Mounting installation for temperature sensing switch
United States Patent 3883717
The temperature of water within the tubular reservoir of a baseboard heater or the like is sensed through its end cap. The cap has an outstanding annular flange, and on its end has a planar indentation to seat the temperature-sensing face of a thermoswitch. A spring clip with outstanding spring-like leg portions, slotted to fit onto the cap flange, presses the temperature-sensing face of the thermoswitch into close contact with the surface of the planar indentation. In addition to low cost fabrication and ease of installing and changing, there is an improved response of the thermoswitch to the temperature of the liquid.
US Patent References:
Metering rod biasing support
Krein - May 1960 - 2936789
Liquid circulation type electric baseboard space heater
Uhlig - April 1965 - 3179788
Thermostatic control for hot water tanks and the like
Hatch - December 1967 - 3357421
Electric hot water unit heater utilizing replaceable cartridge
Barbier - December 1968 - 3418451
FURNITURE TRAY
Steanson, Jr. - April 1974 - 3807319
Metering rod biasing support
Krein - May 1960 - 2936789
Liquid circulation type electric baseboard space heater
Uhlig - April 1965 - 3179788
Thermostatic control for hot water tanks and the like
Hatch - December 1967 - 3357421
Electric hot water unit heater utilizing replaceable cartridge
Barbier - December 1968 - 3418451
FURNITURE TRAY
Steanson, Jr. - April 1974 - 3807319
Application Number:
05/456986
Publication Date:
05/13/1975
Filing Date:
04/01/1974
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
392/501, 236/96, 392/357, 211/26, 337/380, 219/516, 392/377, 248/229.160
International Classes:
F24D13/04; F24H9/20; H01H37/54; F24D13/00; H01H37/00; H01H37/04; H05B1/02
Field of Search:
219/328,341,365,364,516 248/226E,229 24/73B,81FC 237/16-18 236/95,96 337/380,327 211/26
Primary Examiner:
Bartis A.
Claims:
I claim
1. For sensing the temperature of a fluid within and adjacent to an end of a cylindrical member,
2. A thermoswitch installation as defined in claim 1, wherein
3. A thermoswitch installation as defined in claim 1, wherein
4. For mounting a thermoswitch of the type having a temperature-sensing face in contact with the flanged end cap of a fluid containing member,
1. For sensing the temperature of a fluid within and adjacent to an end of a cylindrical member,
2. A thermoswitch installation as defined in claim 1, wherein
3. A thermoswitch installation as defined in claim 1, wherein
4. For mounting a thermoswitch of the type having a temperature-sensing face in contact with the flanged end cap of a fluid containing member,
Description:
BACKGROUND OF THE INVENTION
Temperature-responsive electrical switches are conventionally used as limit switches to control heating of fluids as in circulation hot water systems. Where the liquid is contained in a pipe or other cylindrical member, the conventional manner of installing such thermoswitch is by clamping it to the outer cylindrical surface. Since such cylindrical members may be of varying diameter, close contact with a standard thermoswitch is possible over only a small area; and thermoswitches so installed do not respond to changes in temperature of the enclosed liquid with precision and exactness. For example, in a water-filled baseboard heater to limit the temperature which may be developed to say 300° F., it may be necessary to set the limit switch at 290° or less, to be sure the desired 300° limit is not from time to time exceeded.
In baseboard heaters of the type shown in U.S. Pat. No. 3,281,574, a sealed-off well for a thermoswitch has been provided within the reservoir, so that the entire well surface will be subjected to the heat of the liquid. The construction of such wells adds excessively to the construction cost, especially since conventional thermoswitches do not sense temperature over an outer cylindrical face which might be fitted in such a wall.
SUMMARY OF THE INVENTION
The present invention, applied at the end of a preferably cylindrical tubular member containing a fluid whose temperature is to be sensed, is a thermoswitch installation characterized by exceptional response characteristics. An end cap, preferably formed of ductile metal such as copper, is sealed onto such cylindrical member, as by brazing. Closely adjacent to its end surface, the cap has an outstanding flange. Formed in the end surface is a planar, indented temperature-sensing face, which may be circular assuming the thermoswitch to be accommodated therein has a corresponding circular temperature-sensing face.
A clip formed of springy metal includes a base portion and a thermoswitch-holding portion extending at an angle thereto, and preferably substantially parallel to the planar indentation. At the other end of the base portion, leg members extend outward and are thence bent angularly to be substantially opposed to each other and reaching to a spacing less than the diameter of the cap. The legs have slots lying in a common plane; preferably the base portion also has a slot in this plane; the slots being wider than the thickness of cap flange.
On mounting the thermoswitch to the clip, the slotted leg members are engaged over opposed portions of the cap flange, on which the slot in the base portion is also fitted; and the flange portions projecting therethrough may be staked back. The thermoswitch temperature-sensing face will thus be spring-urged to make and maintain intimate contact with the planar surface indentation of the end cap.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the present installation in place on a water-filled baseboard heater tubing assembly, shown fragmentarily and partly schematically.
FIG. 2 is an enlarged, somewhat fragmentary view of the left end portion of FIG. 1.
FIG. 3 is an end view as seen from the left of FIG. 2.
FIG. 4 is an auxiliary view of the spring clip as seen along line 4--4 of FIG. 3, prior to installation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the embodiment illustrated the invention is used as a limit switch installation in a baseboard heater tubing assembly generally designated a. Such assembly includes a horizontal cylindrical reservoir tube b leading to a reducer section c to which a lower horizontal tube d is brazed. The tube d leads into an upward-extending tube e which at midheight has a T-connection to an upper horizontal tube f, but projects thereabove curvingly to provide a closed-end expansion tube portion g. The upper horizontal tube f, equipped with closely spaced fins h, extends above and parallel to the lower members b, c, d, to join a riser tube j which is brazedly connected into the upper surface of the reservoir tube b near its end opposite the reducer section c.
Onto the outstanding end of the reservoir tube b shown enlarged in FIG. 2, I sealedly attach, as by brazing, an end cap generally designated 10. The cap 10 is formed of a brazable copper, characterized by ductility. It includes an end surface 11 having a cylindrical drawn margin 12, which terminates in an outstanding flange portion 13. The cap margin 12 is sealedly brazed to the reservoir tube b.
The end surface 11 of the cap 10, as seen in FIGS. 2 and 3, has two outward drawn tubular nipples 14, one of them being somewhat below its midheight. In them are sealedly mounted the outstanding electrical terminal ends k of a conventional hair pin shaped electrical resistance heater m, which extends therefrom inward into the reservoir tube b, in a canted plane. The terminal ends k are to be connected to a power source, not shown, controlled by the thermoswitch hereafter referred to.
A thermoswitch generally designated n, of a conventional type is shown installed somewhat above the canted resistance heater m. The thermoswitch n is a type adapted, through conventional circuitry not shown, to break the electrical circuit to the resistance heater m when water in the reservoir tube b reaches a predetermined limit temperature. It has a generally cylindrical body o and a planar circular temperature-sensing end face p, whose diameter is slightly larger than that of the switch body to provide a mounting shoulder q.
A precisely planar surface indentation 17, of such size to closely accommodate the thermoswitch surface p, is stamped or drawn in the cap end surface 11. The indentation 17 is bounded by a shallow sloping wall 18 which aids in locating the face p of the thermoswitch n in precise position.
To mount the thermoswitch n, a spring metal clip generally designated 20 is provided. It includes a flat base portion 21, best seen in FIG. 3 with a pair of spring-like leg members 22 extending laterally outward therefrom and bent at a spacing corresponding somewhat to the diameter of the end cap 10 to provide opposed leg portions 23. In unstressed condition prior to installation they are somewhat inclined toward each other, as seen in FIG. 4. When installed as shown in FIG. 3 they are spread from such normal position to grasp the end cap 10 by its flange portion 13. To provide such grasp, aligned slots 24 are provided in the clip opposed leg portions 23, and a base slot 25, aligned therewith, is also provided. The slots 24, 25 are slightly greater in width than thickness of the cap flange 13 so that, as seen in FIGS. 2 and 3, parts of the flange portion 13 will project therethrough. The clip 20 may be staked in place by bending back projecting parts of the flange portion 13, as the bent back flange part 26 of FIG. 2.
From the clip base portion 21 there extends at a fixed spacing from the slots 24, 25 a thermoswitch holding portion 27, which may be tab shaped as shown in FIG. 3 and rounded inwardly as seen in FIG. 4. It is bent to an angle nearly 90° and which, on installation will be substantially parallel to the end cap planar surface 17. It includes a circular cutout 28 through which the cylindrical body of the thermoswitch n is fitted. The portion 27 presses against the shoulder q of the thermoswitch, retaining it securely as shown in FIG. 2.
Inasmuch as the clip 20 is formed of springy metal, the temperature-sensing face p will be continuingly urged by it into close contact with the planar surface indentation 17 of the end cap 10. Retention is assured by staking back the parts of the cap flange portion 13 which project through the clip slots 24, 25, as the part 26 seen in FIG. 1.
Installations made according to the present invention have shown excellent and reliable response to changes in temperature of water within the reservoir tube b. Where, for purpose of safety, the tubing assembly a is to be limited to a pressure which corresponds to a temperature of 300° F., a thermoswitch n may be selected to break the circuit at almost precisely this temperature, and it will function reliably regardless of such known variables as changes in ambient temperature. In contrast, installations made as taught by the prior art are so affected by such variables as to cut off the heating current over an undesirable wide range of temperatures; to provide for such range it was necessary to select a thermoswitch setting at least 10° lower than the desired 300° F. limit. This reduced the maximum utilizable heating capacity of the heater, a disadvantage which the present invention has overcome.
From the present specification, modifications in detail will be apparent to those skilled in the art.
Temperature-responsive electrical switches are conventionally used as limit switches to control heating of fluids as in circulation hot water systems. Where the liquid is contained in a pipe or other cylindrical member, the conventional manner of installing such thermoswitch is by clamping it to the outer cylindrical surface. Since such cylindrical members may be of varying diameter, close contact with a standard thermoswitch is possible over only a small area; and thermoswitches so installed do not respond to changes in temperature of the enclosed liquid with precision and exactness. For example, in a water-filled baseboard heater to limit the temperature which may be developed to say 300° F., it may be necessary to set the limit switch at 290° or less, to be sure the desired 300° limit is not from time to time exceeded.
In baseboard heaters of the type shown in U.S. Pat. No. 3,281,574, a sealed-off well for a thermoswitch has been provided within the reservoir, so that the entire well surface will be subjected to the heat of the liquid. The construction of such wells adds excessively to the construction cost, especially since conventional thermoswitches do not sense temperature over an outer cylindrical face which might be fitted in such a wall.
SUMMARY OF THE INVENTION
The present invention, applied at the end of a preferably cylindrical tubular member containing a fluid whose temperature is to be sensed, is a thermoswitch installation characterized by exceptional response characteristics. An end cap, preferably formed of ductile metal such as copper, is sealed onto such cylindrical member, as by brazing. Closely adjacent to its end surface, the cap has an outstanding flange. Formed in the end surface is a planar, indented temperature-sensing face, which may be circular assuming the thermoswitch to be accommodated therein has a corresponding circular temperature-sensing face.
A clip formed of springy metal includes a base portion and a thermoswitch-holding portion extending at an angle thereto, and preferably substantially parallel to the planar indentation. At the other end of the base portion, leg members extend outward and are thence bent angularly to be substantially opposed to each other and reaching to a spacing less than the diameter of the cap. The legs have slots lying in a common plane; preferably the base portion also has a slot in this plane; the slots being wider than the thickness of cap flange.
On mounting the thermoswitch to the clip, the slotted leg members are engaged over opposed portions of the cap flange, on which the slot in the base portion is also fitted; and the flange portions projecting therethrough may be staked back. The thermoswitch temperature-sensing face will thus be spring-urged to make and maintain intimate contact with the planar surface indentation of the end cap.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the present installation in place on a water-filled baseboard heater tubing assembly, shown fragmentarily and partly schematically.
FIG. 2 is an enlarged, somewhat fragmentary view of the left end portion of FIG. 1.
FIG. 3 is an end view as seen from the left of FIG. 2.
FIG. 4 is an auxiliary view of the spring clip as seen along line 4--4 of FIG. 3, prior to installation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the embodiment illustrated the invention is used as a limit switch installation in a baseboard heater tubing assembly generally designated a. Such assembly includes a horizontal cylindrical reservoir tube b leading to a reducer section c to which a lower horizontal tube d is brazed. The tube d leads into an upward-extending tube e which at midheight has a T-connection to an upper horizontal tube f, but projects thereabove curvingly to provide a closed-end expansion tube portion g. The upper horizontal tube f, equipped with closely spaced fins h, extends above and parallel to the lower members b, c, d, to join a riser tube j which is brazedly connected into the upper surface of the reservoir tube b near its end opposite the reducer section c.
Onto the outstanding end of the reservoir tube b shown enlarged in FIG. 2, I sealedly attach, as by brazing, an end cap generally designated 10. The cap 10 is formed of a brazable copper, characterized by ductility. It includes an end surface 11 having a cylindrical drawn margin 12, which terminates in an outstanding flange portion 13. The cap margin 12 is sealedly brazed to the reservoir tube b.
The end surface 11 of the cap 10, as seen in FIGS. 2 and 3, has two outward drawn tubular nipples 14, one of them being somewhat below its midheight. In them are sealedly mounted the outstanding electrical terminal ends k of a conventional hair pin shaped electrical resistance heater m, which extends therefrom inward into the reservoir tube b, in a canted plane. The terminal ends k are to be connected to a power source, not shown, controlled by the thermoswitch hereafter referred to.
A thermoswitch generally designated n, of a conventional type is shown installed somewhat above the canted resistance heater m. The thermoswitch n is a type adapted, through conventional circuitry not shown, to break the electrical circuit to the resistance heater m when water in the reservoir tube b reaches a predetermined limit temperature. It has a generally cylindrical body o and a planar circular temperature-sensing end face p, whose diameter is slightly larger than that of the switch body to provide a mounting shoulder q.
A precisely planar surface indentation 17, of such size to closely accommodate the thermoswitch surface p, is stamped or drawn in the cap end surface 11. The indentation 17 is bounded by a shallow sloping wall 18 which aids in locating the face p of the thermoswitch n in precise position.
To mount the thermoswitch n, a spring metal clip generally designated 20 is provided. It includes a flat base portion 21, best seen in FIG. 3 with a pair of spring-like leg members 22 extending laterally outward therefrom and bent at a spacing corresponding somewhat to the diameter of the end cap 10 to provide opposed leg portions 23. In unstressed condition prior to installation they are somewhat inclined toward each other, as seen in FIG. 4. When installed as shown in FIG. 3 they are spread from such normal position to grasp the end cap 10 by its flange portion 13. To provide such grasp, aligned slots 24 are provided in the clip opposed leg portions 23, and a base slot 25, aligned therewith, is also provided. The slots 24, 25 are slightly greater in width than thickness of the cap flange 13 so that, as seen in FIGS. 2 and 3, parts of the flange portion 13 will project therethrough. The clip 20 may be staked in place by bending back projecting parts of the flange portion 13, as the bent back flange part 26 of FIG. 2.
From the clip base portion 21 there extends at a fixed spacing from the slots 24, 25 a thermoswitch holding portion 27, which may be tab shaped as shown in FIG. 3 and rounded inwardly as seen in FIG. 4. It is bent to an angle nearly 90° and which, on installation will be substantially parallel to the end cap planar surface 17. It includes a circular cutout 28 through which the cylindrical body of the thermoswitch n is fitted. The portion 27 presses against the shoulder q of the thermoswitch, retaining it securely as shown in FIG. 2.
Inasmuch as the clip 20 is formed of springy metal, the temperature-sensing face p will be continuingly urged by it into close contact with the planar surface indentation 17 of the end cap 10. Retention is assured by staking back the parts of the cap flange portion 13 which project through the clip slots 24, 25, as the part 26 seen in FIG. 1.
Installations made according to the present invention have shown excellent and reliable response to changes in temperature of water within the reservoir tube b. Where, for purpose of safety, the tubing assembly a is to be limited to a pressure which corresponds to a temperature of 300° F., a thermoswitch n may be selected to break the circuit at almost precisely this temperature, and it will function reliably regardless of such known variables as changes in ambient temperature. In contrast, installations made as taught by the prior art are so affected by such variables as to cut off the heating current over an undesirable wide range of temperatures; to provide for such range it was necessary to select a thermoswitch setting at least 10° lower than the desired 300° F. limit. This reduced the maximum utilizable heating capacity of the heater, a disadvantage which the present invention has overcome.
From the present specification, modifications in detail will be apparent to those skilled in the art.