US3323460A

US3323460A - Thermo-torque motor

Info

Publication number: US3323460A
Application number: US406370A
Authority: US
Inventors: Bliss Robert Wayne
Original assignee: Magnavox Co
Current assignee: Philips North America LLC
Priority date: 1964-10-26
Filing date: 1964-10-26
Publication date: 1967-06-06
Anticipated expiration: 1984-06-06

Description

4June 6, 1967 R. w, Buss 3,323,460

THERMO -TORQUE MOTOR Filed 001,. 26, 1964 INVENTOR l ROBERT WAYNE Buss l BY WM @Wk/f' y/olgus United States Patent O 3,323,460 THERMO-"ICORQUIEl MTOR Robert Wayne Bliss, Champaign, Ill., assignor to The Magnavox Company, Fort Wayne, Ind., a corporation of Delaware Filed Oct. 26, 1964, Ser. No. 406,370

2 Claims. (Cl. 102-76) This invention relates generally to actuators or motors used in devices where one-time yoperation is required, and more particularly to a motor which utilizes a chemical combustion directly for imparting a rotary motion to an output member.

Known types of explosive actuated drive devices such as dimple motors, bellows motors, and piston motors, are used to provide some type of linear output motion or force from which rotary motion or torque can be achieved by mechanical linkages. However, in view of the nature of the work to be performed by such devices and in view of the simplicity of the present invention, such prior art devices are rather complex. This results in an excessive space requirement and necessitates the incorporation of more parts than is 'desired for assuring reliabality.

It is therefore a general object of the present invention to provide a device which can yield a rotary motion or torque directly from an exothermic chemical reaction without the necessity of means for converting linear to rotary motion.

A further object is to provide a device achieving this result with maximum reliability in minimal space and using materials which are readily available.

Described briefly, a typical embodiment of the present invention includes a case having a chamber therein and a rotor having a shaft extending through a wall of the case and mounted for rotation in the case. The chamber has a pyrotechnic compound therein with some type of igniter communicating therewith so as to enable ignition of the compound by the application of some external initiator thereto such as, for example, an electrical voltage.

A bimetal spiral is embedded in the pyrotechnic compound and has its outer end affixed to the case. The inner end of the spiral is connected to the rotor shaft. Application of a voltage to the igniter initiates combustion in the pyrotechnic compound whereupon the heat generated causes the spiral to unwind, rotating the rotor. In a typical example, this rotation is used to align an explosive charge mounted in the rotor with an explosive charge and detonator means in an arming device.

The full nature of the invention will be understood from the accompanying drawing and the following description and claims.

FIG. 1 is a longitudinal section through an arming device constructed according to a typical embodiment of the present invention.

FIG. 2 is a cross section taken on the line 2-2 in FIG. 1, and viewed in the direction of the arrows.

Referring now to the drawings in detail, the illustrated arming device includes a cylindrical housing 11 with a block 12 in one end thereof having a booster charge 13 disposed in an aperture therein. A block 14 is disposed in the housing and doweled by the pin 16 to the block 12. A cavity 17 is formed between the block 12 and the block 14 for receiving a disc portion 18 of a rotor 19 mounted in a bearing block 21 for rotation therein on the axis 22.

A 'block 23 having a chamber 27 is also secured in the housing 11. A pin 24 or other suitable means can be used to join the block 23 to the block 21 and to the block 14, to prevent relative rotation between the

blocks

23, 21, 14 and 12. A bimetal coil which is illustrated in the form of a at spiral 26, but which could have other configurations, is received in the chamber 27 in the block 23. The spiral 26 has its outer end 28 received in an axially extending groove in the block 23 and aflixed thereto. The inner end 29 of the spiral 26 is received in an axially extending groove 30 in the rotor 19 and is aiiixed thereto. In the illustrated example, the means aixing the

ends

28, 29 of the spiral 26 to the block 23 and the rotor 19 happens to be a force tit. Other means could also be employed if desired.

The spiral 26 has a bimetal construction with two

layers

31, 32. The first or inner layer 31 is made of a metal that has a higher rate of thermal expansion than does the metal of the second or

outer layer

31, 32 joined thereto. These layers make up a unit which, when subjected to increases of temperature, tends to straighten out. The spiral 26 is embedded in a rapid burning or pyrotechnic compound 33 in the chamber 27 and, when this compound 33 is ignited -by a suitable igniter 34 and burned, the heat transmitted to the spiral 26 rotates the rotor 19. The spiral 26 should provide this rotation prior to being melted or without being melted by the heat of the ignited compound 33. The igniter 34 may be chemical, electrical or mechanical in nature, the electrical type being illustrated with two

leads

36 and 37.

In the arming device the rotor 19 is normally disposed with an explosive charge 38 disposed 180 out of line with the booster charge 13 and a detonator 39.The detonator 39 can be electrical, chemical or mechanical, in nature. The detonator 39 and the explosive charge 38 are spaced the same radial distance from the axis 22 on a straight line passing through the axis 22. A hole 41 is provided in the rotor 19 and is normally disposed 180 away from a detent pin 42 in the block 14, this pin 42 being spring loaded by the coil spring 43. When the igniter 34 is initiated -or set oil to ignite the compound 33, the spiral 26 is heated, rotating the rotor 19. When the rotor 19 rotates 180, the detent pin 42 can be received in the hole or aperture 41 in the rotor 19 to thereafter retain or lock the rotor 19 in an armed condition with the detonator 39, the explosive charge 38, and the booster charge 13 aligned. Therefore, even if the spiral 26 cools, it can not rewind or turn the rotor 19 to the unarmed position.

Of course there may tbe instances in which the novel motor of the present invention is desired to return the rotor to its original position or some position intermediate the original position and the armed position after cooling, and this can be accomplished.

In the illustrated example, the arming device has the 180 out-of-line safety features and yet can be armed as desired upon receipt of an arming signal at the igniter 34, utilizing essentially no mechanical linkage and providing reliable operation. When the device is armed, the desired explosive output can be obtained by providing a firing signal to the detonator 39. Other angles of position and rotation, for example may be used in place of the 180 position and rotation described.

Using readily available materials, the rotation of the rotor upon application of energy to the igniter occurs so quickly that it cannot be followed by the human eye. Among the advantages of the present invention are: low cost, long shelf life, freedom from maintenance, compact, lightweight, safe to handle, reliability, simplicity, adaptability to electrical or mechanical initiation, rugged construction, versatility of form factor, capability for high amplification or attenuation, tolerance for very small or very high input signals.

While the invention has been disclosed and described in some detail in the drawings and foregonig description, they are to fbe considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

I claim: 1. An arming device comprising: a housing;

a rotor mounted for rotation in said housing, said rotor having an elongated shaft and having a rotor disc on said shaft, said disc having an axially extending aperture therethrough disposed at a predetermined radius from the rotor rotational axis, said aperture having a first explosive charge therein;

an electrical detonator aixed in said housing;

an explosive booster charge disposed in said housing, said rotor disc being normally disposed in a space between said detonator and said booster charge and isolating said detonator from said booster charge when said rotor is in an unarmed position, said rst explosive charge being in a position remote from said detonator and charge when said rotor is in said unarmed position;

an electrical igniter disposed in said housing and communicating With a motor chamber therein;

a pyrotechnic compound disposed in said chamber and ignitable -by said igniter;

a bimetal spiral disposed in said chamber and embedded in said pyrotechnic compound, the outer end of said spiral being affixed to said housing and the inner end of said spiral being aflixed to said rotor, said spiral being responsive to combustion of said pyrotechnic compound to rotate said rotor shaft and thereby said rotor from said unarmed position to an armed position wherein said rst explosive charge is aligned with and in communication with said detonator and said explosive booster charge;

and first detent means in said housing and second detent means in said rotor, said rst and second detent means being aligned and operable When said rotor is in said armed position to maintain said rotor in said armed position.

2. An arming device comprising:

a housing;

a rotor mounted for rotation in said housing, said rotor having an elongated shaft and having a rotor disc on i said shaft, said disc having an axially extending aperture therethrough disposed at a predetermined radial distance from the rotational axis of said rotor;

a detonator lmounted on said housing on one side of said rotor disc;

an explosive booster charge mounted on said housing on the opposite side of said rotor disc;

said detonator and said booster charge being positioned along an axis that is parallel to said rotational axis and spaced from said rotational axis by said radial distance so that said rotor disc isolates said detonator and said booster charge with said rotor aperture spaced from said -detonator and said booster charge in an unarmed position of said rotor;

motor chamber positioned in said housing around said rotor shaft;

a bimetallic spiral disposed in said motor chamber, said spiral having one end fastened to said housing and the other end fastened to said rotor shaft whereby said spiral causes said r-otor shaft to rotate in response to said spiral being heated;

a combustible material positioned in said motor chamber around said spiral;

and means for selectively igniting said combustible material to cause said rotor to rotate to an armed position with said aperture in alignment with said detonator and said booster charge.

References Cited BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner.

Claims

2. AN ARMING DEVICE COMPRISING: A HOUSING; A ROTOR MOUNTED FOR ROTATION IN SAID HOUSING, SAID ROTOR HAVING AN ELONGATED SHAFT AND HAVING A ROTOR DISC ON SAID SHAFT, SAID DISC HAVING AN AXIALLY EXTENDING APERTURE THERETHROUGH DISPOSED AT A PREDETERMINED RADIAL DISTANCE FROM THE ROTATIONAL AXIS OF SAID ROTOR; A DETONATOR MOUNTED ON SAID HOUSING ON ONE SIDE OF SAID ROTOR DISC; AN EXPOSIVE BOOSTER CHARGE MOUNTED ON SAID HOUSING ON THE OPPOSITE SIDE OF SAID ROTOR DISC; SAID DETONATOR AND SAID BOOSTER CHARGE BEING POSITIONED ALONG AN AXIS THAT IS PARALLEL TO SAID ROTATIONAL AXIS AND SPACED FROM SAID ROTATIONAL AXIS BY SAID RADIAL DISTANCE SO THAT SAID ROTOR DISC ISOLATES SAID DETONATOR AND SAID BOOSTER CHARGE WITH SAID ROTOR APERTURE SPACED FROM SAID DETONATOR AND SAID BOOSTER CHARGE IN AN UNARMED POSITION OF SAID ROTOR; A MOTOR CHAMBER POSITIONED IN SAID HOUSING AROUND SAID ROTOR SHAFT; A BIMETALLIC SPIRAL DISPOSED IN SAID MOTOR CHAMBER, SAID SPIRAL HAVING ONE END FASTENED TO SAID HOUSING AND THE OTHER END FASTENED TO SAID ROTOR SHAFT WHEREBY SAID SPIRAL CAUSES SAID ROTOR SHAFT TO ROTATE IN RESPONSE TO SAID SPIRAL BEING HEATED; A COMBUSTIBLE MATERIAL POSITIONED IN SAID MOTOR CHAMBER AROUND SAID SPIRAL; AND MEANS FOR SELECTIVELY IGNITING SAID COMBUSTIBLE MATERIAL TO CAUSE SAID ROTOR TO ROTATE TO AN ARMED POSITION WITH SAID APERTURE IN ALIGNMENT WITH SAID DETONATOR AND SAID BOOSTER CHARGE.