Jan. 15 1924. 1,481,213
P. T. KING ELECTRIC MOTOR Filed April 30. 1923 2 Sheqts-Sheet 1 n U W :EI /l /l i g 3 /3 l?/ //YVNTOR.
J ptorz gc f Jan. 15 1924. 1,481213 I P. T. KING ELECTRIC MOTOR Filed April so. 5923 2 Sheets-Sheet 2 2 w bat/MM 125% Patented Jan. 15, 1924.
UNITED STATES PERCY T. KING, OF LUTON, ENGLAND.
Application filed April 30, 1923.
To aZZ whom it may concern Be it known that I, PERCY THOMAS KING, a subject of the Ring of Great Britain and Ireland. residing at 17 Manchester Street, lniton. Beail'lordshire, England, have invented new and useful Improvements in Electri Motors (on which application has been made for Letter Patent in Great Britain, No. 193,580, tiled 19th December, 1921, and in -l'ermany, filed 20th March, 1923), of which the following is a specification.
The present invention relates to an im prOVed method of starting, stopping and controlling electric motors and more particularly those electric motors in which both membe s of the motor are adapted to rotate the motor frame being fitted with armature bearings, field coils and other motor parts and controlled by hand brake mechanism, in such a manner as to permit of the armature rotating at, variabl speeds in an opposite direction to that of the field, frame. An alternating current electric induction motor has been suggested more particularly designed for driving trams, in which the vehicle brake is constituted by a band brake on the rotor of the motor while a similar brake is provided for the spinner of the motor. These brake bands are operated through levers by a common handle and so arranged that normally the weight of the handle. or a spring. keeps the brake applied to the spinner in engagement and the brake applied to the rotor released. Upon the lifting of the handle to a limited extent, both brakes are released. whilst a further elevation of th handle causes the rotor brake to be applied to retard the vehicle without again applying the spinner brake.
The present invention is designed more particularly to provide an electric motor suitable For the purpose of driving small machines such as sewing machines which are usually fitted with a foot control.
The present invention comprises a variable speed controlfor an electric motor, in which both the field magnet and armature members rotatable and each member is brake controlled, both brakes being operated through one lever arm and each brake being adjusted so that the brake tension of one of said brakes is dependent on the amount of brake tension of the other brake and consequently a the brake on one member is increased the brake on the other member is decreased at he same time. In ord r Serial No. 635,708.
toprevent excessive over-loading, the brake blocks are spring-controlled and their tension adjustable.
My invention is illustrated by way of eX ample in the accompanying drawings. in which-- Figure 1 shows a side view of a motor of the type described, fitted with the brake mechanism of my invention.
Figure 2 shows an end View of Figure 1.
Figure 3 shows an end View of Figure 1 taken from the opposite end to F igure 2, and Figure 4 shows a sectional view of the bearings.
Referring now to the drawings, the field frame 1 carrying the brush gear and end plates is rotatablv mounted on the armature shaft 2 by means of ball bearings 3 housed in the end plates. The armature shaft is carried in ball bearings 4 housed in a fixed framework 5. The field frame 1 is provided with slip rings 6 shrunk ontothe frame over an insulating covering of mica or the like. Brakes 7 pivoted on a shaft 8 co-act with the slip rings, and brushes 9 mounted on springs 10 behind the brakes 7 also co-act with the slip rings and serve to supply the current to the motor. When the brakes 7 are disengaged the circuit will. be broken in the manner of a double pole switch. A brake disc 11 is secured to the armature shaft 2 and a brake 12 pivoted on the shatt 8 co-acts therewith. The brakes 7 and 12 are connected to the shatt 8 through springs 15. so that as the shaft 9 turned one brake is applied while the other is released the tension of one increasing and of the other decreasing. The provision ol springs enables the field to slip it the motor is overloaded. A. spring 14 is connected so that the brake 12 is normally held in engagement. A lever 15 secured to the shaft 8 enables the brakes to be operated and this may conveniently be controlled by a treadle 16 when the motor is used for drivinfi' sewing machines or similar mechanism.
It will be noted that, the above described brake mechanism is applied to a motor in which the field magnet and armature member are rotatable and each member is brakecontrollcd. both brakes or sets of brakes being operated from one lever arm and each brake being adjusted so that the brake ten sion of one of the brakes is dependent on the amount of brake tension of the other brake and, consequently. as the brake on one member of the motor is increased, the brake on the other member is decreased at the same time. A. sensitive variable speed control is thus obtained, since as he brake is increased on one rotatable member the speed of this member is reduced and the speed of the opposite member increased. The brake tension on that member which is used for regulating or the opposite member to the driving member is spring-controlled. and consequently allows of the said stationary member to rotate when the motor is even loaded.
it should be understood th the field 'rame may be us d instead oi: the ar" iat-nre.
ll hat claim is:
l. A variable Speed control for electric motors, comprisii a framework, bearings therein carrying the whole motor, slip rings on the field magnet, brnshei-i carried in said framework co-acting; with slip rings, a brake co-acting with said field magnet and adapted when disengaged to lift said brushes out of contact with said slip rings. a brake co-acting with the, armature of said moton and a single arm operating; both said brakes so that the brake tensionv of one of said brakes is dependent on the amount of brake tension of the other brake and consequently as the braking: force of one brake is increased that of the other is decreased.
2. A variable speed control for electric motor, comprising a framework, bearings therein carrying the whole motor, slip rings on the field magnet, brushes earriel in said framework co-actine; with said slip rings, a brake co-actingr with said field magnet and adapted when disengaged to lift said brushes out of contact with said slip ring, a brake co-acting with the armature of said motor, a. ingle arm mounted on said framework operating both said brakes, and spring n'ieans (re-acting with said arm and said ln'akes so that the brake tension of one of said brakes is dependent on the amount of brake ension on the other brake and consequently as the braking force of one brake is increased that of the other is decreased and that the field magnet can rotate when the motor is overloaded.
3. A variable speed control for electric motors, comprising a framework, bearings therein carrying the whole motor by the ar mature shaft. slip rings on the field magnet. brushes carried in said framework co-ecting with said slip rings, a brake co-acting; with said slip rings and brushes so that when said brake is disengaged the brushes are lifted out of contact with the slip rings, a brake disc on said armature shaft. a brake oo-actinn with said brake disc. and a single arm operating both said brakes so that the brake tension of one of said brakes is dependent on th amount of brake tension of the other at. if desired, for the drive brake and consequently as the br king; force 7 the other [\J motors, comprising a frameworn, be. therein carryingthe whole motor by the armature shaft, slip rings on the field magnets. a shaft parallel with said arn'iatare shaft carried in said framework. brushes yieldably carried on said shaft coacting wi h said slip rings, brakes yield-ably mount ed on said shaft adapted to co-act with said slip rings so that, when disengaged they oriishes out of contact with said slip rings and so that the iield magnet can rotate when the motor is overloaded. a brake disc mounted on said armatn shaft, a. brake yieldabl mounted on said parallel shaftadapted to co act with said brake disc on the opposite side o the said field magnet brakes, spring means cont-ting with said parallel shaft and said framework So as normally to hole said field magnet brakes in action, and an operating arm attached to said parallel shaft adapted on movement to more said armature brake into action as it mores said field magnet brakes out of action.
5. A variable speed control for electric motors, comprising a. framework, bearings therein carrying the whole motor by the armature haft, slip rings on the field not of said motor, a shaft parallel with said armature shaft carried in said framework, brakes 7*Ott1lttlll5l mounted on said parallel shaft adapted to co-act with said slip rings, a spring adjnstably attached to said parallel shaft, connecting said parallel shaft with said brakes so that, th field magnet can r0- when the motor is overloaded. leaf springs attached to said brakes, brushes mounted on said leaf springs adapted to c0- act with said slip rings and be lifted out of rontact by said brakes in their o DOSltimL, brako disc on said armature shaft, an armature brake rotalabl -x mounted on said parallel shaft on opposite side to said field map;- netbrakes, a sprino adjustably attached to said parallel shaft connecting said parallel shaft with said armature brake, an adjustable member on said parallel shaft, a spring connecting said adjustable member with said framework so as normally to hold said field magnet. brakes in action, a second framework, a foot pedal mounted thereon, a lever carried by said foot pedal and a single arm. slotted to receive and be operated by said lever, attached said parallel shaft, adapted when operated to more said arma lure brake into action as it moves said field man net brakes out of action.
In witness whereof I have signed my name to this specification.
P. T. Kll'ltl.