US2842646A - Balanced carbon pile - Google Patents

Description

July 8, 1958 A. B. ESSEX ETAL BALANCED CARBON FILE 2 Sheets-Sheet 1 Filed Nov. 23, 1956 S min w TERN m mfikm 0 mix m if m m7: Aam M M July 8, 1958 A. B. ESSEX EI'AL 2,842,646

BALANCED CARBON PILE Filed Nov. 25, 1956 2 Sheets-Sheet 2 ATTORNEY ljnited States l a BALANCED CARBON PILE Alois B. Essex, Glendale, and Elmer E, Garrett, Freeport, N. Y., and Henry F. McKenney, Weston, Mass assignors to Sperry Rand Corporation, Ford instrument Company Division, Long Island City, N. Y., a corporation of Delaware Application November 23, 1956, Serial No. 523,845 3 Claims. (Cl. Till-51) This invention relates. to variable resistance devicesof the carbon pile type which are especially adapted for use in airplanes and guided missles which are subjected to vibrations and rapid accelerations and decelerations.

Carbon pile rheostats of this character generally corn: rise a pile of carbon discs which are held under compression' by the action of a spring diaphragm, and a solenoid which is operative when energized torelieve the spring pressure upon the pile of discs and thus control the pile resistance. The spring diaphragm has an armature rigidly secured thereto through which the solenoid acts to relieve the pressure exerted by the spring diaphragm upon the pile of disCS, aI1d adjusting means are provided by which the maximum pressure exerted by the diaphragm upon the pile of discs-may beregulated as desired. When such a resistance device is axially accelerated in one direction the armature, due to inertia, reacts to increase the pressure upon the carbon-piles and thereby decrease the resistance of the pile; and when the device is accelerated in the opposite direction the armature reacts to decrease the pressure upon the carbon pile and thereby increase the resistance of the pile, and the same reactions occur during deceleration. This inherent characteristic of carbon pile resistance devices of this character renders them objectionable for uses wherein they are subjected to axial vibrations and accelerations.

It is therefore the principal object of this invention to provide means in a carbon pile resistance device of the aforesaid character by which the vibration and acceleration effects upon the carbon pile are counteracted whereby the pile resistance is maintained constant under all conditions of use. This may be accomplished by providing two similar carbon pile rheostats disposed back to back in axial alignment with the carbon piles electrically connected in series and the armature ends thereof pointing in opposite directions. With this arrangement under acceleration the resistance of one carbon pile will be increased and the resistance of the other carbon pile will be proportionately decreased whereby the combined resistance of the two carbon piles will always be maintained constant.

The principal object of the invention having been stated other and more specific objects of the invention will be apparent from the following specification and the accompanying drawings forming a part thereof wherein,

Fig. l is a central longitudinal section illustrating one form of the invention in which two similar carbon pile resistance units are disposed back to back in axial alignment with the carbon piles electrically connected in series and the armature ends thereof pointing in opposite directions; and

Fig. 2 is a view similar to Fig. l of a slightly modified form of the invention in which two opposed oppositely pointing carbon piles are utilized.

The two forms of the invention shown in the drawings will now be specifically described in detail with the use of reference numerals, the same numerals being applied ice to like parts in the diiferent forms of the invention shown. Referring first to Fig. l of the drawings the numeral 1 indicates generally a variable resistance mechanism which comprises two similar conventional carbon pile variable resistance units 2 and 3 which are bolted together back to back in axial alignment with a separating-plate 4 of insulation thcrebetween. Each of the units 2 and'3 comprises a casing 5 provided with heat dissipating fins 6. A pile 7 of carbon discs is mounted in an open ended tube and which is disposed in a longitudinally extending axial bore 9, in the casing 5, which communicates at the inner end thereof with an enlarged annular chamber 10 at one end of the casing 5. A spring diaphragm 11', which is suitably secured in fixed position in the chamber 19 has secured to one side thereof a button 12 which is adapted toengage one end of the carbon pile 7 and to the other side thereof an armature 1-3 which coacts with a solenoid 14 which is also secured in fixed position in the chamber 10. The carbon discs in the pile 7 are held under compression by the spring diaphragm 11 acting through the button 12. and the pressure exerted by the diaphragm 11 upon the carbon pile 7 is regulated by an adjusting screw 15 which engages the opposite end of the carbon pile and is carried by a removable plate 16 which closes the outer end of the bore 9. The solenoid 14 is of conventional construction and comprises the winding 17 and the core 18 which is carried by the closure plate 19, of the chamber it in axial alignment withthe diaphragm i1 and carbon pile 7. When thesolenoid 141's energized the core 18 attracts the armature 13 which re.- duces the compression of the pile 7 and thereby increases the resistance of the pile 7 to the flow of current therethrough. The carbon piles '7 in the units 2 and 3 are electrically connected together in series as indicated at 20, with the armature or solenoid ends of the two piles facing in opposite directions. In operation either one or both of the solenoids 14 may be energized to increase the resistance to the flow of current through the two carbon piles. When the resistance mechanism 1 is accelerated to the right, as shown in Fig. 1, the armature 13 in the unit 2, due to inertia, will react to decrease the pressure upon the carbon pile in the unit 2; and at the same time the armature 13 in the unit 3 will react to proportionately increase the pressure exerted upon the carbon pile 7 in the unit 3. The decreasing of the compressive pressure upon the carbon pile 7 in the unit 2 will increase the resistance thereof to the flow of current; and the increasing of the compressive pressure upon the carbon pile 7 in the unit 3 will proportionately decrease the resistance thereof to the flow of current. Conversely when the mechanism 1 is accelerated to the left as shown in Fig. l the resistance of the carbon pile 7 in the unit 2 will be decreased and the resistance of the carbon pile 7 in the unit 3 will be proportionately increased. Obviously the armatures 13 in the units 2 and 3 will react in a like manner during deceleration of the mechanism 1. The combined resistance of the two carbon piles will therefore always be maintained constant during both acceleration and deceleration of the mechanism 1.

In Fig. 2 a slightly modified form of the invention shown in Fig. 1 is disclosed. In this form of the invention the solenoid 14 in the unit 3 is omitted. Otherwise the two forms are identical. in this form of the invention the compressive pressure upon the carbon pile 7 in the unit 3 is set by the adjusting screw 15 for the minimum resistance desired and only the pressure upon the carbon pile 7 in the unit 2 is decreased by the action of the solenoid 14 to increase the combined resistance of the two carbon piles. During acceleration and deceleration of this form of the invention the two armatures 13 will react upon the two carbon piles 7 in the same manner as described in connection with Fig. 1, and thereby maintain the combined resistance of the two carbon piles constant during both acceleration and deceleration.

From the foregoing it will be apparent to those skilled in this art that we have provided very simple and efiicient means for accomplishing the objects of the invention; and although the solenoid is shown and described herein as operative when energized to decrease the compression upon the carbon pile and thereby increase the resistance thereof, it is to be understood that the invention contemplates thev reverse action of the solenoid wherein the solenoid is operative when energized to increase the compressive pressure upon the carbon pile and thereby decrease the resistance thereof. 1 And it is to be further understood that we are not limited to the specific constructions shown and described herein as various modifications may be made therein within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. A variable resistance mechanism or" the character described comprising two opposed oppositely facing axially aligned carbon piles secured in fixed spaced relation to each other, spring diaphragm means by which said carbon piles are held under compression disposed between the opposed ends of said carbon piles, solenoid means operative when energized to decrease the pressure exerted by said spring diaphragm means upon one of said carbon piles, each of said carbon piles being operative to counteract the acceleration effects upon the other of said carbon piles during axial acceleration of said variable resistance mechanism.

2. A variable resistance mechanism of the character described comprising two similar variable resistance units each of which comprises a carbon pile, a spring diaphragm 'by which said carbon pile is held under compression, an

armature'secured to said diaphragm, a solenoid operative when energized to attract said armature and thereby decrease the compressive force exerted by said diaphragm upon said carbon pile, said units being disposed in axial alignment with each other with the solenoid ends of the carbon piles thereof facing in opposite directions, whereby each of said units counteract the acceleration etlfects upon the other of said units during axial acceleration of said variable resistance mechanism.

3. A variable resistance mechanism of the character described comprising two opposed oppositely facing axially aligned carbon piles disposed in fixed spaced relation to each other, a spring diaphragm disposed between the opposed ends of said carbon piles by which one of said carbon piles is held under compression, an armature secured to said diaphragm in axial alignment with said carbon piles, a second spring diaphragm disposed between the opposed ends of said carbon piles by which the other of said carbon piles is held under compression, a counterbalancing weight secured to said second spring diaphragm in axial alignment with said carbon piles and said armature, a solenoid operative when energized to attract said armature and thereby decrease the compressive force exerted by said spring diaphragm upon the said one of said carbon piles, said armature and said counter- References Cited in the file of this patent UNITED STATES PATENTS Turbayne Oct. 19, 1920 Austin Feb. 5, 1946

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