US2313401A - Electromagnetic motor - Google Patents

Description

Much 9, 1943.

J. A. TRAYLOR EIAL ELECTROMAGNETIC MOTOR Filed Aug. 6. 1941 1 zum zzfoz a I7 19 202 el 51"z 5 33 8 rFh 7 5l 4 p 42 47 4.5 i i "5 1 m' 46 .m'

BY TTOP.

Patented Mar. 9, 1943 ELECTROMAGNETIO MOTOR John A. Traylor, deceased, late of Denver, Colo., by Tessie S. Traylor, Edna T. Eisenhaud, and John B. Traylor, executors, Denver, Colo., and John B. Traylor, Denver, Colo.

Application August 6, 1941, Serial No. 405,724

7 Claims.

Our invention relates to an electromagnetic motor and has particular reference to an electromagnetic reciprocating tool finding particular utility when employed as a rock drill or like percussion tool.

Many attempts have been made prior to our invention to construct a compact and eflicient reciprocating electromagnetic motor, but lthese attempts have not been entirely successful in that the devices were heavy, operated at low efficiency and were incapable of delivering large out-puts of power without destructive overheating.

When one of the prior electromagnetic reciprocating tools was used as a percussion rock drill, difficulty was often encountered in the sticking of the drill in the hole due to the packing of rock dust and chips behind the cutting head of the drill. Whenever a drill became stuck in the hole, the electromagnetic motor was useless as a device for removing the drill since it would produce only downwardly directed impacts serving only to stick the drillstill tighter.

The present invention is directed to the provision of an electromagnetic motor of the character above discussed and it is an object of our invention to provide a motor which overcomes the above noted disadvantages and which is relatively compact and eiiicient in operation.

It is also an object of our invention to provide an electromagnetic motor of the reciprocating type employing a plunger which is reciprocated by the alternate energization of opposed electromagnets.

It is a still further object of our invention to provide a motor of the character set forth in the preceding paragraphs in which a central portion of the plunger is enlarged and tapered to coact with conical throat portions of the electromagnets to produce an air gap pull at the throat in addition to the presently utilized solenoid pull and air gap pull at the inner stop.

It is an additional object of our invention to provide a motor of the character set forth in the preceding paragraphs in which a novel form of electromagnet winding is employedfto reduce the self-inductance of the coil to thereby increase the speed of action of the motor and to provide for a higher operating eillciency than has been hitherto possible to reduce the size and weight of the device.

It is alsoan object of our invention to provide an electromagnetic reciprocating percussion device capableof producing both upwardly and downwardly directed impacts upon a percussion tool.

It is additionally an object of our invention to provide a percussion device of the character set forth in the preceding paragraph which includes a means for adjusting the strength or violence of the upwardly directed impact at will and without aiecting the strength of the downwardly directed impacts.

Other objects and advantages of our invention will be apparent from a study of the following specifications, read in connection with the accompanying drawing, wherein:

Fig. 1 is a perspective view illustrating the electromagnetic motor of our invention as embodied in a novel form of percussion tool such as a rock drill;

Fig. 2 is an enlarged elevational view of the device shown in Fig. 1 with parts broken away and other parts shown in section to illustrate the details of construction;

Fig. 3 is a fragmentary end view of the device taken substantially along the line III-III of Fig.2; and

Fig. 4 is a schematic wiring diagram illustrating the electrical connections employed to operate the device.

Referring to the drawing, We have illustrated in Fig. l an electromagnetic percussion device as including a pair of opposed magnet structures I and 2 adapted to eiect a reciprocation o'f a longitudinally movable plunger 3 to thereby create work producing impacts on a percussion actuated tool such as a rock drill 4.

Each of the stationary electromagnet struc- 'tures I and 2 is preferably constructed as illustrated in detail in Fig. 2 and includes a substantially cylindrical shell portion 5 of a suitable magnetic material carrying longitudinally extending radial fins 6 employed principally for the purpose or assisting in the dissipation of heat generated within the device. A selected group of the fins 6 are provided with circumferentially extending feet I which may be interengaged .by suitable fastening means such as rivets or screw threaded bolts 8 to secure the magnet structures I and 2 to eacn other and hold these structures in the desired spaced relation and in axial alignment with each other.

The magnet shell 5 is preferably internally bored as indicated at 9 to provide a cylindrical recess within which an electromagnet coil l0 is received. The coil I0 is preferably wound upon a spool consisting of an inner cylindrical spool shank I I formed of a suitable non-magnetic material and carrying spool end flanges I2 and I3 formed of a suitable insulating material such as fiber, Bakelite, or similar substance.

In winding the magnet II, .there is preferably first Wound an innermost layer I4 of insulating material such as glass tape, mica-paper or asbestos tape (a preference being expressed for those insulating materials capable of withstanding relatively high temperatures). Upon the spool shank I I there is then wound a plurality of independent coaxial multi-layer solenoid coils I5, each of the coils I 5 being insulated from adjacent coils as by means of interposed layers I5 of a heat-resistant insulating material.

Exteriorly of the spool ends I2 and I3 we position inner and outer terminal rings I1 and Il suitably insulated from the coil III and from the magnet structure 5 as by means of insulating material I9. Like terminals of each of the coils I5 are connected as by conductors 2i! to the ring I1, for example, and the opposite like terminals of the coils are connected as by means of conductors 2| to the ring I8. 'I'hus the rings I1 and I8 comprise in-put and output terminals, respectively, for all of the individual coils I5, which coils are connected in parallel between such input and out-put terminals.

By employing a plurality of solenoid coils I5 mounted coaxially with respect to each other and connected in parallel in the manner above described, we have been able to provide a solenoid capable of producing a relatively large magnetomotive force which is characterized by having a relatively low self-inductance. It is important to keep the self-inductance of the coil as low as possible since the speed of action of the electromagnetic motor is limited primarily by the selfinductance of the coil. Furthermore, coils having, a high self-inductance cause burning and rapid destruction of the contacts which are employed to energize and de-energize the coils.

After the coil is assembled, it is preferably impregnated with cement or other impregnating material having the property of withstanding relatively high temperatures and having reasonably high heat conductivity. One such impregnating material which we have found to be eminently satisfactory consists of a mixture of extremely ne sand and Luminite cement with water, which mixture after impregnation sets to form a hard, solid and mechanically strong onepiece structure. Luminite is a special Portland type cement manufactured by the Atlas Cement Company and characterized particularly by having an extremely low shrinkage and rapid setting characteristic.

The coil structure thus formed is retained within the cylindrical recess 9 as by means of a cover plate 22 which is secured to the magnet shell 5 as by means of bolts 23 threadedly engaged in tapped holes provided in boss-like portions 24 formed integrally with a selected plurality of the Ventilating fins 6.

The interior bore of the spool shank II serves as a guiding bore for receiving a cylindrical portion 25 of the plunger 3. The end of the cylindrical portion 25 is preferably provided with a conical or tapered form indicated at 26 to coact with a similarly tapered cone-shaped recess 21 formed in the innermost end of a fixed stop member 28 formed by preference integrally with the end cap member 22. Upon energization of the solenoid coil I0, the plunger is drawn upwardly to bring the conical end 26 into engagement with the conical recess 21.

Magnetic sticking of the plunger to the stop member 23 may be avoided by lining the conical recess 21 with a thin layer 28 of non-magnetic material such as manganese steel or other suitable alloy having the requisite strength and 5 hardness. Cushioning of the plunger or resistance to upward movement of the plunger resulting from air being trapped in the conical recess 21 may be avoided by providing a breather opening 30 extending into communication with the exterior of the magnet structure.

'I'he lower portion of the magnet shell l is preferably formed of considerable thickness and provided with a tapered throat portion or entrance aperture 3| which is adapted to coact with a similarly tapered portion 32 of the plunger 3. The plunger 3 is enlarged at its central portion as indicated at 33 to provide a pair of the tapered conical portions 32 Awhich extend in opposite directions from the enlargement 32.

The lower end of the plunger 3 is preferably identical in form and shape to the upper end which is illustrated in Fig. 2 and the lower magnet structure 2 is preferably identical in construction with the magnet structure I above described with the exception that the lower 'magnet structure 2 is provided with a movable lower stop member 34. This member, like the stop member 28, is provided. with a conical recess adapted to coact with the conical lower end of the plunger but instead of being formed integrally with the lower end cap is mounted for axial sliding movement relative thereto as by being extended through a suitable aperture II formed in the end cap 35.

The stop member 34 may be shouldered as indicated at 31 to provide a seat adapted to coact with the end cap 35 in confining a compression spring 38 between the shoulder 31 and the end cap. The stop member 34 may include a bleeder 40 port 39 which may, by means of transversely extending bores 40, be extended into communication with the annular space within which the compression spring 33 is received. 'Ihe outermost end of the stop member 38 may be bored and threaded as indicated at 4I or otherwise arranged to carry a chuck member 42 within which the shank portion 43 of the rock drill 4 is received. i i i i In the form shown in Fig. 2, the chuck member 42 is provided with a tapered bore 44 and the shank portion 43 of the drill 4 is similarly tapered, whereby engagement of the two tapered surfaces provides the necessary detachable engagement of the rock drill with the chuck member. The shank of the drill 4 is preferably provided with an annular enlargement 45 positioned behind a U-shaped clip member 45 (see Figs. 2 and 3) which is in turn carried by a pair of forwardly extending arms 41 pivotally secured as indicated at 4I in bosses 43 formed on the exterior surface of the end cap 35.

It will be observed that whenever a downward pressure is exerted on the magnet structures I and 2 as by means of handles 50 when the rock drill 4 is engaged with the piece to be drilled, the movable stop member 34 will be urged upwardly relative to the stationary magnet structures I and 2 until a shoulder 5I formed on the chuck 42 engages the under side of the cap member 35. This serves also to position the enlargement 45 a considerable distance upwardly from the U-shaped yoke 46. If the electromagnets retained within the magnet structures I and 2 are thereupon alternately energized and de-energized, the plunger 3 will be reciprocated in synchronism with such alternation and will, upon each downward stroke, strike the upper end of the movable stop member 34 and deliver an impact thereto which, by virtue of the connection afforded in the chuck member 44, will be transmitted to the drill 4 to cause the drill to perform the desired work.

In case the drill becomes stuck in the hole, the tool may be used to exert outwardly directed impacts on the drill for the purpose of assisting in the removal of the stuck drill. This is accomplished by merely exerting an upwardly directed vforce on the handles 50, whereupon the yoke member 46 is moved upwardly until it engages the enlargement 45 of the drill shank. Alternate energization and de-energization of the magnet structures and 2 thereupon produces a reciprocation of the plunger 3 which, upon striking the upper stop member 23, will deliver an impact to the stationary magnet structures I and 2 tending to move such structures forwardly in the direction of the force which is exerted thereon. These upwardly directed impacts are transmitted directly to the drill 4 through the arms 41 and the yoke 46 and by this means removal of the stuck drill is greatly facilitated.

We have illustrated in Fig. 4` the electrical connections which may be employed to control the operation of the electromagnetic motor above described. In Fig. 4 a suitable source of direct current is illustrated as comprising a direct current generator 52, one terminal of which is connected as by means of a conductor 53 through a control switch 54 to interconnected ends of the upper magnet coil |01 and the lower magnet coil |02. The other terminal of the generator 52 is connected as by means of a conductor 55 to the movable member 56 of a commutating switch. The movable member iS adapted to be driven by a suitable drive means 51 which may comprise a clockwork or an electric motor energized from a suitable source of power.

In its rotation the member 56 is adapted to make alternate contact with a plurality of contact points 58 and 59. The contact points 58 are all connected in 'parallel and are connected to the free end of the coil |02 as by means of a conductor 60 and similarly the contact points 59 are all connected in parallel and are connected as by means of a conductor 6l to the free end of the magnet coil |01. Thus, as the arm 56 rotates, the magnet coil |02 is rst energized and then de-energized and then the magnet coil |01 is energized and subsequently de-energized so as to produce the above described reciprocation of the plunger 3.

We have found it desirable to provide a means for regulating the violence or intensity of the blow which is struck by the plunger 3 when it is moved to its uppermost position and for this purpose we interpose in the conductor 6| a tapped resistance 62, the various taps of which are extended into connection with a selector switch 63, the movable arm portion 64 thereof being connected to the conductor 6|. Thus, the selector switch 63 may be employed to insert all of the resistance 62 in circuit with the coil |01 or to progressively cut out portions of the resistance 62 until all of the resistance is cut out to apply full voltage to the coil |01. It is intended that the switches 63 and 54 be mounted in a suitable manner upon the magnet structure l so as to be conveniently available for manipulation by an operator using the tool.

At this point attention is particularly directed to the enlarged central portion 33 of the plunger 3, the coned sections 32 adjacent thereto, and the similarlyl coned throat portion 3| which is provided on each of the magnet structures and 2. By employing this form of construction we have been able to obtain a greater tractive force upon the plunger 8 from a given number of ampere turns in the electromagnet coils II than has hitherto been possible.

The pull which is exerted by the magnet coill I0 on the plunger 3 comprises, in the form of construction above described, three components:

namely- (1) The solenoid effect tending to pull the cylindrical portion 25 into the magnetic center of the coil |0, l

I(2) 'I'he air gap pull at the upper stop 2l tending to pull the conical end 26 into engagement with the conical recess 21, and

-(3) An air gap pull at the throat 3| tending to pull the coned collar portion 32 into engagement with the coned throat 3|.

By forming the surfaces 3I-32 and 26--21 as cones rather than as radially extending plane surfaces, a much longer stroke is permissible without producing an excessive air gap between the plunger and the component parts of the magnetic circuit formed by the stop member 28, the shell 5 and the throat portion 3 I.

From the foregoing it will be observed that we have'provided a novel form of reciprocating electromagnetic motor which is characterized particularly by employing a novel magnet construction resulting in a low self-inductance ofthe solenoid employed and permitting the solenoid to be operated with higher eiliciency than has been hitherto possible. Furthermore, the use of the cement or similar hardening, impregnating material hereinbefore described permits the solenoid coils to successfully withstand the shocks and jars resulting from the operation of the device.

The magnet structures are further characterized by the employment of the coned central collar portion of the plunger which provides for a much greater tractive effort from a magnet of a given magnetomotive force than has hitherto been realized.

It will also be observed from the foregoing that we have illustrated and described a, novel form of percussion tool adapted to produce both inwardly and outwardly directed impacts upon a rock drill or similar tool and that means has been provided for regulating the force of the upwardly directed impacts to permit these impacts to be used at will for the purpose of removing drills which have become stuck in the drill holes.

While we have shown and described the preferred embodiment of our invention,'we do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

We claim:

1. In an electromagnetic reciprocating motor, the combination of: a pair of opposed electromagnet structures having aligned plunger receiving bores; a plunger reciprocal in said bores, said plunger including end portions received in said bores and a central enlargement, said enlargement defining opposed conical surfaces; and a magnet housing for each of said electromagnet structure, said housings having their inwardly facing ends formed with a conical throat portion contoured to coniorm to and'closely receive the conical portions of said central enlargement.

2. In an electromagnetic reciprocating motor, the combination of: a plunger comprising a cylindrical member having a central enlargement defining opposed conical portions disposed with their bases adjacent each other; a pair of multiturn solenoids one for each end of said plunger, each having a plunger receiving bore therein; and a magnet casing for each of said solenoids, each of said casings including a cylindrical portion surrounding said solenoid, an outer end cap dening an outer stop for arresting movement of said plunger into said solenoid, and an inner end member having a plunger receiving aperture 'formed therein in alignment with said plunger receiving bore, said aperture being of conical form deiining a tapered surface conforming to and closely receiving said conical portion of said plunger when said plunger is moved into said solenoid.

3. In an electromagnetic reciprocating motor, the combination of: a pair of encased opposed electromagnet structures, each of said structures including a plurality of longitudinally extending radial heat dissipating fins, at least a part of said fins on each of said structures being extended to a point substantially midway between said structures and terminating in transversely extending feet; and means securing the feet carried by one structure to the feet carried by the other structure to thereby secure said structures to each other and hold the same in a predetermined axial spaced relation to each other.

4. In an electromagnetic percussion device, the combination of: interconnected upper and lower electromagnet structures; means for alternately energizing said structures; a plunger reciprocal between said structures in response to said alternate energization; a movable stop carried by said lower structure in a position to receive downwardly directed impacts from said plunger; means on said movable stop for holding a percussion tool and transmitting said impacts thereto; an upper stop fixed on said upper electromagnet structure in a position to receive upwardly directed impacts from said plunger; and means carried by said lower structure for engaging said tool and transmitting said upwardly directed impacts thereto.

5. In an electromagnetic percussion device, the combination of: interconnected upper and lower electromagnet structures; means for alternately energizng said structures; a plunger reciprocal between said structures in response to said alternate energization; a movable stop carried by said lower structure in a position to receive downwardly directed impacts from said plunger; means on said movable stop for holding a percussion tool and transmitting said impacts thereto; an 5 upper stop fixed on said upper' electromagnet structure in a position to receive upwardly directed impacts from said plunger; and means on said lower structure normally disengaged from said tool and engageable therewith in response to upward movement of said interconnected structures relative to said tool for transmitting said upwardly directed impacts to said tool.

6. In an electromagnetic percussion device, the combination of: interconnected upper and lower l5 electromagnet structures; means for alternately energizing said structures; a plunger reciprocal between said structures in response to said alternate energizatlon; a movable stop carried by said lower structure in a position to receive downwardly directed impacts from said plunger;

means on said movable stop for holding a percussion tool and transmitting said impacts thereto; an upper stop iixed on said upper electromagnet structure in a position to receive upwardly directed impacts from said plunger; means carirled by said lower structure for engaging said tool and transmitting said upwardly directed impacts thereto; and means for adjusting the strength oi said upwardly directed impacts independently 'of the strength of said downwardly directed impcts.

7. In an electromagnetic percussion device, the combination of interconnected upper and lower electromagnet structures; means for alternately energizing said structures; a plunger reciprocal between said structures in response to said alternate energization; a movable stop carried by said lower structure in a position to receive downwardb' directed impacts from said plunger;

40 means on said movable stop for holding a percussion tool and transmitting said impacts thereto; an upper stop fixed on said upper electromagnet structure in a position to receive upwardly' directed impacts from said plunger; means carried by said lower structure for engaging said tool and transmitting s aid upwardly directed impacts thereto; and means for adjusting the electrical potential applied to said upper structure upon energization thereof to adjust the strength oi' said upwardly directed impacts.

. TESSIE S. 'I'RAYLOR,

EDNA T. EISENHAND, JOHN B. TRAYLoR,

Co-Executofs of the Estate of John A. TrayZOr,

5s Deceased.

JOHN B. TRAYLOR.

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