US1685935A - Motor snap switch - Google Patents

Description

Oct. 2, 1928.

H. G. BAXTER MOTOR SNAP SWITCH Filed March l, 1925 mvENToR a Ham/d Bax/er TTORNEY Patented Oct. r2, 1928.

UNITED STATES PATENT OFFICE.

HAROLD G, BAXTER, F BALDWIN, NEW YORK, ASSIGNOR T0 WESTINGHOVUSE ELEC- TRIO @c MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOR SNAP SWITCH. v

Application filed March 1,

My invention relates to snap switches and more particularly to starting switches for small motors.

One object of my invention is to provide a snap switch which is composed of feW parts and is simple in construction.

An object of my invention is to provide a snap switch in which a shaft or crank member moves in the same direction for both making and breaking an electrical Contact upon the occurrence of overload conditions.

It is a further object of my invention to provide a snap switch for controlling the several circuits employed in starting a singlephase induction motor.

It is also an object of my invention to p'rovide a snap switch with a trip-free handle for automatic release from overloads Without the removal of the operators hand from the handle.

Figure 1 is a diagrammatic illustration of apparatus and circuits embodying my invention.

Fig. 2 is a plan view of a snap switch embodying my invention.

Fig. 3 is a longitudinal sectional view thereof.

Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3.

Figs. 5, 6 and 7 are diagrammatic illus* trat-ions of the Off, Starting and Running positions of the switch, respectively'.

In Vthe preferred embodiment of my invention, an electrical device 1, such as a single-phase motor, is connected, by an electrical circuit 2. to any suitable source of electrical energy, through a switch 3, embodying my invention.

The switch 3 is of the snap type and comprises a base member 4, of suitable insulatingr material, provided With a cover or casing 5,

` preferably of cylindrical form. A turn-button 6, is attached to shaft 7 which has an offset portion or crank 8 intermediate its ends. A pair of bifurcated arms 9 and1'1 are mounted on the shaft 7 to straddle the crank portion 8. A spring 12 connects the crank portion 8 to the arm 11.

Secured to the outer end of arm 9 is an insulated member 13 of any suitable material, such as micarta material, which carries a contact member 14 constituting a shuntswitch, and Contact members 15 and 16 con- Stituting a starting switch, that are adapted 1923. vSerial No. 622,052.

to engage fixed contact members 17, 18 and "ff 19, respectively. i

In Ffg. 2, an insulated member 21 is shown secured to the outer end of the arm 11. Member 21 carries an. extension 22, having legends such asOn and Off inscribed thereon to co-operate with an opening 23 in the cover 5. Member 21 also carries- contact members 24 and 25 constituting-a running switch Which cooperate With the stationary contacts 26 and 27, respectively.

A spring 28 connects the arms 9 and 11. A balanced latch 29, controlled by a spring 30, is adapted to extend through an opening in arm 9 to secure the arm, in a manner to be hereinafter described. The latch 29 is controlled by a lever 31 actuated by the piston 32 of a dash pot 33.

A. ratchetvvheel 34 is mounted on a sleeve 45 that constitutes an extension of the handle 6. Another ratchet Wheel 35 is secured to the shaft 7 near its outer end for co-operation With a paWl 35a on the handle 6. A helical spring 36 surrounds the shaft- 7, one end being secured to the base 4 and the other end to the arm 9. y

An electromagnet core 37 is energizedfby a coil 38 to operate an armature member 39, against the force of a spring 40. A notch 41 is cut in one end of the armature member 39, and a paWl is pressed against the ratchet wheel 34 by a spring 43. Armature 39 and pawl 42 are connected by a rod 44 around which the spring 43 is coiled. Pavel 42 is directly connected to the handle 6 by the ratchet Wheel 34. and a sleeve 45 that constitutes an extension of handle 6 but is free. from the shaft 7.

Coil .38 has a compensating tap 47 which serves to reduce the number of turns of the coilivhich are effect-ive on the overload mechanism during the starting operation of the motorat which time the current value is high. When full motor speed is reached and the current is reduced, the number of effective turns in the coil is automatically increased.

In the starting operation of my switch` the handle 6 is turned in a counter-clockwise direction to cause the ratchet-andpawi mechanism 35, 35EL to turn the shaft 7 in the same direction.

Contacts 15-18 and 16-19, controlling the starting circuits, are already held in closed positions by spring 36, The movement of crank 8 causes an elongation and tensioning of spring 12. As crank 8 turns over, it strikes the end of lever 31, which depresses piston 32 of dash pot 33, allowing the crank 8 to pass by the end of lever 31. When the crank portion 8 reaches its dead-center position with reference to the arm 11, the spring 12 is at a maximum tension. A slight movement beyond the dead-center position permits Y the spring 12 to contract, by a sharp movement of the crank into contact with the notch 41, to actuate the arm 11 and its movable contact members 24 and 25 into Contact with stationary contact members 26 and 27. The electrical connections are then as shown in Fig. 6.

The movement of the arm 11 causes spring 28 to be placed under tension to exert'a pulling force upon arm 9 in opposition to the latch 29. At the end of a period, corresponding to the time interval required for the motor 1 to reach its running speed,`the dash pot 33 causes its piston 32 to lift the lever 31 which bears against latch 29 and thus overcome the force exerted by the spring 30, thereby releasing arm 9. The latter snaps into the position for effecting engagement of contact members 14 and 17, as is shown in Fig. 7, simultaneously tensioning spring 36.

If an overload exists in the motor supply circuit 2, the electromagnet 37'-38 is energized to a degree at which the force of spring 40 is overcome, and armature member 39 is drawn downwardly thereby releasing the crank portion 8 from the notch 41. Spring 12 then draws the crank -portion 8 and the arm 11 into the starting relation, and spring 3G actuates arms 9 and, 11 and crank portion 8 of shaft 7 into the foff position, as shown in Figs. 4 and 5.

It is to be observed that, by the assembly of pawl-and- ratchet mechanism 35, 35, sleeve 45 and ratchet wheel 34, with relation to handle 6, movement of shaft 7 in a forward or counter-clockwise direction is not transmitted to the handle 6. This construction provides a trip-free attachment for the switch, even though the operators hand is still on the switch handle.

In order to stop the motor, a clockwise impulse is given handle 6 which is imparted by sleeve 45, ratchet 34, pawl 42 and rod 44 to armature member 39. As shown in Fig. 4, the movement just mentioned releases the crank member 8 from notch 41, allowing the switch to snap into its ofi7 position. Spring 43 maintains the pawl 42 in engagement with the ratchet wheel 34.

It is apparent that I have devised a starting switch of the snap type which is characterized by a unidirectional movement of a crank section of a shaft or pivot member whereby a trip-free mechanism is obtained.

My invention is not limited to the specific structure illustrated, as it may be variously modified without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. In a switch, a shaft having a crank mounted thereon, a handle on said shaft, means for imparting a turning movement to said shaft upon movement of said handle in a single direction, and means for imparting movement to the shaft in the same direction upon movement of the handle in an opposite direction.

2. In a switch, a shaft, a crank formed on said shaft, a handle on said shaft, means for imparting a turning movement to said shaft upon movement of said handle in one direction, means for imparting movement to the shaft in the same direction upon movement of the handle in an opposite direction, and circuit-controlling means associated with said crank.

3. In a switch, a shaft, a crank mounted on said shaft, 'means associated with said crank for controlling an electrical circuit, a handle mounted on said shaft, and means comprising an electro-magnet, an armature cooperating with said electro-magnet, a pawl mounted on said armature, and a ratchet attached to said handle for releasing said crank from said handle upon the occurrence of overload conditions in said electrical circuit.

4. In a switch, a shaft, a crank mounted on said shaft, a handle mounted on said shaft, a ratchet mounted on said sha-ft, a pawl mounted on said handle to co-operate with said ratchet, a ratchet mounted on said handle,-and means connecting the last named ratchet with said crank whereby said shaft may be actuated by said handle or said shaft may ope-rate independently of said handle.

5. In a switch, a shaft, a crank mounted on said shaft, a handle mounted on said shaft, a ratchet mounted on said shaft, a pawl mounted on said handle to co-operate with said ratchet, a ratchet mounted on said handle, and means connecting the last named ratchet with said crank whereby said shaft may be actuated by said handle or said shaft may operate independently of said handle, and an electromagnet for effecting said independent movement under conditions of overload.

6. Switch mechanism comprising a pair of relatively movable switch members, yielding means for normally holding one switch member in closed position and the other in open position, and having a portion for biasing the first switch member toward a second closed position when the second switch member is in closed position, means for releasably retaining the first switch member in closed position and means for moving the second switch member to closed position.

7. Switch mechanism comprising a pair of relatively movable switch members, yielding means for normally holding one switch member in closed position and the other in open position, and having a portion for biasing the first switch member toward a second closed ition when the second switch mem- \ber is 1n closed position, automatically-actu switch member in closed position and means for moving the second switch member to closed position.

8. Switch mechanism comprising a. pair of relatively movable #switch members, yielding means for normally holding oneswitch mem'- ber in closed position and the other in open position, and having a portion for biasing the first switch member toward a second closed position when the second switch member is in closed position, time control means for relcasably retaining the first switch member in closed position and means for moving the second switch member to closed position.

9. Switch mechanism comprising a pair of relatively movable switch members. means for normally biasing one of the members toward closed position, means for releasably retaining the said switch member in closed position, means for closing the other switch member, and a yielding means connecting the Switch members whereby the first switch member is moved to a second closed position against the action of the said biasing means when the second switch member is in closed positionV and after the first switch member is released from its first closed position.

10. Switch mechanism comprising a pair of relatively movable'switch members, means forl normally biasing one of the members toward closedposition, means for releasably retaining the said switch member in closed position, means for closing the other switch member, a yielding means connecting the switch members whereby the first switch member is moved to a second closed position against the action of the said biasing means when the second switch member is in closed position and after the first switch member is released, and automatically-actuated means for releasing the first switch member.

11. Switch mechanism comprising a pair of relatively movable switch members, one of which is alternately movable into engagement with separate contact members, and the other into and out of engagement -with a third contact member, yieldmg means for normally holding the first switch member in engagement with one ofthe first said contact members and the second switch member out of engagement with the third contact member, and having a portion for biasing the first switch member toward the other of the first contact members when the second switch member is closed, means for releasably retaining the first switch member in its initial position and means for moving the second switch member to closed position.

ated means for releasa-blyretaining the first 12. Switch mechanism comprising a. rotatable unidirectional operating shaft, a Switch member movable to open and to closed positions in response to rotary movement of the operating shaft, means for arresting move- .ment of the operating shaft when the switch member has moved to closed position, an operating handle for rotating the shaft, means for connecting the shaft and the handle whereby rotation of the shaft is permitted independently of the handle and irrespective of the position of the handle, and means actuated by the handle when turned in the direction opposite to that in which the shaft rotates for releasing the shaft-arresting means to permit opening movement of the switch member.

14. Switch mechanism comprising a rotatable unidirectional operating shaft, a switch member movable to open and to closed positions in response to rotary movement of theV operating shaft, .means for arresting movement of the operating shaft when the switch member has moved to closed position, an operating handle for rotating the shaft and means responsive to current conditions and also actuated by the handle when the latter is turned in the direction opposite to that in ,which the shaft rotates for releasing the shaft-arresting means to permit opening movement of the switch member.

15. In a switch mechanism, the combination with a rotatable unidirectional operating shaft, and a pivotally mounted switch member, of an overcenter spring connecting the switch member and shaft for moving the switch member to closed position in response to a predetermined movement of the shaft,

means for arresting movement of the shaft aft/er the switch is closed, and yielding means tensioned by closing movement of the switch member for moving the switch to open position when the shaft has been released.

16. In a switch mechanism, the combination with a rotatable unidirectional operatincluding a second switch member tensioned to open position by closing movement of the first switch member for moving the first switch member to open position, and the second switch member to closed position when the shaft is released.

17. In a switch mechanism, the combination with a rotatable unidirectional operating shaft, and a pivotally mounted switch member, of an overcenter spring connecting the switch member and shaft for moving the switch member to closed position in response to a predetermined movement of the shaft, means for arresting movement of the shaft after the switch member isl closed, yielding means including a second switch member tensioned by closmg movement of the switch member for moving theswitch member to open position when the shaft has been re# leased, timecontrolled means for releasing the second switch member for permitting opening movement thereof, and a current-responsive means forreleasing the operating shaft.

18. In a switch mechanism, the combination with a rotatable unidirectional operat- Aing shaft, and a pivotally mounted switch member, of an overcenter s ring connecting the lswitch member and shafifl for moving the switch member to closed position in response to a predetermined movement of the shaft, means for arresting movement of the shaft after the switch is closed, yielding means including a second switch member tensioned by closing movement of the switch member for' moving the switch member to open position when the shaft hasI been released, and separate automatically-actuated means for releasing the second switch member for permitting opening movement thereof and forr releasing the'operating shaft.

19. A motor-starting switch comprising a running switch, a starting switch, an electromagnet for controlling the running switch and provided with a magnetic coil having a portion only thereof connected in the running switch circuit when the starting switch is closed and means for connecting additional coils in the running switch circuit when the starting switch is open.

20. A motor-starting switch comprising a running switch, a starting switch, an electromagnet for controlling the running switch and provided with a magnetic coil having a portion thereof connected in the running switch circuit when the starting switch is closed and means for connecting another por-- tion in the running switch circuit when the starting switch is open.

21. A motor-starting switch comprising a running switch, a starting switch, an electromagnet for controlling the running switch connected in the running switch circuit and means for rendering the electromagnet .operative at lower current values when the sta-rt ing switch is open.

22. Switch mechanism comprising a pair of switch members, movable in opposite directions to close their respective circuits, a unidirectional operating shaft, means for connecting the shaft with one of the switch members whereby movement of the shaft causes alternate opening and closing movements thereof, means for normally yieldingly retaining the other switch in closed position, means for releasably latching the switch member in closed position, means actuated by the first switch member for biasing the second switch member toward open position against the action of the said yielding means and time control means forl releasing the second switch member.

In testimony whereof, I have hereunto subscribed my name this seventh day of February 1923.

HAROLD G. BAXTER.

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