US2784272A - Electric switch units and adjusting and actuating means therefor - Google Patents

Description

March 5, 1957 U. F. CARTER 2,784,272 E ELECTRIC swITcH UNITS AND ADJUSTING AND ACTUATING MEANS THEREEOR Filed March 8,I 1954 2 Sheets-Sheet l 64 42a sa sa 4a U. F. CARTER 2,784,272 TRIC SWITCH UNITS AND ADJUSTING ND ACTUATING MEANS THEREFOR 2 Sheets-Sheet 2 March 5, 1957 Flled March 8 1954 55a so I l I III] vii/@QV (/ll: VWS .wh/0% W. M. .Huf

United States Patent O ELECTRIC SWITCH UNITS AND ADJUSTING AND ACTUATING MEANS THEREFOR Uriel F. Carter, Wauwatosa, Wis., assigner to Cutler- Hammer, Iuc., Milwaukee, Wis., a corporation of Delaware Application March 8, 1954, Senal No. 414,565 5 Claims. (Cl. 20G-33) This invention relates to improvements in electric switch units and adjusting and actuating means therefor.

A primary object of the invention is to provide improved and simplied means for relating switches to their mechanical actuators.

Another object is to provide improved means for translating the action of condition-responsive mechanism to electric switches.

Switches of the type herein disclosed may be employed as temperature control switches in refrigerators, and another object of the invention is to provide an improved and simplified switch unit for this purpose.

Refrigerator control devices commonly employ a switch, a pressure responsive or temperature responsive power element connected to actuate the switch at selected pres- Vsures or temperatures and means to permit selection by the user of the conditions at which the switch is actuated.

Also, such units are usually provided with means for making a factory adjustment to insure correspondence between the users selector means and the pressure or temperature at which the switch is actuated. In the past cumbersome and complex mechanism, such, for example, as a compression spring for loading the power element and means to adjust the spring compression, have been employed to permit user and factory adjustments. Another object of the invention is to provide switch units of the character described having an adjustment mechanism which is less expensive to manufacture, more simple,

. more accurate, and more readily adaptable to refrigerators of different makes and models than switch units as heretofore proposed.

Other objects and advantages of the invention will hereinafter appear.

Certain embodiments of the invention will now be described, it being understood that modification may be made in the embodiments illustrated, and that various other embodiments of the invention are possible without departing from the spirit of the invention or the scope of the appended claims.

In the drawings,

Figure l is a plan view of a switch unit embodying the invention and with its cover member removed.

Fig. 2 is a cross-sectional view, taken along the broken line 2 2 of Fig, l, with certain parts shown in elevation.

Fig. 3 is a cross-sectional View, taken on line 3-3 of Fig. l, with certain parts shown in elevation.

Fig. 4 is a cross-sectional view of a modification of the switch unit shown in Fig. l, with certain parts shown in elevation.

Fig. 5 is a fragmentary view in elevation of a preferred form of one of the cam members, a portion thereof being shown in section.

Fig. 6 is an enlarged sectional view, on the broken line 6 6 of Fig. 1, with certain of the parts shown in elevation.

Fig. 7 is an enlarged fragmentary sectional view similar to Fig. 6, butin a different plane, to better illustrate the operative relationship of the cams to each other and to y secured to its other end, is adapted the insulating base member of the switch unit; and showing the manner in which the inner adjustable cam may be tilted by movement of the boss forming part of the eX- pansible diaphragm.

Fig. 8 is a top plan view of the resilient insulating cam shown in the other figures of the drawings.

Fig. 9 is a sectional View, on the line 9-9 of Fig. 8, showing the peripheral downwardly extending cam portion, which cooperates with the other cam member to adjustably control the operation of the switch mechanism, and

Fig. 10 is a side elevational view of the cam member shown in Figs. 9 and 10, and in other figures of the drawings.

Referring to Figs. 1, 2, and 3 of the drawing, the switch unit there shown comprises a hollow molded insulating base 10 and an insulating cover member 12, an electric snap switch 14, a power element 16, and cams or spacers 18 and 20.

The switch 14 is substantially like the switch disclosed in United States Patent No. 2,663,770, granted December 22, 1953, to Cutler-Hammer, Inc., as assignee of Irvin W. Cox; which patent may be referred to for a detailed explanation of the mode of operation of this switch 14.

Brietiy, it comprises a fixed combined wiring terminal and Contact plate 22 (Figs. l, 3, 4 and 6), which is held in place by conformations in the base 10 and cover member 12; a wiring terminal and movable contact supporting plate 24 (Figs. l, 2, 3 and 6), which is likewise held in xed position on the opposite side of the switch unit by conformations in the base 10 and cover member 12; a iiat punched sheet metal member 26 of good electrical conductivity which is secured at one end to plate 24 and which extends across the switch unit so that a contact tip 33, for movement into and out of engagement with said fixed contact plate 22, or with a stationary contact tip 22a attached to the latter, and which is provided with two U-shaped, nested slots (as shown at 26d and 26e in Fig. i) to form a triple reed structure; a snap spring 28 (Fig. l) which is held under compression between the inner reed 26a and the intermediate reed 26b of member 26; and an actuator 30 formed integrally with and extending downwardly from the inner reed 26a of member 26 (see Figs. 3 and 6). The switch 14 further comprises a differential adjustment screw 32 which is threadedly disposed in an opening in the cover 12 opposite the contact tip carrying portion of plate 22. The outer reed 26c carries contact 33 which normally engages Xed contact tip 22a secured to plate 22.

Spring 28 is attached to inner reed 26a by a gland 27 and it is attached to intermediate reed 26b by a gland 2i. The latter gland 29 is formed with side extensions which are slotted. The sides of the outer reed 26c are disposed within the respective slots. Thus when by movement of actuator 30, the spring 28 is carried over-center with respect to reeds 26a and 26h, the spring gland 29 is in motion before the edges of its slotted ends engage reed 26C to actuate the switch. Therefore, the switching motion of contact 334 is made very rapid and, when the switch is opened, the pressure of contact tip 33 on contact tip 22 is maintained at a fixed value until the instant that the contacts are opened.

The power element 16 comprises an outer cup member 34 and a diaphragm insert 36. The diaphragm 36 preferably is self-loaded. Itis made sutiiciently resilient so that it will offer proper resistance to pressure within the powerelement, thus to obviate necessity for employing the usual loading spring. The cup and diaphragm are sealed together to form a hollow unit which is connected to a pres sure or temperature pick-up device (not shown) through a tube 38. The diaphragm 36 is provided with a central upwardly extending boss 36a.

essere The boss .36e communicates with the interior of the cavity formed by base 10 and cover 12 through an opening 4@ in the lower portion of base l0.

As best shown inFigs. Al, 5,6 and 7, the cam 1S comprises a substantially annular insulating molding having a skirt or flange 42 extending approximately one-half of the way around the lower end portion thereof. Opposite side portions of the upper edge of the cam 1S are olfset downwardly, as shown to form a semi-annular ridge 44 which is of the cross-sectional form best illustrated in Fig. 5. The lower edge of the cam 18, opposite the ridge 44, has portions shaped to form a cam surface 46 and an off position notch 4S. The sector skirt or flange 42 is provided with teeth on the upper surface thereof which are adapted to engage a gear 50, Figs. l and 2, which is secured to a shaft 52 a portion of which is located exteriorly of the switch unit.

The cam 20 is preferably formed of resilient insulating material and, as illustrated in Figs. 1, 2, and 3, is preferably of annular form. The upper surface of cam 20 is substantially flat. Its lower surface is provided at its outer periphery with a downwardly extending lip S5 which is substantially semicircular in cross-section and which varies in depth to provide a lower cam surface 55a, Fig. 3. The inner periphery of the cam is tapered inwardly, as best shown in Fig. 3, to provide an edge 5d. A factory adjustment pin 56 is mounted vertically in the base so that portion 56a thereof, which is provided with axial serrations, engages the peripheral edge 54 of the opening in cam or spacer 2t), to provide for rotary adjustment of the latter in one direction or the other.

Switch 14 is disposed in the upper portion of the cavity formed by base 10'and cover 12. Power element 16 is disposed on the lower side of the base 10 so that its central boss 36a extends within the cavity formed by base 1t? and cover 12 and so that side extensions 34a of the cup 34 are arranged to hold the cover 12 and base 19 together securely. Cam 1S is disposed against the bot tom wall of base 1@ so that its underside, and cam surface 46 (Fig. 5) in particular, is engaged by boss 36a. Cam is interposed between actuator 30 of `switch 14 and the semi-circular rim 44 (Figs. l, 2, 3, 6 and 7) of cam 18.

These components are arranged so that boss 36a, the working point of cam surface 46 of cam 1S, the contact point on rim 44, the working point on surface 55'M1 (Figs. 3 and 6) of cam 20, and actuator 30 (Figs. 3, 6 and 7) are in vertical alinement. Cam 18 may be rotated by rotation of shaft 52 so that boss 36a engages selected points on cam surface 46 or olf notch 48 (Fig. 5) to adjust the spacing between boss 36a and cam surface 55 of cam 2Q. Upon rotation of factory adjustment pin 56 its serrations effect rotationfof cam 20 to vary the spacing desired between the semi-circular rim 44 of cam 18 and the actuator 30. v

Cams 13 and 20 are held in proper relationship by conformations in base l() in which they are respectively dispo-sed. No fastening member or `additional mechanism is required to hold the cams in proper position.

Cams 18 and 20 are oriented so that their respective center lines, drawn through the point of contact of the cams, are at right angles; as best illustrated in Figs. l, 3 and 6. Thus it is insured that movement of one cam will not interfere with movement or the adjustment of the other.

As the control condition varies to alter the pressure within power element 16, diaphragm 36 is actuated and boss 363 ioves vertically (see Fig. 3). This motion is translated through cams 18 and 20 to actuator 39 of i switch 14. At some critical pressure, actuator 3ft will be moved inwardly sufficiently far to effect snap opening of switch 14. As the pressure within power element 16 increases, actuator 3@ (Figs. l, 3 and 6) will be raised and at some higher critical pressure, determined by the'spacing between the differential adjustment screw 32 and fixed contact plate 22 and by the spring characteristics of the switch mechanism 14, switch 14 will snap downwardly to the closed circuit position. As boss 36E moves vertically, cam 18 tilts and cam 2f; flexes about the points of their connection with gear 50 and factory adjustment pin 56, respectively.

The modified form of switch unit shown in Fig. 4 differs from that shown in Figs. l, 2, 3, 6 and 7, in that no cam corresponding to cam 2i) has been included, and in that the actuator 36 has been replaced by a factory adjustment screw 5t? which is threadedly engaged in and supported by the snap switch 62. The screw 60 is directly engaged. by the single cam 64 which serves as the switch actuator. Cam 2!) of Figs. 1, 2 and 3 and screw 6i) of Fig. 4 are intended to be adjusted at the time the control unit is produced. This adjustment is made to change the spacing between the power element and switch actuator independently of the user adjustable cam 18 or 64 to compensate for minor diiferences in individual units from a desired standard power element sensitivity and switch operating pressure sensitivity.

Cam 54 differs from cam E S only in that a portieri of the upper edge thereof is not formed to provide a semicircular rim, such as rim of cam 1. Such construction is employed in cam 18 to coperate with a similar semi-circular shaped cam surface S5a of cam 24) so that the spacing afforded by cams 18 and Ztl between boss 36a and the rounded end of switch actuator 34E, for a given settino of said cams, remains constant as the latter are lifted and lowered by boss 35a. VA similar result is assured in the switch unit of Fig. 4 by rounding the lower end of factory adjustment screw 69. In both switch units frictional forces are small since the cams are made to tilt or flex about their respective adjustment means.

When cam 's is rotated by means of shaft 52, to the off position, notch 43 is vertically alined with boss 36E. The notch is sufficiently deep so that boss 3611 cannot engage and lif the cam to actuate switch 14 to its on position.

I claim:

l. En combination, a snap acting switch having an actuator movable to elfect switching actions, a power element having a portion movable toward and away from said actuator an amount determined by the magnitude of a variable quantity, a spacer rotatable about an axis spaced from and substantially parallel to the line of movement of said power element, said spacer having diametrically oppositely disposed arcuate portions, one of said arcuate portions being of different thickness at successive points along its periphery and being interposed at one of said points between said actuator and said movable portion of said power element, and spacer rotating means engaging the other of said arcuate portions at a point substantially opposite said one of said points and being operative to rotate said spacer about said axis, said spacer being free to tilt about the point of its engagement with said spacer rotating means Vwhereby said spacer may transmit motion of said power element to said actuator substantially without impedance to such motion.

2. In combination, a hollow base, an electric switch mounted on said base at one end thereof, an actuator for said switch, a self-loaded hollow power element mounted on the other end of said base, said power element having a portion movable toward and away from said actuator an amount determined by the internal pressure of said element, a spacer having diametrically oppositely disposed arcuate portions, one of said arcuate portions being of different thickness at successive points along its' periphery, said base having intermediate its ends a conformation shaped to accommodate said spacer and to confine the same to rotary motion about an axis sub stantially perpendicular to the line of movement of'said power element and in which said spacer is disposed Vwith one of said points of said one arcuate portion interposed between said movable portion of said power element and said actuator, said conformation further being shaped to permit said spacer to tilt about a peripheral point on the other arcuate portion of said spacer substantially opposite said one point interposed between said power element and said actuator, and means engaging said spacer at said point on said other of said arcuate portions and being operable to rotate said spacer within said conformation.

3. In combination, an electric switch, an actuator for said switch, a self-loaded pressure responsive power element having a portion movable toward and away from said actuator an amount determined by the pressure within said power element, a generally circular spacer lying in a plane substantially normal to the line of movement of said power element, said spacer being of diierent thickness at successive points along the portion of its periphery and being interposed at one of said points intermediate said actuator and said movable portion of the power element, means engaging said spacer at a peripheral point substantially diametrically opposite said one point and acting as a pivot about which said spacer is free to tilt, said means further being operative to rotate said spacer in said plane.

4. The combination defined in claim 3, in which there is a second circular spacer lying in a plane substantially normal to the line of movement of said power element, said second spacer being of different thickness at successive points along a portion of its periphery and being interposed at one of said points intermediate said one point of said spacer first mentioned and said actuator, means engaging said second spacer at a peripheral point substantially diametrically opposite said one point of said second spacer about which said second spacer may ex, said means being operative to rotate said second spacer, the plane along which sa-id first said spacer first mentioned is tilted being perpendicular to the plane in which said second spacer is ilexed.

5. In combination, an electric switch, an actuator for said switch, a pressure responsive power element having a portion movable toward and away from said actuator an amount `determined by the pressure within said power element, a generally circular spacer lying in a plane substantially normal to the line of movement of said power element, said spacer being of different thickness at successive points along a portion of its periphery and being interposed at one of said points intermediate said actuator and said movable portion of the power element, the diametrically opposite portion of said spacer being provided at its periphery with gear teeth, gear means engaging said teeth at a point on said spacer substantially diametrically opposite said one point and acting as a pivot about which said spacer is free to tilt and further being operative to engage the teeth of said spacer and to rotate said spacer.

References Cited in the tile of this patent UNITED STATES PATENTS 2,033,417 Dezotell Mar. 10, 1936 2,493,190 Fuchs Ian. 3, 1950 2,556,716 Viol June 12, 1951 2,658,121 Gray et al Nov. 3, 1953 2,671,839 Cox Mar. 9, 1954

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