US3182155A - Hermetic thermostat - Google Patents

Description

y 1 c. A. ELLIS 3,182,155

HERMETIC THERMOSTAT Filed Oct. 25. 1961 =1 2; CHARLES .A. ELLIS INVENTOR United States Patent 3,182,155 HERMETIC THERMOSTAT Charles A. Ellis, Point Road, Box 145, Marion, Mass. Filed Oct. 25, 1961, Ser. No. 147,612 4 Claims. (Cl. 200-137) This invention relates to improvements in thermostatic control devices and has particular reference to novel means and method of adjustment of the operating point of an hermetically sealed thermostat without disturbing or changing its sealed condition.

.One of the principal objects of this invention is to provide an improved hermetically sealed thermostatic device which is simple in construction, eflicient in operation and adapted to volume production.

Another object is to provide .a novel enclosure for an hermetically sealed device wherein adjustment of the internal mechanism may be made externally of the device while preserving the sealed condition of the enclosure.

Another object is to provide adjusting means for an hermetically sealed device embodying equipment so constructed as to permit a controlled adjustment of the mechanism within predetermined limits.

Another object is to provide adjusting means for an hermetically sealed device that is hand operated and easily portable so that adjustment of devices may be conveniently made at the point of use of such devices.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view in partial section of a thermostatic device embodying the invention.

FIG. 2 is a plan view of a portion of the adjusting mechanism showing one jaw of the holding device open and with the hermetic device secured in position as for adjustment in the closed second jaw.

FIG. 3 is a side elevation of the adjusting device of FIG. 2 seen in the direction 33 showing a device in position and the adjusting screw and index.

Referring more particularly to the drawings wherein like characters of reference designate like parts throughout the several views, numeral 2!? refers generally to the hermetically sealed device of this invention. The hermetic enclosure is comprised of a tubular body member 21 and two end caps or headers generally designated by the numerals 22 and 23. The header 22 consists of a flanged metallic cup 25 containing a glass insulating body 26 in which two pins 27 and 28 are supported. The metal of the cup and pins is chosen so as to be compatible with the glass and all are assembled by well known processes to accomplish hermetically tight junctions between the metal surfaces and the adjacent glass. The header 23 consists of a flanged metallic cup 24 containing a glass insulating body 29 in which two pins 39 and 31 are supported, the glass being fused to the metal to form hermetically tight seals therewith. Pins 27 and 28 extend a short distance downwardly beyond the glass surface on the flanged end of header 22 to serve as terminal connections to the internal mechanism of the thermostatic device. At the upstanding end of pins 2'7 and 28 a cross member 32 is positioned upon one side of each pin and parallel with the cup flange and this cross member is fastened to the pins preferably by resistance welding. A contact arm 33 is located upon and at a right angle with the cross member centrally between the pins and it is fastened to the cross member also by resistance welding. The contact arm is bent substantially at right angles forming a short and a long arm with the center of the short arm being welded to the cross member 32. When properly located upon the cross member, the short arm lies parallel with the header flange and the long arm extends away from the header. At the open end of the short arm is located a flattened and enlarged portion 34 containing a socket depression 35. A contact 36 consisting of a short length of a contact making material such as silver is welded at the extremity of the long arm. The header 22, carrying the mounted contact arm 33, is placed within one end of the body member 21, and is hermetically sealed thereto by any satisfactory means such as solder. The flange on the header cup serves to definitely locate the header axially relative to the body. Returning to the second header 23, the pins 30 and 31 extend above the flanged surface to serve also as terminal connectors. A fixed contact 37 is welded to the opposite downwardly projecting end of pin 31 with the wire extending beyond the end of the pin and at right angles thereto and generally parallel with the adjacent edge of the header. Pin 30 has a long strut 38 butt welded to it on the side opposite the terminal extension. Portion 38 is preferably of a material having a very low coefficient of expansion such as a 36% nickel-iron and its outer end 39 is formed to a conical tip with slightly rounded end. When header 23 is properly positioned in the end of body tube 21 the conical tip 39 of strut 38 is located in the depression 35 on contact arm 33. Fixed contact 37 is located at right angles with contact 36 and in the path of 36 as it is caused to rotate about cross member 32 as a center. A final hermetic seal between header 23 and the body tube 21 completes the assembly.

Body member 21, in addition to being generally tubular in form, is preferably of a material of high coefficient of expansion and has a series of embossed rings 46 extending outwardly from its outer surface. These rings have a wall thickness substantially equal to the wall of the tubular portions and in longitudinal section they are generally semi-circular as illustrated. The essence of this invention lies in these ring sections since they are the key to the adjustment of the sealed device as will be described in greater detail.

This thermostat operates on the well known principle of differential expansion of metals. The strut 38 of Invar or other suitably low expansion material is the reference element. The sensitive element is the high coeficient material of the tubular case element 21. Properly assembled and adjusted the contacts 36 and 37 are slightly separated from each other by pressure from strut member 38 acting against the short arm of contact arm 33. The pressure of the strut actually introduces a torsional restoring force into the cross member 32. If exposed to an increased temperature the body 21 will expand faster than the strut with a net effect of reducing the pressure and allowing the contacts to approach one another. At some point actual contact will be made which can then be used for indication or control purposes. If the unit is then cooled the contact will reopen and provide a reverse signal. It will be noted that with member 32 as the center of rotation a mechanical advantage is introduced for opening the contacts proportional to their distance from 32 divided by the distance of the depression 35 from 32.

In the design of this device the header flanges provide assembly reference points for control of dimension of the header sub-assemblies and the over all length of the tube is easily controlled. In spite of these aids the sensitive nature of a device of this kind results in units having slightly different operating points. A controlled ad- 3 justment of the overall length of the device will be seen to have the same effect as a change in temperature. It is for the purpose of affecting such an adjustment that the rings 4i? have been introduced. Two separate functions are accomplished by these rings. They provide an added degree of elasticity to the tubular member lengthwise so that if the ends are firmly grasped the tube may be stretched or compressed slightly in length. However, such a handling of the tube ends over the seals might easily damage the seal. By using the two end rings as the area of application of longitudinal force the end seals are preserved intact during the adjustment operation. It

is also to be noted that such adjustments may be considered as permanent in nature since they are brought about by stressing the tubular section beyond its elastic limit. This is in contrast to flexible bellows type devices wherein a bellows may be used to preserve a seal but must be supported in the selected positions by other structural members. a

FIG. 2 shows a portion of a tool for use in adjusting the operating point of the hermetically sealed device 20. In this case the tool is in the form of parallel-jaw plier of which only the jaws, generally indicated by the numerals 41 and 42, are shown. Each jaw is made of two major parts; a base section 43 or 43 and a top section 44 or 44 hinged at one end on pivot pins 45 carried in the base sections. Both top and bottom jaw sections have aligned cut-out sections having one portion 46 of a diameter equal to the outer diameter of the cylindrical portion 21 of enclosure 20, and a second portion 47 of larger diameter for receiving the rings 40 of the enclosure walls. An upstanding pin 4% is located in each lower jaw which cooperates with a slot 49 at the end of each upper jaw to prevent relative sidewise motion of the upper and lower jaw parts in use. When an enclosure is placed in the lower jaw cutouts and the upper jaw folded over above it, the article is securely held for the application of the longitudinal adjusting force. In order to simplify the adjustment of the operating point, a calibrated screw mechanism is incorporated in the lower jaw members. This consists of a body screw 50 passing through a tapped hole 51 in jaw 4-2, and having a reduced cylindrical section 52, somewhat longer than the jaw width passing through a clearance hole 53 in the second lower jaw 43'. The head of the screw 54is enlarged and carries a series of index numerals. Also fixed in the jaw adjacent this head is a post 55 extending parallel to the body of screw Si) and serving as a position reference point in reading the index numerals. At the other end of the screw at the extremity of the reduced section is a fixed stop button 56, larger in diameter than clearance hole 53. The numerals on the screw head aid in making a direct adjustment of the hermetic device. For example; assume that a device has been testedand its operating point found to be three degrees high in temperature. This indicates that the body portion 21 was slow in action or short in length. The device is placed in the adjusting tool with the top jaws closed over it. The screw mechanism is then moved by adjustment of its head. 54 until the inside of button 56 is in contact with the outer surface of the adjacent jaw.

This establishes the reference length of the body. The

' 'beprovided to stretch the ring section to the elastic limit of the case material and'this will bea constant amount 1 for a stretching operation: an added amount for length correction makes up the total setting. Again it has been 6.. found that slightly different values for initial elastic stretching have to be used than are found when shortening is the objective. This difference can be minimized by increasing the number of intermediate rings between the two end ones used for application of force.

The side elevation of the jaws shown in FIG. 3 further illustrates the relative positions of the jaws in open and closed condition and the location of the device 20, as it is held for adjustment. It will be understood that the jaws 41 and 4-2 may also be constructed as .a portion of any other parallel motion device such as a screw vise or power driven clamp without departing from the spirit of the invention. Slots 57 and 5'7 and holes 53 and 58 have not been previously mentioned since their function is limited to the attachment to the plier handles for providing parallel motion in manner that is well known.

It is apparent that all of the objects and advantages of the invention have been accomplished.

details of construction and arrangement of parts shown and described without departing from the spirit of the invention as expressed in the accompanying claims. Therefore, it is to be understood that all matter set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. An hermetically sealed electric switching device comprising in combination an electric switch together with an hermetic enclosure having an outer cylindrical wall of metallic material having a plurality of integral embossed circumferential bands of metal in which the majority of the band section lies outside of a surface the plane of the cylindrical wall, at least one of said bands serving as the point of application of force longitudinal of the enclosure body and adapted to being stretched or compressed beyond the elastic strength of the material under such force, whereby the length and hence the operating point of the device may be permanently adjusted without disturbance of the hermetic sealed condition of the enclosure.

2. In a thermostatic switch the combination of a thermostatic switch element together with an hermetic casing having a plurality of integral embossed circumferential bands, said casing being formed of metal of high thermal coefficient and serving as one element of the thermostatic structure, the circumferential bands characterized by being soformed as to place the major portion of their section away from a surface the plane of the cylindrical wall, two of said bands adapted to the application of tensile or compressive force longitudinal of said device and further adapted to orderly deformation when loaded beyond the elastic limit whereby the length of the device and its operating point may be permanently adjusted by the application of such'longitudinal forces without harm to the sealed hermetic condition of the device.

3. in a thermostatic switch the combination of a sealed thermostatic switch operating element together with a generally cylindrical. outer'casing acting. as one element of the thermostatic system and including a plurality of integralcircumferential bands so'formed as to place the major portion of their section away from'a surface the. plane of the cylindrical wall, at least two of said bands a fixed change of length of the device whereby its operating point is likewise changed, the lengthchang'e'being brought about without effecting the sealed hermetic condition of the device.

4'. The combination of a switch element together with an hermetically sealed casing for a thermostatic device having a generally cylindrical \vall'including a number i of integral circumferential bands so formed as to place It will also be apparent, however, that changes may be made in the References Cited by the Examiner UNITED STATES PATENTS 364,417 6/87 Jaeger 22072 2,660,646 11/53 Fritzinger 200-137 2,664,483 12/53 Broekhuysen 200137 LOUIS R. PRINCE, Primary Examiner.

ISAAC LISANN, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,182,155

Charles A. Ellis Column 4, lines 32 and 33,

48 and 62 and 63, line 2, strike out the plane",

each occurrence.

Signed and sealed this 19th day of October 1965.

and column 5,

SEAL) test:

[NEST W. SWIDER EDWARD J. BRENNER Tasting Officer Commissioner of Patents May 4, 1965

Claims (1)

1. AN HERMETICALLY SEALED ELECTRIC SWITCHING DEVICE COMPRISING IN COMBINATION AN ELECTRIC SWITCH TOGETHER WITH AN HERMETIC ENCLOSURE HAVING AN OUTER CYLINDRICAL WALL OF METALLIC MATERIAL HAVING A PLURALITY OF INTEGRAL EMBOSSED CIRCUMFERENTIAL BANDS OF METAL IN WHICH THE MAJORITY OF THE BAND SECTION LIES OUTSIDE OF A SURFACE THE PLANE OF THE CYLINDRICAL WALL, AT LEAST ONE OF SAID BANDS SERVING AS THE POINT OF APPLICATION OF FORCE LONGITUDINAL OF THE ENCLOSURE BODY AND ADAPTED TO BEING STRETCHED OR COMPRESSED BEYOND THE ELASTIC STRENGTH OF THE MATERIAL UNDER SUCH FORCE, WHEREBY THE LENGTH AND HENCE THE OPERATING POINT OF THE DEVICE MAY BE PERMANENTLY ADJUSTED WITHOUT DISTURBANCE OF THE HERMETIC SEALED CONDITION OF THE ENCLOSURE.

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