US499769A - Regulator for electric motors - Google Patents

Description

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G. H. WHITTINGHAM. REGULATOR FOR ELECTRIC MOTORS.

No. 499,769. PatentedJune 20, 1893.

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No. 499,769. Patented June 20, 1893.

UNITED STATES PATENT OFFICE.

GEORGE HERBERT WHITTINGHAM, OF BALTIMORE, MARYLAND.

REGULATOR FOR ELECTIaIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 499,769, dated June 20,1893.

Application filed March 24, 1892.

To all whom it may concern.-

Be it known that I, GEORGE HERBERT WHIT- TINGHAM, a citizen of the United States, and a resident of Baltimore city, in the State of Maryland, have invented certain new and use ful Improvements in Automatic Switches, of which the following is a specification.

My invention relates to an automatic switch for protecting the armature of an electric motor, when the current isshutoff andsuddenly turned on again. If a full current be turned into a motor when at rest the quantity of current will be so great as to burn the insulation by heating the wires of the armature, and the armature rendered unfit for use. To prevent this, various devices have been designed to throw into the armature circuit an artificial resistance, when the current is first turned on, and then automatically reduce this-resistance as the counter-electro-motive force of the armature, which increases with its speed, has become great enough to counteract the tendency of the current to heat the conductor and burn the insulation of the armature. Some of these devices are entirely automatic, such for instance as that described in my United States PatentNo. 415,487, dated November 19, 1889; and some are only partially automatic such as are described in my Patents No. 396,791, dated January 29, 1889; No. 423,462, dated March 18,1890; No.452,151, dated March 12, 1891; and No. 415,487, dated Novemberltl, 1889. The apparatus described in this application is an improvement of the device shown in my Patent No. 415,487, and particularly in that form of the structure shown in Figure 4.

The object of the invention described herein is to supply for use in the armature branch of an electric motor, a switch whichwill protect the armature under all circumstances and which requires no attention whatever from the person operating the motor. The current is turned on to the motor by an ordinary snap switch, which anyone can operate without the slightest effort, and this invention is brought into play by the passage of the current and does its work without the attention of any one. On the other hand if for any reason the current on the line should be shut down without the knowledge of the person attending the motor, this device will automatically in- Serial him-426,198. (No model.)

troduce the artificial resistance into the armature circuit, just in proportion as it is required by'the reduction of the counter-electro-motive force of the armature and the resistance will be again automatically removed from the circuit when the current is turned on again from the generator.

There are several features of the invention. The solenoid is wound with a coil of low and also with one of high resistance, connected to one another so as to form a continuous circuit, but the solenoid of high resistance may beshort'circuited and cut out of the circuit by a suitable mechanism at a predetermined period. The introduction of the resistance into the circuit when the current is shut 011" is carefully governed so as to be approximately equal to the decrease of the electromotive force of the armature. The core of 7c the solenoid'is lifted by the force of the solenoid of low resistance alone, consuming, while lifting it say four amperes at one hundred and ten volts, but when the armature reaches its highest point the high resistance coil is thrown into circuit and the consump-' tion of current reduced to one-tenth of an ampere at the same voltage. The solenoid is provided with an iron cap which under the influence of induction becomes magnetized 8o suflicientlyto hold the armature at its highest point within the solenoid when the cur rent is passing, but will release it when the current'is shut OE and let it gradually descend under the influence of the governor. It is a general rule that the attractive force of a solenoid increases as the armature advances into it. This is true up to the point of saturation of the core or armature. I regulate the motion of my core by placing it within the arv o mature a sufficient distance when at its lowest-point, to cause it to be completely saturated with the magnetic force of the solenoid, so that when the current is turned on the core will be at once saturated and will move with- 5 in the solenoid at a uniform rate of speed, under a given governor resistance.

In the drawings, Fig. 1, is a sectional elevation of my solenoid showing details of construction of one form of my device.

a diagrammatic elevation of the same form of my device showing all'of its connections. Fig.

Fig. 2, is

3, is a diagrammatic view of almodified form bf my device in which thesolenoid consists of but one coil which is in series with the field magnet coils when the currentis full on. Fig. 4, is a diagrammatic view of another modified form of my device in which a lamp is used in place of the solenoid of high resistance. Fig. 5, is a diagrammatic view of another modified form of my device.

In the drawings, Fig. 1, 1 represents a solen-oidof coarse copper wire of low resistance wound upona cylinder 2. 3 is a solenoid of fine wire'of high resistance wound upon the first solenoid. 4: is an iron cap secured on the top of the solenoid and preferably but not necessarily, having a central projection or core 5 which enters the top of the solenoid, a distance of half an inch or more. The cap 4 is perforated in its center with an aperture 6, through which passes a rod 7 secured at its upper end to a bridge piece of conducting materialS; this bridge piece is preferably made of carbon. ducting material resting upon the cap 4 and secured to it. 10, 10 are blocks of conducting material preferably carbon, secured upon the top of the insulating ring 9, and upon which the extremities of thebridge piece 8 rest,.and-with which it is in electrical contact. To the blocks 10, 10, are secured the terminals of the two solenoids. The coil 1 is divided in the center and these separated ends are secured one to each of the blocks 10, 10. The external or high resistance coil is continuous from block to block while the lower extremities of the coil of low resistance are connected to the two sides of the line. 11 isa ring surrounding the rod 7 and secured to the top of the insulating ring 9. Below this ring 11 and surrounding the rod 7 is a spiral spring 12, the lower end of which is secured to the rod at 13, or rests there upon a transverse pin through the rod. The upper end of the spring 12 bears upon the under side of the ring 11, by which it is compressed,-

so as to hold the bridge'S firmly upon and in electrical contact with the blocks 10, 10. 14 is the armature or core of the solenoid of a size to move freely within the cylinder 2.

Referring to Fig. 2, 15 is a dash pot or other governor. If a dash-pot be used it is preferably filled with oil and has a reciprocating plunger 16 within it which consists of a rod with a piston upon its extremity. The piston is either provided with a hole in it or is made smaller than the interior of the cylinder'so that the-oil can flow around it as it rises or falls. Such a dash-pot will govern the motion of the armature or core during both its upward and downward motion. important feature as described above as it permits the resistance to be introduced into or removed from the circuit exactly in proportion as the electro-motive force of the armature increases or decreases. 17, 17 isa rheostat composed of two series of plates of metal 9 is an insulating ring of non-con- This is anthe individual plates of each series being con- I nected by coils of German silver wire, and to I opposite pairs of plates, and as the amature moves up or down includes more or less coils in the armature circuit.

The operation of the device is as follows: When the current is turned on to the line a portion of the incoming current passes to the resistance coils and armature while another portion goes to the field, and a third portion passes to the shunt in which the solenoid is included. The bridge-8 being in contact with the blocks 10, 10, the high resistance coil will be short circuited and the current will flow freely through the low resistance coil, thereby exerting a large amount of power upon the core so as to lift it freely and easily. The

solenoid and core are considerably longer than the rheostat so that the core may rest at all times a considerable distance within the solenoid far enloughzto cause the core to be saturated with the magnetic force of the co m lenoid as soon as the current is turned on, after which the motion of the core will be regular and uniform. As the core rises toward the top of the solenoid it is attracted by the magnetic force of the iron cap t which has itself become magnetized under the influence of the induction of the solenoid, and the last half inch of its motion will therefore be much stronger and faster than the preceding portion. This rapid motion serves an important function. The end of the rod 7 protrudes below the inner side of the cap 4 and when the core let rises to the top of the solenoid it will strike this rod and force it upward and break the contact between the bridge piece 8 and the blocks 10, 10. To do this properly an d perfectly requires more force than the solenoid alone will exert. Hence the attraction of the cap is important to the successful operation of the device.

Referring to Fig. 2, 15 and 16 are the line binding posts. 17 18 and 19 are the motor binding posts, 19 being connected with the armature, 18 with the field on one side of the motor, and 17 being connected with both field and armature on th other side of the motor. The binding post 1 the field of the moton on the same side as the post 18 and the post 15 is connected with the binding post 17 directly and therefore with the field and armature of the motor on the opposite side from the incoming current.

is included in .a shunt from the main line,

.and that the resistance coils are included in the branch of the main line which leads to is'also connected with It will be noticed by this, figure that the auto" matic switch illustrated in this application the armature. The operation of the device will be'readily understood from the figure.

Fig. 3 shows a modified form of the solenoid and connections by which the coils of the field of the motor are placed in series with the main solenoid of the switch by a mechanism arrangedin the same general manner as the rod 7 and bridge 8 of Fig. 1, and the coils of the field are employed as a substitute or equivalent for the high resistance coil 3 of Fig. 1. In Fig. 3 the binding posts are the same as in Fig. 2, the circuits and mechanism being difierent. On the core, solenoid 20 is wound, of low resistance and high power.- The lower terminal of this coil is connected to the binding post 15 while the upper end is divided into two branches, each of which is connected to a contact point, of conducting material, 21 and 22, which are mounted upon an insulated ring similar to the. insulating ring 9 in Fig. 1. I, 23 is a rod passing through the center of the cap of the solenoid and similar in construction to the rod 7 of Fig. 1. It is weighted so as to fall by gravity upon the insulating ring 24, when not pushed up from below. 25 is a fulcrum for a lever 26, which is formed of three parts, the two ends being of conducting material while the center is of insulating material 27 which comes in contact with the top of the rod 23. The lever 26 is fulcrumed at 25 and is held down by the spring 28, so that the extremity 29 will be in contact with the block 22. Y The contact point 21 is secured to an insulating block 30, and is so arranged that the end of the lever 26, which is nearest to said contact point, will make contact with it when it is depressed. 31 is a contact point upon the upper end of the insulating block 30, and which is connected by a wire with the binding post 15 The fulcrum 25 is connected to the binding post 18 and to one side of the field magnet coils. The operation of this device is as follows: The current entering at 15, divides and goes to the resistance coils and from there to the armature, and a portion of it goes through the solenoid to the contact 22, the contact 21 being out of circuit, thence-into the lever 26 and out through a wire which is connected to the end thereof at 32, to the other binding post 16; this circuit being one of low resistance will take a large amount of current, while only a small portion of it will go to the field by way of wire 30%, the contact 31, the le ver 26, the fulcrum 25, and the binding post 18 As soon as the core of the solenoid has reached its highest point, and has struck the end of the rod 23 and driven it up against the under side of the lever 26, thereby breaking the contact between said lever and the contact point 22, but making. contact between the lever and the contactpoint 21, the circuit of low resistance through the contact 22 and the short circuit line to pole 16 will be broken and the current will flow through the solenoid to the contact 21, lever 26, fulcrum 25, and

line to post 18 and field of the motor 17, and

"17 18 and 19. In this -case an incandescent lamp is introduced in place of the secondary coilof high resistance shown in Figs. 1 and 2 the apparatus is constructed in exactly the same Way as that shown in Fig. 1, and operates exactly in the same way, except that when the core has reached the top of the solenoid, the bridge 8 is raised and the current compelled to pass through the solenoid, then through the lamp, and then to line; but while the bridge 8 is in contact with its contact points'the lamp will be short-circuited.

A modified form is'shown in Fig. 5, in which the. coils of high and low resistance are not connected together. The coils are the same as in Fig. 1; 1 being the coil of low resistance, 2 a cylinder upon which it is wound, 3 the coil of high resistance, and 14 the core. 33 is a rod or'stem similar to rod 7 of Fig.1. 34 is a spring surrounding the rod 33, and secured-to it at the lower end while resting below a perforated plate 35, and maintaining the rod 33 and the bridge borne by it in the position shown in Fig. 5. 36 is a bridge of insulating material secured to the top of rod 33, to

the extremities of which are-secured contacts 37 and 38. To these contacts are connected the terminals from the main line. 39

39 are two contacts to which the extremities of the solenoid of low resistance are secured. 40, 40, are two contacts to which the terminals of the coil of high resistance are secured. The contacts 39, 39 and 40, 40, are mounted upon insulating blocks, 41, 41. .It will be seen that so long as the device is in the position shown in Fig. 5, the solenoid of low resistance will be in circuit and the solenoid will be drawn up. As soon as the core reaches the top and strikes the rod 33, the bridge 36 will be raised and the contact with 39, 39, broken, and that with 40, 40, established, when the solenoid of low resistance will be cut entirely out of the circuit and the coil of. high resistance into circuit.

I have described the magnetic attraction of the cap as the means by which I prefer to hold the core at its point of highest elevation without afiecting or changing the real operation o f my invention.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is F 1. In an automatic switch,the combination of a main line which is divided into two branches said branches re-uniting again, an electric motor the field of which is included in one branch and the armature in the other, resistance coils and a contact device co-operating therewith to cut portions of said resistanceinto or out of the circuit of the armature branch of the main line, a governor connected to and controlling the motion of said contact device in both directions of its motion when increasing or decreasing the resistance in the armature circuit, and an electric device controlled by the main line current for moving the contact device in one dimotion, and a weight or other equivalent device for moving the contact device in the opposite direction, substantially as described.

2. In an automatic switch, the combination of a main line which is divided into two branches said branches re-uniting again, an electric motor the field of which is included in one branch and the armature in the other, resistance coils and a contact device for operating therewith to cut portions of said resistance into or out of the circuit, said resistance coils being included in the armature branch of the main 1ine,a governor connected to and controlling the motion of the contact device of the resistance coils so adjusted as to permit said contact device to move, to increase or decrease the resistance in the armature circuit inversely as the counter-electro-motive force of the armature increases or decreases, and an electrical device controlled by the main line current for moving the contact device of the resistance coilin one direction, and a weight or other equivalent device for moving the contact device in the opposite direction. 1

3. In an automatic switch, the combination of a solenoid wound with two coils one of low and the other of high resistance, said coils being connected together at one extremity of each soas to be continuous, an iron cap upon said solenoid, and an iron core reciprocating within the solenoid under the influence of its magnetism, the iron cap being magnetized by the solenoid so as to hold the reciprocating core by magnetic attraction when it makes contact with it, and means for introducing the high resistance coil into the circuit when the core makes contact with the cap.

4. The combination of a solenoid of low resistance and a conductor of high resistance connected thereto, a reciprocating iron core within the solenoid, means for holding the core at any predetermined point Within the solenoid when it reaches it, until the current is shut 01f and which will automatically release the core when this occurs, a circuit closer controlling the conductor of high resistance, and means operated by the reciprocating core for closing the circuit and throwing the conductor of high resistance into circuit with the solenoid of low resistance, substantially as described.

5. The combination of a solenoid of low resistance, a conducter of high resistance conwhen the core reaches any predetermined position within the solenoid, substantially as described.

6. The combination of a solenoid of low resistance,.a conductor of high resistance connected to one of the terminals of the SOlOik oid, a short-circuiting device for short-circuiting the conductor of high resistance, an

an iron cap upon the solenoid, and means connected with the short-circuiting device of the high resistance conductor which is operated by the reciprocating core to break said short-circuit and throw the conductor of high resistance into circuit.

7. The combination of a solenoid of low resistance,aconductor of high resistance connected to one of the extremities thereof, an iron cap located upon the top of the solenoid, a short-circuiting device for short-circuiting the conductor of high resistance, an iron core reciprocating within the solenoid, means operated .by the reciprocating core to break the short-circuit of the high resistance conductor and throw it into circuit with the solenoid, and a governor connected to the core and controlling its motion. I

8. The combination of a solenoid of low resistance, a conductor of high resistance con- .iron core reciprocating within the solenoid,

nected to one of its extremities, an iron cap 9. The combination of a solenoid of low resistance, a conductor of high resistance which consists of the coils of the field magnets of the rnotor in series with the solenoid, an iron cap upon the solenoid with which the core.

makes contactwhen it reaches the top of the solenoid, a'circuit-bre aking device for throwing the conductor of high, resistance into circuit with the solenoid, a reciprocating iron core within the solenoid, and means connected to the circuit-breaking device whereby the core will close the circuit and throw

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