US3662670A

US3662670A - Blast-actuated valve-closure system

Info

Publication number: US3662670A
Application number: US40527A
Authority: US
Inventors: Robert Gordon Mccoy
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1970-05-26
Filing date: 1970-05-26
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

A blast-actuated valve-closure system for closing an opening in response to the overpressure of a blast. The system comprises a plurality of louvers disposed across the opening in a normally open position. The louvers are fastened by cranks to a rod which is adapted to be moved by a rotatable actuating crank driven by a torsion spring. Normally, rotation of the actuating crank is blocked by two spring-loaded rollers interposed in a detent therein. A rotatable triggering crank is responsive to the impingement of a blast pressure wave on the louvers for unblocking the actuating crank which then effects movement of the rod for tilting the louvers to their closed position. A rotatable resetting crank is provided for restoring the actuating crank and the rod to their initial positions thereby moving the louvers to their open position. In addition, the actuating crank may alternatively be unblocked by electromechanical means which has its energization controlled either electrically by sensing devices or manually by an attendant.

Description

United States Patent McCoy 51 May 16, 1972 [54] BLAST-ACTUATED VALVE-CLOSURE SYSTEM [7 21 Inventor: Robert Gordon McCoy, Whippany, NJ.

Bell Telephone Laboratories, Incorporated, Murray Hill, Berkeley Heights, NJ.

[22] Filed: May 26,1970

[21] Appl.No.: 40,527

[73] Assignee:

Primary Examiner-Edward J. Michael AltomeyR. J. Guenther and William L. Keefauver [57] ABSTRACT A blast-actuated valve-closure system for closing an opening in response to the overpressure of a blast. The system comprises a plurality of louvers disposed across the opening in a normally open position The louvers are fastened by cranks to a rod which is adapted to be moved by a rotatable actuating crank driven by a torsion spring. Normally, rotation of the actuating crank is blocked by two spring-loaded rollers interposed in a detent therein. A rotatable triggering crank is responsive to the impingement of a blast pressure wave on the louvers for unblocking the actuating crank which then efi'ects movement of the rod for tilting the louvers to their closed position. A rotatable resetting crank is provided for restoring the actuating crank and the rod to their initial positions thereby moving the louvers to their open position. In addition, the actuating crank may alternatively be unblocked by electromechanical means which has its energization controlled either electrically by sensing devices or manually by an attendant.

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BACKGROUND OF THE INVENTION This invention relates to valve-closure systems and, more particularly, to an improved valve-closure system that is actuated automatically in response to the over-pressure of a blast.

Protection against blasts from atomic bombs or other severe explosions may be obtained by constructing a strongly reinforced chamber in a favorable location, such as at a suitable depth under the surface of the earth. A chamber of this type is usually equipped with a ventilating system having a number of ducts extending from the chamber to the surface of the ground. Some of these ducts function as intake ducts for admitting fresh air to the chamber while other of the ducts serve as exhaust ducts for removing stale air from the chamber. Both of these types of ducts are, in general, provided with valve-closure devices for sealing or closing them against overpressure when a blast occurs. This is especially necessary in the event of an atomic explosion in order to exclude radioactive fallout and destructively high blast pressures.

These valve-closure devices can be controlled by various types of sensing systems which are designed to detect the occurrence of a blast. The sensing systems are usually designed to operate the valve-closing devices so that they will be closed before the arrival of an airblast wave. In addition, as a safety precaution against a possible failure of a sensing system, it is desirable that the valve-closing devices be so designed as to become closed automatically when a sudden overpressure impinges upon them.

Heretofore, such automatically operated valve-closing devices have not been fully satisfactory because they have employed large closure members, usually a single closure member for a large valve. Because of the large unit blast pressures over large closure areas, the closure members and, consequently, all associated moving parts, as well as bearings and fixed hardware, must be very massive to withstand the large static and dynamic loads resulting from airblast pressure loading, shock-front interaction, and heavy impact on seating. This heavy construction has been objectionable because it is expensive and its operation is not sufficiently rapid.

SUMMARY OF THE INVENTION The present invention is designed to overcome the objections discussed above by providing an improved automatically operated valve-closure system which is safer, faster, simpler, cheaper, and more reliable than valve closures of the prior art. The valve-closure system of this invention comprises a plurality of louvers pivoted near their centers and mounted across the opening of a ventilating duct in a normally open position. The louvers are individually fastened by connecting cranks to a common operating rod which is adapted to be moved by a rotatable actuating crank driven by a torsion spring. Normally, the rotation of the actuating crank is blocked by locking means comprising two rollers interposed in a detent formed therein.

A rotatable triggering crank is responsive to the impingement of a blast pressure wave on the louvers for efiecting the unblocking of the actuating crank through the removal of the rollers from their interposed positions. Upon being thus unblocked, the actuating crank is rotated by the torsion spring and drives or pulls the operating rod to a position where the associated connecting cranks effect the tilting of the louvers to their closed position thereby closing the opening in the ventilating duct.

A rotatable resetting crank is provided for utilizing the rollers and the detent to restore the actuating crank and the operating rod to their initial positions thereby effecting the return of the louvers to their normally open position.

The unblocking function of the rotatable triggering crank may alternatively be performed by electromechanical triggering means having its energization controlled either manually by an attendant or electrically by a suitable blast-sensing device.

BRIEF DESCRIPTION OF THE DRAWING The features of this invention are more fully discussed hereinafter in relation to the following detailed description of the drawing in which:

FIG. 1 is a front view of an exemplary embodiment of the valve-closure system of this invention;

FIG. 2 is a perspective view of the valve-closure system mounted across the opening of a duct that is located in a concrete emplacement;

FIG. 3 is an exploded perspective view of the chief operating components of the valve-closure system;

FIG. 4 is a side view, partly in section, of a portion of the valve-closure system with the louver blades in their normally open position and some of the components of the valveoperating equipment in their normally unoperated or idle positions;

FIG. 5 is a side view that is somewhat similar to FIG. 4 but showing the louver blades in their closed position with some of the other components of the valve-operating equipment in their operated or active positions;

FIG. 6 is a side view that is somewhat similar to FIG. 5 but which shows the resetting crank, which is employed in the valve-operating equipment, in its operated or active position;

FIG. 7 is an end view, partly in section, of the locking mechanism and the triggering mechanisms which are used in the valve-operating equipment;

FIG. 8 is a partly sectionalized side view that is somewhat similar to FIG. 4 but which illustrates a number of additional components of the valve-operating equipment;

FIG. 9 is a partly sectionalized side view taken from the opposite direction of that used for FIG. 8 and showing additional components of the valve-operating equipment;

FIG. 10 is a schematic diagram of exemplary circuits utilized for controlling the operation of the motor employed in the valve-operating equipment; 7

FIG. 11 is a schematic diagram of exemplary circuits used for controlling the energization of the solenoid that is incorporated in the valve-closing equipment;

FIG. 12 is a partly sectionalized side view, taken along the line 12-12 in FIG. 7, of the locking mechanism;

FIG. 13 is a detailed side view, partly in section, of normally unoperated resetting means which is adapted for resetting the locking mechanism after it has been released;

FIG. 14 is a detailed side view that is somewhat similar to FIG. 13 but which shows the resetting means in a partly operated condition;

FIG. 15 is a detailed side view that is somewhat similar to FIG. 14 but which shows the resetting means in a fully operated condition; and

FIG. 16 is a detailed side view, partly in section, of a portion of the operating rod and some of the components of the valveoperating system that are associated with it.

DETAILED DESCRIPTION An exemplary blast-actuated valve-closure system in accordance with this invention is broadly illustrated in FIG. 1 and FIG. 2. It can be seen in FIG. 2 that the valve-closure system is associated with a ventilating duct 1 extending to an underground chamber which is not shown as it forms no part of the invention. The duct 1 may be either an intake duct or an exhaust duct and is securely held by a concrete emplacement or support 2. The mouth or opening of the duct 1 may have any convenient shape, such as that of arectangle. A louver valve-closure device 3 is securely mounted in abutting relationship across the opening of the duct 1 as is represented by FIG. 2.

The louver valve-closure device 3 is provided with a heavy rectangular frame 4 having a number of strong cross-ribs 5. The ribs 5 are spaced equidistantly apart and are immovably fastened to the frame 4. Each of the ribs 5 has a louver blade 6 pivotally attached thereto by suitable continuous hinge means 7. Each of the hinge means 7 is disposed near the center of the cross-section of its associated louver blade 6 as is best seen in FIG. 3 and FIG. 8. The louver blades 6 are parallelly disposed and, when closed, form covering means for the opening of the duct 1. Each of the blades 6 has a tapered chevron-shaped cross-section, as is best seen in FIG. 8,.and is designed to rotate through a stroke of about 70.

One of the blades 6 is shown in the upper portion of FIG. 8 and it should be noted that the distance between its right edge and the hinge 7 is slightly less than the distance between its left edge and the hinge 7. This hinge eccentricity is provided for the purpose of assisting in developing aerodynamic torque and to insure that blast pressure impinging on the valve 3, after it has been closed, cannot reopen it.

A plurality of connecting cranks 8 are associated with the louver blades 6. Each of the cranks 8 has one end fixedly and immovably attached to a respectively different one of the blades 6 at a point in the middle of the length thereof. The other end of each of the cranks 8 is pivotally attached by appropriate hinge means 9, as is best indicated in FIG. 3, to a hollow operating rod 10 which is adapted to be moved up and down along its longitudinal axis by means described hereinafter.

A portion of one side of the rod 10 is cut away so that the ends of the cranks 8 can enter the cavity formed by the hollow interior of the rod 10 and thus receive the hinge means 9. Theoretically, the operating rod 10 may be constituted by a unitary member. However, as a practical expedient, it is shown in the drawing as being a composite rod which is formed in sections that are joined together by conventional coupling means.

When the operating rod 10 is moved to the limit of its extent of travel in one direction, the connecting cranks 8 effect the rotation of the louver blades 6 to their open position where, as is shown in FIG. 2 and also in FIG. 4, they uncover the opening of the duct 1. Then, when the operating rod 10 is moved to the limit of its extent of travel in the opposite direction, the pivotally-mounted connecting cranks 8 will pull the louver blades 6 into their closed position where, as is shown in FIG. 1 and also in FIG. 5, the blades 6 overlap in flat array thereby covering, or closing, the opening of the duct 1.

It should be noted that the tapered chevron shape of the cross-section of each of the louver blades 6 minimizes air flow losses and assists, in combination with the above described location of the hinge means 7, to produce aerodynamic closing torques.

The construction and configuration of the valve-closure device 3 is especially suited for fast closing action because of its low inertia. This is because the valve-closure device 3, instead of being a large, single device, comprises a number of low-inertia blades 6. For equal closing times, the ratio of the actuating force required for this valve to that required for most of the prior art valves is less than 0.01. This ganged array of balanced blades 6 has the additional advantages of minimizing the energy which must be absorbed when it is rapidly closed, and of spreading the minimized impact energy fairly evenly over the large elastic field of the blades 6.

The louver blades 6 are normally in an open position because the operating rod 10 is normally in its unoperated position shown in FIG. 3 and also in FIG. 4. When it is desired to tilt the louver blades 6 to their closed position, the operating rod 10 must be moved to its operated position shown in FIG. 5. This movement of the operating rod 10 is effected by an actuator crank 11.

THE ACTUATOR CRANK As is shown in FIG. 3, one end of the actuator crank 11 is bifurcated or divided into two branches. The ends of these branches are pierced for receiving therein an instrumentality, constituted by a coupling pin 12, which extends through the walls of the hollow operating rod 10. A blade 13, having a shouldered end, is vertically disposed inside the cavity formed by the hollow interior of the rod 10. As is shown in FIG. 16, the blade 13 has its shouldered end in engagement with that portion of the coupling pin 12 which extends between the branches of the bifurcated end of the actuator crank 11. The function performed by this blade 13 is explained hereinafter.

The actuator crank 11 is normally in its idle position, shown in FIG. 3 and also in FIG. 4, wherein it holds the operating rod 10 in its unoperated position. This causes the operating rod 10 to hold the covering means, comprising the louver blades 6, in its open position. The actuator crank 11 is rotatably mounted on a pivot rod 14 and is adapted to be rotated to its active position, shown in FIG. 5, in response to a driving force exerted by a coiled torsion spring 15 which is best seen in FIG. 3. This torsion spring 15 has one end fixedly connected by any suitable means, such as a clamp, to an anchor plate 16 which, as is indicated by broken lines in FIG. 3, is fastened to a portion of the valve-operating equipment frame 35 by any convenient means, such as bolts. The other end of the torsion spring 15 is fixedly attached to a driving thimble 30 by appropriate clamping means 300 and 30d. The driving thimble 30 is rotatably mounted on the pivot rod 14, as is indicated by a broken line in FIG. 3. The bottom part of the driving thimble '30 has a protruding portion with a squared end 301': which is adapted to be received within a hole 30b in the actuator crank 11 and is securely retained therein by axial confinement for the purpose of applying a driving torque to the actuator crank l 1.

In this exemplary embodiment of the invention, the torsion spring 15 is normally wound so as to be torsionally stressed. It is designed to exert a starting torque of approximately 900 inch-pounds which can be used for rotating the actuator crank 11 so that its bifurcated end will move downward to its active position, shown in FIG. 5, thereby moving the operating rod 10 downward to its operated position. This movement of the operating rod 10 will cause the covering means, comprising the louver blades 6, to move to its closed position wherein the opening of the duct 1 will be closed.

THE LOCKING MEANS However, the driving force of the torsion spring 15 and the rotation of the actuator crank 11 are normally blocked by locking means. The locking means have a first position for normally holding, or locking, the actuator crank 11 in its idle position. In addition, the locking means have a second position adapted for unblocking or releasing the actuator crank 11. The locking means comprise two locking, or trip, rollers 17 normally interposed one above the other in a composite detent.

Specifically, this composite detent comprises a hole or cavity 18 formed in the actuator crank 11. The cavity 18 contains two spaced pins or double fingers 19 which are attached to the actuator crank 11 by means described hereinafter and which are so disposed as to support the lower one of the rollers 17 as is shown in FIG. 7. The detent further comprises a third pin or holding finger 21 attached to a resetting crank 22. This resetting crank 22,which is normally stationary, is rotatably mounted on the pivot rod 14 in a position adjacent to one side of the actuator crank 11 for a purpose that is explained hereinafter.

The third finger 21 is adapted to protrude from the resetting crank 22 in such a manner as to bear on the upper one of the trip rollers 17 as is shown in FIG. 7. Thus, the holding finger 21 and the locking rollers 17 function to prevent the double fingers 19 and their associated portion of the actuator crank 11 from moving upward. It should be noted that the position of the holding finger 21 is above a space 23 which, as is shown in FIG. 12, is formed between the two pin or finger elements of the double fingers 19. This space 23 is made atleast equal to the width of the holding finger 21 and is sufficiently large to allow the holding finger 21 to pass therethrough when the locking rollers 17 are removed from their interposed position and the double fingers 19 are moved upward by the actuator crank 11 in the manner described hereinafter.

THE TRIGGER MEANS Trigger means are provided for moving the locking rollers 17 from their interposed position to their second position for effecting the release of the actuator crank 11 from its idle position. The trigger means comprise a trigger spring 24 coiled around a trigger plunger 20. As is best seen in FIG. 7, both the spring 24 and the plunger 20 are disposed in a cavity 25 formed in a block 26 which is securely fastened to one side of the actuator crank 1 1. One end of the plunger 20 extends through a hole in the block 26 for a purpose that is described hereinafter. One end of the trigger spring 24 rests against a portion of the block 26 and its other end bears against the enlarged head of the plunger 20 for pressing it against one side of the rollers 17. Normally, the trigger spring 24 is compressed so that it exerts pressure against the rollers 17.

The force exerted by the spring 24 and the plunger 20 against one side of the rollers 17 is normally ineffective to move them because the other side of the rollers 17 abuts against a disk 27 which is fastened to one end of a plunger 28 in a solenoid 29. The solenoid 29 is normally energized and, consequently, pushes its plunger 28 and the disk 27 toward the left in FIG. 7 with sufficient force for holding the rollers 17 firmly against the head of the trigger plunger 20 thereby overcoming the force exerted by the trigger spring 24. The vertical alignment of the rollers 17 is maintained by the fact that the disk 27 also causes the ends of the rollers to press against the interior face of the block 26.

It should be noted that a portion of the resetting crank 22 is recessed for forming a cavity 31 in the area around the disk 27. This cavity 31 is of sufficient size to receive therein the rollers 17 but they are normally prevented from entering it by the presence of the disk 27 which is held therein at this time by the force exerted by the solenoid 29.

CLOSING THE LOUVER BLADES When it is desired to move the louver blades 6 to their closed position for closing the opening of the duct 1, the restraining or blocking force presented by the solenoid 29 must be overcome. This can be accomplished by several different methods which are explained hereinafter. In response to using any one ofthese methods, the plunger 28 and the disk 27 are forced to move toward the right in FIG. 7 thereby vacating the left portion of the cavity 31, This permits the trigger spring 24 and the trigger plunger 20 to push the locking rollers 17 into the cavity 31 thereby unblocking or releasing the double fingers 19. Accordingly, the double fingers l9 and their associated portion of the actuator crank 11 are now free to be rotated or moved upward in response to the driving force exerted by the torsion spring which is normally wound so as to be torsionally stressed.

It should be noted that this portion of the actuator crank 11 has an arcuate groove or trough 32 formed therein as is best seen in FIG. 12. This groove 32 is of sufficient size to accommodate or to receive therein the end portion of the holding finger 21. The reason for this is that the holding finger 21 is attached to the resetting crank 22 which remains stationary during the upward rotation of this portion of the actuator crank 11. Accordingly, when this portion of the actuator crank 11 is rotated upward, the groove 32 and the space 23 between the double fingers 19 travel past the protruding portion of the holding finger 21 and thus enable the actuator crank 11 to rotate freely without, at this time, being blocked by the holding finger 21.

When the double fingers l9 and their associated portion of the actuator crank 11 rotate upward, the other, or bifurcated, portion of the actuator crank 11 rotates downward to its active position, as is represented in FIG. 5. As was stated above, since this end of the actuator crank 11 is joined by the coupling pin 12 to the operating rod 10, this rotation of the actuator crank 1 1 causes the operating rod 10 to be pulled down to its operated position thereby tilting the louver blades 6 to their closed position, as is shown in FIG. 5, and thus closing the opening of the duct 1.

The resulting abutment of the edges of the louver blades 6 against each other restrains the operating rod 10 from further downward movement and this, in turn, prevents further rotation of the actuator crank 11.

It should be noted that the operation of the actuator crank 11 and the operation of the torsion spring 15 are entirely rotary; This rotary operation produces the following advantages: it minimizes inertia of the parts, simplifies the constructional details, minimizes the number and complexity of the bearings, and also minimizes the effects of friction.

STARTING THE UPWARD ROTATION OF THE RESETTING CRANK At a point in time near the end of the abovementioned rotation of the actuator crank 11, a cam 33, which is attached to one side of the actuator crank 11, moves into engagement, as is represented in FIG. 5, with a normally open control switch 34 which is fastened to the frame 35 of the valve-closure equipment. The engagement of the cam 33 with the control switch 34 closes the switch 34 and thereby closes an obvious circuit, shown in FIG. 10, for energizing a relay 53.

In response to being energized, the relay 53 operates its armature and thereby efiects the closure of a forward power supply circuit 36 for applying electric energy from a suitable source 37 of electric power for operating a conventional reversible electric gear motor 38 in a forward direction. This gear motor 38 has a shaft 39 on which a pinion gear 41 is mounted in meshing engagement with gear teeth 42 formed in an edge of the resetting crank 22. Accordingly, the motor 38 is now energized in a forward direction so as to cause its pinion gear 41 to drive the gear teeth 42 in a direction such that the resetting crank 22 will be rotated upward in the same direction as that in which the actuator crank 11 was rotated when it effected the closure of the louver blades 6.

THE TRIGGER RESETTING MECHANISM Attention should now be directed to the trigger resetting mechanism which is associated with the solenoid 29. As is shown in FIG. 7, the solenoid 29 is enclosed within a container 43 which is securely fastened by means of screws driven into a plurality of studs 44 formed on one side of the resetting crank 22. Thus, when the resetting crank 22 isrotated, it carries the container 43 and the solenoid 29 with it. The trigger resetting mechanism is positioned within the container 43 and is located adjacent to the right end of the solenoid 29.

The trigger resetting mechanism, as is shown in FIG. 13, includes a collapsible spring-loaded linking-mechanism comprising a compressed spring 45 disposed between a left washer 46 and a right washer 47 which are adapted to slide back and forth within the container 43. The left washer 46 has an axially extending bushing on each of its sides. The right bushing on the left washer 46 is designed to function as a sliding bearing for assisting in stabilizing the left washer 46 by preventing it from tilting. The left bushing on the left washer 46 has a central bore for receiving therein the head of a retaining shouldered screw 48 which normally abuts against the left washer 46.

The screw 48 extends through the spring 45 and also through a hole in the right washer 47. The point of the screw 48 is driven into the base of a control button 49 which abuts against the right washer 47 This control button 49 is slidably positioned in a hole in the end of the container 43. Due to the pressure exerted by the spring 45 against the right washer 47, the conically-shaped external end of the control button 49 normally protrudes outside the container 43 to the extent Shown in FIG. 13.

When the resetting crank 22 approaches the limit of its rotation, control means must be utilized to effect its stopping at the proper point. These control means include a cam 51 which, as is shown in FIG. 9, is mounted on the resetting crank 22 near the toothed edge thereof. The control means also include a normally closed limit switch 52 which is mounted on a bracket 40 that is attached to the frame of the valve-closure equipment.

While the toothed edge of the resetting crank 22 is rotating upward, it moves the cam 51 upward to its position shown in dotted lines in FIG. 9. This upward position of the cam 51 causes the cam 51 to engage and open the normally closed limit switch 52. As can be understood from inspection of FIG. 10, the opening of the switch 52 effects the deenergization of the relay 53 which consequently releases its armature and thereby effects the opening of the power supply circuit 36 of the motor 38. This stops the motor 38 and thus terminates the upward rotation of the resetting crank 22.

PINNING THE ACTUATOR CRANK TO THE RESETTING CRANK Slightly before the motor 38 is stopped, the solenoid container 43, which is being carried along with the rotating resetting crank 22, is moved upward to its position shown in dotted lines in FIG. 9. This upward position of the solenoid housing 43 causes the conical end of its control button 49 to come into engagement with a stationary cam 54 that is fastened to the frame 35 of the valve-closure equipment.

The resulting engagement of the control button 49 with the cam 54 causes the protruding portion of the control button 49 to be pushed toward the solenoid 29 as is shown in FIG. 14. Normally, as is shown in FIG. 13, the control button 49, which can now be understood as constituting a cam-operable instrumentality, abuts against the right washer 47 which is inside the solenoid container 43. In moving inward, the control button 49 pushes the washer 47 toward the left, as is shown in FIG. 14, thereby further compressing the spring 45, as is also represented in FIG. 14. The inward motion of the control button 49 causes the head of the screw 48 to move toward the left inside the left bushing on the left washer 46.

The compressional force thus produced in the spring 45 tends to push the left bushing on the left washer 46 toward the left in FIG. 14 so as to increase its pressure against the plunger 28 of the solenoid 29. This increased pressure tends to push the plunger 28 and its disk 27 toward the left in FIG. 14 but such movement of the plunger 28 is blocked at this time because the rollers 17 are held within the cavity 31 by the presence of the adjacent side of the actuator crank 11. Accordingly, this pressure is maintained without producing any useful result until the rotation of the resetting crank 22 is nearly terminated.

Just before the rotation of the resetting crank 22 is terminated, the rollers 17 in the cavity 31 will be carried into alignment with the cavity 18 in the actuator crank 11. Now,

' the pressure exerted by the spring 45, which is being transmitted by the left washer 46 through the plunger 28 and the disk 27 to the rollers 17, becomes effective to force the rollers 17 out of the cavity 31 in the resetting crank 22 and into the cavity 18 in the actuator crank 1 1. This permits the plunger 28 and the disk 27 tomove to their positions shown in FIG. 7. Also, the left washer 46 now moves to its position shown in FIG. 15.

It should be noted that the trigger spring 24 and the plunger oppose the entry of the rollers 17 into the cavity 18. However, since the pressure exerted by the spring 45 is designed to be greater than that exerted by the spring 24, the rollers 17 will enter the cavity 18 at this time and will assume their previously described interposed position between the double fingers 19 on the actuator crank 11 and the holding finger 21 on the resetting crank 22. This serves to pin the actuator crank 1 1 to the resetting crank 22. The trigger resetting action is now terminated with the above-mentioned opening of the motor energizing circuit 36. The valve-closure system now remains in this closed and reset condition.

OPENING THE LOUVER BLADES When it is desired to open the louver blades 6, a conventional manual control switch 55, which is normally open as is shown in FIG. 10, is manually operated for closing an obvious circuit for energizing a relay 50. Upon being energized, relay 50 operates its armature to close a suitable reverse energizing circuit 56 for connecting the power supply source 37 to the motor 38 in such a manner as to cause the motor 38 to operate in the reverse direction from that previously described. Accordingly, the pinion gear 41 will now be rotated in a direction opposite to that described above and will consequently drive the gear teeth 42, which are on the edge of the resetting crank 22, in such a manner as to cause the resetting crank 22 to rotate in a direction which is the opposite of its previously described rotation.

The reverse rotation of the resetting crank 22 will be accompanied by corresponding reverse rotation of the actuator crank 11 due to the fact that they are pinned together by the double fingers 19, the rollers 17, and the holding finger 21 as was explained above. The reverse rotation of the actuator crank 11 carries the cam 33 out of engagement with the switch 34 which thereupon reopens. Immediately thereafter, the reverse movement of the resetting crank 22 carries the cam 51 out of engagement with the limit switch 52 which, consequently, becomes closed.

During the reverse rotation of the actuator crank 11, the torsion spring 15, which has one end fixedly connected to the actuator crank 11 as was described above, will be wound so as to return to its original fully energized state or condition of being under full torsional stress. Also, at this time, the coupling pin 12, which couples the actuator crank 11 to the operating rod 10, will force the operating rod 10 to move upward. This upward movement of the operating rod 10 will cause the connecting cranks 8, which couple the operating rod 10 to the louver blades 6, to force the louver blades 6 to return to their open position.

STOPPING THE DOWN WARD ROTATION OF THE RESETTING CRANK The reverse movement of the above-mentioned parts continues until it is terminated in response to a cam 57 moving into engagement with a limit switch 58 to effect its operation. The cam 57 is shown in FIG. 9 to be attached to one side of the resetting crank 22 at a point near the previously described cam 51. The limit switch 58 is mounted on a bracket 60 that is attached to the frame 35 of the valve-closing equipment.

FIG. 9 shows the cam 57 in engagement with the limit switch 58. However, the portion of the resetting crank 22, that is shown in solid lines in FIG. 9, represents the idle position of the resetting crank 22 as is illustrated in FIG. 4. It should be noted that, prior to the occurrence of the reverse movement of the resetting crank 22, this portion of the resetting crank 22 had been rotated upward to its active position as is illustrated in FIG. 6. This active position of the resetting crank 22 is represented with broken lines in FIG. 9. The rotation of the resetting crank 22 to its active position causes the cam 57 to be rotated upward out of engagement with the limit switch 58. This permits the limit switch 58 to become closed as is represented in FIG. 10.

When the resetting crank 22 is now rotated to return to its idle position, the cam 57 is carried into engagement with the limit switch 58 as is illustrated in FIG. 9. This action operates and opens the limit switch 58 thereby opening the energizing circuit of the relay 50. This causes the relay 50 to release its armature thus opening the reverse power supply circuit 56 of the motor 38. Accordingly, the reverse rotational movements of the resetting crank 22 and the actuator crank 11 are now terminated. The manually operable switch 55, which has been maintained closed during this movement of the resetting crank 22, can now be moved to its open position that is shown in FIG. 10. It should be noted that the terminating function of the cam 57 is so designed that the above mentioned reverse movements are not terminated until the louver blades 6 are fully restored to their normally open position.

LOCKING THE RESETTING CRANK It should be noted that, when the motor 38 is not energized, the pinion gear 41 is held stationary due to the fact that it is coupled to the motor 38 by a conventional worm gear reduction drive mechanism 70 that is represented in FIG. 9. The reduction gear mechanism 70, which is of a type well known to those skilled in the art, is so designed that it does not allow the pinion gear 41 to rotate unless the motor 38 is energized. Accordingly, since the pinion gear 41 is normally locked in a stationary position by the reduction gear mechanism 70, the pinion gear 41 functions, in turn, through its engagement with the gear teeth 42 on the rim of the resetting crank 22, to hold or lock the resetting crank 22 in a normally stationary position.

As a result, due to the above-mentioned pinning action between the actuator crank 1 l and the resetting crank 22, the actuator crank 11 is normally prevented from rotating. Therefore, this locked, or stationary, condition of the actuator crank 11 imposes a restriction upon the movement of the operating rod 10 during the time that the rollers 17 are in their interposed position. This pinned and stationary condition of the actuator crank 11 renders the torque exerted by the torsion spring 15 ineffective to rotate the actuator crank 11 at this time.

UNLOCKING THE LOCKING MEANS It was stated above, in describing the procedure that should be followed in tilting the louver blades 6 to their closed position, that the operating rod 10 cannot be moved to its operated position until the locking means, which comprise the rollers 17, has released the actuator crank 11 for rotation thereof. It was also explained above that the rollers 17 are normally held in their locking position by pressure exerted by the normally energized solenoid 29. It was further stated above that the blocking force presented by the solenoid 29 can be overcome by several different methods. These methods will now be described.

UNLOCKING BY MANUAL MEANS The simplest method is to open manually a normally closed circuit 59 which is adapted to energize the solenoid 29. This energizing circuit 59, which is illustrated in FIG. 11, serves to connect a suitable source 61 of electric energy to the winding of the solenoid 29. A manually operable switch 62, which is normally closed, is connected in series with the energizing circuit 59 so that, by manually opening the switch 62, the energizing circuit 59 will be opened and the solenoid 29 will become deenergized.

Accordingly, the plunger 28 of the solenoid 29 will now cease its normal opposition to the force exerted by the trigger spring 24 and the trigger plunger 20. Therefore, the trigger plunger 20 will now move toward the right in FIG. 7 thus pushing the rollers 17 into the cavity 31 in the resetting crank 22 and thereby releasing the actuator crank 11 for rotation in response to the driving force exerted by the torsion spring 15. The louver blades 6 will now be moved to their closed position in the manner described above. The solenoid 29 can be subsequently reenergized by manually closing the switch 62 either during or after the above described upward rotation of the resetting crank 22.

UNLOCKING WITH A BLAST-SENSING DEVICE A second method is to employ a suitable conventional blastsensing device 63, such as a remotely located blast-pressure detector or a gamma detector, which, as is well known to those skilled in the art, will produce an electric output in response to the occurrence of a blast. The electric output from the blast-sensing device 63 is adapted to open an obvious circuit 65 which is normally closed for energizing a relay 64, as is shown in FIG. 11. The opening of the circuit 65 causes the normal energized relay 64 to become deenergized. Accordingly, the relay 64 will now release its normally operated armature thereby opening the energizing circuit 59 of the solenoid 29. This deenergization of the solenoid 29 effects the release of the rollers 17 in the same manner as that described above and for accomplishing the same results, i.e., rotation of the actuator crank 11 and the consequent closure of the louver blades 6.

After the effects of the blast have subsided, the electric output from the blast-sensing device 63 is discontinued thereby effecting the reclosing of the energizing circuit 65 with the consequent reenergization of the relay 64. This subsequent reenergization of the relay 64 will cause it to operate its armature thereby reclosing the energizing circuit 59 to effect the reenergization of the solenoid 29. This restores the system to the condition required for reopening the louver blades 6.

UNLOCKING WITH AERODYNAMIC TORQUE A third method is to utilize the aerodynamic torque which is generated at the louver blades 6 and which is applied by them to the operating rod 10 when a sudden over-pressure impinges upon the valve-closure system. This is accomplished by employing an aerodynamically operated trigger crank 66 which is positioned adjacent to the actuator crank 11 and which is rotatably mounted on the same pivot rod 14 as is indicated in FIG. 3. The left end of this aerodynamic crank 66 extends to the operating rod 10 and has an arcuate slot 67 formed therein as is best seen in FIG. 16. A pin 68, which is attached to the operating rod 10, as is best shown in FIG. 3, protrudes through the slot 67. Thus, the pin 68 and the operating rod 10 serve to couple the aerodynamic crank 66 to the plurality of louver blades 6.

When a blast occurs, its overpressure impinges on the louver blades 6 and, because of their cross-sectional shape, applies a downward torque to them and they, in turn, translate this into a downward force upon the operating rod 10. The rod 10 accordingly moves downward carrying with it the pin 68 and thereby forcing the associated end of the aerodynamic crank 66 to rotate downward about the pivot rod 14. When the downward torque exerted by the louver blades 6 is sufficiently great, as is explained hereafter, it will initiate the movement of the aerodynamic crank 66 from its idle or unrotated position, shown in FIG. 4, to its active or rotated position. Thus, the overpressure of the blast effects the rotation of the aerodynamic crank 66 about the pivot rod 14.

It should be noted that, when the actuator crank 11 is released for rotation by either of the two methods previously described above, it pulls the operating rod 10 downward in the manner explained above. This, in turn, causes the pin 68 to move downward thereby forcing the aerodynamic crank 66 to rotate in the manner described immediately above. However, since the actuator crank 11 is also rotating, the accompanying rotation of the aerodynamic crank 66 performs no useful function at this time. Whenever the actuator crank 11 has been rotated to effect the closing of the louver blades 6, the arcuate slot 67 will have been moved toward the left, as is shown in FIG. 5, so that at any point during subsequent reopening of the louver blades 6, the aerodynamic crank 66 can respond to a blast pressure wave and can reclose the louver blades 6 if they are partly opened.

THE BIASING MEANS FOR THE OPERATING ROD Since, in spite of the normally locked condition of the actuator crank 11, the operating rod must move downward to a certain extent in order to initiate rotation of the aerodynamic trigger crank 66, a limited degree of freedom of movement is provided for the operating rod 10 by mounting the actuator coupling pin 12 in two slots 69 formed in opposite sides of the hollow operating rod 10. Due to the fact that, at this time, the actuator coupling pin 12 is held stationary, the operating rod 10 can move up and down within the limits imposed by the lengths of the slots 69.

Normally, the operating rod 10 is pushed upward, to the upper limit permitted by the slots 69, by means of a coiled biasing spring 71. This biasing spring 71 is under compression and is coiled around the blade 13 which, as was previously described, is vertically disposed inside the rod 10 with its shouldered end in engagement with the coupling pin 12, as is represented in FIG. 16.

The lower end of the biasing spring 71 abuts against the top edge of the shouldered portion of the blade 13, and the upper end of the spring 71 pushes upward against the bottom of a small block 72 which is securely fastened inside the cavity formed by the hollow interior of the rod 10. This block 72 has a central slot formed therein for receiving the upper end of the blade 13. Accordingly, when the rod 10 moves downward and further compresses the spring 71, the slot in the block 72 will slide downward around the upper portion of the blade 13.

Normally, since the spring 71 is under compression, it pushes against the block 72 and thus forces the operating rod 10 upward to the furthest extent permitted by the slots 69. As a result, the bottoms of the slots 69 normally abut against the coupling pin 12. Also, the position of the pin 68 is normally toward the left end of the arcuate slot 67 in the aerodynamic crank 66 as is shown in FIG. 16 and also in FIG. 4. It can therefore be understood that the downward force exerted by the louver blades 6 upon the operating rod 10, as a result of the overpressure of a blast, will not be effective to move the rod 10 downward unless it is greater than the opposing force exerted by the biasing spring 71.

When the overpressure of a blast causes the downward force exerted by the louver blades 6to exceed the biasing force of the spring 71, the operating rod 10 will be forced downward so that the top edges of the slots 69 will approach the top edge of the coupling pin 12. This action further compresses the spring71 by forcing the block 72 downward over the blade 13. The downward movement of the operating rod 10 forcesthe adjacent, or left, end portion of the aerodynamic trigger crank 66 to rotate downward correspondingly and thereby causes the other, or right, end portion of the aerodynamic crank 66 to rotate upward as was explained above.

As is indicated in FIG. 3, a small block 73 is adapted to be securely fastened to the right end portion of the aerodynamic trigger crank 66. This block 73 functions as a clamp for holding a shaft on which a trigger roller 74 is rotatably mounted. As is represented in FIG. 8, the trigger roller 74 protrudes beyond the right edge of the block 73. Thus, the trigger roller 74 is mounted to rotate in a plane which is tangent to the end of the actuator crank 66.

Another small block 77 is located near the first block 73. As is indicated by the broken lines in FIG. 3, this block 77 is adapted to be fixedly fastened to the block 26 which is designed to be attached to the actuator crank 11. The block 77 is mounted in such a manner as to overlap the right edge of the aerodynamic trigger crank 66 without normally applying any binding force to it. The purpose of this block 77 is to provide a stabilizing support for limiting the extent of any deflection or motion of the aerodynamic crank 66 outside of its desired plane of rotation.

A somewhat similar block 78 is fixedly secured to the resetting crank 22 near the toothed edge thereof as is best seen in FIG. 8. A portion of the block 78 overlaps the right edge of the actuator crank 11 but does not normally apply any binding force to it. This block 78 functions to restrict the motion of the actuator crank 1 l to its desired plane by stabilizing, or limiting, the extent of any deflection therefrom which might tend to be caused by axial forces produced by the tripping of the locking rollers 17.

THE AERODYNAMIC TRIGGER MEANS As is shown in FIG. 7 and also in FIG. 8, the block 26, which is attached to the actuator crank 11, has one end of an instrumentality, constituted by a spring-hinged lever-cam 75, fixedly secured thereto in the manner indicated in FIG. 3. The unattached end of this lever-cam 75 is tilted outward in a direction leading toward the aerodynamic trigger crank 66 for forming a ramp 76 as is best seen in FIG. 7. This instrumentality, or lever-cam, 75 is designed to bear against the roller 74 with a frictional engagement. As is best shown in FIG. 7, the trigger roller 74 normally engages that portion of the lever-cam 75 which is opposite that end of the trigger plunger 20 which is normally protruding through a hole in the block 26. The lever cam 75 is positioned close to the protruding end of the trigger plunger 20 and may touch it lightly. It should be noted that, when the trigger roller 74 is in the position shown in FIG. 7, neither it nor the lever-cam 75 apply any significant pressure to the protruding end of the trigger plunger 20.

When the right end portion of the aerodynamic trigger crank 66 is rotated upward, as was described above, it carries with it the trigger roller 74. In thus moving upward, the frictional engagement between the lever-cam 75 and the roller 74 produces rotation of the roller 74. The upward movement also causes the trigger roller 74 to move against the outwardly extending ramp 76 of the lever-cam 75.

Since the lever-cam 75 is spring-hinged, the movement, or rotation, of the trigger roller 74 upward along the ramp 76 will force the lever-cam 75 to move toward the face of the block 26 on the actuator crank 11. At the same time, the intermediate portion of the lever-cam 75 will be forced to move toward the block 26 and will consequently press against the protruding end of the trigger plunger 20. This pressure is transmitted to the enlarged head of the trigger plunger 20 which, in turn, applies pressure to the left side of the locking rollers 17.

When this pressure applied to the left side of the rollers 17, combined with the pressure exerted by spring 24, is greater than the opposing pressure applied to the other side of the rollers 17 by the operated disk 27 and plunger 28 of the solenoid 29, the disk 27 and the plunger 28 will be forced toward the right in FIG. 7. Accordingly, the locking rollers 17 will now be pushed into the cavity 31 which is formed in one side of the resetting crank 22. This action unlocks the actuator crank 11 and allows it to be rotated by the driving force exerted by the torsion spring 15 in the manner described above and thereby effects the tilting of the louver blades 6 and the closing of the opening in the duct 1. Thus, the trigger roller 74 constitutes rotatable initiating means which, through its rotation, effects the rotation of the actuating means formed by the actuator crank 11. Also, the aerodynamic crank 66 constitutes rotatable control means which, through its rotation, effects the rotation of the initiating means constituted by the trigger roller 74.

What is claimed is:

l. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast,

said system comprising movable covering means having a closed position for covering said opening and an open position for uncovering said opening,

said covering means having a surface adapted for receiving the force of a blast pressure wave,

rotatable actuating means adapted for effecting through its rotation the movement of said covering means from said open position to said closed position,

rotatable initiating means adapted for effecting by its rotation the initiation of the rotation of said actuating means,

and rotatable control means adapted for effecting through its rotation the rotation of said initiating means,

said control means being further adapted to be rotated in response to the impingement of a blast pressure wave on said covering means.

2. A blast-actuated valve-closure system in accordance with claim 1 and further comprising locking means having a first position adapted for blocking rotation of said actuating means,

said locking means having a second position adapted for unblocking rotation of said actuating means,

said rotatable initiating means including a roller adapted for effecting through its rotation the placing of said locking means in its second position and for thereby effecting the initiation of the rotation of said actuating means,

and said rotatable control means having means adapted for carrying said initiating means during rotation of said control means and for thereby effecting rotation of said roller.

3. A blast-actuated valve-closure system in accordance with claim 2 and further comprising an instrumentality attached to said actuating means and adapted to bear against said roller with a frictional engagement adapted for producing rotation of said roller in response to the carrying of said roller by said control means during its rotation.

4. A blast-actuated valve-closure system in accordance with claim 3 wherein said instrumentality is constituted by a springhinged lever-cam having a tilted portion for forming a ramp,

said ramp being adapted for sloping in a direction away from said locking means.

5. A blast-actuated valve-closure system in accordance with claim 1 wherein said covering means comprise a plurality of parallelly disposed louver blades,

and further comprising coupling means for coupling said plurality of louver blades to a portion of said control means,

said coupling means including an operating rod,

a plurality of connecting means each having one end attached to the middle of a respectively different one of said louver blades and having another end attached to said operating rod,

said control means having means defining an arcuate slot formed in said portion thereof,

and a pin attached to said operating rod and disposed in said slot,

the position of said pin in said slot being adapted to be changed in response to rotation of said control means.

6. A blast-actuated valve-closure system in accordance with claim 5 wherein said operating rod includes means defining a cavity formed therein,

and further comprising an instrumentality extending through said rod and into said cavity,

a block fixedly fastened inside said cavity,

biasing means for normally forcing said pin to move toward one end ofsaid slot,

said biasing means including a blade having a shouldered end,

said blade being slidably disposed within said cavity with said shouldered end in engagement with said instrumentality,

and spring means encircling said blade for pressing in one direction against said shouldered end of said blade and for pressing in an opposite direction against said block.

7. A blast-actuated valve-closure system in accordance with claim 1 and further comprising a shaft,

and means for mounting both said actuating means and said control means on said shaft for rotation thereabout.

8. A blast-actuated valve-closure system in accordance with claim 1 wherein said actuating means has an unrotated position in which it normally rests and a rotated position to which it moves in response to its rotation,

and further comprising rotatable resetting means adapted for returning said actuating means from its rotated position to its unrotated position.

9. A blast-actuated valve-closure system in accordance with claim 8 and further comprising a shaft,

and means for mounting said actuating means and said control means and said resetting means on said shaft for rotation thereabout.

10. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast,

and rotatable control means adapted for effecting through its rotation the consequent rotation of said actuating means,

11. A blast-actuated valve-closure system in accordance with claim 1 and further comprising rotatable initiating means adapted for effecting through its rotation the initiation of the rotation of said actuating means,

said initiating means having its rotation effected in response to the rotation of said control means.

12. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast,

control means for effecting the initiation of the rotation of said actuating means from an idle position to an active position,

and resetting means for returning said actuating means from said active position to said idle position.

13. A blast-actuated valve-closure system in accordance with claim 12 and further comprising locking means having a first position adapted for holding said actuating means in its idle position,

said locking means having a second position adapted for releasing said actuating means from its idle position for movement to its operated position,

said locking means including a composite detent having two holding means,

one of said holding means being fixedly attached to said resetting means, I

and the other of said holding means being secured to said actuating means.

14. A blast-actuated valve-closure system in accordance with claim 13 wherein one of said holding means includes a holding finger and the other of said holding means includes a double finger having two finger elements spaced apart by a distance at least equal to the width of said holding finger.

15. A blast-actuated valve-closure system in accordance with claim 14 wherein said holding means that is fixedly attached to said resetting means is constituted by said holding finger,

said holding finger having an end portion,

and further comprising means defining an arcuate groove in said actuating means for receiving therein said end portion of said holding finger.

16 A valve-closure system in accordance with claim 12 wherein said actuating means include means defining a cavity therein and wherein said resetting means include means defining a cavity therein,

and further comprising locking means adapted for locking said actuating means in its idle position,

said locking means including a first portion and a second portion,

said first portion being fixedly disposed in said cavity in said actuating means, i

and said second portion being fixedly disposed in said cavity in said resetting means.

17. A valve-closure system in accordance with claim 16 wherein one of said portions of said locking means includes a single holding pin,

and wherein the other of said portions of said locking means includes a double holding pin having two pin elements spaced apart by a distance at least equal to the diameter of said single holding pin.

18. A valve-closure system in accordance with claim 16 and further comprising roller means normally having a position interposed between said first and second portions of said locking means,

and first pushing means positioned in a first one of said cavities and adapted for pushing said roller means into a second one of said cavities for effecting the unlocking of said actuating means.

19. A valve-closure system in accordance with claim 18 and further comprising second pushing means positioned in said second one of said cavities and adapted for pushing said roller means out of said second one of said cavities after having been pushed therein by said first pushing means.

20. A valve-closure system in accordance with claim 19 and further comprising activating means for effecting movement of said second pushing means,

said activating means including spring means,

and a cam-operable instrumentality adapted for compressing said spring'means for effecting movement of said second pushing means. 21. A valve-closure system in accordance with claim 16 and further comprising roller means normally having a position interposed between said first and second portions of said locking means,

first pushing means positioned in a first one of said cavities and adapted for exerting pushing force against said roller means in a direction toward the second one of said cavities, 1

second pushing means positioned in said second one of said cavities and adapted for exerting pushing force against said roller means in a direction toward said first one of said cavities.

22. A valve-closure system in accordance with claim 21 and further comprising trigger means for effecting the movement of said roller means out of said interposed position,

said trigger means including means for causing the pushing force exerted by one of said pushing means to become relatively stronger than the pushing force of the other of said pushing means.

23. A system for alternatively covering and uncovering an opening,

said system comprising covering means having a closed position for covering said opening and an open position for uncovering said opening,

operating means adapted for moving said covering means alternatively from one of said positions to the other of said positions,

said operating means having an unoperated position for holding said covering means in its open position and an operated position for holding said covering means in its closed position,

actuating means adapted for moving said operating means from its unoperated position to its operated position,

said actuating means having an idle position for holding said operating means in its unoperated position and an active position for holding said operating means in its operated position,

locking means having a first position adapted for holding said actuating means in its idle position,

said locking means having a second position adapted for releasing said actuating means from its idle position,

trigger means adapted for moving said locking means from its first position to its second position for effecting the release of said actuating means from its idle position,

rotatable driving means responsive to said release of said actuating means for driving said actuating means to its active position whereby said operating means is moved to its operated position thereby moving said covering means to its closed position,

and resetting means adapted for returning said actuating means from its active position to its idle position.

24. A system in accordance with claim 23 wherein said rotatable driving means includes torsion means,

and further comprising coupling means for coupling said torsion means to said actuating means,

said torsion means being normally in a wound condition and in a state of torsional stress,

and said torsion means being adapted to assume an at least partly unwound condition in response to driving said actuating means to its active position.

25. A system in accordance with claim 24 wherein said resetting means has an unoperated position and alternatively has an operated position,

said resetting means being normally in its unoperated position when said actuating means is in its idle position,

and gear means adapted for producing a driving action for placing said resetting means in its operated position in response to the movement of said actuating means to its active position.

26. A system in accordance with claim 25 and further comprising control means for reversing the driving action of said gear means for effecting the return of said resetting means from its operated position to its unoperated position,

said actuating means being adapted to be returned from its active position to its idle position in response to the movement of said resetting means from its operated position to its unoperated position,

and said torsion spring being adapted to resume its wound condition and return to its state of being torsionally stressed in response to the movement of said resetting means from its operated position to its unoperated position.

27. A system for alternatively covering and uncovering an opening,

said system comprising covering means including a plurality of parallelly disposed louver blades having a closed position for covering said opening and an open position for uncovering said opening,

- an operating rod having means for connecting it individually to each of said louver blades for alternatively moving them from one of said positions to the other of said positions,

said operating rod having an unoperated position for holding said louver blades in their open position and an operated position for holding them in their closed position,

a rotatable actuating crank adapted for moving said operating rod from one of its positions to the other of its positions,

said crank having two end portions,

a pivot rod for rotatably supporting said actuating crank at a point intermediate said end portions,

said actuating crank having an idle position for holding said operating rod in its unoperated position and an active position for holding said operating rod in its operated position,

and connecting means for connecting one end portion of said rotatable actuating crank to said operating rod for effecting movement thereof.

28. A system in accordance with claim 27 and further comprising torsion driving means adapted for imparting rotary motion to one of said end portions of said actuating crank for ef fecting rotation of said actuating crank from its idle position to its active position,

said connecting means being responsive to said rotation of said actuating crank for efiecting movement of said operating rod from its unoperated position to its operated position and for thereby moving said louver blades from their open position to their closed position,

and a rotatable resetting crank rotatably mounted on said pivot rod in a position adjacent to one side of said actuator crank,

said resetting crank being adapted for effecting the return movement of said actuating crank from its active position to its idle position and for thereby effecting the return of said operating rod to its unoperated position and the consequent return of said louver blades to their open position.

29. A system in accordance with claim 28 and further comprising gear means adapted for normally holding said resetting crank in a stationary condition,

and locking means adapted for normally holding said actuator crank in a stationary condition thereby overcoming the driving influence of said torsion driving means,

said locking means including means for normally pinning said actuator crank to said resetting crank.

30. A system in accordance with claim 29 and further comprising trigger means for effecting the unpinning of said actuator crank from said resetting crank,

said torsion driving means being responsive to said unpinning of said actuator crank for effecting the rotation of said actuator crank to its active position and for thereby effecting the movement of said operating rod to its operated position with the consequent movement of said louver blades to their closed position.

31. A system in accordance with claim 30 and further comprising operating means adapted for operating said gear means for rotating said resetting crank in the same direction as that in which said actuator crank was rotated,

and means for limiting the extent of said rotation of said resetting crank to the same extent as that in which said actuator crank was rotated from its idle position to its active position,

and said locking means including means adapted for repinning said actuator crank while in its active position to said rotated resetting crank.

32. A system in accordance with claim 31 and further comprising reversing means adapted for reversing the operation of said gear means for effecting the rotation of said resetting crank in a direction opposite to that of its previous rotation,

and means for limiting the extent of said reverse rotation of said resetting crank to the same extent as that of its previous rotation,

said reverse rotation of said resetting crank being adapted to effect the return of said repinned actuator crank to its idle position.

Claims

1. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast, said system comprising movable covering means having a closed position for covering said opening and an open position for uncovering said opening, said covering means having a surface adapted for receiving the force of a blast pressure wave, rotatable actuating means adapted for effecting through its rotation the movement of said covering means from said open position to said closed position, rotatable initiating means adapted for effecting by its rotation the initiation of the rotation of said actuating means, and rotatable control means adapted for effecting through its rotation the rotation of said initiating means, said control means being further adapted to be rotated in response to the impingement of a blast pressure wave on said covering means.

2. A blast-actuated valve-closure system in accordance with claim 1 and further comprising locking means having a first position adapted for blocking rotation of said actuating means, said locking means having a second position adapted for unblocking rotation of said actuating means, said rotatable initiating means including a roller adapted for effecting through its rotation the placing of said locking means in its second position and for thereby effecting the initiation of the rotation of said actuating means, and said rotatable control means having means adapted for carrying said initiating means during rotation of said control means and for thereby effecting rotation of said roller.

4. A blast-actuated valve-closure system in accordance with claim 3 wherein said instrumentality is constituted by a spring-hinged lever-cam having a tilted portion for forming a ramp, said ramp being adapted for sloping in a direction away from said locking means.

5. A blast-actuated valve-closure system in accordance with claim 1 wherein said covering means comprise a plurality of parallelly disposed louver blades, and further comprising coupling means for coupling said plurality of louver blades to a portion of said control means, said coupling means including an operating rod, a plurality of connecting means each having one end attached to the middle of a respective1y different one of said louver blades and having another end attached to said operating rod, said control means having means defining an arcuate slot formed in said portion thereof, and a pin attached to said operating rod and disposed in said slot, the position of said pin in said slot being adapted to be changed in response to rotation of said control means.

6. A blast-actuated valve-closure system in accordance with claim 5 wherein said operating rod includes means defining a cavity formed therein, and further comprising an instrumentality extending through said rod and into said cavity, a block fixedly fastened inside said cavity, biasing means for normally forcing said pin to move toward one end of said slot, said biasing means including a blade having a shouldered end, said blade being slidably disposed within said cavity with said shouldered end in engagement with said instrumentality, and spring means encircling said blade for pressing in one direction against said shouldered end of said blade and for pressing in an opposite direction against said block.

7. A blast-actuated valve-closure system in accordance with claim 1 and further comprising a shaft, and means for mounting both said actuating means and said control means on said shaft for rotation thereabout.

8. A blast-actuated valve-closure system in accordance with claim 1 wherein said actuating means has an unrotated position in which it normally rests and a rotated position to which it moves in response to its rotation, and further comprising rotatable resetting means adapted for returning said actuating means from its rotated position to its unrotated position.

9. A blast-actuated valve-closure system in accordance with claim 8 and further comprising a shaft, and means for mounting said actuating means and said control means and said resetting means on said shaft for rotation thereabout.

10. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast, said system comprising movable covering means having a closed position for covering said opening and an open position for uncovering said opening, said covering means having a surface adapted for receiving the force of a blast pressure wave, rotatable actuating means adapted for effecting through its rotation the movement of said covering means from said open position to said closed position, and rotatable control means adapted for effecting through its rotation the consequent rotation of said actuating means, said control means being further adapted to be rotated in response to the impingement of a blast pressure wave on said covering means.

11. A blast-actuated valve-closure system in accordance with claim 1 and further comprising rotatable initiating means adapted for effecting through its rotation the initiation of the rotation of said actuating means, said initiating means having its rotation effected in response to the rotation of said control means.

12. A blast-actuated valve-closure system adapted for closing an opening in response to the overpressure of a blast, said system comprising movable covering means having a closed position for covering said opening and an open position for uncovering said opening, said covering means having a surface adapted for receiving the force of a blast pressure wave, rotatable actuating means adapted for effecting through its rotation the movement of said covering means from said open position to said closed position, control means for effecting the initiation of the rotation of said actuating means from an idle position to an active position, and resetting means for returning said actuating means from said active position to said idle position.

13. A blast-actuated valve-closure system in accordance with claim 12 and further comprising locking means having a first position adapted for holding said actuating means in its idle position, said locking means having a second position adapted for releasing said actuating means from its idle position for movement to its operated position, said locking means including a composite detent having two holding means, one of said holding means being fixedly attached to said resetting means, and the other of said holding means being secured to said actuating means.

15. A blast-actuated valve-closure system in accordance with claim 14 wherein said holding means that is fixedly attached to said resetting means is constituted by said holding finger, said holding finger having an end portion, and further comprising means defining an arcuate groove in said actuating means for receiving therein said end portion of said holding finger.

16. A valve-closure system in accordance with claim 12 wherein said actuating means include means defining a cavity therein and wherein said resetting means include means defining a cavity therein, and further comprising locking means adapted for locking said actuating means in its idle position, said locking means including a first portion and a second portion, said first portion being fixedly disposed in said cavity in said actuating means, and said second portion being fixedly disposed in said cavity in said resetting means.

17. A valve-closure system in accordance with claim 16 wherein one of said portions of said locking means includes a single holding pin, and wherein the other of said portions of said locking means includes a double holding pin having two pin elements spaced apart by a distance at least equal to the diameter of said single holding pin.

18. A valve-closure system in accordance with claim 16 and further comprising roller means normally having a position interposed between said first and second portions of said locking means, and first pushing means positioned in a first one of said cavities and adapted for pushing said roller means into a second one of said cavities for effecting the unlocking of said actuating means.

20. A valve-closure system in accordance with claim 19 and further comprising activating means for effecting movement of said second pushing means, said activating means including spring means, and a cam-operable instrumentality adapted for compressing said spring means for effecting movement of said second pushing means.

21. A valve-closure system in accordance with claim 16 and further comprising roller means normally having a position interposed between said first and second portions of said locking means, first pushing means positioned in a first one of said cavities and adapted for exerting pushing force against said roller means in a direction toward the second one of said cavities, second pushing means positioned in said second one of said cavities and adapted for exerting pushing force against said roller means in a direction toward said first one of said cavities.

22. A valve-closure system in accordance with claim 21 and further comprising trigger means for effecting the movement of said roller means out of said interposed position, said trigger means including means for causing the pushing force exerted by one of said pushing means to become relatively stronger than the pushing force of the other of said pushing means.

23. A system for alternatively covering and uncovering an opening, said system comprising covering means having a closed position for covering said opening and an open position for uncovering said opening, operating means adapted for moving said covering means alternatively from one of said positions to the other of said positions, said operating means having an unoperated position for holding said covering means in its open position and an operated position for holding said covering means in its closed position, actuating means adapted for moving said oPerating means from its unoperated position to its operated position, said actuating means having an idle position for holding said operating means in its unoperated position and an active position for holding said operating means in its operated position, locking means having a first position adapted for holding said actuating means in its idle position, said locking means having a second position adapted for releasing said actuating means from its idle position, trigger means adapted for moving said locking means from its first position to its second position for effecting the release of said actuating means from its idle position, rotatable driving means responsive to said release of said actuating means for driving said actuating means to its active position whereby said operating means is moved to its operated position thereby moving said covering means to its closed position, and resetting means adapted for returning said actuating means from its active position to its idle position.

24. A system in accordance with claim 23 wherein said rotatable driving means includes torsion means, and further comprising coupling means for coupling said torsion means to said actuating means, said torsion means being normally in a wound condition and in a state of torsional stress, and said torsion means being adapted to assume an at least partly unwound condition in response to driving said actuating means to its active position.

25. A system in accordance with claim 24 wherein said resetting means has an unoperated position and alternatively has an operated position, said resetting means being normally in its unoperated position when said actuating means is in its idle position, and gear means adapted for producing a driving action for placing said resetting means in its operated position in response to the movement of said actuating means to its active position.

26. A system in accordance with claim 25 and further comprising control means for reversing the driving action of said gear means for effecting the return of said resetting means from its operated position to its unoperated position, said actuating means being adapted to be returned from its active position to its idle position in response to the movement of said resetting means from its operated position to its unoperated position, and said torsion spring being adapted to resume its wound condition and return to its state of being torsionally stressed in response to the movement of said resetting means from its operated position to its unoperated position.

27. A system for alternatively covering and uncovering an opening, said system comprising covering means including a plurality of parallelly disposed louver blades having a closed position for covering said opening and an open position for uncovering said opening, an operating rod having means for connecting it individually to each of said louver blades for alternatively moving them from one of said positions to the other of said positions, said operating rod having an unoperated position for holding said louver blades in their open position and an operated position for holding them in their closed position, a rotatable actuating crank adapted for moving said operating rod from one of its positions to the other of its positions, said crank having two end portions, a pivot rod for rotatably supporting said actuating crank at a point intermediate said end portions, said actuating crank having an idle position for holding said operating rod in its unoperated position and an active position for holding said operating rod in its operated position, and connecting means for connecting one end portion of said rotatable actuating crank to said operating rod for effecting movement thereof.

28. A system in accordance with claim 27 and further comprising torsion driving means adapted for imparting rotary motion to one of said end portions of said actuating crank for effecTing rotation of said actuating crank from its idle position to its active position, said connecting means being responsive to said rotation of said actuating crank for effecting movement of said operating rod from its unoperated position to its operated position and for thereby moving said louver blades from their open position to their closed position, and a rotatable resetting crank rotatably mounted on said pivot rod in a position adjacent to one side of said actuator crank, said resetting crank being adapted for effecting the return movement of said actuating crank from its active position to its idle position and for thereby effecting the return of said operating rod to its unoperated position and the consequent return of said louver blades to their open position.

29. A system in accordance with claim 28 and further comprising gear means adapted for normally holding said resetting crank in a stationary condition, and locking means adapted for normally holding said actuator crank in a stationary condition thereby overcoming the driving influence of said torsion driving means, said locking means including means for normally pinning said actuator crank to said resetting crank.

30. A system in accordance with claim 29 and further comprising trigger means for effecting the unpinning of said actuator crank from said resetting crank, said torsion driving means being responsive to said unpinning of said actuator crank for effecting the rotation of said actuator crank to its active position and for thereby effecting the movement of said operating rod to its operated position with the consequent movement of said louver blades to their closed position.

31. A system in accordance with claim 30 and further comprising operating means adapted for operating said gear means for rotating said resetting crank in the same direction as that in which said actuator crank was rotated, and means for limiting the extent of said rotation of said resetting crank to the same extent as that in which said actuator crank was rotated from its idle position to its active position, and said locking means including means adapted for repinning said actuator crank while in its active position to said rotated resetting crank.

32. A system in accordance with claim 31 and further comprising reversing means adapted for reversing the operation of said gear means for effecting the rotation of said resetting crank in a direction opposite to that of its previous rotation, and means for limiting the extent of said reverse rotation of said resetting crank to the same extent as that of its previous rotation, said reverse rotation of said resetting crank being adapted to effect the return of said repinned actuator crank to its idle position.