US1907666A

US1907666A - Thermic switch

Info

Publication number: US1907666A
Application number: US384577A
Authority: US
Inventors: Estel C Raney
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-08-09
Filing date: 1929-08-09
Publication date: 1933-05-09
Anticipated expiration: 1950-05-09

Description

y 9, 3 E. c. RANEY 1,907,666

THERMIC SWITCH Filed Aug. 9. 1929 r1r: z 1 1 E 90 1'1 l 1 e1 6 -3 the body portion of the fixed contact. The that protrude from the ends of the V-shaped Patented May 9, '1933 UNITED STATES PATENT OFFICE ESTEL c. RANEY, OF COLUMBUS, OHIO .THERMIC SWITCH Application tiled August a, 1929. Serial No. 384,577.

The invention particularly provides a portion 9 is embedded in the end wall of thermic switch that may be formed of parts the part 2 of the head, .The' portion 9 has that may be made at a low cost of 'producatits end edges a plurality of serrations 1O lion and set for etlicient operation of the which securely lock the fixed contact in the switch at definite temperatures. insulating material of which the head is The invention may be contained in formed. The terminals 6 are formed narswitches that vary in their details and, to ilrower tha n the contacts .5. They protrude lustrate a practical application of the invenfrom the head whereby the terminals may tion, I have selected a switch containing the be inserted 1n the end of a plug for connect- 10 invention as an example of the various eming the switch to an external circuit. bodiments of my invention and shall de- The movable contact 15 of the switch is scribe it hereinafter. -The particular strucformed of a pair of plates 16 that are conturc selected, as an example, is shown in the nected together for pivotal movements one acctimpanyin c drawing. relative to the other. Preferably, the con- Fig. 1 illustrates a vertical section of the tiguous ends of the plates 16 are located switch. Fig. 2 is a view of a section taken in recesses of a part of a switch actuating on the plane of the line 2-2 indicated in member and springs 17 are connectedto ears Fig. 1.- Fig. 3 illustrates a vertical section 18 located at the outer corners of the plates of a part of the switch taken on a plane at 16. The springs 17 operate to produce a 5 right-angles to the plane of the section of thrust or pressure components-in the planes Fig. 1. Fig. 4 is a composite view ofparts of the plates 16 towards each other and latoi' the switch. indicating the assembly of eral components that tend to angularly move su ch parts. Fig. 5 is a perspective view of the plates 16 relative to each other. Co p a fixed contact of the SWltClL. Fig. 6 is a tacting pressure between theouter ends of view of a sectioutaken on the plane of the the plates 16 and the arcuate edges of the line 66 as indicated in Fig. 1. fixed contacts 5 is produced when the lateral The instrun'ient illustrated in the drawcomponents are in one direction and when ingis provided with a head of insulating the lateral components are in the opposite dimaterial that contains the switch, and a rection the plates 16 move from the fixed stem, that is connected to the head, which contacts 5. Preferably, the end edges of the contains the thermic material that operates plates 16 are curved and the ears 18 pmthe switch. Thejhead 1 is formed of two trude from the corners of the plates in the

parts

2 and 3 that may be interconnected by line ofthe .curvature of the end edges. The means of the threaded portions 4. The fixed length of the fixed contacts 5 are substancontacts 5 of the switch are provided with tially the same as the length of the curved the electric terminals 6 for connecting the edges 0t the plates 16 between the ears, fixed contacts with an external circuit. The whereby a compact arrangement of the parts fixed contacts 5 are provided with curved is provided for locating the switch within flange portions 7 that extend-substantially a cylindrical head which has a relatively at right-angles to the body portions 8 of the small diameter and yet provides a large confixed contacts. The flanged portions are. tact area between the contacts of-the switch. curved on a center. located substantially in The movable contact 15 isconnected to the .axis of the instrument. --T he edges of an actuating member'by means of a pair the flanged portions 7 form the contacting of sheet metal strips 20. The strips 20 have arcasof the switch. Each contact 5 is also portions bent to form V-shaped channel provided with a portion 9 that extends subportions 21 having a length substantially the stantially parallel to the direction in which same as the width of the body portions of the flange 7 extends, but in a direction oppothe plates 16. The ends of thechannel site to that in which the flange extends from portions 21 are provided with lugs 22 channels 21 and are bent so as to cover or enclose the corners of the inner ends of the plates 16 when they are inserted in the V-shaped channels. The strips 20 are so placed that the channel openings of the strips extend in opposite directions. They are secured in this position, when assembled, by means of a pair of

discs

25 and 26. Preferably, the strips 20 are provided with tongues 27 having a width narrower than the body portion of the strips 20 and the

discs

25 and 26 are provided with slots that fit the tongues 27 when they are placed side by side, so that when the

discs

25 and 26 are forced over the tongues 27, they will securely bind the strips 20 together.

The movable contact 15, together with its connecting member, is supported for movements relative-to a plate 30 that is secured in the head 1 between the

parts

2 and 3 of the head. The plate 30 -is die pressed to shape and there is formed in the plate 30 raised V-shaped portions 31. For purposes of securing the plate 30 in position, and insuring registration of the protruding portions 31 of the plate 30, -.rela- I tive to the fixed contacts, the part 20f the shell may be provided with a suitable recess 32 and the plate 30 may be provided with a tongue 33 that, substantially fits the recess 32. The plate 30 is also provided with a slot 34 "that-is located between, and extends parallel to, the ridges 31. The slot 34' has a size substantially the same as that of the cross section of the strips 20, when they are placed back to back, to permit free movements of the strips 20 through the slot 34 of the plate 30.

The plate 30 is located in a plane substantially parallel to the plane of the contact edges of the fixed contacts 5. This locates the plane of the tops of the ridges parallel to the plane of the contacts and preferably the parts are so formed that these planes are in close proximity to each other and the ridges are placed close to the axisof theinstrument or about midway between the axis of the instrument and the fixed contacts.. The tops of the ridges 31 are therefore located intermediate the points of connection of the ends of the springs with the plates 16 and the inner ends of the plates and comparatively close to the axis of the instrument. In the operations of the movable contact 15, by the springs 17, the protruding ridges 31 of the plate 30 coact to produce a wide opening of the contacts andan early closingof the contacts in thef movement of the actuating member that operates the switch through the connecting member formed by the strips 20. When the inner ends of the plates pass through the plane of the fixed contacts, the outer endsof the plates will be moved away from the fixed contacts and so as to strike the ridges 31 of the plate 30. The points of connection of the ends ofthe springs 17 being located on the outside of the ridges, the springs tend to draw the outer ends of the plates towards each other as the plates pivot on the tops of the ridges 31 In the reverse movement of the actuating member, the plates will tilt on the ridges 31, moving the'outer ends of the plates 16 towards the contact edges of the fixed contacts by a relatively short movement of the connecting strips 20, and until the inner ends of the plates 16 pass through and contraction of atherniic element, the

expansion movements operating on the movable contact member to break the circuit through the contacts and a compression spring operating on the movable contact, as

the element contracts, to complete the circuit through the contacts. A thimble 40,

. formed of insulating material, is located in an opening formed in the end'wall of the part. 3 of the shell, 1 and' is reciprocally movable therein. A cup 41is located in the thimble 40. The cup 41 has a flange 42 that rides on the edge of the thimble 40. The flange is skirted to provide a recess for receiving the end ofac'onvolutc spiral spring 43 located between the flange 42 and the plate 30. The plate 30 has a centrally raised portion to form a seat'44 for the larger end of the convolute spring 43. The convolute spring enables relatively free -moveinerit of the turns of the spring and causes the return movements of'ends of the plates 16.

The bottom of the cup 41 is located in spaced relation to the bottom of the thimble 40-and a-compression spring 45 is located within the cup 41 and intermediate the disc 25 and the bottom of the cup. The lower ends of the strips 20 extend through a slot formed in the bottom of the cup and the disc 26 is located beneath the bottom of the cup 41 and is movable between the limits provided by the bottom of the cup 41 and the bottom of the thimble 40. When, therefore, the thimble 40 is moved by the expansion of the thermic element, it compresses the spring 45 against the vertieal component induced at the inner ends of the plates -.16 by the tension of the springs 17. The

spring 45 is compressed until the disc 26 engages the bottom of the thimble 40. Continued upward movement of the thimble 40 moves the strips 20 and the inner ends of the contact plates 16 until the lateral com ponent induced by the spring 17 is' less than the pressure produced by the spring, 45. At this point the lateralcomponent, however, is sufficiently great for a good contact pressure between the contacts of the switch. The lateral component at the outer ends of the contact plates 16, which is the pressure applied at the ends of the movable contact against the fixed contact, is greater than the lateral component at the inner ends .of the plates by reason of the relative location of the connecting points of the springs 17. When this contact pressure diminishes to a certain point, which, however, is still sufliciently great to maintain a good contact pressure, the spring 45 will cause the inner ends of the plates to snap through the plane of the contact edges of the contacts 5 and the lateral components of the spring 17 will be reversed which will operate to raise the disc from the bottom of the thimble 40 and to separate the contacts as the central portions of the plates strike the ridges 31 of the plate 30. When the thermic element contracts, the thimble 40 is moved downwardly by the spring 43 and the inner ends of the plates 16 will immediately move downwardly by reason of the interengagement of the disc 26 on the bottom of the cup 41. The contact plates tilt on the ridges 31 and quickly raise the outer ends of the plates above the plane of the tops of the ridges 31 and reverse the lateral components produced by the springs 17, to cause a. quick connection by a very short reverse movement of the inner ends of the plates 16.

The spring 43 operates to maintain the thimble 40 in contact with a sheet metal bellows 50 located in a metal sleeve 51 that protrudes from the end wall of the part 3 of the shell 1. The sleeve 51 is provided with outwardly turned ears 52 which anchor the sleeve 51 in the insulating material of the shell 1. The thimble 40 is located in one end of the sleeve 51 and is moved therein by the expansion bellows 50 or the spring 43 when the bellows contracts. Preferably, the thimble 40 is provided with a recess 54 for receiving the tip 53 of the expansion bellows which operates to maintain the upper end of the bellows in axial alignment in the instrument.

The lower end of the bellows 50 is connected to a shell 55. The interior of the bellows 50 communicates with the interior of the shell 55 and the two are filled with a suitable thermic material that has, preferably, a large coefficient of expansion.

Fluids, such as water or mixtures of liqu ds,

or plastics, that melt or solidify at substantially definite temperatures, may be used.

Preferably materials, or mixtures of,materials, are used that at definite temperature points have increasing coefiicients of expansion. The points at which their physical condition changes may be varied by forming mixtures of definite proportions of the materials, in the manner well known in the art. In the particular form of construction shown in the drawing, the bellows 50 and the shell 55 are filled With a mixture of water and alcohol in a desired proportion. The water and alcohol mixture is particularly advantageous by reason of the fact that it affords a reliable and definiteexpansion point at which the movable contact may be operated and thus insures certainty of operation at the same point in the succeeding operations of the refrigerating apparatus controlled by the switch. In the operation of refrigerating apparatus, the water will freeze and portions of the frozen ice will subsequently melt to cause corresponding changes in movement ofthe movable contact by the movement of the bellows containing the mixture, which will produce a reliable operation of the switch when a definite portion of the Water has changed physically. Consequently, the switch will, in its repeated operation, always operate at the same thermic or temperature point. The bellows 50, being located within the sleeve 51, it is, by reason of the air space between the bellows and the sleeve, shielded to a certain extent from the transmission of heat therefrom, while the shell 55 is in a more d rect heat conductive relation, with reference to exterior bodies and, consequent- 1y, heat is more readily transmitted to and from the shell 55 than to and from the bellows. The shell 55 is not only connected to the bellows 50, but is also. connected to the end of the sleeve 51. Preferably, the ends of the sleeve 51 and the shell 55 are threaded to enable adjustment of the bellows with reference to the movable contact in order to bring about operation of the switch at the desired times. Thus the material within the bellows and the shell may be, if de-v sired, raised or lowered to the desired temperature at which the switch is to be opened and, upon insertion of the bellows within the sleeve 51, the shell may be threaded into the sleeve 51 until the switch is tripped open, whereupon the shell and the sleeve may be secured in this adjusted relation by either soldering or reaming, or any other suitable interlocking means. In the form shown. the shell is provided w th a channel 56 and the end of the sleeve 51 is spun or forced into the channel 56 so as to seal and interlock the sleeve 51 to the end of the shell 55 in this adjusted relation.

The thermic material is introduced into the bellows and the shell 55 through the con- -tracted end 57 that is closed by means of the plug 58. Solder 59 may be placed on the end of the shell so as to cover and seal the end of the shell.

The end 57 of the shell 55 is tapered so as to form between the plug 58 and the surfaces of the tapered end, a space for the thermic material that conforms to a cylindrical punch having a central openmg and a sharp knife edge. The part that conforms to the knife edge is located intermediate the flaring inner surface of the tapered wall of the end 57 and the surface of the plug 58 which protrudes well into the interior of the shell. The 'thermic material that thus surrounds the plug, and located within the tapered wall, is surrounded by and contains within itself a relatively large amount of metal which has high heat conductivity and, since the material between these highly conductive parts is thinned down to a sharp edge or line, the temperature of the thermic material at this point will be substantially the same as that of the outside atmosphere contiguous to the tip of the shell and, by reason of the tapered walls or flaring surfaces that extend from a line on the said surfaces, crystallization or solidification will leadily set up in such a chamber or space and thus bring about prompt solidification or crystallization in the body of the shell.

The shell 55 is also provided with a heat distributor for conducting and transmitting the heat from the wall of the shell throughout the material located in the central portion of the shell. A sheet metal corrugated member 60, having a length substantiall the same as the shell, is located therein. t has portions in contact with the surface of the wall of the shell and portions located in proximity to the axis of the shell whereby heat will be readily transmitted through the member to and from the wall of the shell into that portion of the material located well within the shell and more or less remote from the wall' of the shell. Preferably, the heat conductor 60 is provided with a plurality of tapered tongues 61 that extend towards the bellows 50 which reduces the conductivity of the member at the end of the shell that is connected to the bellows. This rovides a means that insures the solidification of the thermic material within the shell 55 in advance of solidification of the material within the bellows 50. The bellows is also shielded by the sleeve 51, while the shell 55 is rovided with heat conductive walls and t e interior member 56 aids in the ready absorption or transmission of heat from the thermic material in the shell and the early crystallization and solidification of the thermic material therein. The expansion occurring thereby is transmitted to the non-solidified material in the shell and bellows which causes the bellows to expand and eventually operate the switch.

I claim:

1. In a switch, a pair of fixed contacts, a. pair of movable plates adapted to make contact with the fixed contacts at their ends, a pair of sheet metal members having V- shaped channel parts for receiving the ends of the plates for maintaining the ends of the lates in position, a pair of springs for pro ucing an end thrust of the plates against the bottoms of the channels of the a pair of sheet metal members havlng-V- shaped channels at its end for receiving ends of the plates for moving the said ends of the plates through the plane of the contacting surfaces of the said fixed contacts and to force the said sheet, metal members against each other.

3. In a switch, a pair of fixed contacts, a movable contact formed of a pair of plates, a pair of springs connected to end portions of the plates for producing an endwise thrust in the plates towards each other and lateral components towards and away from the fixed contacts. a third plate formed of sheet metal, the said third plate having ridges struck up therefrom, a channel member for receiving the inner ends of the first named plates and movable through the said third plate for moving the inner ends of the first named plates across the plane of the contacting surfaces of the said fixed contacts and the plane of the tops of the said ridges.

4. In a switch, a pair of fixed contacts, a movable contact formed of a pair of plates, a pair of springs connected to end portions of the plates for producing an endwise thrust in the plates towards each other and lateral components towards and away from the fixed contacts, a. third plate formed of sheet metal, the said third plate having ridges struck up therefrom, the said last named plate having a recessed portion, a

movable member having a skirt portion and.

a convolute spring located intermediate the skirt portion and the recessed portion of the second named plate, a channel member operatively connected to the movable member and to the inner ends of the first named plates for moving the said plates through the plane of the contacts and the plane of the ridges.

5. In a switch, a pair of fixed contacts, a movable contact comprising a pair of plates adapted to electrically connect the fixed contacts, a pair of springs connected to end portions of the plates for producing an end thrust in the plates towards each other and lateral pressure components towards and away from the contacts, a movable member for actuating the inner ends of the plates and comprising a cup, a channeled member for receiving the inner ends of the plates and extending through the bottom of the cup, 2. spring located intermediate the bottom of the cup, and connected to the channel member for moving the inner ends of the plates through the plane of the fixed contacts.

6. In a switch, a pair of fixed contacts, a movable contact comprising a pair of lates adapted to electrically connect the fixe contacts, a pair of springs connected to end portions of the plates for reducing an end thrust in the plates towar s each other and lateral pressure components towards and away from the contacts, a movable member for actuating the inner ends of the plates and comprising a cup, a channeled member for receiving the inner ends of the plates and extending through the bottom of the cup, a spring located intermediate the bottom of the cup and connected to the channel member for moving the inner ends of the plates through the plane of the fixed contacts, a third late formed of sheet metal and having ri ges struck up therefrom, the ridges located intermediate the line of movement of the inner ends of the plates and the ends of the plates, the last named plates having a recess for yieldingly resisting the movement of the cup, and a convolute spring having an end portion for fitting the said recess, the said clup having a skirt portion for receiving the other end of the convolute spring.

7. In a switch, a pair of fixed contacts, a movable contact comprising a pair of members adapted to electrically connect the fixed contacts, a pair of sprin s connected to the end portions of the mem ers for producing an end thrust in the members towards each other and lateral pressure components towards or away from the contacts, a plate having a pair of ridges, the plane of the ridges being located parallel to and in close proximity to the plane of the said fixed con tacts, the ridgesbeing located opposite the points between the contacts and in close proximity to the line of movement of the inner ends of the members, a movable thermic element responsive in its movements to changes of temperature, means for interconnecting the thermic element with the inner ends of the said members and comprising a pair of channeled strips for receiving the inner ends of the members, and a cup connected to the strips, the cup and strips having means for producing limited free movements of the strips relative to the cup, a compression spring connected to the strips and to the'cup for yieldingly resisting the movement of the strips relative to the cup, a compression spring located intermediate the cup and the plate for causing return movements of the inner ends of the members upon return movement of the thermic element.

In witness whereof I have hereunto signed my name to this specification.

- ESTEL C. RANEY.