US2883485A

US2883485A - Safety baroswitch

Info

Publication number: US2883485A
Application number: US715476A
Authority: US
Inventors: David S Willard
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-02-14
Filing date: 1958-02-14
Publication date: 1959-04-21
Anticipated expiration: 1976-04-21

Description

April 21, 1959 D. s. WILLARD SAFETY BAROSWITCH Filed Feb. 14, 1958 1 M 2; NW 54 UL'HI 4 0'6 WI 7 5 i I I J0 W 1: 49 a i lull l 6 22 3W n DAV/D .$:?FZZ%0 BY Wk add, I" I,

firr wim- United States Patent SAFETY BAROSWITCH David s. Willard, High Rolls, N. Mex., assignor to the United States of America as represented by the Secretary of the Air Force Application February 14, 1958, Serial No. 715,476 3 Claims. (Cl. 200-83) (Granted under Tifle 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a barometric pressure responsive switch with pressure-controlled means which, as illustrated herein, prevents closure of the switch points until a predetermined altitude has been reached in ascent but permits closing the contacts at a predetermined altitude on descent.

In balloon flights carrying instruments, it is frequently desirable to have the balloon go as high as possible and this invention would be useful in releasing a load, which might well be attached to a parachute, after a balloon has passed a predetermined altitude and on descent again reaches the predetermined level.

It will be particularly useful, where a balloon has burst after passing a predetermined altitude, to release the load on descent and prevent entanglement with the balloon debris.

It is an object of this invention to provide a simple, trouble-free mechanism which complies with a CAA requirement concerning balloon flights.

It is a further object of this invention to provide a selfarming device consisting of a safety latch controlling a switch arm actuated by a barometric responsive bellows which switch arm on release, permits closure of contacts of a micro switch to complete an electrical circuit actuating any one of a number of conventional parachute or load releases.

The drawing is a cross-sectional view of the invention showing the essential elements.

The body or frame can be of any suitable metal such as aluminum. A conventional bellows 12, which may be partially evacuated, is responsive to barometric pressure as will later become apparent. The bellows 12 is secured in the frame 10 by a threaded stud 14 and locknut 16 and is provided on its free end with an extension 18. A switch arm 24 is pivoted on a pin 26 and carries opposite the bellows extension 18 an adjustment screw 20 held in adjusted position by a locknut 22. Near the lower end of switch arm 24 is a slot or notch 28 which receives the free end of a tensioned safety latch spring 30. The spring 30 is secured to the frame 10 by suitable machine screws 32 and 34 and is provided with an adjustment screw 38 held in place by locknuts 40 and 40'. A coiled spring 36 is held under tension by adjustment screw 38 and an adjustment screw 42 which is threaded in the lower end of the switch arm 24. An adjustment screw 44 is threaded in the lower end of the switch arm 24 communicating with the notch 28 to adjust the depth that the end of the safety spring 30 enters said notch 28. A micro switch 46 is fastened to the frame 10 by a screw 48 and is provided with push button 49 and an extension 50. An extension 52 of the switch arm 24 has threaded therein an adjustment screw 54 opposed to the micro switch extension 50 and maintained in adjusted position Patented Apr. 21, 1959 by a loeknut 56.- Leads 58 and 60 are provided for connecting the micro switch 46 to a suitable source of electric power.

In operation, the switch arm 24 is held in the safety position shown in the drawing by the tension ofthe spring 36 against the end of the safety latch spring 30 which rests in the notch 28. When the device is carried by the balloon to the predetermined altitude, which is set by adjustment screw 20, the expansion of the barometric bellows 12 forces the bellows extension 18 against the screw 20 to swing the lower end of the switch arm 24 to the right. The free end of the flexed safety latch spring 30 is removed from the notch 28 whence its spring action carries it to a position below the said switch arm. This so conditions the device that the switch arm 24 is free to move to the left whenever the tension of main spring 36 is greater than the expansion force of the bellows 12. As the device falls to a lower level, the bellows 12 contracts and the main spring 36 pulls the switch arm 24 to the left forcing the adjustment screw 54 against micro switch extension 50 closing the switch contacts and thus activating the releasing apparatus.

This invention has many features which make it invaluable for use in balloon flights. The altitude at which the safety switch can be set is limited only by the capability of the barometric bellows 12. The mechanical design is such that the invention allows adjustment to any altitude between sea level and excess of 70,000 feet. The safety spring 30, held in position by the coiled main spring in the notch 28 of the switch arm 24, insures stability and prevents premature operation of the device by accidental shock or jars in handling and in flight.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. A circuit controlling device comprising a supporting frame, a gas-filled bellows fixed to said frame and having a portion movable relatively thereto in response to variations in barometric pressure, an arm pivoted in said frame for movement in response to a predetermined barometric pressure, a spring latch normally preventing movement of said arm toward said bellows, spring means for normally maintaining said arm and said latch in engagement until said arm is swung by said bellows in response to movement of said bellows upon reaching a predetermined barometric pressure, said spring latch being biased in a direction to prevent subsequent reengagement of said latch and arm after movement of said arm in response to movement of said bellows, a circuit controlling switch, and an extension on said arm arranged to actuate said switch when the biasing pressure on said arm from said biasing means exceeds the pressure of said bellows on said arm and upon returning to said predetermined barometric pressure.

2. A pressure-responsive device including a self-arming device consisting of a frame of any suitable metal, a bellows sensitive to barometric pressure secured by one end thereto, an extension on the free end of said bellows, a lever arm pivoted on said frame and having a slot in one end thereof, an adjustable screw secured in said lever arm opposed to said extension on said bellows, a spring latch supported in said slot, a spring biasing said lever arm against said spring latch and opposed to the expansion of said bellows, an extension on said lever arm, and a micro switch with a plunger arm opposed to said extension of said lever arm, said micro switch to be actuated when the device has reached or passed a predetermined altitude and on descent again reaches said altitude.

3. In a switch sensitive to barometric pressure for actuating a device for releasing a load from a balloon after it has reached and passed a predetermined altitude, a

latch spring =and to permit the said lever arm to actuate said micro switch on descent to the 'prefieterrni'nee level.

References Cited inthe file of this patent UNITED STATES PATENTS Zeller etal May 25, Stadler Aug. 14, Murphy June 1.

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