US1407315A - Thermodynamically-controlled knife switch - Google Patents

Description

MALCOLM H. BAKER, DECD.

MARIE H- BAKER, ADMINISTRATRIX.

THERMODYNAMICALLY CONTROLLED KNIFE SWITCH. APPLICATION FILED OCT. 8. 1915. RENEWED APR. 14,1919.

1,407,31 5, Patented Feb. 2], 1922.

UNITED STATES PATENT OFF-ICE.

MALCOLM n. BAKER, or 3mm, mnssacnusn'r'rs; MARIE n; mxnn. ummus-v rnarmx or moon: a BAKER, DECEASED, nssrenon, :sr mnsnn assronnnn'rs, T rumour PRODUCTS COMPANY, A oonronnrron or massacnusnrrs.

Application 'filed October 8, 1915, Serial No. 54,882. Renewed April 14, 1919. Serial No. 290,084.

Toall whom it may concern."

Be it known that I, MALCOLM H. BsKER, a citizen of the United States, and a resldent of- Braintree, in the county of Norfolk and Cdmmonwealth of Massachusetts, have invented certain new and useful Improvements in Thermodynamically-Controlled Kn fe Switches, of which thefollowing is a specification 1 Myinvention relates to switches for electric circuits formed with pivoted or swinging, blades, of the type usually lmown as f knife switches.

The object of my invention is toprovide, in combination with such a switch, means, under the control of the operater, whereby the said switch maybe closed fora contin uous period of time, as required for normal operation of the controlled circuit, and whereby, when it is desired to open the switch, an automatically performed opening movement may be had, operative a predetermined time after the actuation of the controlling means of the switch; the preferred arrangement being one whereby the same controlling member, actuated manually or otherwise, which ispsed to -close the switch is also employed to put into operation the delayed automatic 0 ening means. 7

In other applicatlons filed by melt have illustrated and broadly claimed such retard- .ed automatic switch opening devices as broadly applicable to various well known types of switches for electric circuitsg and specifically as applicable to snap switches,.

socket switches, and various other forms.

I have illustrated a preferred embodiment of my present invention in the accompanymg drawings, in which Fig. 1 is a front elevation of my im roved thermo-dynamically controlled kni e swvitch; Fig. 2 is an elevation looking at the right .of Fig. 1; Fig. 3 is a horizontal section taken on the plane A-A in Fig. 1; and Fig. 4 is a diagram of electrical connections.

Throughout the several views of the drawings identical parts are designated bylike reference numerals. In the drawings, a base 1, of suitable insulating material, is shown carrying contact clips 2, 3, having engagement Wlth blades6, 6, which are pivoted in posts4, 5, mounted upon the base 1. An

switch closed.

insulating bar-7 connects the blades 6, 6.. A second structure composed of metal bars 8, 8, having a control handle 10 is pivoted at 12 to the base 1. The blades 6, 6, have rilgid connection with an extension 13 to w ich is attached a coiled spring 14 fast at the other end to the'bracket 15 on the base -1., Contact clips 16, 17, are arranged on the base 1 to engagethe ends of the pieces 8, 8, when this structure is swung downwardly by means of the handle 10.' This engagement closes a shunt circuit, across the cllps 16, 17, (seeF'ig-d). Spring clips 11 serve to hold the structure 8, 8, in the raised position, and a thermostat 18 havin a wind ing 19, of suitable resistance wire, is attached to a block 20. on the base 1.

The upper end 21 of the said thermostat is bent around a rod 22, said'rod engaging with a slot in the end 23 of a bell-crank causing movement of its free end 21, of the I rod 22, and 'of the downwardly extending detent lever end 23 in a direction away from the insulating base 1. The other end of the lever 23, shown at 24, engages a projection 25 on the cross piece 7, so as to hold the The operation is as follows-to close the switch the handle 10 is pushed u which swingsthe structure 8, 8, against .t e cross bar 7, thus carrying up the blades 6, 6, into engagement with their clips 2, 3, to complete the electric circuit. At the same time the projection 25 is engaged by the end 24 of the lever 23, the thermostat giving, or springing, slightly to permit such engagement, and the switch thus locked closed against the action of the spring 14; a

When it is desired to open the switch, the

handle 10, is pulled down, the said handle mevingdihe structure 8, 8,-away from con-- tact with the blade S l'uGt I- I'Q 6, 6, and the Specification ofLetters Patent. Patented Feb, 21, 19,22. 1 l I manual, or other, controlling pull beingsufficient to disengage 8, 8, from the clips 11. This action forces the ends of the pieces 8, 8, into the clips 16, '17, thus connecting the winding 19 in shunt to the switch load. The thermostat is now heated, bends, moves the lever 23 as above described, and frees the end24 thereof from engagement with the projection 25,'thus permitting the spring l l to snap the blades 6, 6, out of their clips 2, 3, to open the circuit.

The desired time element, or delay, be tween the actuation of the handle 10 and the opening of the circuit is obtained through the time required to heat to operation the thermostat 18, and this time element can of course be broadly varied by altering the amount of wire in the winding 19, or the amount of engagement of the lever end. 24 with the projection 25.

, It will be noted that, since the thermostat circuit is shunted across the load side of the switch, said circuit is dead when the switch is opened.

It is of course easily possible to apply my invention to a single pole knife switch in place of the double pole herein illustrated, in which casethe' thermostat circuit would be energized by being placed in series with the switch circuit, as set forth in my other applications referred to.

As a thermo-dynamic device tosecure opening of the" switch I have shown a bimetallic thermostat, but any other suit-able type of such device may, of course, be emplo ed.

ithout, therefore, limiting myself to the precise embodiment herein shown, what I claim as my invention is,-

1. In an electric knife switch having a stationary contact terminal and a pivoted, swingable, blade device adapted at one extreme position thereof conductively to engage with said terminal, in combination controlling means arranged by insulated engagement with said device to swing the latter into engagement with said terminal contact and against the resistance of resilient means arranged to oppose such engagement; and a thermo-dynamic device and associated mechanism. controlled thereby, adapted when thermally energized to cause the se aration of said blade device from said terminal; to-

gether with an electric heater .for said thermo-dynamic device arranged operatively to be governed by said controlling means.

2. In an electric knlfe switch having a stationary contact terminal and a pivoted,

swingable, blade device adapted at one extreme position thereof conductively to engage with said terminal, in combination manuall operable controlling means ar ranged hy insulated engagement with said device to swin the latter into engagement with said terminal contact and against the resistance of resilient means arranged to oppose such engagement; and a thermo-dynamic device with associated mechanism controlled thereby, adapted when thermally energized to cause the separation of said blade device from said terminal; together with an electric heater for said thermo-dynamic device arranged operatively to be governed by said controlling means.

3. In an electric knife switch having a stationary contact terminal and a pivoted, swingable, blade device adapted at one extreme position thereof conductively to engage with said terminal, in combination ;-controlling means arranged by insulatedengagement with said device to swing the latter into engagement with said terminal contact and against the resistance of resilient means arranged to oppose such engagement; a detent normally positioned to prevent separation of said ,blade device from said terminal; at thermo-dynamic device operatively related to said detent when thermally energized to cause said separation, together with an electric heater for said thermo-dynamic device arranged operatively to be governed by said controlling means.

4. In a knife switch for electric circuits, including a stationary contact member and a swinging contact member adapted conductively to vengage therewith, in combination manually controllable means adapted to move said swinging member into circuit making engagement with said stationary member; detent means arranged normally operative to maintain such engagement; a thermo-dynamic device adapted, when thermally energized, to render said detent means inoperative; resilient mechanism arranged tending to separate said swinging member from said stationary member; an electric heater for said thermo-dynamic device; a normally open circuit in shunt to the switch governed load and containing said heater; and auxiliary switch means operably related to said manually controllable meansand arranged, upon designed movement of the latter, to close said thermo-dynamic device adapted, when thermally energized, to render said detent means inoperative; resilient mechanism arranged tending to separate said swinging member fromsaid stationary member; an electric heater for said thermodynamic device; and normally lnoperatlve circuit connections operably related to said manually control- 'lable'tmeans and adapted upon designed movement of the latter to energize said heater from the switch circuit.

6, jIn aknifeswitch for electric circuits including a stationary contact member and a co-operative swinging contact member, manual controlling means adapted to move said swinging member into engagement with said stationary member, thermostatically governed means adapted to maintain such en- *gagement, spring mechanism adapted to separate said swinging member from said stationary member, an electric heater for the thermostat, a normally open shunt circuit across the switch, and including said heater, and means, governed by a reversed movement of said manual controlling means, adapted to close said shunt circuit.

' 7. In a knife switch for electric'circuits including a stationary contact member anda co-operative swingmg contact'member, 1n

combination, manualv cdntrolling means to,

move the latter member into engagement with the former member, detent means adapted to retain such engagement, sprlng mechanism tending to separate said latter member from said former member, in thermostat ada ted, when energized, releasingly to move sai retaining means,'an electric heater for said thermostat, an electric circuit including said heater, and means, controlled by a reverse movement of said manual controlling .means from their switch closing position,

adapted operatively to relate said last mentioned circuit to the switch circuit, 7

8. In an 'automatically delayed-opening electric knife switch, in combination ;---a

a conductive blade structure pivoted for swinging'movement and arranged'normally to be automatically "locked in circuit-making position at one extreme of its travel, a controlling frame for said structure, also pivoted for swinging movement and arranged by insulated positive engagement with said structure tofmove the atter into its said circuit-making position, together with autof matic instrumentalities arranged o eratively on withdrawal of said frame 0111 said structure, to cause delayed circuit-breaking movement of said structure.

9. 1n a'knife switch for electric circuits, in combination; a stationar tively to engage with said clip; an auxillary, pivoted, and manually controllable frame, adapted by insulated engagement.

with said blade member, to move the latter:

' into circuit-making engagementwith said clip, a thermostaticall controlled detent arranged mormally to r tam said blade memher in said circuit-making engagement with said clip; auxiliary contacts positioned to a be connected electrically by said auxiliary frame when the latter-is) withdrawn from engagement withsaidmember; an electric ,rately pivoted actuatin 7 contact clip;

a pivoted blade member a apted conducheater for the thermostat; and a circuit, in shunt to the switch governed load, and including said heater and said auxiliary contacts in series therewith; together with spring mechanism adapted to se arate said blade member from. its associa ed contact clip, whereby, when said .heater is electrically energized by withdrawal of said frame from said member, the said mechanism is automatically rendered operative to open the switch after a predetermined time.

10. An electric knife switch structure including electrically energized means for the automatic control thereof and embodying in combination with a swinging conductive blade andstationary circuit terminals positioned to be contacted thereby in the circuitmaking position thereof; an auxiliary, separately pivoted, actuating frame for said blade a apted by positive and insulated engagement in one direction therewith to swing said blade into its circuit-making position; a resilient detent device positioned gieldingly to retain said frame and said lade in said circuit-making position ofthe latter; and auxiliary stationary circuit terminals operatively related to said means and positioned to be conductively connected by engagement of said frame therewith upon withdrawal of the latter from engagement with said bladeand whereby said means are operatively energized.

11. An electric knife switch structure including electrically ener 'zed means for the automatic control thereo and embodying in combination with a swinging conductive blade and stationary circuit terminals positioned to be contacted thereby in the circuit gieldingly to retain said frame and said lade insaid circuit-making position of the latter and auxiliary stationary circult terminals operatively related to said means and positioned to be conductively connected by enga ement of said frame therewith upon with rawal of the latter from engagement with said blade and whereby said means are operatively energized.

12. An electric knife switch structure including electrically energized means for the automatic control thereof and embodying in combination with a swinging conductive blade and stationary circuit terminals positioned to be contacted thereby in the circuitmaking position thereof; an auxiliary, separately pivoted actuating frame for said blade comprising two side bars having conductive extensions on one side of the pivot and adapted by positive and insulated engagement with said blade on the opposite side of said pivot and by means of an insulated handle secured to said frame, to swing said blade into its circuit-making position; a resilient detent device positioned yieldingly to retain said frame and said blade in said circuit-making position ofthe latter; and two auxiliary contact clips operatively related to said means and posi tioned each to be conductively engaged. by one of said bar extensions of said frame upon withdrawal of the latter from engage-.

with said blade and whereby said means are operatively energized.

Signed at Braintree, in the county of Norfolk and Commonwealth of Massachusetts, this 7th day of October, 1915.

MALCOLM H. BAKER.

Witnesses R. W. SMITH, SILvIo AMoRoso.

Images