US2768263A - Switch mechanism - Google Patents

Description

Oct. 23, 1956 CALUHAN 2,763,263

SWITCH MECHANISM Filed Jan. 6, 1955 ITS l- [NVEN TOR.

i g w 171113.15 H. FALLIHAN;

United States Patent SWITCH NIECHANISM Dale H. Callihan, Mansfield, Ohio, assignor to Pace, Inc., Mansfield, Ohio, a corporation of Ohio Application January 6, 1955, Serial No. 480,121 8 Claims. ((31. 200-438) This invention relates to electrical switch mechanism and more especially to switches of the thermoresponsive type provided with means for manually adjusting a component of the switch mechanism for operation of thermostatically actuated switch means at predetermined temperatures.

Switch mechanisms embodying a manually adjustable member and a thermostat or thermoresponsive means for controlling an electrical circuit of a heating element have been used with or embodied in electrical appliances such as pressing irons, coffee making devices, bread toasters and other forms of electrical appliances where it is desirable to manually adjust the mechanism to a position at which the thermostat construction under the influence of heat will interrupt the electrical circuit by disengaging contacts of the switch mechanism at the predetermined temperatures determined by the relative position of the manually adjustable means. Mechanisms of this character heretofore used have been equipped with a manually rotatable member operable through a pin or strut formed of insulating material to move a contactcarrying arm for adjusting the position of the arm whereby the thermoresponsive means is effective to disengage the contacts when the thermoresponsive means is subjected to a predetermined temperature. In constructions heretofore used, the manually adjustable means has been limited in its extent of rotation by means of a transversely extending pin cooperating with a nut having a projecting portion disposed exteriorly of the appliance and engageable with the pin on the manually adjustable member for defining the extent or range of rotation of the manually adjustable member. Constructions of this character have been expensive to manufacture and are difficult of assembly.

The present invention has for an object the provision of a switch mechanism embodying a manually adjustable means wherein an improved arrangement is provided for determining the range of adjustment of the manually adjustable means.

An object of the invention is the provision of improved means of mounting a manually adjustable mechanism for a switch wherein improved means is provided for limiting the movement of the manually adjustable means, providing an arrangement whereby effective control of the position of a component of the switch mechanism is attained to assure operation of a thermoresponsive means at a predetermined temperature.

Another object of the invention is the provision of a switch mechanism embodying a thermoresponsive means and a manually adjustable means for determining the position of a switch member at which the thermoresponsive means is enabled to interrupt or make a circuit through the switch means and in which movement limiting means is provided for the manually adjustable mechanism which may be easily and quickly assembled and which will be reliable in its operation.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

Figure 1 is an enlarged sectional view illustrating a switch mechanism embodying a form of the invention;

Figure 2 is a sectional view taken substantially on the line 2 2 of Figure 1;

Figure 3 is an elevational View partly in section illustrating a manually adjustable component or element of the switch mechanism;

Figure 4 is an enlarged end view of the construction shown in Figure 3;

Figure 5 is an isometric view illustrating one form of stop or movement-limiting means for the manually adjustable element of the switch mechanism;

Figure 6 is a fragmentary, detail sectional view illustrating another form of stop means for the manually adjustable construction of the switch mechanism;

Figure 7 is a bottom plan view of the construction shown in Figure 6;

Figure 8 is an enlarged, fragmentary, detail sectional view illustrating another form of stop means for the manually adjustable mechanism of the switch construction, and

Figure 9 is a bottom plan view of the construction shown in Figure 8.

The switch mechanism of the invention is especially adapted for use in controlling the temperatures of appliances such as electric irons, percolators, pressure cookers, bread toasters and the like, and it is to be understood that the invention may be used with other types of mechanism wherever the same may be found to be desirable or to have utility.

Referring to the drawings in detail and especially Figure 1, there is illustrated a portion of an electrical appliance, for example, a bread-toasting device, which is inclusive of a frame 10 and a housing construction 11, portions of these components being shown in Figure l. The frame of the appliance supports a heating element of the resistance type, diagrammatically illustrated at 14, which is connected in circuit with the switch means shown in Figure l.

The switch means embodying the invention is carried or mounted on a support or supporting means which includes a plate-like member 16 and a sleeve member 18. The switch mechanism embodies relatively movable switch arms or members 20 and 22 which are carried by the supporting means in a manner hereinafter described, the switch arms or members being provided respectively with contacts 24 and 25 for establishing and disestablishing a circuit through the heating element 14. The switch mechanism incorporates a thermostat or thermoresponsive means 27 for actuating or moving one of the switch arms. In the embodiment shown, the thermostat actuates the switch arm 22.

The thermoresponsive means or element 27 in the illustrated embodiment is of a bimetallic type, fashioned of two strips 28 and 29 of different metals bonded or joined together throughout their length, the strips having dissimilar coefficients of expansion whereby variations in temperature adjacent or ambient the thermoresponsive means 27 cause flexure or relative movement thereof. The thermoresponsive element 27 is supported upon the sleeve 18 forming a component of the switchsupporting means.

The sleeve-like member 18 is formed at one end with an outwardly extending flange 31, and the thermoresponsive element 27 is provided with an opening whereby the element 27 is received on the sleeve 13 and disposed in the position shown in Figure l. The body of the sleeve, before assembly of the parts, is of uniform diameter, and after assembly of the parts of the switch mechanism, the upper end portion or zone of the sleeve is swaged over as shown at 33 to hold the components of the switch mechanism in proper assembled position.

Disposed above the thermostat 27 is a disk-like member 34 of insulating material having a tenon portion 35'. The switch member 20 is provided with a cylindrical opening of a size whereby the switch member is snugly received upon the tenon 35 of the insulating member 34. A terminal member 37 is also bored to be received upon the tenon 35 as shown in Figure 1, and through this method of assembly the switch member 29 and its terminal member 37 are insulated from the supporting sleeve 13.

Disposed above the terminal member 37 is a second disk-like member 38 of insulating material having a tenon portion 39 which extends into openings formed in the switch member 22 and a terminal member 40 to insulatingly support the switch member and terminal upon the sleeve 13 of the supporting means. Disposed above the terminal member 38 is another washer or disk-like member 4-2 of insulating material. Arranged between the insulating washer 42 and the supporting member 16 is a plate-like member 45 shown in detail in Figure which, in the form of the invention shown in Figure l, is formed with a stop means for limiting the extent of rotation or range of movement of the manually adjustable mechanism of the switch means, a construction which will be hereinafter described in detail.

After assembly of thermostat element 27, switch arms 20 and 22, terminals 37 and 40 and insulating washers or disks on the sleeve 18, the projecting portion of the sleeve above the member 16 is swaged to form the ledge portion 33, thus holding the above-mentioned components of the mechanism in assembled relation. A bolt 47 may be provided extending through aligned openings in the wall 11 of the appliance housing and through the sleeve 35 to secure the switch mechanism to the housing wall 11, a nut 48 being threaded upon the end of the bolt 47.

Provided at the free or movable end zone of the thermoresponsive means 27 is a flanged pin or button-like member 59 formed of ceramic, lava or other suitable highcmperature-resistant insulating material which is secured to the thermoresponsive element 27 by means of a metal clip 52. When the ambient temperature is such as to flex the thermcresponsive element to a predetermined point, the upper end of the member 50 engages and moves the switch arm 22, disengaging the switch contact 25 from the contact 24 and interrupting the current flow through the heating element 14.

When the heating element cools and the temperature ambient the thermoresponsive element 27 is reduced, the element 27 is flexed in the opposite direction, withdrawing the pin 50 from engagement with the switch arm 22, the arm 22, by reason of its inherent tension, is refiexed downwardly to re-engage the contact 25 with the contact 2 and i e-establish a circuit and current flow through the heating element 14. As diagrammatically illustrated in Figure l, the terminal 37, in contact with the switch arm 29, is connected by means of a conductor 56 with the heating element 14, the other end of the heating element being connected with a supply line L]. as shown in Figure l. The other terminal 40, in contact with the switch member 22, is connected with the other conductor L2 of the current supply line.

The temperature at which the thermostat element 27 through pin 50 functions to move the switch arm 22 is dependent upon the relative position of the switch arm The present invention is inclusive of manually adjustable means for changing or modifying the relative position of the switch arm 20 so as to predetermine the temperature range within which the thermostat element 27 is effective to interrupt and/ or complete the circuit through the heating element 14. The manually adjustable means for accomplishing the above-stated purpose is mounted upon or carried by the plate-like member 16 forming a component of the switch-supporting means.

As particularly shown in Figure 1, there is provided a member or fitting 60 formed with a threaded external portion 61., an outwardly extending flange or ledge 62 and a tenon portion 63, the latter being received in a suitable opening in the supporting member or plate 16. The tenon portion 63 has a knurled or roughened external surface which is snugly received in the opening in member 16, the end zone or portion of the tenon 63 projecting below the member 16 being swaged over or ringstaked as shown at 64. By this means, the fitting 6t; is fixedly secured to the supporting means 16. The threaded portion 61 is adapted to receive a securing nut as for securing the fitting 60 to the wall 11 of the appliance in the manner shown in Figure l.

A manually adjustable or rotatable means is associated with the fitting 6% for varying the relative position of the switch arm 2t). The interior bore in the fitting as is threaded to receive a threaded portion 7% of a manually rotatable element 72, the member 72 having a knurled portion 74 adapted to snugly receive a manipuiating knob 76 as shown in Figure l. The manipulating knob is preferably formed of molded insulating material of a shape convenient for rotating the element 72. The snob 76 is equipped with a plate 78 formed with an indicator 7 9 which registers with indicia (not shown) inscribed upon the wall 11 of the appliance for the temperature range of operation of the thermostat and indicates the positions of adjustment of the manual means for determining the temperatures at which the thermostatic element will control the energization of the circuit through the heating element by interrupting or engaging the contacts 24 and 25.

The hollow interior of the manually adjustable element 72 is threaded as at 82 to receive a threaded member or screw 84 provided with a kerf 85 to receive a tool for adjusting the position of the screw 84 with respect to the element 72. Disposed between the screw S 5- and the switch arm 29 is a strut or member 86 formed of lava or ceramic material having high-temperature-resistant characteristics for communicating longitudinal movement of the manually adjustable member 72 to the switch arm or member 29. The strut or pin 86 is formed with a wedge-shaped extremity 38 which extends into an opening 89 in the switch arm 20 to prevent relative rotation of the pin 86 with respect to the switch arm The upper extremity of the pin 86 is of semispherical shape and rests or engages in a conically shaped recess 2t formed in an end of the thread or screw 84. The function of the threaded member 84 is to secure minute adjustment or proper coordinated relation between the manually adjustable element 72 and the switch arm 2% to initially determine and fix the range of rotative movement of the manually adjustable member to correspond with a predetermined range of movement or flexure or" the thermostat element 27. Through the arrangement of mounting of the pin 86 whereby it is held against relative rotation through the wedge-shaped engagement in a rectangular opening in the switch arm 20, providing for rotation of the screw 84 and element '72 relative to the pin 86, precision adjustment of the position of the switch arm 2% is assured.

In the arrangement of the invention, the manual means may be arranged for rotation throughout the range of operating temperatures desired in the thermostat, the extent of rotation usually being less than a complete rotation of the manual means. As shown in Figure 2, the range of movement of the manual means may be less than the lines A and B indicating the maximum and minimum positions of adjustment of the manual means for predetermining a range of operation of the thermoresponsive element 27. A movement-limiting arrangement is provided for the manually adjustable member or element '72 by means associated with the plate 45. As illustrated in Figures 1 through 4, the end zone of the element 72 adjacent the switch arm 22 is formed with a projection 92 extending longitudinally of the element 72 which is of semiannular cross section as shown in Figure 2 and is defined by edge walls 93.

The member or plate 45 is formed with a stop means in the form of a projection or tongue 95 which is bent or inclined upwardly as shown in Figures 1 and 5 and extends into the path of rotation of the projection 92 on the manually adjustable element 72. Engagement of the edge walls 93 of the projection 92 with the stop member 95 determines the limits of rotation of the manually adjustable element 72.

In assembling the parts and components of the mech anism shown in Figure 1, a preassembly is effected of the fitting 6%, element 72, supporting plate or member 16 and the stop means 45. The fitting 60 is assembled with the member 16 with the tenon portion 63 of the fitting extending through an opening formed in member 16. The portion of the tenon 63 projecting beyond the member 16 is then swaged or ring-staked to form the head or ledge 64 snugly engaging the lower surface of the member 16 to secure the fitting 60 thereto. The manually adjustable element 72 is threaded into the fitting 60 until the projection 92 extends beyond the ledge 64 as shown in Figure 1. The stop plate 45 is then secured to the supporting plate-like member 16 by spot welding indicated at 100 in Figures 1 and 2, the opening 98 in the stop means 45 being first aligned with the opening in the member 16 which accommodates the supporting sleeve 18. In this assembly the projection 95 extends into the path of rotation of the projection 92 to limit rotation of the element 72. The spot welding 100 provides an inexpensive means or method of securing the stop means to the supporting member 16.

Through the abovedescribed preassembly, the rotation of the manually adjustable element 72 is limited in both directions by the projection 92 engaging the stop member 95. In the final assembly, the plate or member 16, carrying the stop plate 45, element 72 and fitting 60, is assembled on the sleeve 18 together with the thermoresponsive means 27, the switch arms 20 and 22, terminals 37 and 49 and the insulating washers or members 34, 38 and 42, after which the projecting portion of the sleeve 18 is swaged or staked into the shape as shown at 33 to secure all of the components of the switch mechanism in assembled position.

The pin or strut 86 is inserted in the threaded passage in the element 72, and the screw 84 is threaded into the element 72 to occupy the position shown in Figure 1. By rotating the screw 84, an accurate and precise adjustment may be had of the relative positions of the element 72 and the switch arm 20 to thereby adjust the range at which the thermostat is eifective between the maximum and minimum adjustments or positions of the manually adjustable element 72. After the proper adjustment of the screw 84 has been made, a small quantity of cementitious material 1G2 may be deposited in the longitudinal passage in the element 72 and in contact with the upper end of the screw 84 to hold the latter in its position of adjustment.

The switch arm 20 is normally fabricated so as to be inherently stressed to normally occupy an upwardly inclined position as shown in Figure 1. In this condition, the contact 24 thereof is normally biased to engage the contact 25 of the switch arm 22 with the pin 50 carried by the thermoresponsive element 27 out of engagement with the switch arm 22. By rotating the manually operable member 72, the position of the switch plate 20 is changed by reason of the rotation of the manual member 72 being transferred into longitudinal movement of the pin 86 through the spiral lead or pitch of the threads of the threaded engagement of manually adjustable member 72 with the stationary fitting 60. Thus, by modifying or changing the relative position of the switch arm 20, the temperature at which the thermostat element 27 is flexed to engage the pin 50 with the switch arm 22 is determined so as to interrupt the circuit by disengagement of contacts 24 and 25, through the upward pressure of the thermostat element as the temperature adjacent the same is elevated. Through the disengagement of the contacts 24 and 25, the energizing circuit through the heating element 14 is interrupted. Upon cooling of the heating element 14 below the temperature necessary for the thermostat element 27 to hold the switch arm 22 in contact-disengaging position, the thermostat element will cool and is flexed in the opposite direction. The cooling of the thermoresponsive means results in the pin 50 being moved in a direction away from the switch arm 22, permitting the contacts 24 and 25 to be re-engaged, the circuit through the heating element 14 re-established and the heating element again energized. The circuit will remain closed until the thermostatic element 27 again causes a disengagement of the contacts 24 and 25.

The extent or amount of rotation of the manually operable element 72 is determined by the edge walls 93 of the projection 92 engaging the stop means 95. It is found that a relative rotation of member 72 of approximately l or less is usually sufiicient to embrace the desired temperature range of operation of the thermostatic element 27, but the extent of rotation of element 72 may be varied by changing the size of the projection 92.

A modified form of stop means or movement-limiting means for the manually adjustable element is illustrated in Figures 6 and 7. in this form of construction, the supporting means in the form of the plate-like member 16' is formed with a projection adapted to extend through a notch or recess 106 provided in the projecting portion 63 of the fitting 60' which is similar in construction to the fitting 60. The projection 165, in the position illustrated in Figure 6, projects into the path of the extension or projection 92 on the manually adjustable element 72 illustrated in Figure 3 whereby the edge walls 93 of projection 92 are adapted to alternately engage opposite side zones of the projection 105 to limit the range or extent of rotation of the element 72 in the same manner that the projection 95 limits the rotation of the manually adjutsable element illustrated in Figure l. The ledge or flange portion 62 of the fitting 60 shown in Figures 6 and 7 may be spot welded as indicated at 107 to the plate 16' so as to fixedly secure the fitting 6th to the plate 16. It is to be understood that other forms of fastening means may be employed to secure the fitting 60 to the supporting means or plate-like member 16.

Another form of stop means or movement-limiting means for the manually adjustable element 72 is illustrated in Figures 8 and 9. In this form of construction a fitting 116, similar to the fitting 60, is provided with a sleeve or tenon portion 112 adapted to extend through an opening formed in the supporting means or plate-like member 16". A ledge or flange portion 111 engages the upper surface of the plate 16" to determine the posi tion of the fitting 11%) with respect to the plate-like member 16". The sleevelike portion is of a length to eX- tend to the position indicated in broken lines at 114 and, during assembly of the fitting with the member 16", the end zone of the tenon portion 112 is swaged or ring-staked to the position shown at 115 to securely fasten the fitting 111 to the plate or member 16". A portion of the sleeve 112 is bent or formed radially inwardly to provide the projection or stop 118. When the manually adjustable element 72 is threaded into the threaded bore in the fitting 110, the projection 118 is normally disposed in the path of the projecting portion 92 of the element 72, the stop means or projection 118 serving to limit or define the limits of rotation of the manually adjust- 7 able element 72 in the same manner as the arrangement illustrated in Figure 1.

in the form of construction shown in Figures 8 and 9, the element 72 is threaded into the fitting 110 prior to the swaging operation. In assembling the construction the element 72 is threaded to the position wherein the stop means or projection 118 is in the path of rotation of the projection 92 of the element 72. The assembled fitting 119 and element 72 are inserted through the opening in the plate 16", after which the end zone of the annular projection or tenon portion 112 of the fitting indicated by broken lines 114 is swaged, staked or distorted into the position at 115 in snug engagement with the lower surface of the plate 16 to hold the fitting and plate 16" in fixed position. At the same operation, the portion 113 of the sleeve-like portion 112 of fitting lid is formed inwardly and radially of the axis of the fitting lit to the position shown in Figures 8 and 9 so that it is disposed in the path of rotation of the projection 92 on the element 7... In this position, it is adapted to be engaged by the edge zones 33 of the projection 92 for limiting the rotational movement of the manually adjustable means or element 72 of the switch construction.

From the foregoing description it will be apparent that the invention provides a positive and reliable stop means or method for defining or determining the extent of rotation of the adjustable element 72 for varying the temperature at which the thermostatic element 27 is effective to control the circuit through a heating element in order to maintain a substantially constant temperature for the appliance with which the switch mechanism is used.

It is apparent that, within the scope of the invention, modifications and diiferent arrangements may be made other than i herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. Switch mechanism including, in combination, a supporting means, relatively movable switch members carried by the supporting means, thermoresponsive means arranged to influence the position of one of said switch members, rotatable means, an element engaging said rotatable means and a second switch member whereby rotation of the rotatable means changes the position of said second member, a generally semiannularly shaped portionintegrally formed at one end of the rotatable means, and an abutment associated with the supporting means arranged to be engaged by the said portion on the rotatable means for limiting the extent of movement of the rotatable means.

2. Switch mechanism including, in combination, a supporting means. a relativeh movable switch arm carried by the supporting means, coo erating contacts for establishing a circuit, one of said contacts being carried by the switch arm, thermoresponsive means influencing the rela tive position of the other of said contacts, means for changing the relative position of the switch arrn including a rotatable element having a sleeve-like portion, the sleeveill--16 portion of said element having an integral extension longitudinally of the element, and means associated with the supporting means and disposed'in the path of rotation of the extension on said element for limiting the extent of rotation of the element.

3. Switch mechanism including, in combination, a supporting means, relatively movable switch members carried by the supporting means, thermoresponsive means arranged to influence the position of one of said switch members, manually rotatable member having a sleeve portion formed at one end, an element engaging said manually rotatable member and the other of said switch members whereby rotation of the rotatable member changes the position of said switch member, said sleeve like portion terminating in a generally semiannularly shaped section, and an abutment associated with the supporting means arranged to be engaged by the said semiannularly shaped section for limiting the extent of movement of the manually rotatable member.

4. Switch mechanism including, in combination, a supporting means, relatively movable switch members carried by the supporting means, thermoresponsive means arranged to influence the position of one of said switch members, manually rotatable hollow shaft, an element engaging said manually rotatable shaft and the other of said switch members whereby rotation of the rotatable shaft changes the position of said switch member, a generally semiannularly shaped extension integrally formed on one end of the manually rotatable shaft, a plate-like member carried by the supporting means, and an abutment formed on said plate-like member arranged to be engaged by the said extension for limiting the extent of movement of the manually rotatable means.

5. A circuit-controlling means for a heating element including, in combination, a switch mechanism having two relatively movable switch arms, cooperating contacts carried by said switch arms for establishing a circuit through the switch arms, a thermostat element disposed to be influenced by heat from the heating element, supporting means for said switch arms and thermostat element including a member, a fitting carried by said member having a threaded bore therein, a manually rotatable hollow shaft threaded into said bore, an insulating pin disposed between the element and one of said switch arms, the other of said switch arms being arranged to be moved by said thermostat element, said manually rotatable shaft being formed with an integral extension of semiannular cross-section disposed adjacent one of the switch arms, and stop means disposed in the path of movement of the extension of the manually rotatable shaft for limiting the extent of rotation thereof.

6. A circuit-controlling means for a heating element including, in combination, a switch mechanism having two relatively movable switch arms, cooperating contacts carried by said switch arms for establishing a circuit through the switch arms, a thermostat element disposed to be influenced by heat from the heating element, supporting means for said switch arms and thermostat element including a member, a fitting carried by said member having a threaded bore therein, a manually rotatable element threaded into said bore, an insulating pin disposed between the element and one of said switch arms, the other of said switch arms being arranged to be moved by said thermostat element, said manually rotatable element having an integral sleeve-like projecting portion disposed adjacent one of the switch arms, and stop means formed on said fitting and disposed in the path of movement of the projecting portion of the manually rotatable element for limiting the extent of rotation thereof.

7. Switch mechanism including, in combination, a supporting means, relatively movable switch arms carried by the supporting means, cooperating contacts carried by the switch arms for establishing a circuit, thermoresponsive means for moving one of the switch arms, manually adjustable mean for regulating the relative position of the other of said switch arms, said adjustable means including a rotatable element, said element having an integral sleeve-like portion of partially annular cross section extending longitudinally of the element at one end thereof, and a stop means associated with the supporting means and disposed in the path of rotation of the projection on said element for limiting the extent of rotation of the element.

8. Switch mechanism including, in combination, a supporting means, relatively movable switch arms carried by the supporting means, cooperating contacts carried by the switch arms for establishing a circuit, thermoresponsive means for moving the first of said switch arms, manually adjustable means for regulating the position of the second of said switch arms, said adjusting means including a rotatable clement, said element having an 2,768,263 9 10 integral projection spaced from the axis of the element to determine the initial position of said first switch arm and extending longitudinally of the element at one end Within the effective range of the thermoresponsive means. thereof, said supporting means including a plate-like member, a projection associated with the member and References Cited in the file of this patent disposed in the path of rotation of the projection on said 5 UNITED STATES PATENTS element for limiting the extent of rotation of the element,

a hreaded member carried by the manually rotatable f X- elernent, and means formed of insulating material en- 2,715,167 Z 55 gageable with said threaded member and the second 2718572 --S -20 1955 switch arm for communicating movement of the ele ent 10 t ams to the switch arm, said threaded member being adjustable

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