Device for Separation and Launch of a Body With Linear and Rotational Velocity

1. Field of Invention

This invention relates to an apparatus for launching an object such that the object has linear and rotational velocity imparted to it. More specifically, the invention relates to a cylindrical collet-release launch mechanism in which a piston driven by expanding gases launches an object with linear and rotational motion.

2. Description of Prior Art

There are numerous occasions, especially in aerospace applications, in which devices providing simple, reliable mechanical separation of two or more objects are required. Such devices are subject to very strict design requirements such as very long storage life, precise actuation characteristics, and survival under high stress loading and at extreme high and low temperatures.

The present invention provides a novel method for separation of a object and ejection with gradually increasing acceleration such that the object is given a precise velocity and a specified rotation rate. The invention is simple, quite strong, light weight, self-contained and meets the most stringent design requirements of any conventional aerospace application.

Briefly described is an apparatus for securely holding two objects together until release is desired and then providing reliable separation and ejection. The apparatus has a ram driven by a piston in a cylinder. A pyrotechnic charge initiates a gas expansion underneath the piston and the expanding gases drive the ram. The ram has a helical groove along its longitudinal axis which is engaged by a cam pin in the cylinder wall to impart a rotary motion to the ram as it is displaced linearly in the cylinder. A mass is engaged by the ram and is ejected from the cylinder with both a linear and rotational velocity.

A primary object of invention is to provide an apparatus for separating and ejecting one object from another at a precise velocity and with a specific rotation rate.

FIG. 1A is a cross-sectional view of the invention.

FIG. 1B is an enlarged view of the tip of the ram that engages the object to be launched.

FIGS. 2A-2E are schematic sectional views of the invention in operational sequence.

A cross-section view of the preferred embodiment of the present invention is shown in FIG. 1A. A launch tube 10 encloses the release/ejection mechanism that is the subject of the present invention and the object (not shown) to be released. The tube 10 is attached to a base plate 12 and a hole is bored through the bottom of the tube 10 along the longitudinal axis and through the base plate 12 to accomodate a pyrotechnic cartridge 14 and cartridge adaptor 16. A hollow cylindrical housing 18 is coaxially aligned with and positioned inside the tube 10 and has the lower portion extend through the bore at the tube base to engage the cartridge adapter 16. A mechanical insert 20 is held in a locked position atop the housing 18 by a collet release mechanism in which the collet fingers 22 are under a tensile load in the spread or locked position. An adapter plate 24 is attached to the top of the insert 20 and a layer of shock absorbing material 26 overlays the adaptor plate 24. The object to be launched, not shown, sits upon the absorbing material 26 and substantially occupies the remaining upper portion of the tube 10. Inside the housing 18 and coaxially aligned with it is a generally cylindrical ram 28 having a substantially smaller diameter than the cylindrical housing 18 such that an expansion chamber for the gases created by actuation of the pyrotechnic cartridge is formed between the ram and the inner wall of the housing. The ram 28 is joined to a piston 30 at its base and the piston 30 is held in place by a shear pin 32 extending into the piston 30 from the base of the cylindrical housing 18. The ram has a tapered upper neck portion having a cylindrical bore coaxial with the cylindrical housing 18 and a shoulder extends from the inner wall of the cylindrical housing to encircle the ram 28 just below the taper and still permit linear and rotational motion of the ram. A helical groove 34 extends from the beginning of the taper to the base of ram 28 and is engaged by a cam pin 36 extending from the shoulder of the cylindrical housing 18. The tip of the cam pin 36 engaging the groove 34 is surrounded by a thrust pad 38 shaped like a roller bearing to minimize friction between the cam pin 36 and the groove 34. A pair of vent holes 37 in the cylindrical housing 18 are located just below the shoulder to permit venting of any gases in the expansion chamber as the piston 30 advances. The hollow upper portion of the ram 28 spreads the collet fingers 22 in the locked position engaging the insert 20. Two protrusions 40 extend down from the adapter plate 24 into the bore in the upper portion of the ram 28 to engage a torque pin 42. An enlarged view of the protrusions 40 and the torque pin 42 is shown in FIG. 1B.

Referring to FIGS. 2A-2E, the sequence of operation of the present invention is shown. The pyrotechnic cartridge 14 is actuated causing hot gases 44 to form under the piston 30 such that it shears the shear pin 32 and begins to force the ram 28 upward in the expansion chamber of the cylindrical housing 18. As the ram 28 moves upward, the collet fingers 22 collapse inward on the tapered portion of the ram unlocking the adapter plate 24 such that it is free to move upward in the launch tube. As the ram 28 moves upward in the expansion chamber, the helical groove 34 along its length is engaged by the cam pin 36 such that the ram is given a rotational motion as well. Vent holes 37 in the cylindrical housing 18 provide venting of any gases in the expansion chamber ahead of the advancing piston 30. The protrusions 40 of the adapter plate 24 are engaged by the torque pin 42 of the advancing, rotating ram 28 and this motion is imparted to the adapter plate 24 and the object 46 fastened to the plate which is to be ejected. When the piston 30 contacts the shoulder of the cylindrical housing, motion of the ram 28 is halted and the object 46 is launched with the desired motion characteristics. Thus the present invention provides a single mechanism for holding an object until release is desired and then releasing, ejecting and spinning the object with precise values of linear and rotational velocity.