position, the piston top  63  (FIG. 5) is urged against the underside of cap  52  as seen in FIGS. 16, 17. Piston  60  comprises a generally cylindrical base  90  that is integral with a generally conical bottom  92 . The flat top piston surface  63  seats against surface  52 A of cover  52  when piston  60  is in its upper work cycle point. Conical piston bottom  92  seats against seat  122  within housing  40  when piston  60  is at its lowest point. A plurality of air vents  93  (FIG. 8) are defined in piston bottom  92 , and these are in fluid flow communication with the interior piston passageway  98 . As best seen in FIG. 10, the upper circumferential portion  104  is gently chamfered. A circumferential groove  94  defined in piston base  90  seats a resilient, deflectable O-ring  96  (FIG. 7). The elongated through-passageway  98  includes a chamfered valve seat  98 B (FIG. 8) that is coaxial with the center of the piston. Seat  98 B forms a boundary with a lower, coaxial chamber  100  (FIG. 8) that gradually increases in diameter towards the bottom of the piston. The bottom surface boundary  106 A (FIG. 8) of chamber  100  is radially surrounded by orifices  93  that vent the passageways. A resilient ball  102  forms a check-valve. Movement of the ball  102  is between surface  106 A at the bottom of the chamber  100 , and the upper seat  98 B previously described.  
         [0055]    Operation:  
         [0056]    Referring now to FIGS.  12 - 17 , air enters passageway  49  via the solenoid as indicated by arrow  120  (FIG. 12). This pushes piston  60  downwardly into contact with internal valve seat  122  (FIG. 12) defined within the housing  40  coaxially within body  46  below cylinder  45 . At this time ball  102  is also displaced, and it is deflected downwardly (i.e., as viewed in FIGS.  12 - 16 ) out of contact with its seat  98 B (FIG. 8, 13) formed in the piston. Air now passes through the interior of piston  60 , exiting vents  93  and entering the interior of the blast aerator to fill it, as indicated by arrows  129  (FIG. 6). The air blaster tank fills until the tank is at a sufficient line pressure and remains on standby until fired. The piston  60  stays sealed because of the piston O-rings and the seat-to-surface seals. Since the area exposed to air pressure is larger on the solenoid side than at the tank side, the piston is held firmly against the seat  122 .  
         [0057]    When the solenoid depressurizes passageway  49  (i.e., FIG. 12) at the piston rear, check ball  102  pops upwardly into contact with seat  98 B (FIG. 14) and closes as in FIGS. 14, 16, and  17 . Tank pressure now progressively blows the piston  60  back against housing cap  52  very quickly. As indicated by arrows  130  (FIGS. 14, 16) this backpressure is vented to atmosphere through radially spaced apart, housing orifices  51  (FIG. 16) as the resilient, surrounding band  54  expands. Now pipe passageway  65  (FIG. 3) is depressurized, and tube  36  (FIG. 1) activates the large blast aerator valve assembly  23  to detonate and fire the aerator. After detonation, the pressures equalize, and subsequent overpressure applied by the solenoid to passageway  49  again closes the piston for recharging. The cycle continues in the fashion, as governed by the electrical programming of the control solenoid.  
         [0058]    Prior Art:  
         [0059]    Referring to FIGS.  18 - 21 , prior art devices are discussed. When air indicated by arrow  142  (FIG. 18) is introduced into a conventional inlet port  141 , the diaphragm  143  is forced onto the exhaust seat  147 . The outer lip  148  of the diaphragm  143  is deflected downward, away from the wall, allowing air  144  to flow into the tank with a minimum of restriction through passageway  149  . The diaphragm  143  will remain in on the exhaust seat  147  as long as the inlet pressure is equal to or greater than the tank pressure. Air  145  fill out tank through outlet port  146 . When the tank is fully charged (FIG. 20) and air is no longer flowing from inlet  141  to tank port  145 , the outer lip  148  of the diaphragm  143  will assume its normal shape and will contact the outer wall. The diaphragm  143  wilt remain on the exhaust seat  147 . When pressure indicated by arrow  150  (FIG. 20) at the inlet port  141  is vented to atmosphere (thru the control valve) the air in the pipe, which is at a pressure level higher than atmosphere , will force the diaphragm  143  upwards to the inlet port  141 . This will shut off the inlet port  141  and allow air  152  in the pipe to flow directly to atmosphere.  
         [0060]    Extreme wear and ear appears at the graduated ends  148  of the diaphragm  143 . Flexure and deterioration in this region cases premature actuator and aerator failure. In my design, the full effects of the extremes of pressure buildup and discharge, and the concomitant displacement of the piston within the chamber cylinder, is moderated over time by the combined action of the captivated check valve ball within the piston, and the radial sideways path of the piston discharge vents. In effect, trapped air within the piston forms a pneumatic cushion that eliminates the requirement of separate mechanical springs.  
         [0061]    From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure.  
         [0062]    It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.  
         [0063]    As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.