US3041970A - Gas liberating devices - Google Patents

Description

July 3, 1962 H. c. FOSTER GAS LIBERATING DEVICES Filed July 14, 1959 mu 0 A mu 9 mu 2 a a nm J/ Q T m. f

& F0 5. :T v N E M m H at W M HY 3,041,970 GAS LIBERATING DEVICES Harry Clark Foster, East Alton, lll., assignor to Olin Mathieson Chemical Corporation, East Alton, lll., a

corporation of Virginia Filed July 14, 1959, Ser. No. 827,055 4 Claims. (Cl. 10225) This invention relates to gas liberating devices and more particularly to such devices adapted to effect the sudden liberation of a charge of compressed gas to serve as a work performing medium. While such devices are applicable to many commercial applications, they have been used most extensively as blasting cartridges utilizing a gas under pressure.

Material breaking cartridges using compressed gas to execute the required work are well known and widely used in the mining industry. Such cartridges or blasting de-' vices are all reliant upon the sudden release of compressed gas to give a quasi explosive effect. The predecessors of this type of blasting cartridges consisted essentially of a cylindrical gas-containing cartridge having venting means. The cartridges were charged with gas under considerable pressure, sealed and then conveyed to the face to be worked. The compressed gas within these cartridges was released by elaborate remote control means. More recently, the practice has been to place an unchanged cartridge in the bore hole and pump gas through a suitable conduit into the cartridge in situ. Conventionially, 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 gas from the cartridge body. Since the amount of pressure that can be built up in the cartridge body is dependent upon the strength of the expendable member, the quantity of energy developed by the liberation of the gas can be controlled within relatively close limits. Such cartridges are generally satisfactory 'but have one serious inherent drawback. After each shot, the discharge end of the cartridge must be dismantled to remove the expendable portion which has ruptured or sheared and to replace it with a new one.

This shortcoming has been well recognized and has led to a concerted eifort for the development of automatic shells. While many so-called automatic shells have been presented, they have met with only a modicum of success. The previous types of automatic cartridges are operable, but they are very heavy, complex and unreliable. Although the expendable portions of the shell have been eliminated, this elimination has introduced new and more serious problems. Normally, the known automatic shells rely upon a series of two or more control or pilot valves to initiate the main release valve. Such complexity of design leads to cartridges that are difiicult to control and exceedingly difficult to discharge at a desired predetermined pressure. In addition, the great number of moving parts in the automatic shells prior to the advent of the present invention has confronted the in dustry with a formidable sealing problem.

Furthermore, the previously known blasting cartridges in which a small portion of the gas is vented to actuate the main valve are so designed that the main valve, discharge ports and the controlling vents are located at the same end of the cartridge. This makes the cartridge difl'lcult to handle because a large proportion of its weight is concentrated at one end. Also, it seriously detracts from the utility of the cartridge in other applications, such as metal working, forming, and the like.

Therefore, it is an object of this invention to provide new and improved gas liberating devices. A further object of this invention is to provide a device of this character having novel gas release means. Another object of itecl States Patent C) M 3,41,970 Patented July 3, 1962 this invention is to provide a simplified gas liberating device overcoming the disadvantages of the prior art. A more specific object of this invention is to provide such gas liberating devices in which the discharge ports and valve actuating vents are remote from one another.

The manner in which these and other objects are accomplished will be apparent from the following specification together with the drawing in which:

FIGURE 1 is a longitudinal sectional view of a blasting device illustrating an embodiment of the present invention; and

FIGURE 2 is a longitudinal sectional view (partially schematic) of a blasting device illustrating another embodiment of the present invention.

The same numbers are used in describing both figures to identify similar components.

Referring to FIGURE 1 which illustrates a preferred embodiment of the invention, an elongated tubular body formed of metal, reinforced plastic, or other material of a strength to contain gas under high pressures, for example -6,000 to 20,000 pounds per square inch, is indicated generally at 1. Suitable means, indicated at 2, are provided for introducing compressed gas into the main chamber 3. One end of the body is screw threadedly attached to end cap 4 as indicated at 5, the joint between the body and the end cap being sealed by resilient O- ring 6. The opposite end of the body terminates in head 7 which is also screw threadedly afiixed to the body. A plurality of discharge ports 8 pass through the wall of the tubular body.

The main chamber is closed at one end by a rigidly fixed disc 9 and main valve 10 defines the other end of the main chamber. That portion of the main chamber adjacent the valve is of reduced diameter as indicated at 11 so as to formvalve seat 12. A vent 13 in disc 9 passes from main chamber 3 to secondary chamber 14. Piston 15 is slidable in the secondary chamber and forms one end thereof. Connecting rod 16 joins piston 15 and main valve 10 in a rigid assembly which can be altered by lock nuts 17 at either end of the connecting rod.

The end cap 4 is connected to valve body 18, and vent 19 communicates between the secondary chamber and the valve body. A control valve 20 is contained in the valve body and is normally urged into a position closing vent 19 by control spring 21 in cooperation with spring support 22. The pressure exerted by the spring can be altered by set screw 23 which is maintained in position by lock nut 24. One or more vents 25 pass from the valve body to the atmosphere.

In operation, compressed air or other suitable gas is introduced into main chamber 3 through gas inlet means 2. This gas also passes into secondary chamber 14 through orifice 13. Thus, during charging, the pressure in the secondary chamber is substantially equal to the pressure in the main chamber. Some leakage of air about connecting rod 16 into the secondary chamber augments this pressure equalizing action. Since the diameter of piston 15 is greater than the eifective diameter of main valve 10, the sealing pressure of the main valve against valve seat 12 increases progressively until a predetermined discharge pressure is reached.

At that time, the pressure in the secondary chamber acting upon control valve 20 through orifice 19 forces the valve from the seat and permits the gas in the secondary chamber 14 to be evacuated through orifice 19 and vents 25. Since the effective cross-sectional'area of orifice 19 and vents 25 is considerably greater than the effective cross-sectional area of orifice 13 in disc 9, the pressure in the secondary chamber is very rapidly reduced. With this reduction in pressure in the secondary chamber, valve 10 is substantially instantaneously unseated and the charge of gas in main chamber 3 is effectively discharged from the chamber through ports 3. The discharge is quite rapid and thus substantially all of the energy of the compressed gas in chamber 3 is made available in a very short period of time.

After the gas has been discharged from main chamber 3, the device is returned to position for recharging by the action of helical spring 26 on piston 15. Also, control spring 21 returns control valve 20 into sealing position with orifice 19. In this way, the device is rendered completely automatic and is in condition for refiring immediately after each discharge.

The device shown in FIGURE 2 illustrates another embodiment of the present invention. In this embodiment, one end of tubular body 1 terminates in valve body 18 and the other end in a closed head '7. Main chamber 3 is provided with gas inlet means 2 and one end of the main chamber is of reduced diameter as indicated at 11 to form valve seat 12 for main valve 10. The seal be tween main valve and portion 11 of the body is made gas tight by resilient O-ring 27. A passageway .28 in the main valve provides communication between main chamber 3 and secondary chamber 14. The main valve is slidable upon exhaust tube 29 which extends throughout the entire length of the main chamber to valve body 18. Helical spring 26 in the secondary chamber normally maintains the main valve 10 in a position spanning ports 8 which are sealed from the secondary chamber by resilient 0-ring 30.

Valve body 18 in this embodiment is substantially the same as that shown in FIGURE 1 but is positioned axially to the main chamber. Control valve 20 is normally held in sealing relationship with the end of exhaust tube 29 by control spring 21 in cooperation with spring support 22. Here again, the tension exerted by the spring can be controlled by set screw 23 which is provided with lock nut 24. One or more vents 25 pass through the valve body to the outside of the cartridge. As described above, it is essential that these vents have a greater effective cross-sectional area than passageway 28 in main valve 10.

The operation of this embodiment is as follows. A charge of compressed gas is introduced into main chamber 3 through gas inlet 2. The gas passes through passageway @28 and to a lesser extent around exhaust tube 29 so as to insure a substantial equalization of pressure in main chamber 3 and secondary chamber 14. Since the diameter of the main valve 10 is greater in the secondary chamber than in the main chamber, the valve is urged with progressively increasing force against the valve seat 12. Also, the pressure in the secondary chamber 14 acts on control valve 20 through exhaust tube 29. When the predetermined discharge pressure is built up within the body, control valve 20 is forced against control spring 21 thus opening exhaust tube 29 to vents 25. This results in a very rapid reduction in pressure in the secondary chamber 14 and the concurrent opening of valve 10. The rapidity with which the valves move is accentuated by their rapidly increasing effective area as they are unseated. Thus, the gas in main chamber 3 is very rapidly liberated through ports 8.

The device of this embodiment is also completely automatic and valves 10 and 20 are returned to discharge position after firing by helical springs 26 and 21, respectively. When semi-automatic or manual operation is preferred the helical spring 26 in secondary chamber 14 can be augmented or replaced by a plunger slidable in head 7 and adapted to return the main valve to a closed position. Also, various types of valve seats can be utilized in the device of the present invention. Thus, the valve seat can be a fiat metal-to-metal seal as well as the types illustrated in the drawing.

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 in suddenly liberated to act as a work performing medium. Such devices include metal working and shaping devices, cutting devices, power cartridges, and the like.

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

What is claimed is:

l. A device for instantaneously liberating a charge of compressed gas as a work performing medium comprising an obturated, substantially cylindrical housing having a main chamber for containing a charge of compressed gas, means for introducing gas under pressure into the chamber, a secondary control chamber and a discharge port proximate one end of the longitudinal axis of the housing, a main valve slidable in the housing between the main chamber and the secondary control chamber and normally positioned to span and seal the discharge port, the diameter of the valve in the secondary control chamber being greater than the diameter of the valve in the main chamber, a passageway between the chambers, an exhaust tube extending through the main valve and the main chamber from the secondary control chamber to the opposite end of the housing, a vent to the outside of the housing in communication with the exhaust tube, and automatic control valve means normally closing said vent and responsive to a predetermined pressure in the chamber to open the vent and allow the pressure in the secondary chamber to be quickly reduced.

2. The device of claim 1 in which spring means is positioned in the secondary chamber to urge the valve into sealing engagement with the discharge ports.

3. A device for instantaneously liberating a charge of compressed gas comprising a cylindrical housing closed at one end by an end cap and at the other end by a head cap, a fixed disc positioned adjacent the head cap and dividing the housing into a main chamber and a secondary chamber, said disc having a vent opening connecting the chambers, said housing having a plurality of discharge ports positioned adjacent the end cap, valve seat means formed integral with the housing adjacent the discharge ports, a main valve slidable in the main chamber between the valve seat means and the end cap and cooperating with said valve seat to close the discharge ports, a piston slidable in the secondary chamber and forming one of the end walls of said chamber, spring means positioned between the piston and the disc to urge the piston away from the disc, the effective area of the piston exposed to the pressure in the housing being greater than the effective area of the main valve exposed to the same pressure, means rigidly connecting the piston and the main valve, means for connecting the main chamber to a source of compressed gas, a vent in the walls of the secondary chamber opening said chamber to the atmosphere, and a pressure responsive adjustable valve means normally closing the vent until a predetermined pressure has been reached in the housing and automatically opening the vent at the predetermined pressure to quickly reduce the pressure in the secondary chamber, a reduction in pressure in the secondary chamber causing the piston and the main valve to move in a given direction to open the discharge ports and vent the main chamber to the atmosphere.

4. A device for automatically releasing a charge of compressed gas at a predetermined pressure comprising a cylindrical housing closed at both ends and having means to admit gas under pressure, a fixed disc partitioning the housing into a main chamber and a secondary chamber, said disc having a vent to communicate the main chamber with the secondary chamber, a plurality of discharge ports positioned at the end of the main References Cited in the file of this patent UNITED STATES PATENTS chamber removed from the fixed disc, a main valve slidable in the main chamber, valve seat means limiting the movement of the valve toward the disc and cooperating with said main valve to close the discharge ports, a piston Ca a an J an. 20, 1891 slidable in the secondary chamber having a larger di 5 2,083,979 Armstr ng June 15, 1937 eter than the diameter at the main valve, said piston 2,083,980 Armstrong June 15, 1937 forming one of the end walls of the secondary chamber, 2,122,706 Armstrong y 1938 rigid means connecting the main valve and the piston, 9 Armstrong Aug. 27, 1940 spring means urging the piston away from th disc, a 2,498,542 Gardlner Feb. 2, 1950 vent in the walls of the secondary chamber, and uro- 10 2,676,543 Ayers et a1. Apr. 27, 1954 matic valve means normally closing the vent in the sec- 2,720,167 HCSSOH u Oct. 11, 1955 ondary chamber and responsive to a predetermined pres- 2,720,168 Hesson Oct. 11, 1955 sure in the chamber to open the vent and allow the pres- 2,720,169 Smith Oct. 11, 1955 sure in the secondary chamber to be quickly reduced, ,0 Callahan Nov. 20, 1956

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