US3098442A - Gas liberating cartridge - Google Patents

Description

July 23, 1963 R. v. WAKEFIELD ETAL 3, 2

GAS LIBERATING CARTRIDGE Filed Oct. 11, 1960 4 Sheets-Sheet 1 v w A m V N 9 0' LI 0| INVENTORS. RALPH V. WAKEFIELD & HARRY CLARK FOSTER A TTORNEKS' R. v. WAKEFIELD ETAL 3,098,442

GAS LIBERATING CARTRIDGE 4 Sheets-Sheet 3 July 23, 1963 Filed Oct. -11, 1960 vmim mm $951K KQQ mm mm Q Q m mNKOQbQKND qmz mm m OE om m me 8198 o @o; mo; m9 3 mo vo. Q N

INVENTORY. RALPH V. WAKEFIELD 8. HARRY CLARK FOSTER E 0% ATTORNEYS July 23, 1963 R. v. WAKEFIELD ETAL 3,

GAS LIBERATING CARTRIDGE 4 Sheets-Sheet 4 Filed Oct. 11. 1960 h DE NQ Q Q QQ NE @t om wy My INVENTORS. RALPH \Z WAKEFIELD & LARK FOSTER HARRY C United States Patent Ofifice 3,098,442 Patented July 23, 1963 This invention relates to gas liberating devices and more particularly to such devices adapted to efiect the sudden release 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.

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 devices 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 uncharged cartridge in the bore hole and pump gas through a suitable conduit into the cartridge in situ. Conventionally, 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 gas from the cartridge body at a predetermined discharge pressure. The shear member can be replaced by a pressure responsive automatic valve that is actuated exclusively by the gas pressure within the cartridge. These valves are normally considered advantageous in that they can be used repeatedly and the need of replacing the expendable member is eliminated.

However, all such prior art devices depend exclusively on the liberation of substantially all of the gas confined within the cartridge at one location on the longitudinal axis of the bore hole. Thus, the material being working is subjected to non-uniform forces. That portion of the quasi explosive force, whereas that portion of the material separated therefrom can be broken only by the force transmitted through the material itself. Such operation militates against the subsequent size reduction ognized that they do not take advantage of all of the potential energy of the compressed gas confined within the cartridge.

Therefore,

performing of the bore FIGURE 2 is a schematic view of a device illustrating another embodiment of the present invention;

FIGURE 3 is a longitudinal sectional view of a gas release mechanism that can be employed in accordance with the present invention;

FIGURE 4 is a fragmentary longitudinal sectional view of another gas release device that can be employed in accordance with the present invention;

FIGURE 5 is a longitudinal sectional view embodiment of the present invention; and

FIGURES 6 and 7 are fragmentary longitudinal sectlonal views of additional embodiments of the present invention.

of a specific ample 6,000 to 20,000 pounds per square inch,

FIGURE 2 of the drawing illustrates another embodiment in which the tubular cartridge body is provided with a third gas release means 9 in conjunction with a third set of lateral discharge ports 10. Thus the cartridge illustrated in FIGURE 2 is provided with three sets of discharge ports 4, 6, and 10, which are normally closed by gas release means 3, 5, and 9, respectively. Likewise, the cartridge of this embodiment is divided into three internal chambers 7, 8, and 11, by the gas release means. As in the above embodiment, chambers 7, 8, and 11, are in communication with one another by any well known means.

ber 8. Thus, during charging, the pressures in chambers 7 and 8 are substantially equal. When the predetermined discharge pressure has been built up within chamber 8, gas release means 5 liberates the gas in chamber 8 through lateral outlet ports 6. The gas is liberated subsubstantial reduction of pressure in chamber 8, the pressure responsive gas release means 3 is moved from its sealing position with respect to lateral results in the liberation of the charge of compressed gas within chamber 7 as a work performing medium.

The cartridge illustrated in FIGURE 2 operates in substantially the same manner as that described above. compressed gas within tubular body 1 is liberated in three increments rather than two. When gas is introduced into the body, it enters chamber 7, passes through gas release means 3 into chamber 8, and thence through gas release means 5 into chamber 11. Thus, during charging, the pressures within chambers 7, 8, and 11 are substantially equal. When the predetermined discharge pressure has been obtained in chamber 11, gas release means 9 no longer seals lateral exhaust ports 10. Thus, the charge of gas within chamber 11 is efiiciently and substantially instantaneously exhausted through ports as a work performing medium. The sudden reduction of pressure in chamber 9 causes gas release means 5 to unseat from its sealing position with ports 6. The charges of gas contained within chambers 8 and 7 are then seqentially discharged as described above in connection with FIGURE 1.

While in the above embodiments the first increment of gas was liberated at a point remote from the gas inlet and subsequent gas discharges were progressively closer to the inlet, it will be readily appreciated that this sequence can be modified in any desired fashion. Thus, in utilizing the device in FIGURE 1, the charge of gas in chamber 7 can be liberated through ports 4 and this liberation followed by the substantial evacuation of chamber 8 through ports 6. Likewise, in employing the embodiment of FIGURE 2, ports 4 can be opened to evacuate chamber 7 followed by evacuation of chamber 8 through ports 6 and of chamber 11 through ports 10. Alternately, the chambers 7 and 11 can be sequentially exhausted followed by the discharge of the gas in chamber 8 through ports 6.

Practically any of the well known gas release mechanisms can be employed in accordance with the present invention to effect release of the compressed gas from the chambers within the tubular body. The gas release means in association with the ports that are initially opened can be either a rupturable member or reactive automatic or semiautomatic pressure responsive valve. The gas release means subsequently activated are preferably pressure responsive valve means.

FIGURES 3, 4, 5, and 6 illustrate gas release means that can be advantageously employed in accordance with the present invention.

One type of a gas discharge valve mechanism particularly well suited for use as the initially operated discharge means of the present cartridges is shown in FIGURE 3. Valve mechanisms of this type are described and claimed in the copending application, Serial No, 14,440, now abandoned, filed March 11, 1960, by Harry Clark Foster. As shown in FIGURE 3 an elongate tubular body is indicated generally at 12. The end of the body remote from the gas inlet is screw threadedly attached to an adapter 13 as indicated at 14. The adapter in turn is screw threadedly attached as indicated at 15 to a head cylinder 16. The adapter is provided with a groove 17 proximate one end to accommodate a resilient sealing means such as O-ring 18 to complete the seal between the adapter 13 and head cylinder 16. The end of the head cylinder remote from the adapter terminates in an internally threaded portion 19 by means of which it is connected to cylinder plug 20. The joint between the head cylinder 16 and cylinder plug 20 is sealed by means of resilient O-ring 21 positioned in groove 22 of the fixture. The external portion of the assembly is completed by nose cap 23 which is screw threadedly attached to cylinder plug 20 as shown at 24. The nose cap is provided as shown with one or more vents 25, and plug 20 is provided with indentations 62 to accommodate a spanner wrench or the like.

The head cylinder 16 is provided with a plurality of lateral exhaust ports 26 which are normally spanned and closed by sleeve valve 28, the seal being completed by O-ring 29 in groove 30 of the head cylinder. Sleeve valve seat 31 is slidably mounted within head cylinder 16 and is in sealing engagement with head cylinder 16 by means of O-ring 32 and groove 33. The end of the sleeve valve seat in contact with sleeve valve 28 is in the form of a modified knife edge 34. 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 34 of sleeve valve seat 31 can assume any desired configuration to provide a metal-to-metal seal between these two members.

A control piston 35 is slidable within sleeve valve 28 with sufficient space 27 between them to permit a how of compressed gas around the control piston into spring chamber 36. The control piston is provided with annular flange 37 which rests on sleeve valve 28 and forms a sliding fit with the internal diameter of head cylinder 16. The control piston is provided with a plug 38 terminating in a portion 39 of reduced diameter within valve chamber 40. Valve chamber 40 is in communication with chamber 41 and chamber 36 through annular space 27 and passageway 42, and passageway 43, respectively. Ball valve 44 is normally urged against valve seat 45 by helical spring 46. That portion of the control piston remote from sleeve valve 28 terminates in a tubular section 47 having a central passageway 48.

A control adjusting stem 49 is seated on cylinder plug 20. A portion 50 of the control adjusting stem is of reduced diameter and is in telescopic engagement with terminal portion 47 of control piston 35. The seal between control adjusting stem 49 and control piston 35 is completed by resilient O-ring 51. The control adjusting stem terminates in a centrally positioned pin 52. The stem has a passageway 53 substantially throughout its entire length and one or more orifices 54 provide communication between passageways 48 and 53. Control spring 55 extends from flange 37 of control piston 35 to control spring seat 56. The force of the control spring is readily adjustable by means of the screw threaded attachment 57 between the control adjusting stem 49 and spring seat 56. The seal between cylinder plug 20 and control adjusting stem 49 is completed by resilient O-ring 58 in groove 59 of cylinder plug 20. Groove 59 is preferably covered by stern thrust washer 60 on which the control adjusting stem rests.

In operation, compressed gas is introduced into chamber 41 through an appropriate gas inlet. The compressed gas then enters chamber 36 through the annular space 27 about the periphery of the control piston 35 and by means of passageways 42, valve chamber 40 and passage- Ways 43. Therefore, the pressure in chambers 41 and 36 is substantially equal during the charging of the cartridge. Thus, during charging of the cartridge, both ends of the sleeve valve 28 and of the control piston 35 are subjected to substantially the same pressure.

However, since the effective cross-sectional area of that end of the sleeve valve facing nose cap 23 is greater than the effective area exposed at that end of the sleeve valve in contact with valve seat 31, the valve is normally urge-d into a closed position. As the pressure increases within the cartridge, the sealing pressure exerted on sleeve valve 28 also increases. On the other hand, pressure responsive control piston 35 has an effective differential cross-sectional area such that an increase in pressure urges the control piston away from the ports in the direction of the nose cap 23 in opposition to control spring 55.

As the pressure within chambers 41 and 36 increases, the control piston is thus gradually forced to the right. This sliding motion continues until ball valve 44 contacts pin 52. At this point the seating pressure of ball valve 44 augments the force of control spring 55. The movement of the control piston is then interrupted with the tubular portion 47 of control piston 35 a short distance from shoulder 64 of control adjusting stem 49. This position is maintained until the predetermined discharge pressure is attained. It will be noted that when the control piston 35 is in this position that flange 37 of the control piston has traveled away from sleeve valve 28. Thus, sleeve valve 28 is then maintained in a sealing position with relation to ports 26 only because of its differential effective cross-sectional area.

Upon reaching the predetermined discharge pressure, the ball valve is unseated and the tubular portion of piston 35 abuts shoulder 64 of control adjusting stem 49 and spring chamber 36 is vented to the atmosphere through vents 43, passageway 48, vent 54, passageway 53 and vents 25. The effective cross-sectional area of this venting system is much greater than the eliective crossse-ctional area of the passageway 27 from chamber 41 into chamber 36. Thus, the pressure in chamber 36 is reduced. The pressure on the right side of sleeve valve 28 is also suddenly reduced through passageways 42 and pressure on the left side causes the valve to open, liberating through exhaust ports 26 the charge of compressed gas contained in chamber 41. After the charge of compressed gas is substantially expelled from chamber 41, sleeve valve 28 and control piston 35 are returned to their original closed position.

FIGURE 4 of the drawing illustrates a simplified and reliable type of valve assembly that can be utilized in any position of the cartridges of the present invention. Structures of this type are disclosed and claimed in the c pending application, Serial No. 828,812 now abandoned, filed July 22, 1959, by Lionel E. Golf. A portion of the cartridge body is indicated at 66. The end of the body 66 remote from the gas inlet is screw threadedly attached to sleeve 67 as indicated at 68. The seal between these two components is completed by resilient O-ring 69. The other end of the sleeve is closed with end cap 70 which is screw threadediy attached to sleeve 67 as indicated at 71 with the seal between these two members also being completed by resilient sealing means, such as O-ring 72. The interior of the cylindrical body is divided into chambers 73 and 74 by valve 75 which is slidable in the body. The valve is normally maintained in a closed position spanning lateral discharge ports 76 by helical spring 77 positioned in annular space 78 between sleeve 67 and central extension 79 of end cap 70. The valve is slidably sealed to the central extension 79 of the end cap by resilient sealing means, such as O-ring 80.

As shown in the drawing, the base portion 81 of the valve is provided with a passageway 82 so as to maintain the pressure within chambers 73 and 74 substantially equal while the chambers are being charged with compressed gas. Valve 75 is also provided with one or more lateral vents 83 in the area of reduced diameter adiacent the base of the valve. The valve is normally held in sealing relationship with metallic seal ring 84 which is slidably sealed to sleeve 67 by suitable resilient means such as O-ring 85. Metallic sealing ring 84 is responsive to the pressures built up within main chamber 73 but is restricted in its movement by its abutment with tubular body 66 and also by shoulder 86 of sleeve 67. As shown in the drawing, the sealing ring 84 terminates in a modified knife edge 87 at its point of contact with shoulder 88 of the sleeve valve.

The internal diameter of metallic seal ring 84 is larger than the outside diameter of the basal portion 81 of the valve so as to form a small clearance between these two components. If this clearance is made sufilciently large, sulficient air from chamber 73 will pass therethrough into chamber 74 so as to equalize the pressure within these two chambers. In such instances, passageway 82 in the base portion of the valve 75 can be eliminated.

This assembly is so designed that the valve 75 has a greater elfe-ctive area exposed to the gas pressure in chamber 73 than to the gas pressure in chamber 74. Also, the effective area of the metallic sealing ring 84 exposed to gas pressure is greater at that end proximate body 66 than at the other end. These differential areas of valve 75 and metallic seal ring 84 cause these members to move in a direction away from body 66 as the pressure within the cartridge is increased.

In operation, compressed gas is introduced into chamber 73. The gas passes through passageway 82 and lateral vents 83 in main valve 75 into chamber 74. Thus, the pressure on either side of main valve 75 is substantially equalized and is maintained equal throughout the charging operation. Because of the greater effective cross-sectional area of valve 75 and metallic seal ring 84 in chamber 73 than in chamber 74, the valve and the ring are a sliding movement.

urged in a direction toward end cap in opposition to helical spring 77.

This sliding movement of valve and seal ring 84 continues until a predetermined discharge pressure has been built up in chambers 73 and 74. At this point, further movement of the metal seal ring 84 is prevented by its contact with shoulder 86 on sleeve 67. Continued movement of the valve 75 causes a separation of the valve from the metallic seal ring 84. This separation has two instantaneous effects; an increase in the effective area of the main valve exposed to the pressure in chamber 73, and a reduction of gas pressure in chamber 74 by gas being vented through lateral vents 83 and exhaust ports 76. Thus, the pressure in chamber 74 is reduced at such a rapid rate that it cannot be balanced by gas from chamber 73 entering through passageway 82 and lateral vents 83. The pressure in chamber 73 is thus suddenly unopposed and valve 75 is forced rapidly away from lateral discharge ports 76. Any compressed gas remaining in chamber 74 is exhausted through lateral vents 83 and exhaust ports 76. With the sudden reduction of pressure within chamber 74, the compressed gas in chamber 73 is completely and instantaneously released to the surrounding work face which is to be broken down.

After the compressed gas in chamber 73 has been completely discharged, the valve is returned to its original position by helical spring 77 and is then in position for another discharge.

FIGURE 5 shows in detail a cartridge of the type illustrated in FIGURE 1. The cylindrical body 1 of this cartridge is composed of a series of cylindrical lengths 89 together with interconnecting lengths 98. The body is closed at one end by end cap 91. The tubular cartridge body is provided with a pair of sleeve valves 92 and 93, which normally span and close lateral exhaust ports 94 and 95. These valves as shown have a slightly greater effective cross-sectional area on their right hand sides than on their left hand sides. Thus, during charging the gas pressure within the cartridges urges them to the left and into a closed position. The valves are provided with passageways 96 and 97 respectively to insure the maintenance of substantially equal pressures throughout the cartridge prior to discharge. These valves divide the tubular body 1 into chambers 7 and 8. Valve 92 is slidably sealed to tubular body 1 by O-ring 98 and valve 93 is likewise sealed to the tubular body by O-ring 99.

Metallic seal ring 100 is slidable within tubular body 1 and is sealed thereto by O-ring 101. This ring has a larger effective cross-sectional area at the left hand end than at the right hand end and thus, the gas pressure within the cartridge urges it toward the right. The metallic seal ring terminates in a modified knife edge 102 and forms a metal-to metal seal with valve 92. Member 89 is provided with shoulder 103 which cooperates with radial extension 104 on metallic seal ring 100 to limit its Spring 105 also serves to maintain the valve 92 in a closed position and to return the valve to an operative condition after discharge. This spring is maintained in position by spring retainer 166.

Valve 93 also has a metallic seal ring 187 in association therewith. This seal ring also terminates in a knife edge 108 to form a metal-to-metal seal with valve 93. Seal ring 167 is slidably sealed to the tubular body by O-ring 109 and its axial movement restricted by the cooperation of shoulder 110 on the body and basal extension 111 on the seal ring. Valve seat member 1 12 is sealed to the body by O-ring 113 and cooperates with valve 93 to form eontrol chamber 114. This chamber also accommodates helical spring 115 which acts in substantially the same manner as spring 105. Valve seat member 112 is provided with a central orifice 116 which is normally closed by ball valve 117. The ball valve is secured in piston 118 and is urged to a position closing orifice 116 by spring 119. Lateral vents 12!) pass through the wall of the tubular body and are normally closed and sealed by piston 118.

In operation, compressed gas is introduced through suitable inlet means into chamber 7. The gas then passes through orifice 96 in valve 92 into chamber 8, and thence through orifice 97 in valve 93 into control chamber 114. Thus, during charging, the pressures in chambers 7, 8, and 114 are substantially equal. When the predetermined discharge pressure has been attained in control chamber 114, ball valve 117 is unseated from valve seat 112, and the entire left hand surface of piston 118 is suddenly exposed to the pressure within the cartridge. This results in the piston and ball valve 117 being forced to the right in opposition to spring 119. Since the effective cross-sectional area of lateral vents 120 is substantially greater than the effective cross-sectional area of vent 97 in valve 93, the pressure in control chamber 114 is very rapidly reduced to a value well below that of the pressure in chamber 8. This sudden reduction in pressure on the right hand side of valve 93 causes the valve to be forced to the right, exposing lateral discharge ports 95. The charge of compressed gas in chamber 8 is then suddenly and efficiently discharged as a work performing medium.

Since the gas can escape through ports 95 at a much greater rate than it can enter through passageway 96 in valve 92, the discharge of the gas contained in chamber 8 causes valve 92, to be in an unbalanced condition. With the sudden reduction in pressure on the right side of valve 92, this valve is then forced to the right by gas pressure in chamber 7 and the gas contained therein is then liberated in like manner through lateral discharge ports 94.

The cartridges shown in FIGURES 6 and 7 are particularly well adapted for use when it is desired to alter the sequence of discharge. These figures illustrate devices that can advantageously be employed when it is desired to effect the first discharge of a work producing medium relatively close to the work face and to discharge subsequent increments of the gas toward the inner end of the bore ole.

With particular reference to the cartridge shown in FIGURE 6, that portion of the mechanism to the right of chamber 41 is substantially the same as the device previously described and shown in FIGURE 3 of the drawing. It will be noted, however, that the valve mechanism in association with ports 26 is shown in a different position than in FIGURE 3. The device is shown in FIGURE 3 in an uncharged condition with control piston 35 in contact with the end of sleeve valve 28. Also, ball valve 44 is separated from pin 52 of the control adjust ing stern and tubular portion 47 of the control piston is separated from. shoulder 64 of the control adjusting stem 49. By contrast, the device shown in FIGURE 6 is in position immediately prior to discharge. Ball valve 44 is in contact with pin 52 and the end of tubular portion 47 of the control piston is only slightly separated from the shoulder 64 on control adjusting stem 49.

That portion of the cartridge to the left of control piston 35 is formed of a tubular body portion 12, valve body 120 and a tubular section 121. These members are screw threadedly connected as shown at 122 and 123 with the joints therebetween being sealed by resilient O-rings 124 and 125. The valve body 120 is provided with a plurality of lateral discharge ports 126. These ports are normally spanned and sealed by slidable sleeve valve 127. This valve is provided with one or more restrictcd passageways 128 to permit relative movement of compressed gas between chambers 41 and 129. Alternately the clearance between valve 127 and rod 134 may be sufficient large to serve as a passageway.

Valve 127 is slidably sealed to the internal wall of valve "body 120 by resilientO-ring 130 and forms a metalto-metal seal with follower ring 131. This ring is sealed to valve body 120 by O-ring 132 and is restricted in its movement to the right by shoulder 133 on the valve body. Valve 127 has a greater effective cross sectional area exposed to the pressure in chamber 41 than in chamber 129. Thus, as pressure within the cartridge is increased,

the valve is urged to the left. Likewise, follower sleeve 131 has a greater cross sectional area on its left end than on its right end and is urged to the right with an increase in pressure. Therefore, as the pressure increases, the metal-to-metal seal between these two members is made more secure.

Valve 127 and control piston 35 are connected by operating rod 134. Valve 127 is slidable on rod 134 and this sliding movement is restricted by nut 135 on the end of the rod. It will be noted that in a position immediately prior to discharge nut 135 and valve 127 are separated by a small gap 136. This gap is slightly smaller than the space between shoulder 64 on control adjusting stem 49 and the right hand end of tubular portion 47. That portion of the rod 134 adjacent valve 127 may be provided with a radial extension 137 or other equivalent means to retain valve closing spring 138.

In operation, compressed gas is introduced through suitable inlet means into chamber 129. The gas passes through passageways 128 in valve 127 into chamber 41. The pressure gradually increases within the cartridge and urges follower ring 131 to the right in opposition to the pressure-induced leftward movement of valve 127 so as to make the metal-to-metal seal between these two members progressively tighter. This increase in pressure also urges valve 127 and follower sleeve 131 to the right since these two members as a unit have differential cross sectional areas greater on the left end than on the right end. Simultaneously, the pressure increase in chamber 41 urges control piston 35 to the right in opposition to helical spring 55. This gradual movement of piston 35 continues until pin 52 contacts ball valve 44 as shown in FIGURE 6.

When the predetermined discharge pressure is reached, piston 35 is urged to the right so that the end of tubular section 47 contacts shoulder 64 on the control adjusting stem 49. Before the gap between members 47 and 64 is closed, nut 135 on operating rod 134 pulls valve 127 slightly to the right, thus breaking the seal between the valve and follower ring 131. This action occurs almost immediately because gap 136 is smaller than the space between shoulder 64 and tubular member 47. With the breaking of the seal between valve 127 and follower ring 131, valve 127 is suddenly urged to the right. Lateral exhaust ports 126 are thus opened. This results in the rapid and efficient discharge of the compressed gas from chamber 129.

Concurrently, ball valve 44 is unseated, permitting compressed gas to discharge through stem 50 into chamber 65 and thence to the atmosphere through vents 25. This results in a reduction in pressure in spring chamber 36 and a similar reduction in pressure in chamber 42 at the end of valve 28. With the reduction of pressure in chamher 42, the sleeve valve 28 is urged to the right and discharge of the gas within chamber 41 is effected through lateral discharge ports 26 as previously described in connection with the discussion relative to FIGURE 3 of the drawing. When the pressure is reduced in the system, the valves are returned to operating condition by springs 55 and 138. As rod 134 is returned to the left in response to the action of spring 55, spring 138 urges valve 127 to a closed position.

While sleeve valve 127 and ball valve 44 are unseated practically simultaneously, it will be appreciated that valve 28 will necessarily open subsequent to valve 127. This time differential in the opening of valves 127 and 28 occurs because of the time required to vent chambers 36 and 42. At normal operating pressures, it is estimated that valve 28 opens from. about 50 to milliseconds after valve 127.

The cartridge shown in FIGURE 7 is provided with a tubular body 139, an extension 140, and an end cap 141. These members are secured by screw threads 142 and 143 and the seal between them completed by O-rings 144 and 145. The cartridge is divided into chambers 146 and 147 by fixture 148. Conduit 149 extends through the entire length of chamber 146 and serves as the means for introducing gas into the cartridge. This conduit terminates in radial passageways 150 in fixture 143. Sleeve valve 151 is slidable within the cartridge and cooperates with fixture 148 to define a control chamber 152. Valve 151 is provided with a plurality of relatively large passageways 153 and forms a metal-to-metal seal with follower ring 154.

The forward portion 155 of valve 151 normally closes and spans lateral discharge outlets 156, while the basal portion 157 of the valve forms a sliding fit with body 139. The juncture between the valve and body 139 is sealed by resilient O-ring 158. Valve 157 also cooperates with cartridge body 139 to form an annular obturated chamber 159.

The metallic sealing ring 154 is in sealing relationship with body 139 by means of O-ring 160. The movement of the ring to the left is limited by shoulder 161 on body 139 and to the right by its abutment with the terminal portion 179 of extension 140. The left end of follower ring 154 terminates in a modified knife edge 162. It will be noted that the inside diameter of knife edge 162 is slightly smaller than terminal portion 157 of valve 151.

Lateral discharge outlets 163 adjacent the right end of the cartridge are normally spanned and sealed by valve 164 having a plurality of relatively large passageways 165 passing therethrough. This valve is maintained in a closed position by spring 166 and forms a metal-t-o-metal seal with follower ring 167. O-rings 168 and 169 complete the sliding seals between extension 141 and valve 164 and follower ring 167, respectively. Spring 166 is held in position by shoulder 170 or by any other suitable equivalent means. Follower ring 167 is restricted in its leftward movement by shoulder 172 on extension 140.

The forward portion 177 of valve 164 i radially extended so that its external diameter is substantially greater than the diameter of the valve at its other end as defined by O-ring 168. Also, it will be noted that the inside diameter of the modified knife edge 178 in contact with valve 164 is slightly smaller than the outside diameter of the basal portion 180 of the valve. Thus, an increase of gas pressure within the cartridge tends to urge valve 164 to the right and into contact with follower ring 167.

Valves 151 and 164 are joined by connecting rod 173, the valves being slidable thereon, The connecting rod passes through openings in each ofthe valves and the ends of the red are enlarged as generally indicated at 174 and 175.

In operating the cartridge of FIGURE 7, compressed gas is introduced into the cartridge through conduit 149. The gas passes through radial passageways 150 into control chamber 152 and thence into the discharge chambers 146 and 147. The clearances between fixture 148 and shell 139 and between fixture 148 and valve 151 are of such a magnitude as to permit passage of air therethrough at a slightly retarded rate. Fixture 148 is provided with passageways 171 to provide ready communication between chambers 146 and 147. The air also passes through passageways 153 in valve 151 and passageways 165 in valve 164. Thus during charging and up to the time of discharge, the pressures throughout the various portions of the cartridge are substantially equal. Since both valve 151 and valve 164 in closed position have greater effective cross-sectional areas on their left ends than on their right ends, pressure within the cartridge urges them to the right. Thus, the metal-to-metal seals between the valves and their respective follower rings become progressively tighter as the gas pressure is increased.

When the desired discharge pressure is reached, the operator closes the feed line at a point remote from the cartridge and then vents the line to the atmosphere.

This results in a sudden reduction in pressure in conduit 149 and also in control chamber 152. This sudden lowering of the pressure in control chamber 152 causes sleeve valve 151 to fly to the left, thus opening lateral discharge ports 156 and permitting the gas in chamber 146 to be discharged therethrough.

As valve 151 moves to the left, it contacts enlargement 174 on connecting rod 173. This action pulls the rod 173 a short distance to the left and also results in slight leftward movement of valve 164. Thus, the metal-to-rnetal seal between valve 164 and follower ring 167 is broken. When this seal is broken, the effective cross-sectional area on the right end of valve 164 is greatly increased and the valve is suddenly moved from its position spanning the ports. With the opening of these ports, the compressed gas within chamber 14-7 is efliciently discharged through ports 163.

After the gas has been discharged from chambers 146 and 147, valves 151 and 164 are returned to their original closed position by the action or springs 176 and 166. The cartridge is thus automatically returned to rechargeable condition. Spring 17 6 may be eliminated unless it is desired to close valve 151 before all the gas has been exhausted from the cartridge. Although spring 166 alone will not completely close valve 151, closure of this valve will be completed when charging gas is introduced into control chamber 152.

Various other types of gas discharge mechanisms can be employed. For example, the control valve mechanism of the above embodiment can be replaced by a shearable member of the type shown in US. Patent 2,527,291 issued to Frank H. Armstrong and Edward C. Filstrup, 11'. Likewise, a rupturable disc of the type described in US. Patent 2,778,309 issued to Edward C. Filstrup can also be advantageously utilized.

Although the invention has been described in considerable detail in the foregoing for the purposes of illustration, it is to be 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 inven tion.

What is claimed is:

A gas liberating cartridge including a generally cylindrical body member closed at one end and having means at the opposite end for introducing gas under pressure, first and second discharge ports longitudinally spaced in said body, a first pressure responsive sleeve valve slidably mounted in said body and normally closing said first discharge ports, a second pressure responsive sleeve valve slidably mounted in said body and normally closed and second discharge ports, a control chamber adjacent said second sleeve valve, pressure responsive control piston means slidably mounted in said control chamber and adapted to move away from said second sleeve valve as the charging pressure in the cartridge is increased, a rod connecting said control piston and said first sleeve valve, said rod being effective to move said first sleeve valve out of engagement with said first discharge ports at a predetermined discharge pressure as the control piston is moved in response to the charging pressure in the cartridge, vent means in said control chamber, said control piston being further adapted to simultaneously actuate said vent means in said control chamber and reduce the pressure therein, the reduction in pressure in said control chamber being effective to move and second sleeve valve out of engagement with said second discharge ports to completely discharge said cartridge.

References Cited in the file of this patent UNITED STATES PATENTS 1,035,576 Goodwin et al Aug. 13, 1916 2,083,978 Armstrong June 15, 1937 2,720,167 Hesson Oct. 11, 1955

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