US1496751A

US1496751A - Selectively-operated electric switch

Info

Publication number: US1496751A
Application number: US507923A
Authority: US
Inventors: Morris B Wood
Original assignee: SEARS B CONDIT
Current assignee: SEARS B CONDIT
Priority date: 1921-10-15
Filing date: 1921-10-15
Publication date: 1924-06-03
Anticipated expiration: 1941-06-03

Description

June 3 l924.-

M. B. WOOD SELECTIVELY"; OPERATED ELECTRIC. SWITCH Filed Oct. 15 1,921 3 Sheer, sSheet 1 I june M. B. WOOD SELECTIVELY OPERATED ELECTRIC SWITCH Filed Oct. 15 1921 5 Sheets-Sheet 2 Jun 3, 1924. 1,496,751

- M. .B. WOOD SELECTIVELY OPERATED ELECTRIC SWITCH Filed 0st. 15. 1921 3 Sheets-Sheet 3 Patented June 3, 1924.

UNITED STATES PATENT OFFICE.

MORRIS B. WOOD, 0F SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO SEARS B. OONDIT, OF BROOKLINE, MASSACHUSETTS.

SELEGTIVELY-OPERATED ELECTRIC SWITCH.

Application filed October 15, 1921. Serial No. 507,923.

To (ZZZ whom it may concern:

Be it known that I, Monms B. Noon, a citizen of the United States, residing at Somerville, in the county of Middlesex and State of Massachusetts, have invented an Improvement in Selectively-Operated Electric Switches, of which the following is a specification.

This invention relates to electric switches and has particular reference to switches arranged for the starting of induction motors, although not restricted to such use.

It is common practice to employ two independent oil switches for the starting of induction motors, one to establish the initial connection of the motor to a line through the low voltage taps of a starting transformer and the other to connect the motor directly to the line and eliminate the transformer. The operating handles of the two switches are usually placed side by side and interlocking means, which may be a cam shaft, is extended between the two handles and is so arranged as to govern the operation of the switches in predetermined order and prevent the closing of the running switch when the starting switch is closed and the subsequent closing of the starting switch when the running switch is closed.

It frequently happens that an operative does not move the starting switch completely into closed position or does not hold it in completely closed position for the time required for the motor to come up to speed, but allows the handle to move back slightly from its fully closed position. The contacts of the switch may thereby partially or com pletely separate and an arc may be drawn which may cause serious damage to the contacts; and a relatively large amount of gas may be generated which may become ignited. and explode and do damage to the switch structure and surrounding objects. Due also to the partial separation of the contacts, the starting current may be re-' duced to such a degree that the motor may not have attained sufficient speed when the starting switch is moved to full open position and the running switch is closed. and an excessive current thereby may flow through the motor and cause damage.

An object of this invention is to provide means to constrain an operative to move the starting switch completely into fully closed position for the starting of the motor in .moved into or during the movement of the starting switch handle to open position to move the cam away from locking position with the running switch handle to permit it to be moved into closed position. The same rotation of said shaft mav interpose a second cam into the path of closing move ment of the starting switch handle whereby to hold it in open position while the run ning switch is closed. The cam shaft may be engaged to be rotated by a manually movable member carried by the starting switch handle and means may be provided to render ineffective the control of said manual member except in the fully closed position of the starting switch.

A further object is generally to impr the construction and operation of electric switches.

Fig. 1 is a front elevation of the face plate and motor starting and running switch handles embodying the invention.

Fig. 2 is a sectional vertical elevation of the starting switch along line 22 of Fig. 1.

Fig. 3 is a rear elevation of the starting switch of Fig. 2.

Fig. 4 is a sectional detail. through the starting switch handle and illustrating the position of the governing latch for the starting switch handle and the position of the cams to permit the starting switch to be moved into closed positions and with the running switch handle locked out.

,Fig. 5 is a sectional detail similar to Fig. 4 but with the starting switch in closed position and with the governing latch displaced from governing position to permit the cams to be operated to release the lock on the running switch handle.

Fig. 6 is a view similar to Fig. 4 and i1- lustrates the position of the cams to lock out the starting switch handle and release the lock on the running switch handle.

Fig. 7 is a perspective detail of the cam shaft and cams.-

Fig. .78 is a view along ..line.8 8..of Fig. 1 and illustrates more particularly the toggle mechanism connecting the running switch handle withthe switch operating rod and the locking latch for said handle.

As here shown, the invention is applied to motor starting switches having the starting switch handle 10 and the running switch handle 11 pivot-ally mounted side by side on the face plate 12. Said face plate is usually mounted on a switch board and has operating .rods extended through the boardto the switches disposed in the rear'thereof. In Fig. 2 the starting switch operating rod 13 is illustrated as connectedby the link 14: to thestarting switch handle 10. The running switch handle is preferably arranged to be locked in closed position, which is not the case with the starting switch handle, and'the running switch mechanism is arranged to be tripped free from its handle. pose the switch rod '13 of the running'switch is connected through the toggle links 15 and 1'6 with the running switch handle 11. A latch 17 is pivoted upon the housing'lS for the overload coils for the switch and is arranged to engage a .pin 19 carried by the handle 11 whereby to lock the handle and the switch in closed position. The overload coils are arranged to break the toggle whereby to openithe switch without a corresponding movement of the 'handle and, when the toggle links have moved upwardly a predetermined extent, they are arranged 'to engage a pin 20 fixed in the end of the locking latch and move the latch to release the hantile, and the handle will fall to-openposition by gravity. The running switch may also be opened manually, either by manually breaking the toggle or by depressing the thumb button 21 disposed in the handle. Said button'is fixedon the end of a springpressed rod-.22, the lower end of which is disposed to engage :theend of the latch 17 and move it from looking engagement with the handle when said thumb button is depressed.

The switch-interlocking means includes the cam shaft25 having the cam 26 at the starting switch handle end thereof and the cam .27 .at' the running switch handle end thereof. Said shaft is rotatably supported in Jtheibearings'28 between the two handles and with the cams-in proximity to said'handles. A pin 29 EisQcarried by the starting i switch handle and extends beyondsaid' handlewand-is adapted to engage said cam 26 in acertain :posi'tion thereof whereby to lock thestarting-switch in open position; and a. similar pin 30carr-ied by 'therunning switch handleiis adapted similarlyto'be engaged by the cam 27 to lock the running switch in open vposition.

Said cam shaft is held 'yieldingly in a normal 5 position in which the disposition of the cams is such that the running switch is For this pur-.

locked in .open position and .the starting switch is free to be moved into closed position. Said holding means may include the arm 32 carried by said shaft and extended on opposite sides thereof and the springs 33 disposed in recesses in the overload coil housing. Said springs are adapted to press, through the pins 34:, against said arm 32 andnormally balance each other through said arm but to yield to admit of an angular movement of said shaft.

The starting switch handle. is provided with a thumb button 35 received on the upper end of the rod 36. Said .rod is normally held in an elevated position by the spring 37 and its lower end is secured to the upper end of a frame 38. Said frame is slidably mounted on said handle and isheld in position thereon by the shoulderrivets 39 which are passed through slots 4:0 in said 7 frame and fixed in the handle.

Ears 41 extend from the lower portion of said frame and a pin 42 is carried in'said ears and extends through a slot 43 in aside wall of said'handle to a position above the starting cam 26.

Said cam 26 is formed with an upper arcuate face 26*, the notched-portion 26 disposed below said arcuateface and a second notchedportion 26 disposed below said first notchedportion.

The running cam 27 is formed with the arcuate face 27 and the upper and inset notched-portion 27 The normal position of the cams is indicated in Fig. 4 and the starting cam, 26 is above and free from locking engagement with the pin 29 of the starting-switch handle 10 and the arcuate face 27 a of the running cam is disposed in frontof the pin-30 of the runningswitch handle and said handle consequently is restrained froinmovement into closed position.

In operating the switches. the starting handle is moved into closed position and held manually in closed position for a time sufficient for the motor to be brought up to speed. The pin 29 of said handle will'have been moved into the lower notched portion 26.and will hold the cam 26in-position with the cam 27 in locking-position-with the running switch handle. NVhen the motor has attained sufficient speed the thumb button 35 of the starting handle is "pressed-landthe starting handle is moved itO'WtLI'd open position. Until saidhandle has been'moved suffrom rotation. When, however, the starting handle has been moved sutficiently to bring the pin 29 under the notched portion 26 and clear of said face 26, the thumb button can be depressed downwardly to its full extent of movement and will engage the upper face 26 of said cam 26 to depress said cam and rotate the cam shaft 25 to move the cam 27 away from looking position with the running handle. The running handle will now be moved into closed position and locked in position by its latch 17. The pin 30 of said handle will be moved into the notched por tion 27 of said cam 27 to hold said cam in its depressed position whereby to hold the cam 26 in its depressed position with the pin 29 of the starting handle in the notched portion 26 of said cam and the starting switch consequently locked in open position. The lock will remain on the starting switch until the running switch handle has been moved to open position and one of said springs 33 has functioned to rotate the cam shaft to move the cam 26 free from looking position with the starting handle.

As previously stated, it frequently happens that an operative fails to move the starting switch handle completely into closed position or fails to keep it completely in closed position when operating the switches. The switch members, consequently, may not be fully in contact and the starting current may be so reduced that the motor may not attain sufficient speed in the usual time allowed by the operative, and when the running switch is next closed there may be such an excessive rush of current as to cause damage.

One of the objects of this invention is to provide means to prevent the operation of the running switch if the starting switch. handle has not previously been moved and held in completely closed position.

Said means may include the governing latch 50 pivoted on the pin 51 carried by the starting switch handle 10. Said latch is disposed beneath the pin 42 operated by the thumb button 35 and has an arm 52 formed with a notched portion 53 which is adapted to be positioned beneath and engage said pin 42 when the starting handle is away from completely closed position and thereby lock said pin against downward movement and prevent rotation of the cam structure. A spring 54 serves to hold said latch normally in pin-locking position, see Figs. 4.- and 6. Said latch 50 is formed with a second arm 55, angularly disposed with relation to said first arm 52, and said second arm is adapted to engage a fixed part, as the overload coil housing, of the face plate, but only when the starting switch handle is moved into completely closed position, to rotate the latch to move the arm 52 away from lockingengagement with said pin 42.

Fig. 2 illustrates the position of the latch with the starting switch handle in completely closed position. In this position, the pin 42 may be depressed, as illustrated in Fig. 5,

and, when the starting handle is moved to open position, said pin will rotate the cam structure to permit the closing of the running switch: and the pin 42, in its depressed position, will hold said latch from return ing to locking position with the pin until said pin is restored in raised position.

lVith this arrangement, if the starting handle is not moved completely into closed position or is moved slightly away from completely closed position before the thumb button is depressed, the lock cannot be removed from the running switch; and the starting switch handle must again be moved toward and into completely closed position to remove the lock on the cam operating pin 42 before the running switch can be unlocked.

By switch-closed position is meant that position of the swtich members wherein the contact members are in sufficiently firm engagement to carry the current in a satisfactory manner and without arcing.

The invention may be contained in other modifications without departing from the spirit thereof.

I claim:

1. The combination of two electric switches, means to govern the order of operation of said switches having means to lock one or the other of said switches in open position, means to operate said governing means to remove the lock on one of said switches, and means arranged normally to lock said operating means against operation.

2. The combination of two electric switches, means to govern the order of operation of said switches having means to lock one or the other of said switches in open position, means to operate said governing means to remove the lock on one of said switches, and means to lock said operating means against operation arranged to release said operating means only when the other switch is in completely closed position.

3. The combination of independent operating mechanisms for two electric switches, means to govern the order of operation of said switches having means to lock said mechanisms alternately in switch-open position, manually-controlled means carried by one of said mechanisms to operate said governing means to remove the lock on said other mechanism, and means normally to lock said manually-controlled means and release the lock on said means when the mechanism is in completely switch-closed position.

4. The combination of two switch handles, means to govern the order of operation of s'aid'handles, said means arranged to lock said handles alternately in switch-open position, manually-controlled means carried by one of said handles to operate said governing means normally .to remove the lock on said other handle, and means to lock said manually-controlled means from operation arranged to release the lock on said manuallycontrolled mea'ns in the completely switch closed position of the handle carrying said locking means.

5. The combination of two electric switch handles, means to govern the order of operation of said handles arranged to lock said handles alternately in switch-open osition, said means including a cam-shaft an a locking cam associated with each handle, a manually-controlled pin carried by one of said handles arranged to engage the cam associated with said handle and depress it to rotate said cam shaft and other cam away from locking position with said other handle, and means including a latch arranged normally to lock said pin from operation and be moved from looking position with said pin only when said handle is in completely switch-closed position.

6. The combination of a face plate, starting and running switch-handles pivotally mounted side by side thereon, means to gov ern the order of operation of said handles including a cam shaft journalled on said faceplate between said handles having locking cams at the ends thereof adapted to engageand lock said handles alternately in switch-open position, a manually-depressible pin'carried by said starting handle arranged to be depressed to engage a camand rotate said cam shaft and other cam from locking position with said running handle, and a latch. carried by said handle arranged normally to be held in a position to lock said pin against operable engagement with said cam and to engage said face plate when said starting handle is in completely switchclosed position and release its lock on said 7. The combination of a face plate, starting and running switch handles pivotally mounted side by side thereon, means to govern the order of operation of said handles including a cam shaft journalled on said face plate between said handles having looking cams at the ends thereof adapted to engage and lock said handles alternately in switch-open position, a manually-depressible pinearried by said starting handle arranged to be depressed to engage a cam and rotate said cam shaft and other cam from locking position with said running handle, and a latch carried by said handle arranged normally to be held in a position to lock said pin against-operable engagement with said cam and to engage said face plate when saidstarting handle is in completely switchclosed position and release its lock on said pin, said pin arranged to be depressed in the completely switch closed position of said starting handle to hold said latch away from locking position.

In testimony whereof, I have signed in name to this specification.

MORRIS B. Woon.