US1148256A - Switch. - Google Patents

Description

J.L.SCHUREMAN.

SWITCH.

APPLICATION FILED MAR. 13-. 1911.

Patented July 27, 1915.

I1 TED STATES PATENT OFFICE.

JACOB L. SCHUREMAN, 01? OAK PARK, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE CUTLER-HAMMER MFG. 00., 0F MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

SWITCH.

To all whom it may concern:

Be it known that I, JAooB L. SCHUREMAN, a citizen of the United States, residing at Oak Park, in the county of Cook and State of Illinois, have invented new and useful Improvements in Switches, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to electric switches.

The various objects and advantages of the invention will hereinafter appear in connection with the description of one embodi ment thereof illustrated in the accompanying drawing.

In the drawing, Figure 1 is a perspective view of the switch; and, Fig. 2 is a sectional View on line 22, Fig. 1.

The device illustrated is designed for starting alternating current motors, and as will be hereinafter set forth, it is operated by an electromagnet which in practice is ordinarily connected across one phase of the motor circuit.

The device comprises switches a, Z) and 0, all mounted upon a suitable insulating base, or panel, 1. The structure of the several switches is substantially identical and accordingly, I shall only describe in detail switch 0, the details of this switch being more clearly apparent. Switch 0 comprises an arm 2 fulcrumed to a bracket 3 secured by any suitable means, such as a bolt 4, to the base 1. The arm 2 is provided at its upper end with two circular openings, one arranged directly below the other, said openings forming sockets for cylindrical contacts 5 and 6. .The contacts 5 and 6 are preferably formed of carbon and are free to slide longitudinally in their sockets in the arm 2. Secured to the panel 1 and arranged in alinement with the contacts 5 and 6 are stationary contacts 7 and 8 arranged to be respectively engaged thereby. The contacts 5 and 6 carried by the arm 2 are preferably rigidly connected by clamping members 9 and 10, which may be secured together by any suitable means such as a bolt 11 passing through all of said members and also the contacts. The arm 2 is provided with an outward extension 12 to the endof which are fastened spring members 13 and 14 hearing against the outer ends of contacts 5 and 6 Patented July 27, 1915.

Serial No. 614,016.

respectively. These spring members tend to force the contacts5 and 6 toward their re spective stationary contacts. The clamping members of the contacts 5 and 6 limit the movement of said contacts relative to the arm 2 by engagement with said arm. The bolt a which secures bracket 3 may be used as a binding post and may be electrically connected to the clamping members of contacts 5 and 6 by a flexible conducting strip 15.

Pivoted to the extension 12 of the arm 2 is a link 16 having an enlarged recessed portion 17 the recessed portion having a shoulder 18. Fixed to. the panel 1 beneath the link 16 is an inclined stop 19 with which the extremity of said link is adapted to engage. Extending through the recessed portions of the links 16 of the several switches is a shaft 20 revolubly supported in suitable bearings fixed to the base 1. Fixed to this shaft are members 21 each provided with a pin 22 arranged substantially parallel to the shaft 20 and adapted to engage the shoulder 18 of one of the links 16. The members 21 are so adjusted that the pins 22 are disposed at varying distances from the shoulders 18 which they respectively engage. As illustrated, the pins 22 are so arranged that they will engage their respective parts of switches a, Z and o successively in the order named upon rotation of shaft 20. Also, fixed to the shaft 20 is a pinion 24, with which meshes a vertically disposed longitudinally movable rack member 25. The rack member 25 is connected to and adapted to be moved by the plunger 26 of a solenoid 27 The rack member is held in mesh with the pinion 2 1 by a guide roller 28. The rack member is also connected to the piston of a dash pot 30 preferably of the suction type, which is suitably secured to the supporting base. The solenoid, through the rack and pinion mentioned, revolves the shaft 20, thereby successively moving the pins 22 carried thereby into engagement with their respective switches.

Upon rotation of the shaft 20, the pin 22 associated with switch .a first engages its corresponding shoulder 18 on said switch a, moving the link 16 upwardly, thus causing the arm 2 of said switch to turn on its pivot and move toward the supporting panel 1. Further rotation of the shaft causes the middle pin 22 to engage switch b to cause a similar operation of the arm 2 of said switch, while still further operation of the shaft causes a similar operation of the member 2 of switch 0. Such a movement of the members 2 of the several switches tends to move the contacts carried thereby into engagement with their respective stationary contacts. The dash pot 30 serves to insure a definite time interval between the operation of successive switches. As each switch is moved to closed position, the extremity of its link 16 is moved onto its corresponding stop 19 whereby the switches are maintained in closed position after the pins 22 disengage the shoulders 18.

For a purpose hereinafter set forth, I prefer to provide the dash pot 30 adjacent to its upper end with an inlet port 31 so located as to allow free inrush of air into the dash pot to eliminate its retarding effect after the last switch of the series has been operated.

Before further describing the structure illustrated, I shall consider certain conditions that are met with in practice. Assume that the device is employed for starting an alternating current motor, that each switch upon closing increases the current supplied to the motor and that the solenoid 27 is connected across one phase of the motor circuit. It is well known to those skilled in the art that a sudden surge of current supplied to an alternating current motor will frequently cause a temporary drop in voltage in the motor circuit. Accordingly, if the device illustrated be employed for the purpose above set forth, then closure of the switches a, b and 0 may cause successiy e temporary drops in the voltage of the motor circuit and consequently in the voltage impressed upon the operating solenoid 27. Thus the closure of each. switch tends to temporarily weaken the pull of the solenoid 27. Until all of the switches have been operated and the piston of the dash pot passes inlet port 31, said dash pot not only retards the operation of the solenoid plunger, but in fact exerts a pull thereon in opposition to the pull of the solenoid. In actual practice the solenoid, when of full strength, only predominates the opposing pull of the dash pot to a small degree, just sufficient to close the switches. Hence, if the strength of the solenoid is weakened, immediately upon closure of each switch the suctional pull of the dash pot tends to, and frequently does, predominate the pull of the solenoid to such a degree as to cause the last closed switch to open a fraction of an inch. This results in destructive sparking between the switch contacts.

It is one of the principal objects of my invention to overcome this objectional condition. In the accompanying drawing, I

have shown a very simple means for so doing, which I shall now describe.

Secured to the base 1, above the switch a, is a bracket 32 of any suitable construction carrying a horizontally disposed spring member 33 projecting toward the member 2 of switch a. The free end of the spring member 33 is provided with a downwardly extending projection 34- having oppositely inclined faces. The projection on spring member 33 normally extends into the path of a lug 35 arranged at the extremity of the member 2 of switch a. Said spring member will thus oppose movement of said switch member 2 until the projection 35 of the lat ter member forces aside and passes the projection 34 on the former member. The degree of opposition of the spring member 33 obviously depends upon the resiliency thereof. Switch 6 is provided with a similar opposing device and is also provided with a lug 35 on the member 2 thereof. With these exceptions the switches a and b are of identically the same construction as switch 0.

I shall now more fully describe the operation and functions of the device illustrated under actual working conditions, assuming that it is used for the purpose above set forth. Assume that the switches are all in open position, as illustrated, and that circuit has just been closed through the sol.e noid 27. The solenoid will then tend to draw in its plunger and by so doing move the piston of the dash pot, thereby creating a strong vacuum in the dash pot. The vacuum created in the dash pot immediately checks the movement of the solenoid plunger. Thereafter, the solenoid plunger can only move at a speed proportional to the leakage of air into the dash pot. The dash pot, of course, can be adjusted to regulate the leakage of air into the same and thus vary the opposing pull on the solenoid plunger. In practice, the dash pot is usually so regulated that its pull is almost as great as that of the solenoid, merely allowing the pull of the solenoid to predominate to a degree just suflicient to close the switches. After the initial check on the movement of the solenoid plunger by the dash pot the plunger continues to move at a slow speed, in accordance with the adjustment of the dash pot, to revolve the shaft 20 to close the switches. As has previously been seen rotation of the shaft 20 first actuates switch a, and, as has further been seen, upon initial movement of the switch 2, the same is brought into engagement with spring 33. Continued movement of switch a is thus temporarily opposed by the spring 33. The spring 33 obviously co-acts with the dash pot 30 to augment the load imposed upon the solenoid, or, in other words, increases the opposing forces against movement of the solenoid plunger.

Inasmuch as the strength of the solenoid is only slightly greater than the pull of the dash pot, it is obvious that when switch a engages spring 33 the opposing force of said spring will tend to halt the switch in its movement and, accordingly, tend to check further movement of the solenoid plunger. The leakage of air into the dash pot is continual and,'accordingly, if move ment of the solenoid plunger is momentarily checked, as above set forth, by the spring 33 the opposing pull of the dash pot will be gradually weakened until the strength of the solenoid predominates the combined forces of said dash pot and said spring. The solenoid will thereupon further draw in its plunger moving the switch a past the spring member 33 into closed position. Immediately upon the lug 35 of switch a passing the projection 34 on the spring member 33, the opposing force of said spring member will be eliminated leaving the solenoid opposed only by the dash pot. The pull of the dash pot, however, having been weakened, as above set forth, the difference in the relative strengths of the solenoid and the dash pot will be greater than during the initial operation of the solenoid. In other words, the function of the spring 33 is to retard the operation of the solenoid plunger and the piston of the dash pot, thereby causing a decrease in the vacuum of the dash pot until the predominating pull of the solenoid is augmented. The difference in the relative strengths of the solenoid and dash pot under these conditions will, of course, depend upon the duration of the temporary retardation of the operation of the device by the spring 33. This in turn depends upon the strength of the spring 33 relative to the strength of the solenoid 27 over and above the opposing pull of the dash pot. Thus when the switch 0 is brought into closed position the strength of the solenoid 27 rela tive to the opposing pull of the dash pot is much greater during the closing operation of said switch. Hence, if the parts of the device be properly designed and adjusted, the solenoid 27 may be made to predominate the opposing pull of the dash pot even when its strength is momentarily decreased by the closure of switch a for the reasons aforesaid. Accordingly the contacts of switch a would be firmly held in engagement regardless of the drop in voltage caused by its closure. This, of course, eliminates all danger of sparking.

Switch 7) operates in the same manner as svitch a and with the same results. Ac cordingly it is unnecessary to repeat the cxplanation of its operation.

Switch 0 has no auxiliary opposing device. Such provision is unnecessary for the reason that upon closure of this switch the piston of the dash pot passes the inlet port 31, allowing a free inrush of air into the dash pot, thereby eliminating its opposing effect. Obviously less power is required to hold switch 0 in closed position than is required to move it into such a position. Ac cordingly a properly designed solenoid would, even when weakened by closure of switch 0, retain suflicient strength to hold said switch firmly in closed position.

In addition to the advantages above described, a quick operation of switches a and Z) is insured. This is due to the fact that the leakage of air into the dash pot during the retardation of the switch members by their respective spring members allows the plunger of the solenoid to mon'ientarily accelerate when opposition of the spring members is eliminated. Further the spring members 33, themselves, tend to accelerate their respective switches as said switches pass the inclined projections 3% thereof.

Switch 0 is also insured a quick closure by reason of the free inrush of air into the dash pot through the opening 31.

hen the solenoid is deenergized its plunger moves downwardly, thereby rotating the shaft 20 in a reverse direction to that previously described. Under such conditions the pins 22 successively engage the links 16 of the several switches, disengaging the same from the steps 19 and thereby rendering the switches free to move to open position. When the switches are in closed position their springs 13 and 14 are under tension, whereby as soon as the switches are released as aforesaid, the con'ibined action of these springs and the weight of the parts causes the switches to move outwardly past the projections 3 of the springs 33, thus restoring the parts to normal position.

Having thus described my invention what I claim as new and desire to secure by Let ters Patent, is:

1. In combination, a plurality of successively operating switches, a common retarding means for said switches and means co operating with said switches and re-acting upon said first mentioned means to temporarily decrease the opposing force thereof as each switch is closed.

2. In combination, a plurality of switches, means for operating the same successively, means exerting an opposing force upon said former means to retard the operation of said switches and means temporarily augmenting the retardation of said first mentioned means prior to the closure of each switch to temporarily reduce the opposing force of said second mentioned means.

3. In combination, a plurality of switches, an alternating current solenoid operatively connected to said switches to close same successively, means exerting a force in oppo- SitiOn to said solenoid and means insuring a temporary reduction in the opposing force of said first mentioned means as each of said switches is closed.

l. In combination, a plurality of switches, an alternating current solenoid operatively connected to said switches to close the same successively, means exerting a force in opposition to said solenoid, and means cooperating with said swtiches and reacting upon said first mentioned means to temporarily reduce the opposing force of the latter as each of said switches is closed.

5. In combination, a switch, an operating member therefor,adash-pot opposing movement of said member and auxiliary means opposing movement of said member and reacting upon said dasl1pot to reduce the retarding effect thereof for a certain movement of said switch.

6. In combination, a switch, an operating member therefor, a dash-pot opposing movement of said member and auxiliary means opposing movement of said member and reacting upon said dash-pot to reduce the retarding effect thereof for a certain movement of said switch, said auxiliary means acting only fora temporary period.

7 In combination, a switch, an operating member therefor, a dash-pot opposing movement of said member and auxiliary means temporarily opposing movement of said member in a certain position of said switch to efiect a reduction in the opposing force of said dash-pot for subsequent operation of said switch.

8. In combination, a switch, an operating member therefor, 21. dash-pot opposing movement of said member and restraining means for said switch reacting upon said dash-pot to insure a reduction in the opposing force thereof prior to a certain operation of said switch.

9. In combination, a switch, an operating member therefor, a dash-pot opposing movement of said member and restraining means for said switch reacting upon said dash-pot to insure a reduction in the opposing force thereof prior to a certain operation of said switch, said restraining means being yielding and upon releasing said switch assisting in the operation thereof.

10. In combination, a switch, a yielding restraining device in the path thereof, an operating member for said switch having a non-yielding connection with the restrained part thereof, and a dash-pot opposing oper- Copies of this patent may be obtained for five cents each, by addressing the ation of said member, said switch restraining device reacting upon said dash-pot to vary the effectiveness thereof.

11. In combination, a plurality of switches, means for closing the same successively, a dash-pot exerting an opposing force upon said means and means associated with each of said switches with the exception of the last operated switch for momentarily augmenting the retardation thereof to insure a temporary reduction in the opposing force of said dash-pot upon the closure of each switch.

12. In combination, a plurality of switches, means for closing the same successively, a dash-pot exerting an opposing force upon said means, means associated with each of said switches with the exception of the last operated switch for momentarily augmenting the retardation thereof to insure a temporary reduction in the opposing force of said dash-pot upon the closure of each switch and an alternating current of solenoid for operating said first mentioned means.

13. In combination, a plurality of switches, an alternating current solenoid having its plunger operatively connected to said switches to operate the same successively, a dashpot opposing operation of said solenoid plunger and means cooperating with said switches and reacting upon said dash-pot to temporarily .reduce the opposing force of said dash-pot prior to closure of certain of said switches.

14. In combination, a plurality of switches, an alternating current solenoid, operative connections between said switches and the plunger of said solenoid to effect successive operation of the former upon attraction of the latter, a dash-pot opposing operation of said solenoid plunger, means cooperating with said switches and reacting upon said dash-pot to temporarily reduce the opposing force thereof prior to closure of certain of said switches and means for holding said switches in closed position independently of said solenoid.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

JACOB L. SGHUREMAN. Witnesses:

W. BEOKSTROM, M. C. ALLEN.

Commissioner of Patents,

Washington, D. C.

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