US1959173A - Centrifugal switch - Google Patents

Description

May 15, 1934.

J. w. vWNAHW 1,959,173

GBNTRIFUGAL SWITCH v I Filed Jan, 25. 1934 Jacob W MC Nar'g,

i Patented tiny 15, 1934 1.959.113 cnmurudan swrrcn :mamma um mam' mectriccomgymrationotldework Application January 25, 1934, Serial No. 708.222 4 Claims. (Cl. 20G-80) My invention relates to centrifugal switches and has for an obiect'the provision of a simple, reliable and inexpensive centrifugal switch which operates as a functionl of speed and which indiv s 'cates the direction of rotation.

In applying @an axle-driven generator to rail car service it is necessary to maintain the correct generator polarity regardless of the direction in which the car may be-moving. Heretofore the 1o polarities of small capacity generators have been controlled by the' movement of the brush holder. However, this method of controlling the polarity is not readily applicable vto generators of large size, such fox` example of a. size sumcient for air conditioning service, since the heavy current leads cannot readily'be designed to give suiilcient ilexibility to permit the rotation of the brush holder.

' In carrying out my invention in one form thereof, I provide a centrifugal switch which is arzo ranged to insure the proper polarity for a generator irrespective ofthe direction of rotation of the generator, the energization of the generator being accomplished only after it is operating at a predetermined speed. For a more complete understanding of my invention, reference should now be had to the accompanying drawing wherein -I have shown in Fig. 1 a switch embodying my invention whilst in Fig. 2 I have'shown a view taken on the lines 2 2 of Fig. 1 with a control circuit Ydiagrammatically applied to the contacts of the cenlteferring now to the drawing, I have shown my invention in oneform as applied to the control of the polarity of an axle driven generator10,

the switch being applied to one end of the generator shaft 12. In order to control the polarity of the generator 10 in accordance with the direction y of rotation of the generator shaft 12., apspring 14 has one end' 16 resting against a plate 18 which is secured to an end plate 20,'the plate 20 being suitably secured-to the shaft 12 asyby means of asetscrew22. Theoppositeend24ofthespring 14 bears against a plunger 26 slidably mounted on '45 a cylindrical extension 28 of the plate 18. The outer face of the plunger 26 bears against a friction disk 30 formed of suitable material and supported by a switch member 32 arranged for both rotational and longitudinal movement. As

shown, the spring 14 maintains the switch member 32 in its left-hand position so 'that a contact plate 34 mounted on an insulating member 34a supported from the-switch member 32 is heid in spaced relation with three cooperating stationary contacts 35, 36 and 37. .In order to provide for .in a clockwise direction. It should again be obthe longitudinal movement of the switch member 32 a cylindrical extension 40 of the switch member 32 slidably nests within a cylindrical member 42, a compression spring 44 beingmounted between the opposite ends of the cylindrical members 40 and 42 so as to urge the switch member 32 and the friction disk 30 against the end of the plunger 26. By means of the ball bearings 48 the switch member 32 can be rotated with a minimum amount of frictional resistance, the member 42 being secured'to the inner raceA 48a of the ball bearing assembly.

Assuming now that the shaft 12 is rotated in a clockwise direction, it will be observed that the end member 20, the plate 18 and the plunger 26 are rotated with it, the rotation of the plunger 26 being insured by a pair of lever arms 50 and 52 secured to the plunger 26 and arranged to nest within notches 54 and 55 provided in a pair. of contrifugal weights 56 and 58, .the weights being secured to ledges 18a formed integrally with the plate 18. As the plunger 26 is rotated, the frictional drag exerted on the disk 3G of the switch member 32 causes the switch member to be rotated served that the movable connecting plate 34 is in spaced relation with the stationary contacts. As soon as the connecting plate 34 has been rotated from the position shown in Fig. 2 to a position wherein it -is opposite the stationary members 35 and 36, an outwardly extending projection 60 carried bythe insulating member 34a strikes against a corresponding projection 61 forming a part of a-cylindrical member 62 secured' to the end shield of the generator or stationary support 63. The outer race 64 of the ball bearing and the member 62 are rigidly mounted within a boss 65 of the end shield bymeans of screws 66 which extend through a cover plate'l into threaded engagement with member 62. The cover plate is seated in an annular recess formed in the end shield 63.

As the'speed of the generator shaft 12 is increased .centrilugal force is developed by the A weights 56 and 58 which tends. to overcome the 100 force of the spring 14.- When a predetermined speed is reached the weight 56 moves in a clockwise direction about its pivot 74 which pivot is supported on members 18a, whilst the weight 58 moves in a counterclockwise direction about the same pivot. Each`of said weights is provided respectively with projections "l5 and 76 which bear against rollers 77 and '18 carried by the arms n 50 and 52, which it will be remembered are formed integrally with the plunger 26. The plunger 26 110 is consequently operated in a right-hand longitudinal direction to break the frictional driving connection with the friction disk-'30, the spring 44 thereupon operating the movable switch member 32 in a right-hand direction to complete a connection by the conducting plate 34 between the stationary contacts 35 and 36. l

Since-the plunger 26 and the friction disk 30 forming the driving connection are disengaged upon the attainment of the predetermined speed of the generator shaft 12, it will be observed that there are no frictional losses or any frictional wear on the parts for all operations of the generator above the predetermined speed. Furthermore, since the switch contacts are not operated until after a predetermined speed is reached'the generator eld winding is not energized until the predetermined speed has been attained.

Referring to Fig. 2 of the drawing, it will be observed that the eld winding lof of the generator 10 is controlled by a pair of direction switches and 81, the operating coils 82 and 83 of which are controlled by the speed and directional switch. Thus for example, if it isassumed that the conducting plate or bridging contact 34 completes a connection between the stationary contacts 36 and 37 a circuit can be traced from the positive source of supply 86, stationary contact 36, conducting plate 34, stationary contact 37, conductor 87, operating coil 82 of the direction switch and to the negative source of supply. The direction switch 80 is thereupon operated to the closed position to energize theeld winding 10jv througha circuit which may be traced from the positive source of supply 86, by conductor 89, contacts 90, conductors 91 and 92, neld winding lf, conductor 93, contacts 94 and by conductor 95 to the negative source of supply 88.

Similarly, if it be assumed that the bridging contact 34 completes an energizing circuit through the stationary contact members 35 and 36. the direction switch 81 completes an'energizing circuit lfor the eld winding 10i with its polarity reversed.

Therefore, the generator 10 always causes a current to ow to its load, for example the battery 96, in the same direction irrespective of the direction of rotation o f the' generator armature.

While I have shown a particular embodiment of my invention, it will be understood, of course, thatI do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by letters Patent of the United States, is:-

1. In combination, a speedv and directional switch comprising a plurality of directionselecting contacts, biasing means normally biasing said contacts to a circuit-interrupting position, means mounting said biasing meansffor rotation. centrifugal means operatively associated with said biasing means for operating said biasing means to release said'contacts, friction means forming a driving ,connection between said biasing means and said contacts for producing different circuit-controlling connections between said contactsin response to the direction of rotation of said friction means, means for biasing :said contacts to a circuit-closing position, said centrifugal means disengaging said frictional connection when said switch is rotated .at apredetermined speed. 2; A and directional switch comprising.

a plunger arranged for longitudinal movement between predetermined limits, a spring for biasing said plunger to one of said limits, centrifugal means operatively associated with said plunger for operating said plunger to the other of said limits against said bias, circuit-controlling means operable between open and closed circuit positions and normally biased to one of said positions, a friction plate operatively engaged by said plunger, means mounting said friction plate on said circuit controlling means for maintaining said circuit-controlling. means in the other of its positions against said bias and for forming a frictional driving connection between said plunger andsaid circuit-controlling means, and means permitting relative movement of said circuit-controlling means in accordance with the direction of rotation of said yfriction means whereby said circuit-controlling means is operated in accordance with the direction and the speed of rotation of said centrifugal means.

3. An attachment for a generator comprising an end plate, means Vfor. securing said plate to one end of said generator'shaft, a pair of Scentrifugal weights, means for supporting said 10U weights from said plate, a plunger normally biased to one position and operable by said weights to a second position, means connecting said plunger for rotation with said plate, circuitcontrolling means operatively associated with said plunger, friction material interposed between the face of said plunger and said circuitcontrolling means to form a frictional driving connection between said plunger and said circuitcontrolling means, means for permitting a rotational movement of said circuit-controlling means between predetermined limits, means respcnsive to the rotation of said circuit-controlling means for completing different circuit-controlling connections, Vmeans permitting longitudinal movement of said circuit-controlling means between predetermined limits for disabling said connecting means whereby upon operation of said generator said circuit-controlling means is rotated to one or the other of its positions and 120 is thereafter operated to one or the other of said circuit-controlling. positions after said generator has attained al predetermined speed of rotation, 4. In combination, an axle-driven generator provided with an end shield, a plate, means for driving said plate at the same speed and in the same direction as said axle-driven generator, a plunger operable between predetermined positions, centrifugal weights operatively connected to said plate and to said plunger, biasing means normally biasing said plunger to one of its positions, rollers supported from said plunger and engaging said weights vfor biasing said weights in a predetermined position, circuit-controlling means supported from said end shield of said 4135 generator comprising a. switch member, friction material ,secured to said member and arranged in cooperative relation with said plunger, means mounting said switch member for rotational and longitudinal movements between predetermined 140 limits, a predetermined low speed rotation of Y said plunger in one direction rotating said switch member-to one of its limits and the rotation of said plunger in the oppositedirection rotating said switch member Ato thekother of its limits, saidbiasing means when said generator is rotating at said predetermined iow speed normally maintaining said plunger in engagement with said friction .material and said switch member in 150 tion to permit said switch member to move into engagement with said stationary contacts and to disengage said plunger from said irictional material after said generator speed rises above said predetermined low speed.

- JACOB w. McNAmY.

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