US2525817A - Generator - Google Patents

Description

Oct. 17, 1950 J. E MacAD 2,525,817

GENERATOR Filed May :51, 1945 3 Sheets-Sheet 1 INVENTOR JESSE EDWARD MACAMMS ATTORNEY Oct. 17, 1950 J, E, MaOADAMS 2,525,817

GENERATOR Filed May 31, 1945 3 Sheets-Sheet 2 5'55 EDWARD M4649" is ATTOR-JEY Patented Oct. 17, 1950 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) 3 Claims.

This invention relates generally to portable electrical generators, and particularly, to hand generators of the type commonly employed as blasting machines in mining and demolition operations.

A feature common to all blasting machines in present use is that of manual operability. In these machines, the conversion of muscular effort to electrical energy is effected in two principal ways, to wit, a vigourous twist of an operating handle or a downward thrust of the handle. In both cases, such operation causes relative movement of a conductor in a magnetic field resulting in the induction of an electrical current in the conductor. However, the performance of these blasting machines may at times suffer since their operation is inherently dependent upon human strength and all other factors which can influence the application of such strength to the operating handle-for example, condition of the hands, and state of health of the operator. Consequently, the electrical output from such machines may vary over a wide range and can never be accurately predicted.

In the hand generator of my invention, I have incorporated a number of features which minimize the extent to which human inconsistencies can afiect power output. Even minute and intermittent expenditures of muscular energy are accumulated in my generator and the energy thus collected is released only when it has reached a certain predetermined value. Thus, ever time the generator functions, it functions properly, delivering a known quantity of electricity and assuring the detonation of all of the blasting caps in the circuit. Moreover, my generator is designed to deliver its electrical energy at any predetermined voltage value, and to cut off immediately after a single firing pulse is delivered to the detonator line. The latter feature is particularly important in gassy or dusty mines.

An object of my invention, therefore, is to provide a hand generator suitable for use as a blasting machine in which the electrical output may be substantially predictable.

Another object of the invention is to provide a hand generator, the optimum energy output of which will be substantially independent of the muscular energy used in its operation.

An additional object is to provide a blasting machine which may be used with safety in dusty or gassy mines.

Other and ancillary objects and advantages of my invention will become apparent from a study of the following specifications and drawings in which:

Fig. l is an elevational view, partly in section, of the hand generator of the invention;

Fig. 2 is an enlarged detail of the circuit closing mechanism, and also depicts schematically the relation between the armature coils, the slip rings and the terminals;

Fig. 3 is a sectional View along line 3-3 of Fig. 1;

Fig. 4 is a sectional View along line 44 of Fig. 1;

Fig. 5 is an isometric View, partly in section and with the case removed, of the hand generator of the invention;

Fig. 6 is a sectional view along line 66 of Fig. 1;

Fig. 7 is a sectional view along line 'l--1 of Fig. 1.

In the drawings, particularly in Figs. 1 and 5, it is seen that the generator assembly is enclosed in a substantially cylindrical case I!) having a base plate H which is secured in position by bolts l2 threaded into annular ring l3. Ring 13 also acts as an anchor for screws 25 entering the case from the top, securing the top bell l5 and thus coacting with screws I2 to retain the ends of, and confine the parts within, the casing. A rotatable shaft 14 disposed axially within the case is supported at its extremities by suitable bearings 15 and II, and projects from one end where it is provided with a handle I8 for manual operation.

A ratchet wheel 19 is fixed to shaft I4 by a key 28 and therefore turns with the shaft l4, and at the same rate, whenever handle I8 is manipulated. Another ratchet wheel 2!, slightly larger in tooth-diameter than ratchet wheel I9, is rotatably mounted on shaft 14 and positioned adjacent ratchet wheel iii. A coiled torsion spring 22, disposed in the annular space defined by the hub of ratchet wheel l9 and the peripheral flange of ratchet wheel 21, is secured at one end to the hub of ratchet wheel i9 and at the other end to the peripheral flange of ratchet wheel 2|. A pin 23 carried by ratchet wheel l9 moves in a groove 24 in ratchet wheel 2|, the pin and groove cooperating to limit the relative movement possible between the ratchet wheels. Sping 22 functions to urge ratchet wheel 2! to the position in which pin 23 engages one end of slot 24, at which time the teeth of both ratchet Wheels are in register.

A bushing 26 is rotatably mounted on shaft l4 below the ratchets and carries at its top an integral cup 2! partially enclosing the ratchets and supporting a number of pawls 28. Th pawls are mounted in the conventional manner on pivot screws 29 and adapted to engage the teeth of both of the ratchets.

The main driving spring 36 of the spiral clock type is attached at its inner end to the bushing 26 and at its outer end to a post 3|. Post 3| is held at one end by insertion in an untapped hole in ring l3 and at the other by the setcrew 3| threaded through lug 3H secured to cylindrical case Ill. The spring is wound by turning the bushing 26 in one direction, and of course, exerts its driving force in the opposite direction.

The lower end of bushing 26 projects below the spring to carry another ratchet wheel 32 fixedly attached thereto as by locked threads (undesignated). A multipolar permanent magnet rotor 33 is rotatably mounted on shaft [4 directly below ratchet wheel 32 and is drivable in one direction by such ratchet through the agency of a number of pawls as 34 pivoted on pins 35 fixed in the end of the rotor into engagement with ratchet wheel 32. A cage Bl is keyed to the rotor to provide support for the upper ends of pivot pins 35 and to limit outward movement of the pawls. A number of armature coils 39, electrically connected, are arranged concentrically about the rotor in an essentially conventional manner, as shown, upon the legs of the laminar core 45. The core 40 is secured against relative movement with respect to case Ill by means of bolts l2.

pair of stationary slip rings 4!, suitably insulated from each other and from the casing H by means of annular insulator 42 in which they are mounted, are connected in series with coils 39 and form an open circuit in the armature system. The relation borne by annular conductors 41 to the armature system is shown schematically in Fig. 2.

Inserted in a recess 43 in the rotor 33 is a pendulous centrifugally operable brush assembly designated generally 44 and shown in detail in Fig. 2. Brush assembly 44 essentially comprises a grooved sleeve portion 46, a pendulous arm 47, and a brush 43, Arm 41 is suspended from a pin 49 carried by sleeve 46; brush 48 is pivotally attached to arm 41 by means of pin 59. A hollow plug defines a threaded passage 52 between recess 43 and the outer surface of rotor 33. A spring 53 is disposed in passage 52 and is held under compression by a plug 54; thus, spring 53 normally urges arm 41 radially inwardly and away from the slip rings 4!, thereby maintaining a discontinuity in the electrical circuit containing coils 39 until overcome by centrifugal force.

Referring now specifically to Figures 5 and '7, a pawl 56 fast upon a rod 57 rotatably carried in a bracket 54 attached to the interior of the case It! is engageable with ratchet 2! to prevent rotation thereof in the direction in which it is turned during winding of spring 36. The pivot rod 5'5 projects below the bracket 64 where it is provided with an integral inwardly projecting crank portion 53 adapted to contact the outermost convolution of spring 30. A spring 6!, secured at one end to a pin 62 on pawl 58 and at the other end to an eye bolt 53 in the case l0, urges pawl 56 in the direction of ratchet wheel 2!. When the spring 39 is contracted sufficiently, i. e., wound as tightly as desired, crank 58 allows pawl 56 to drop into the teeth of ratchet 2 I, whereupon subsequent expansion of the spring (as it expends its force), moves the pawl free of the ratchet to permit rewinding of the spring, when desired, and to the extent which the pawl permits. A

4 one-way clutch limiting rotation of shaft M to only one direction is provided by a coil spring 6'! anchored at its outer end to case Ill as by post 68 and wrapped around shaft [4.

Output terminals 69 mounted on the casing Ill enabl the current generated in coils 39 to be delivered as by suitable lead wires (not shown) to an electric detonator.

At the outset of a blasting operation, the generator is in an uncocked condition; spring 30 is in a completely unwound state with its outermost convolution near the inner surface of case Ill. In this position of spring 35, the crank 58 is also swung outwardly and maintains pawl 55 out of engagement with ratchet wheel 2|. Handle I8 is now turned manually thus rotating shaft I4. Since ratchet 'wheel H9 is keyed to shaft i4, it will also turn in the same direction, and will carry with it ratchet wheel 2 I since these ratchet wheels are coupled by means of spring 22. As ratchet wheels 16 and 21 rotate, bushin 26 likewise rotates in the same direction since it is mechanically attached to these ratchets by means of pawls Rotation of bushing 26 causes spring 36 to crank 58, biased inwardly along with pawl 56' under the action of spring El, also moves inwardly. This action continues until th outermost convolution of spring 36 has approached the axis of bushing 26 closely enough to permit pawl 53 to engage a tooth of ratchet 2|. As shaft i4 and ratchet wheel i6 continue to rotate, ratchet wheel i9 moves out of register with ratchet wheel 2! which is confined by pawl 56. This relative motion between ratchet wheels [9 and 2! causes pawls 28 to be cammed outwardly by the inclined backs of the adjacent teeth of ratchet wheel 2|. The teeth of ratchet wheel 2| are slightly higher than those of ratchet wheel l9, and just before the teeth of ratchet wheels I9 and El again come into register the pawls 28 are completely freed from ratchet wheel [9, permitting the pawls with their cupped carrier 21 to move in the opposite direction under the force of spring 33 which by this time has become completely wound. Centrifugal force moves the pawls 28 outwardly from the vicinity of ratchets l9 and 2| and forces them against the inner surface of the cup 21. Spring 30 expends its energy very quickly causing bushing 26 and ratchet wheel 32 to rotate at high speed. Pawls 34 transmit this motion to rotor 33. Pawls 3i: ar held against outward movement by the camming action of the undercut ratchet teeth so long as sufiicient driv When rotor 33 has attained the desired angular velocity, the centrifugal brush 48 closes the generator circuit and a surge of electri ity is delivered to terminals 69 and thence to the electric blasting caps Or detonator or other load.

Dynamic braking of course results as soon as the brush makes contact. This quickly slows the rotor to the point where spring 53 overcomes the centrifugal force acting upon arm 4'? and therefore, disengages the brush. The generator circuit is thus positively opened after a relatively short impulse. Although this impulse is ample to fire detonators and the like, it will be recognized that the elimination of current from the wires as promptly as possible thereafter in the indicated manner is highly desirable to prevent any unnecessary sparking which might constitute a hazard in gaseous and/or dusty locations.

While what has been described is particularly illustrative of a presently preferred embodiment of my invention, it is not intended that the scope of the invention be limited thereto but that it embrace any modifications and changes which fall within the true spirit of the invention, as covered by the appended claims, occurring to those skilled in the art.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In a hand generator of the class described, a casing, a rotatable shaft extending therethrough, a flanged bushing rotatably mounted on said shaft, a spiral spring mounted at its innermost end upon said bushing, a ratchet wheel carried by said shaft, a multipolar magnet rotatably mounted on said shaft, said magnet carrying a pawl for engagement with said ratchet wheel, a plurality of serially connected stationary windings disposed around said magnet, a pair of conductors disposed concentrically around said shaft and adjacent to said magnet, said conductors insulated from each other and electrically connected with said windings forming an open circuit therein, and an electrical conducting portion carried by said magnet, said electrical conducting portion movably responsive to rotary motion of said magnet to contact said circular conductors and close said open circuit for a predetermined interval of time and to open said circuit after said interval of time.

2. In the hand generator set forth in claim 1, means for controlling operation of said spiral spring comprising a first ratchet Wheel fixed on said shaft, a second ratchet wheel loose on said shaft and adjacent said first ratchet wheel, said ratchet wheels having an equal number of teeth, biasing means for normally maintaining said teeth of said ratchets in register, a first pawl fixed to the flange of said bushing and positioned for engagement with both of said ratchet wheels, and a second pawl pivotally mounted to said casing for engagement with said second ratchet Wheel when said spiral spring is wound to a predetermined tension, whereby reiative motion between said ratchet wheels results releasing said first pawl and permitting said spiral spring to unwind.

3. An electrical generator comprising relatively movable field and armature portions, said armature portion having a winding, a pair of output terminals, a pair of insulated spaced contacts, means connecting said Winding to said terminals serially through said spaced contacts, energy converting and storing means having a manually operable input member and an output means releasable automatically upon storage of a predetermined energy by actuation of said manually operable input, means connecting said releasable output means to said movable portion of said generator for utilizing the potential energy of said storing means to impart motion thereto, an elec trically conductive member, means supporting said member in a position normally spaced from said contacts and movable to a position conductively bridging said contacts, said member and supporting means being subject to influence of the movement of said movable portion of said generator whereby said conductive member is moved to a position bridging said contacts for a predetermined interval of time to condition for completion the circuit including said winding and terminals.

JESSE EDWARD MAoADAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,282,512 Williams Oct. 22, 1918 1,379,413 New May 24, 1921 1,670,419 Mayer May 22, 1928 1,972,966 Yost Sept. 11, 1934 2,192,542 Benedetti Mar. 5, 1940 2,318,453 Bernard May 4, 1943 2,322,067 Soreny June 15, 1943

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