Piston-activated valve and methods and apparatus for restraining free play in a device

Abstract

Apparatus and methods for fitting mechanical parts to minimize prevent free play are described. An apparatus having a piston is designed so as to restrain the piston before actuation, and so as to allow the piston to gain momentum before striking an object. The described apparatus are applicable to devices involving shearable elements. An embodiment of the invention relates to a pyrotechnically activated valve incorporating such features to minimize free play in conjunction with such features so as to restrain the piston and also allow the piston to gain momentum.

Description

[0001] This application is a divisional of Applicant's Ser. No. 10 / 044,934 filed in the U.S. Patent & Trademark Office on 15 Jan. 2001, and assigned to the assignee of the present invention. CLAIM OF PRIORITY [0002] This application makes reference to, incorporates the same herein by reference, and claims all benefits accruing under 35 U.S.C. § 119(e) and §120 from my application PISTON-ACTIVATED VALVE filed as a provisional application in the U.S. Patent and Trademark Office as U.S. application Ser. No. 60 / 261,199, filed on Jan. 16, 2001.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to mechanical fittings and tolerancing, in particular to fittings found in shearable devices, and more particularly to pyrotechnically activated devices such as valves. [0005] 2. Background of the Invention [0006] Pyrotechnic valves are commonly used in rockets for valves which must be opened reliably one time. Typically, these valves contain a seal tu...

AI Technical Summary

Benefits of technology

The present invention provides an improved shearable device that is less sensitive to vibration and can be used with pyrotechnic initiators. The device includes an eccentric sleeve and a piston with a shear pin for restraining the piston relative to the mount. The device can be used as a pyrovalve and includes a housing, a pyrotechnic initiator, a seal tube, and a piston with a flowpath and a hollow for encasing the shearable cap. The invention provides improved reliability and accuracy in the operation of the device.

Problems solved by technology

Further, peak pressures are limited by the ability of O-rings and other gas-tight fittings to contain such pressures.

However, such pressure increase in this first potential method can be unacceptable because of a need for initiation redundancy in the device.

A second potential method of addressing the above desired needs in a pyrotechnic valve is to increase the piston area, which can be undesirable for two reasons.

First, increasing the piston area can make the piston physically large and heavy.

Second, more propellant charge or possibly even an additional booster charge would be required in the initiators.

These characteristics can be undesirable from a design standpoint and can generally raise the cost of the pyrotechnic valve device.

Pyrotechnic valve devices, such as those used in rocketry, for example, are often subject to considerable vibration.

If there is “play” between the parts, vibrational damage can result.

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