US3098443A

US3098443A - Gas discharge mechanism

Info

Publication number: US3098443A
Application number: US93889A
Authority: US
Inventors: Russell C Spencer
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1961-03-07
Filing date: 1961-03-07
Publication date: 1963-07-23
Anticipated expiration: 1980-07-23

Description

July 23, 1963 R. c. SPENCER GAs DISCHARGE MECHANISM Filed March '7, 1961 R mm m@ wc. E U DHV. B

United States Patent Olii-ice 3,698,443 Patentes .any 2a, tsss 3,098,443 GAS DHSCHARGE MECHANSM Russell C. Spencer, Farmersburg, ind., assignor to @lin Mathieson Chemical Corporation, East Alton, ill., a corporation of Virginia Filed Mar. 7, 196i, Ser. No. 93,839 3 Claims. (Cl. 1ti225) This invention relates to gas operated devices and more particularly to such devices adapted to efiect the sudden release of a charge of compressed gas to serve as a work performing medium. While such `devices are applicable to many commercial applications, the present invention will be described with particular reference to blasting cartridges utilizing a gas under pressure to provide a quasiexplosive effect.

Material breaking cartridges utilizing compressed gas to execute the required work are well known and widely used in the mining industry. Traditionally, these cartridges are formed of high strength materials and are provided with a relatively weak member which shears or ruptures so as to liberate the charge of compressed gas from the cartridge body. Cartridges of this type are not completely satisfactory because the quantity of energy developed by the liberation of this gas can lbe controlled only within relatively wide limits, and also because the expendable member must be removed and replaced after each discharge.

More recently, various types of so-called automatic compressed gas blasting cartridges have been introduced. These cartridges are provided with various means to effect liberation of a charge of compressed gas within the body of the cartridge only when it has attained a predetermined discharge pressure. After the gas is liberated from the automatic cartridges the devices return to their original uncharged condition and then are repositioned for another operation. The previous types of automatic cartridges are operable and have met with some commercial success, but they generally suffer from a lack of complete reliability and also from a necessary complexity ofdesign. Prior to the advent of the present invention, the most significant contribution in this eld was the development of an automatic shell having a pressure responsive sleevetype valve cooperating with a pressure responsive piston whose movement vented a control valve so as to effect reliable discharge at the predetermined discharge pressure. Blasting devices of this type are described and claimed in co-pending application, Serial No. 75,033 filed December 9, 1960 by Harry Clark Foster. The cartridges described in this co-pending application are completely reliable When the components thereof are carefully dirnensioned. However, if the rather rigid dimensional tolerances are not maintained, the operation of these devices may be erratic and sluggish, and in extreme cases the device Would be rendered inoperable.

Therefore, it is an object of thisl invention to provide new and improved automatic material breaking devices utilizing compressed gas. A `further object is to provide a device of this character having novel gas release means. Another object of this invention is to provide a simplified automatic shell overcoming the disadvantages of the prior art. lt is also an object of this invention to provide an improved automatic gas operated device that is readily adjusted to discharge at different pressures. A more specific object of the present invention is toprovide an automatic shell of the valve-piston type with positive valve opening means which are adaptable to less rigid dimensional tolerances, more positive valve opening action, and less expensive production.

The manner in which these and other objects are accomplished will be apparent from the following speciication together with the drawing which is a longitudinal sectional view of a blasting device illustrating a preferred embodiment of the present invention.

As shown in the drawing, an elongated tubular body formed of metal of a strength to contain gas under high pressure, for example 6,000 to 20,000 pounds per square inch, is indicated generally at 1. Suitable means are provided at one end of the body for introducing compressed gas into it. The outer diameter of the body is such that it may be freely set within a bore drilled in the face of the material to be mined. The end of the body remote from the gas inlet is screw threadedly attached to an adapter 2 as indicated at 3. The adapter in turn is screw threadedly attached as indicated at 4 to a head cylinder S. The adapter is provided with a groove 6 proximate one end of accommodate a resilient sealing means such as O-ring 7 to complete the seal between the adapter 2 and head cylinder 5. The end of the head cylinder remote from the adapter terminates in an internally threaded portion 8 by means of which it is connected to cylinder plug 9. The joint between the head cylinder 5 and cylinder plug 9 is sealed by means of resilient O-ring 101 positioned in groove 11 of the iixture. rIhe external portoin of the 'assembly is completed by nose cap 12 which is 'screw threadedly `att-ached to cylinder plug 9 as shown at 13. The nose cap is provided as shown with one or more vents 14, and plug 9 is provided with indentations 53 to accommodate a Spanner wrench or the like.

The head cylinder 5 is provided with a plurality of lateral exhaust ports 15 which are normally spanned and closed by sleeve valve 17, the seal being completed b-y 0- ring 18 in groove 19* of the head cylinder. Sleeve valve seat 2) is slidably mounted within head cylinder 5 and is in sealing engagement with head cylinder 5- by means of O-ring 21 and groove 22. The end of the sleeve valve seat in contact with sleeve valve 17 is in the form of a modified knife edge 23. Thus, the internal faces of the sleeve valve and sleeve valve seat are both cylindrical with the internal diameter of the sleeve valve being slightly smaller than the internal diameter of the sleeve valve seat. It will be readily appreciated that the terminal portion 23- of sleeve valve seat Zi) can assume any desired configuration to provide a metal-to-metal seal between these two members.

A control piston Z4- is slidable within sleeve valve |17 with sulcient space '16 between them to permit ow of compressed gas around the control piston into secondary chamber 25. The control piston is provided with annular flange 26 which rests on sleeve valve 17 and forms a sliding fit with the internal diameter of head cylinder 5. A considerable portion of the end of piston 24 is of a reduced diameter as indicated generally at 29'. Thus the only point of close t between piston Z4 and the internal surface of sleeve valve 17 is proximate the lefthand end of the piston as shown in the drawing. A snap ring 3d is positioned within a suitable groove on the inner surface of the valve adjacent flange 26 of the control piston. While it is preferred to utilize a snap ring to form an extension on the inner face of the sleeve valve, any other suitable means may be employed to form a continuous or interrupted pro't-uberance extending around the inner surface of the valve. -It is only necessary that the internal diameter of snap ring or ange 30 be greater than the external diameter of portion 2.9 of the piston and smaller than the diameter of the terminal portion of piston 24. Thus in effect, snap ring 3i!` or its equivalent together with the terminal portion of piston 24 form interlocking flanges which prevent complete separation of piston 24 and valve 17. The control piston is provided with a plug 27 terminating in a portion 2,8 of reduced diameter within valve chamber 31. Valve chamber 31 is in communication with main chamber 32 and secondary chamber 25 through annular space 16 and passageway 33 and passagewy 34,

respectively. Ball valve 35 is normally urged against valve seat 36 by helical spring 37. That portion of the control piston remote from sleeve valve 17 terminates in a tubular section 38 having a central passageway 39.

A control adjusting stem 46 is seated on cylinder plug 9. A portion 41 of the control adjusting stem is of reduced diameter and is in telescopic engagement with terminal portion 33 of control piston 24. The seal between control adjusting stem 40 and control piston 24 is completed by resilient O-ring 42. The control adjusting stem terminates in a centrally positioned pin 43. The stem has a passageway 44 substantially throughout its entire length and one or more orices 45 provide communication between passageways 39 and 44. Control spring 46 extends from flange 26 of control piston 24 to control spring seat 47. The force of the control spring is readily adjustable by means of the screw threaded attachment 48 between the control adjusting stem 40 and spring seat 47. The seal between cylinder plug 9 and control adjusting stem 4() is completed by resilient O-ring 49 in groove `50 of cylinder plug 9.

The position of the control spring seat 47 is controlled and maintained by control seat pin 52 extending from the control spring seat into cylinder plug 9. Also, that portion of the control adjusting stem 40 within nose cap 12 has a terminal portion of a flattened or polygonal shape to facilitate adjustment. This is indicated generally at 54.

In operation, compressed air or other suitable gas is introduced into the main chamber 32 through an appropriate gas inlet. The compressed gas also enters chamber 25 by passing through the annular space 16 about the periphery of the control piston 24 and by means of passageways 33, valve chamber 31 and passageways 34. Therefore, the pressure in chambers 32 and 25 is substantially equal during the charging of the cartridge. Thus, during charging of the cartridge, both ends or the sleeve valve 17 and of the control piston 24 are subjected to substantially the same pressure.

However, since the eltective cross-sectional area of that end of the sleeve valve facing nose cap 12 is greater than the effective area exposed at that end of the sleeve valve in contact with valve seat 20, the valve is normally urged into a closed position. As the pressure increases within the cartridge, the sealing pressure exerted on sleeve valve 17 also increases. On the other hand, pressure responsive control piston 24 has an effective differential crosssectional area such that an increase in pressure urges the control piston away from the ports in the direction of the nose cap 12 in opposition to control spring 44.

As the pressure within chambers 32 and 25 increases, the control piston is thus gradually forced to the right. Since piston 24 has a greater eiective cross-sectional area in main chamber 32 than in secondary chamber 25, it is the pressure within the main chamber alone that moves the control piston from its initial position. This sliding motion of the piston continues until ball valve 35 contacts pin 43. At this point the seating pressure of ball valve 35 augments the force of control spring 46. The movement of the control piston by the main chamber pressure is then interrupted with the tublar portion 38 of control piston l24 a short distance from shoulder 55 of control adjusting stem 40. This position is maintained until the predetermined discharge pressure is attained. It will be noted that when the control piston 24 is in this position that flange 26 of the control piston has traveled away from sleeve valve 17. Thus, sleeve valve 17 is then maintained in a sealing position with relation to ports only because of its differential eiective cross-sectional area.

IUpon reaching the predetermined discharge pressure, the pressure in the main chamber 32 is sulcient to move piston -24 further to the right so that the ball valve is unseated and the tubular portion of piston 24 abuts shoulder 55 of control adjusting stem 40 and secondary chamber 25 is vented to the atmosphere through vents 34, passageway 39, vent 45, passageway 44 and vents 14. The effective cross-sectional area of this venting system is much greater than the effective cross-sectional area of the passageway 16 from chamber 32 into chamber 25. Thus, the pressure in chamber 25 is reduced. When the ball valve is initially unseated by pin 43, any further movement of the piston toward shoulder 53 causes the dlange on the piston to contact the snap ring on the sleeve valve. Therefore, during the unseating of ball valve 35 and movement of the piston to the right, the interlocking snap ring and ange on the sleeve valve and control piston respectively serve to move the valve 17 to the right and out of contact with sleeve valve seat 20. Therefore, upon the unseating of the ball valve, two forces cooperate to cause the sleeve valve 17 to y to the right thus liberating through exhaust ports the charge of compressed gas contained in main chamber 3-2. One of these forces is the reduction in pressure on the right side of sleeve valve 17. The other is the pulling effect of the piston which is transmitted to the valve by means of the interlocking members. Accordingly, the gas pressure in the main chamber 32, upon reaching the desired discharge pressure, causes the ball valve to open reducing the pressure in chamber 25 with consequent discharge of the gas from chamber 32 through ports 15.

The cartridge of this invention is `fully automatic. Alfter the change of compressed gas is substantially expelled from chamber 32, sleeve valve 17 and control piston 24 are returned to .their original closed position by control spring 44. The cartridge is then in condition to be recharged.

rEhe discharge pressure Iof cartridges made in accordance with this invention can be readily and precisely controlled. This control can be mfost easily achieved by controlling the relative cross-sectional areas rat contact point of the ball valve seat and the diameter of that telescopic portion of the contr-ol piston which separates and seals the internal pressure trom atmosphere. The cross-sectional area of the ball valve seat is necessarily smaller than the cross-sectional area of said telescopic portion so that there will be available a net tforce due to gas pressure tending to continue movement of the control piston to the right in opposition to the :force of control spring 46. As the size of the ball valve seat increase in relationship to the outside diameter of the telescopic portion, the force required of the control spring to obtain a desired discharge level is materially reduced and smaller, more easily adjusted springs can be employed. Thus, in accordance with the present invention, the force required to unseat the ball valve against air pressure is the major controlling force and the control spring with its adjustment serves in effect as a vernier to control discharge levels within relatively narrow limits. The discharge pressure off cartridges made in accordance with this invention can therefore be adjusted to increments of about 1% or less without relying upon major modifications or heavy springs.

The cartridge of the present invention is exceedingly durable and requires only about half as many moving parts as are normally necessary in automatic devices of this type. Also, the wear on the parts is reduced to a minimum because in most instances they are separated and in eiect lubricated by a layer of high pressure gas. In addition, the normal heating tendency of such gas [operated devices is lobviated in accordance with the present invention by the provision of an expansion chamber 56 within nose cap 12. As the highly compressed gas within the device is vented through passageway 44 into chamber 56, the expanding gas has a pronounced cooling etect upon the nose cap 12 and cylinder plug 9. This cooling effect is carried by con-duction substantially throughout the entire length of head cylinder 5. This prevents any moving portion of the device from reaching temperature ranges which would result in binding of the moving parts or in deterioraiton .of the sliding seals. It also permits handling of the device immediately after discharge.

In some instances, nose cap 12 at the end of the shell has a tendency to become loosened and eventually to separate from the body of the shell. Such an occurrence can be avoided in a number of ways. For example, a compression spring having a reverse helix can be posi- .tioned in chamber 56 about terminal portion 54 of control adjusting stern 40 and in close association with the internal wall of the nose cap. II the nose cap is screwed to the shell .by a right-hand thread, a left-hand helical spring is employed, and vice versa. Likewise, the nose cap poistion can be secured by a weld, bolt, spring latch, knurled mating surfaces or by any other suitable means. In such instances ywhere the nose of the shell is sufrlciently coniine-d in the end of the bore hole to pnovide an expansion chamber about the nose equivalent in effect to chamber 56, nose cap 12 may be omitted. Likewise, the cap may be otherwise constnucted as long as the desired cooling `eifect is obtained.

While the invention has been described with particular reference to blasting or coal breaking cartridges, it will be readily appreciated that it is also applicable to any pressure release device in which a charge of compressed gas is suddenly liberated Ito act as a work performing medium. S-uch devices include metal working and shaping devices, cutting devices, power cartridges, safety valves, and the lik-e.

Although the invention has been Idescribed in considerable detail in the toregoing for the purpose of illustration, it is to ibe understood that such detail is solely for that purpose and that many modifications can be made without departing from the spirit and scope of the invention.

What is claimed is:

l. A gas operated device comprising a cartridge having a substantially cylindrical main chamber adapted to receive a charge of compressed gas, .gas inlet means at one end of the main chamber, lateral discharge outlets for the main chamber intermediate its ends, a secondary chamber positioned adjacent the other end of said main chamber, a pressure responsive sleeve valve positioned between the chambers slidable within the cartridge and normally positioned to span and seal the discharge outlets, the area of said valve exposed rto the pressure in fthe chambers being `greater at one end of said valve than at the opposite end of said valve, the differential effective cross-sectional areas of the valve urging the valve into a closed position during charging of the main chamber, a pressure equalizing passageway between the chambers, a slidable pressure responsive control piston, a portion of the piston being positioned concentrically within the valve, the Valve and piston having interlocking anges to prevent complete removal of the piston from the valve, the area of said control piston exposed to the pressure in fthe chambers being greater at one end odi said control piston than at the opposite end of said control piston, the differential effective cross-sectional areas orf the control piston fuuging it away #from the valve, said piston having a vent opening communicating the interior or said piston with the secondary chamber, a ball valve in the control piston, resilient means urging the ball valve into its seat, the end of .the control piston remote :from the main chamber terminating in a hollow tube integral with the piston, a stationary hollow stent telescopically sealed within the hollow tube, the vent opening, hollow tube and stem providing a passageway between the secondary chamber and the atmosphere, the passageway normally closed by the ball valve, the stem adapted .to lunseat the ball valve and open the passageway when the control piston has traveled a predetermined distance in response to pressure within the main chamber.

2. A gas operated device comprising a cartridge having a substantially cylindrical main chamber adapted to receive a charge of compressed gas, gas inlet means at one end of the main chamber, lateral discharge outlets for the main `chamber intermediate its ends, a secondary chamber positioned adjacent the other end of said main chamber, a pressure responsive sleeve Valve slidable within the cartridge between the chambers and normally positioned to span and seal the discharge outlets, said valve having a greater cross sectional larea at one end exposed to the pressure in the chambers than at the opposite end, the differential effective cross sectional areas of the Valve urging the Valve into a closed position during charging of the main chamber, a pressure equalizing passageway `connecting the chambers, a slidable pressure responsive control piston adjacent the Valve, the piston having :a terminal portion with a diameter slightly less than the inside diameter of the sleeve Valve and being provided with a shoulder having a diameter greater than the inside diameter of the sleeve valve, the terminal portion and shoulder of the piston being joined by la portion of reduced diameter, the terminal portion of the piston being normally positioned within the sleeve valve, and the shoulder portion normally abutting said valve, the cross sectional areas of the piston exposed to the pressure in the chambers being greater at one end than at lthe opposite end of said piston, pressure acting on the differential effective cross sectional areas of the control piston urging it away from the valve, interlocking means between the piston and the valve to prevent complete removal of the piston from the valve, said piston having a vent opening to the secondary chamber at one end and the interior of the piston at the other end, means defining a passageway from the interior of said piston to the atmosphere, control valve means within the control piston normally closing said passageway adapted to vent the secondary chamber `at a predetermined discharge pressure, and means in the secondary chamber operative to open said control valve means upon `a predetermined movement of said control piston.

3. The device of claim 2 in which said interlocking means is a snap ring positioned in la groove formed in the inner periphery of said sleeve valve providing a shoulder adapted to be engaged by said piston as said piston moves relative to said sleeve valve.

References Cited in the tile of this patent UNITED STATES PATENTS 2,422,296 Flader et al. June 17, 1947 2,693,821 `Cornelius Nov. 9, 1954 2,77l,()32 Callahan Nov. 20, 1956 2,950,732 Lambert Aug. 30, 1960 FOREIGN PATENTS 718,166 France Oct. 27, 1931

Claims

2. A GAS OPERATED DEVICE COMPRISING A CARTRIDGE HAVING A SUBSTANTIALLY CYLINDRICAL MAIN CHAMBER ADAPTED TO RECEIVE A CHARGE OF COMPRESSED GAS, GAS INLET MEANS AT ONE END OF THE MAIN CHAMBER, LATERAL DISCHARGE OUTLETS FOR THE MAIN CHAMBER INTERMEDIATE ITS ENDS, A SECONDARY CHAMBER POSITIONED ADJACENT THE OTHER END OF SAID MAIN CHAMBER, A PRESSURE RESPONSIVE SLEEVE VALVE SLIDABLE WITHIN THE CARTRIDGE BETWEEN THE CHAMBERS AND NORMALLY POSITIONED TO SPAN AND SEAL THE DISCHARGE OUTLETS, SAID VALVE HAVING A GREATER CROSS SECTIONAL AREA AT ONE END EXPOSED TO THE PRESSURE IN THE CHAMBERS THAN AT THE OPPOSITE END, THE DIFFERENTIAL EFFECTIVE CROSS SECTIONAL AREAS OF THE VALVE URGING THE VALVE INTO A CLOSED POSITION DURING CHARGING OF THE MAIN CHAMBER, A PRESSURE EQUALIZING PASSAGEWAY CONNECTING THE CHAMBERS, A SLIDABLE PRESSURE RESPONSIVE CONTROL PISTON ADJACENT THE VALVE, THE PISTON HAVING A TERMINAL PORTION WITH A DIAMETER SLIGHTLY LESS THAN THE INSIDE DIAMETER OF THE SLEEVE VALVE AND BEING PROVIDED WITH A SHOULDER HAVING A DIAMETER GREATER THAN THE INSIDE DIAMETER OF THE SLEEVE VALVE, THE TERMINAL PORTION AND SHOULDER OF THE PISTON BEING JOINED BY A PORTION OF REDUCED DIAMETER, THE TERMINAL PORTION OF THE PISTON BEING NORMALLY POSITIONED WITHIN THE SLEEVE VALVE, AND THE SHOULDER PORTION NORMALLY ABUTTING SAID VALVE, THE CROSS SECTIONAL AREAS OF THE PISTON EXPOSED TO THE PRESSURE IN THE CHAMBERS BEING GREATER AT ONE END THAN AT THE OPPOSITE END OF SAID PISTON, PRESSURE ACTING ON THE DIFFERENTIAL EFFECTIVE CROSS SECTIONAL AREAS OF THE CONTROL PISTON URGING IT AWAY FROM THE VALVE, INTERLOCKING MEANS BETWEEN THE PISTON AND THE VALVE TO PREVENT COMPLETE REMOVAL OF THE PISTON FROM THE VALVE, SAID PISTON HAVING A VENT OPENING TO THE SECONDARY CHAMBER AT ONE END AND THE INTERIOR OF THE PISTON AT THE OTHER END, MEANS DEFINING A PASSAGEWAY FROM THE INTERIOR OF SAID PISTON TO THE ATMOSPHERE, CONTROL VALVE MEANS WITHIN THE CONTROL PISTON NORMALLY CLOSING SAID PASSAGEWAY ADAPTED TO VENT THE SECONDARY CHAMBER AT A PREDETERMINED DISCHARGE PRESSURE, AND MEANS IN THE SECONDARY CHAMBER OPERATIVE TO OPEN SAID CONTROL VALVE MEANS UPON A PREDETERMINED MOVEMENT OF SAID CONTROL PISTON.