US2794868A

US2794868A - Delayed action switch

Info

Publication number: US2794868A
Application number: US595464A
Authority: US
Inventors: Mcmorran Francis Elroy; Rafters Neil St Clair
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-07-02
Filing date: 1956-07-02
Publication date: 1957-06-04
Anticipated expiration: 1974-06-04

Description

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3 /8 Y l INVENToR [7 ancisEMvc/[arram jVe l Sjafers M 'Lf United States Patent O DELAYED ACTION SWITCH Francis Elroy McMorran and Neil St. Clair Rafters, Halifax, Nova Scotia, Canada' Application July 2, 1956, Serial No. 595,464

Claims. (Cl. 200-34) This invention relates to switches.

The principal object of the present invention is to provide means for operating a switch to open an electrical circuit, the nal break in the circuit taking place some time subsequent to the operation of said switch, thus allowing the circuit to operate temporarily.

Other objects of the invention are to provide a delayed action switch bearing the above object in mind which is of simple construction, has a minimum number of parts, is inexpensive to manufacture and eflicient in use.

For other objects and for a better understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawing, in which:

Figure l is a vertical sectional view shown partly in elevation of a preferred embodiment of the present invention showing the delayed action switch in the normal open position;

Fig. 2 is a view similar to Fig. 1 but showing the delayed action switch closed and Fig. 3 is a horizontal sectional view taken along the line 3-3 of Fig. 1.

Referring now more in detail to the drawing, represents a hollow, cylindrical casing of electrically nonconductive material, for example plastic, having a bottom wall 11 and a closure 12 at the top thereof of similar material, substantially as illustrated.

The bottom wall wall 11 at one side is integrally formed with the depending valve casing 13 having an internally threaded bore 14 which communicates at its upper end with the frusto-conical bore 15, the smaller, upper end ci which communicates through the narrow opening with the interior of the casing 10, as shown in Fig. l. An externally threaded stud 16 is screwed upwardly into the internally threaded bore 14 and includes an enlarged head 17 at the lower end thereof, a lock nut 18 being provided intermediate Athe head 17 and the valve casing 13. The upper end of the stud 16 is formed with the conical tip 19 which is adapted to be received within the bore 15 when it is desired to close the valve, as will be obvious, and by luring the tip 19 the valve opening may be varied in size. The bottom wall 11 is also provided with a relatively narrow transverse bore 20 which connects the exterior of the casing 10 with the upper end of the' bore 14 and permits air to enter at a controlled rate, determined by the position of the stud 16 and the valve tip 19 thereof.

A circular permanent magnet 21 is integrally formed with a hollow, cylindrical reduced shank 22 which extends downwardly through an opening provided in the center of the bottom wall 11 and is connected to a `terminal 23 which also serves to retain the permanent magnet in position on the bottom wall 11. The terminal 23 is connected to one terminal 24 of a source of voltage by means of the conductor 25.

The top closure 12 at the center thereof is integrally formed with the hub or bearing portion 26 which slidably receives downwardly therethrough the plunger rod 27, to the lower end of which is tixedly connected a plunger plate ice 28 adapted for snug movement within the casing in the manner of a piston. 'Ihe upper end of the plunger rod 27 is formed with the enlarged knob 29 to facilitate the movement of the plunger plate, as will be obvious. The plunger rod, plunger plate and knob 29 are formed of electrically non-conductive material, for example plastic.

A relatively large coil spring 30 of less diameter than the interior of the casing 10 is positioned intermediate the plunger plate 28 and the bottom wall 11 and serves to retain the plunger plate 28 in the raised position of Fig. 1.

A contact and supporting disc 31 is suitably secured to the undersurface of the plate 28 at the center thereof and is integrally formed with a laterally extending nger or contact 32. A terminal 33 is suitably mounted on Ithe closure 12 at one side in vertical alignment with the outer end of the finger 32 and is connected to one terminal of the electric lamp means 34 by means of the conductor 35. A conductor wire 36 is connected to the terminal 33, extending downwardly through an opening in the closure plate 12 and a second vertically aligned opening in the plate 28 where it is connected to the outer end of the contact 32 below the plunger plate, the portion of the conductor wire 36 intermediate the closure plate 12 and plunger plate 28 being coiled so as to permit the downward movement of the plunger plate, as will be obvious.

A switch indicated generally at 37 is connected to the circuit of the lamp means 34 in parallel with the delayed action switch described by means of the

conductors

38 and 39, the switch 37 being normally closed during the operation of the lamp or other electrical accessory 34. The other terminal of the lamp means 34 is connected to the other terminal 38 of the power supply by means of the conductor 40.

The plunger plate 28 n the upper surface thereofA is provided with the downwardly extending relatively large cylindrical bore 41 which communicates at its lower end with the reduced cylindrical bore 42, the latter communieating with the interior of the casing 10 below the plunger plate, while the bore 28 communicates with the interior of the casing above the plunger plate. The plunger rod 27 above the plunger plate and below the closure plate 12 is integrally formed with the laterally extending support 43 which slidably receives therethrough the shaft 44. A soft rubber disc 45 is fixedly carried at the lower end of the shaft 44 and is adapted to close the bore 42. A coil spring 46 sleeves the shaft 44 intermediate the guide 43 and the disc 45 and serves'to normally retain the disc in the closed position shown in Fig, l, to serve as a check valve to permit the escape of air upwardly through the bores 42 and 41 but to prevent its return ow.

A coil spring 47 of conductive material is supported at its upper end on the contact 31 and in turn supports at its lower end the soft iron disc 48.

The tension of the spring 46 is much less than that of the spring 30.

The cover plate 12 is provided with a plurality of angu- Iarly spaced openings 49 to permit the free passage of air into the chamber intermediate the closure and the plunger plates.

As shown in Fig. l, the delayed action switch is normally open and the only path of the current to the lamp means 34 is through the normally closed switch 37. ln order to introduce the delayed action to the circuit the plunger plate 28 is pushed downwardly by means of the knob 29 just prior to the opening of the switch means 37. When the plunger plate 28 is pushed downwardly against the action of the spring 30, it brings the

contacts

48 and 21 together which provides a path for the electric circuit to the lamp means 34. This closed circuit is shown in Fig. 2. While the plunger plate 28 is being pushed down as just described several actions take place. The valve disc 45 will be forced open by the outward rush of air due to the fact that the chamber below the plunger plate 1s airtight except for the valve opening 42 and the relatively narrow opening 20. When the soft iron disc 4SI comes in contact with the permanent magnet 21, the problem of arcing will b e eliminated. This is due to the fact that as the disc 48 comes close enough to the magnet, it will be attracted to the same and the two contacts wil come together almost instantaneously.

As soon as the pressure applied to push the plunger plate down is released, the spring 30 willapply an upward pressure to the plunger plate and the vacuum below the plunger plate will hold the valve disc 45 closed so that the only inward path for air will be through the jet opening 20, which can be adjusted by means of the

valve

16, 17, 19. By means of this adjustment, the air can be allowed to enter the chamber below the plunger plate at any rate desired. As the air enters through the jet opening and through the valve opening 15, the vacuum in the chamber below the plunger plate is gradually reduced to allow the plunger to be forced upwardly by the spring- 30. As the plunger plate moves back to its normal position of Fig. l, the soft iron contact 48 will cling to the permanent magnet 21 until a certain tension is Vreached in the spring 47 sutiiciently strong for the soft iron contact to break away from the attraction of lthe magnet. This break will again be instantaneous to eliminate the problem of arcing, as in the closing of the circuit.

When the two contacts 48 and 21l are separated, as just described, there is no longer a path for the power to the lamp means, which brings to an end one complete cycle of the delayed action circuit.

While various changes may be made in the detail construction, it shall vbe understood that such changes shall be within the spirit and scope of the present invention as defined by the appended claims.

What we claim as new desire to protect by Letters Patent of the United States:

l. A delayed action switch comprising a casing of nonconductive material closed at opposite ends, a plunger plate of non-conductive material slidably positioned withinsaid casing, a plunger rod connected to said plate and extending outwardly through one end of said casing, spring means intermediate said plunger plate and the other end of said casing, serving to normally retain said plunger rod in an outwardly extended position, a permanent magnet conductor plate mounted in said other end of said casing, a first terminal connected to said permanent magnet on the outer face of said other end of said casing, a second terminal mounted on the other face of the casing end receiving said plunger rod therethrough, said lirst and second terminals being connected in the electrical circuit into which it is desired to introduce the delayed action, a contact secured to the face of said plunger plate adjacent said permanent magnet, expandible conductor means connecting said first contact with said second terminal extending through said plunger plate and through the end of the casing, said casing end having said plunger rod extending therethrough having air vents, check valve means carried by said plunger plate adapted to permit the outward movement of air through said vent openings butto prevent itsA return flow, controllable valve means at the end of said casing having said permanent magnet and adapted to per mita controlled rate of entry of air into said casing intercontact, said second spring means being of less strength than said first spring means whereby to close the circuit upon downward movement of said plunger plate by bringing said soft iron Contact into contact with said permanent magnet and to create a vacuum intermediate said permanent magnet and plunger plate which will delay thc return of the plunger plate to its original position, until said vacuum is released by the inward movement of air through said controlled valve means.

2. A delayed action switch according to claim l, said check valve means comprising said plunger plate on the face thereof adjacent said air vents having a relatively large bore extending partially therethrough and connecting with the reduced bore extending through the other side and communicating with the interior of the casing intermediate said plunger plate and permanent magnet, a laterally extending guide iixedly carried by said plunger rod intermediate said plunger plate and said casing end having said vent-openings, a rod slidably positioned within said guide parallel to said plunger rod and aligned with said relatively narrow opening, a soft resilient disc carried by the end of said rod adjacent said relatively narrow opening and adapted to close the same, and a coil spring sleeving said rod intermediate said guard and disc whereby to normally retain said relatively narrow opening closed.

3. A delayed action switch according to claim 2, said control valve means comprising an outwardly extending valve casing connected to the casing end remote from said plunger rod h aving an internally threaded, inwardly extending opening communicating at its inner end with a frusto-conical bore having its smaller end communicating with the interior ofthe casing, an externally threaded valve screw threaded into said internally threaded bore and having an enlarged outer head, said valve at the inner end having a conical point adapted to be received within said valve seat when it is desired to close the valve and to adjust the free space therewithin, lock nut means carried by said stud intermediate said point and head, and a relatively narrow opening extending from said valve seat to the outside of the casing whereby to permit air to enter at a controlled rate depending upon the position of said point relative to the said frusto-conical bore.

4. A delayed action switch according to claim 3, said expandible conductor means comprising a laterally extending iinger connected to said first contact, free end of said finger being aligned with the said second terminal, and a conductor wire connecting said second terminal with the free end of said finger, said conductor wire extending through the end of said casing and through sai-:l plunger plate, said wire intermediate said casing end and plunger plate being coiled so as to expand and contract with the movement of the plunger plate.

5. A delayed action switch according to claim 4, said first spring means comprising a relatively large helical spring positioned within said casing intermediate said plunger plate and the end of said casing having said permanent magnet, said second spring means comprising a relatively small helical spring supported at its upper end mediate said plunger plate and said pgrmanent magnet,

a soft iron contact adapted to contact said permanent magnet on downward movement of said plunger plate against the action of said spring means and second spring means suspending said sott iron contact with said iirst on said first contact and supporting on its lower end saidv soft iron contact, the tension of said second coil spring being less than that of said first spring.

References Cited in the ile of this patent UNITED STATES PATENTS 2,543,090 Ballon Feb. 27, 1951 2,744,177 Barber May l, 1956 FOREIGN PATENTS 8,504 Great Britain 1914