US2751466A - Switch mechanism - Google Patents

Description

June 19, 1956 J. w. HUFFMAN 2,751,466

SWITCH MECHANISM Filed Sept. 9, 1954 United States Patent F SWHTCH MEQHANHSM lei-in W. Hnliman, Mansfield, Ohio, assignor to Pace, Ind, Mansfield, (this, a corporation of Gino Application Eiepternber 9, 1954, Serial No. 454,373

12 Claims. (Cl. 260-439) This invention relates to electrical switches of the thermoresponsive type and more especially to switches of this character provided with means for manually adjustting the switch mechanism for operation of thermostatically actuated switch means at predetermined temperatures.

Manually adjustable switch mechanisms embodying a thermostat or thermoresponsive actuating means have been used with or embodied in appliances such as electrically heated pressing irons, electrically actuated coffeemaking devices and other types of electrical appliances where it is desired to manually adjust the mechanism to a position whereby the thermostat, under the influence of heat, will interrupt the electrical circuit by disengaging the switch contacts at a predetermined temperature. Mechanisms of this character heretofore used provide a manually rotatable member operable through a pin or strut fabricated of insulating material such as ceramic or lava to move a contact-carrying member for adjusting the initial position of a contact-carrying member of a thermostatically actuated switch means. Such constructions heretofore used employed ceramic or lava pins formed with semispherically shaped ends, one of which engaged in a socket in the manually actuated means and the other end rested or engaged the flat, uninterrupted surface of a contact-carrying arm or member. This type of mounting of the pin results in excessive wear, and the necessary clearance for operation permits relative angular displacement of the pin which seriously impairs the accuracy of the adjustment of the contact-carrying arm with consequent erratic variations in the functioning of the switch mechanism.

In circuit control devices of this character, the temperature range is usually of a critical character, and any lost motion or looseness of the elements in the circuit-controlling means causes substantial variations of the temperature control. The lack of proper positioning and coordination between the relatively movable contact-carrying member of the switch mechanism and the actuating pin renders the circuit control mechanism unstable and unreliable in its operation.

The present invention has for an object the provision of adjusting means or mechanism in a thermostatic or thermorcsponsive switch mechanism whereby improved accuracy is obtained of temperature control of applicances with which the switch mechanism may be used.

An object of the invention is the provision of means for adjusting the relative position of an element of a switch mechanism for accurately providing an eifective control for a thermostatically actuated switch whereby the temperature of an applicance may be maintained within a narrow range.

Another object of the invention is the provision of means for regulating the position of a contact arm of a thermostat switch mechanism wherein lost motion is eliminated whereby a thermosensitive element is enabled to accurately function at a proper temperature to actuate the switch mechanism and exercise precision control of the temperature of an applicance with which the switch mechanism may be used.

Another object of the invention is the provision of a switch means embodying a thermostat and an adjustable switch member, the adjusting means being of a character whereby the position of the switch member may be adjusted throughout the operating range of the thermostat so as to provide for precise and reliable control of the switch mechanism within the operating range of the mechanism.

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 l is an enlarged sectional view illustrating a form of switch mechanism of the invention;

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

Figure 3 is an isometric view of an element forming a part of the switch construction;

Figure 4 is an enlarged detail sectional view of a portion of the construction shown in Figure 2;

Figure 5 is an enlarged fragmentary detail view taken substantially on the line 55 of Figure 2;

Figure 6 is a view similar to Figure 5 showing a moditied form of actuating means for a switch member;

Figure 7 is a fragmentary detail View illustrating another form of the invention, and

Figure 8 is a sectional view taken substantially on the line 8-45 of Figure 7.

The switch mechanism of the invention is particularly adapted for incorporation in applicances such as electric irons, percolators, pressure cookers and the like, and it is to be understood that the use of the invention is contemplated with any appliances or devices where thermostatic control may be desirable or necessary.

Referring to the drawings in detail and first with respect to Figure 1, there is illustrated a portion of an appliance 10 which in the illustrated embodiment is the base or shoe of an electric iron containing a heating element 12. The switch means embodying the invention includes a plate or frame member 15 and a disk-like member 17 provided with a sleeve 18. Assembled upon the member 17 is a bimetallic, thermoresponsive element or thermostat 20 fashioned of two strips of metal joined or bonded together. The strips of metal have dissimilar coefficients of expansion whereby variations in temperature adjacent the member 20 cause flexure thereof. A relatively movable, contact-carrying switch member 24 has an opening to receive the sleeve 18 and a second contact-carrying switch member 26 provided with an opening for mounting on the sleeve 18. The switch member 24- is held in spaced relation in reference to the bimetallic element 20 and is insulated from the sleeve 18 by means of a washer or disk 25 of high-temperature-resistant insulating material. A connector or member 28 is also assembled upon the sleeve 18, the connector 28 being in engaging relation with the switch member 24 and insulated from sleeve 18 by an annular portion 29 formed on disk 25. A connector 32 is in engaging relation with the switch member 26. An insulating disk 3% is formed with a sleeve portion 31 to space the contact member 32 and switch member 26 from the metal sleeve 18. A disk 36 of insulating material is disposed between the switch member 26 and connector 32. The upper extremity of the sleeve 18 is swaged or spun over the plate or member 15 as shown at 40 to hold the assemblage of thermostat 20, switch arms 24 and 26, connectors 28 and 32 and insulating washers in an integrated unit. The sleeve 18 is of a dimension to receive a securing bolt 42 threaded into an opening 43 formed in the appliance base or other switch support or supporting means.

The bimetal thermoresponsive means or thermostat 20 is provided at its free or movable end with a member 45 formed of ceramic or other insulating material, The member 45 is formed with a head portion 46 and a kerf or peripheral groove 47 into which a portion of the bimetal element 20 extends to secure the member 45 to the element 20. The other extremity of the pin 45 engages the end zone of the switch arm 26. It will be apparent that as the two ditierent metals of the thermostat 20 have different temperature coefiicients, the position of the thermostatic element 20 is dependent upon temperature variations, and the changes in position under the influence of heat are transmitted through the pin 45 to the switch arm 26. The switch arm or member 24 is provided with a contact t and switch member 26 is provided with a contact 52.

A manual means is provided for regulating or predetermining the relative position of the switch arm 24 to establish a circuit for the appliance-heating unit 12 through the connectors 28 and 32 and power supply conductors 4'6 and 49 and also provides for varying the effective operating range of the thermostatically operated means. The supporting plate or member is formed with an opening adapted to receive a tenon 55 formed on a member 57. The member 57 is fixedly secured to the plate 15 by the swaged portion 58. The member 57 is provided with a threaded bore adapted to receive a threaded portion 59 of an element 60 forming part of the adjusting means. The element 60 is formed with a tenon portion adapted to extend through an opening formed in a horizontal leg 63 of a manipulating arm or means 64. The sleeve is swaged as shown at 66 in Figure 1 to fixedly secure the leg portion 63 to the element 60.

The lower end zone of element 60 is formed with a socket 68 which is preferably of a combined conical-andsemispherical shape or configuration as shown in Figure 4 to receive the semispherically shaped end zone 70 of a pin or switch-actuating member 72 formed of noncurrent-conducting material such as ceramic or lava. The switch arm 24 is formed to accommodate the lower end zone of the pin 72 in a manner to prevent its rotation and a shifting or change in position of the pin 72 with respect to its zone of engagement with the switch arm 2 Figures 2 and 5 illustrate in enlarged views one form of means of engagement of the pin 72 with the switch arm 24 to secure accurate and precise operation of the thermostat on the switch arm 24. As shown in Figures 1, 2 and 5, the switch arm 24 is formed with a generally rectangular opening 75, the opposite walls being indicated by numeral 73 in Figure 5. The metal forming the opposite walls 78 and the end walls 79 defining the opening is turned downwardly, providing flanges which are engaged with the lower end zone 86 of noncircular shape. As shown in Figures 2, 3 and 4, the ceramic or lava pin 72 is formed with a cylindrical body portion 86 terminating at its lower end in a wedge shape or noncircular cross-sectional configuration defined by the angular walls 84, the end being a generally rectangular shape 86 as shown in Figure 5. Thus, the pin 72 is provided with means engaging the switch arm 24 in a manner to prevent lateral and longitudinal displacement or rotation of the pin 72 with respect to the switch arm 24 at the zone of engagement of the pin 72 with the switch arm.

The semispherically shaped end 70 of the pin 72 nests in the socket 68 formed in the member 60. It is to be understood that the socket may be either spherically shaped or conically shaped as either form will receive and accommodate the end 70 of the pin. It is preferred, however, to form the walls of the socket 68 as shown, with conically shaped surfaces 87 and 83 joined with an intermediate, spherically shaped surface 89 as shown in Figure 4. With this form of socket a clearance space is provided at 90, and the bearing engagement between the pin and the socket is established at the spherically shaped surface 89. A film of lubricant may be applied on the spherical end 7% of the pin so as to minimize the friction between the element 59 and the pin 72 during rotation of the element relative to the pin. As the pin 72 does not rotate relative to the switch arm 24 and engages the arm at a particular zone without any lost motion or angular movement of the pin, the position of contact 50 may be accurately adjusted by rotating member 59 relative to the stationary sleeve 57. A suitable dial or indicator (not shown) is arranged for cooperation with the manipulating means 64 to indicate the relative position of the contact 50 with respect to contact 52 and the bimetal element or thermostat 20.

in the operation of the construction shown in Figures 1 through 5, the arm 64 is rotated to a desired position predetermining the temperature at which the contacts 56' and 52 will be engaged or separated by the flexure or distortion of the bimetal element 2%} under the influence of heat so as to regulate and control the operation of the heating means with which the switch mechanism is associated. The thermostat 29, at room temperature, is normally flexed downwardly, the head 46 of the member 45 engaging the upper surface of the base 10 or other suitable abutment; and in this position, the contacts 50 and 52 are engaged in circuit-completing position. The manipulating means or arm 63 is rotated to a position determined by the indicator (not shown) at a temperature setting desired for heating the appliance, and the conductors 43 and 49 are connected with a source of electrical energy. As the elements 12 become heated, the heat is effective on the bimetal element or thermostat 24) and upward deflection of the thermostat ensues. The member 45, carried by the thermostat 20, thereby engages the switch arm 26 and deflects the latter upwardly, thus effecting a separation of contacts 5t) and 52 when the appliance attains the temperature indicated by the position of the manipulating means 63 and cessation of electricity through the heating elements 12. Upon cooling, the thermostat is deflected downwardly, permitting the contact 52 to again engage contact 50, and electrical energy through the heating elements 12 is restored. By this means the temperature of the appliance is maintained within close limits.

Through the engagement of the rectangularly shaped end 86 of pin 72 in the rectangular opening 75, relative rotation between the pin '72 and switch member 24 is prevented, and contact 50 may be accurately positioned to predetermine the temperature at which the bimetal cl ement Ztl actuates the switch arm 26 through the medium of the ceramic pin 45 so as to interrupt the circuit of the heating elements.

Figure 6 is illustrative of a modified form of connection between a movable, contact-carrying switch arm and the manually adjustable means. In this form the switch arm 24' is formed with an elliptically shaped or oval opening 93 bounded by a downwardly extending flange or wall 94 of oval or elliptical shape, fashioned in a manner similar to the downwardly extending flange defined by walls 78 and 79 shown in Figure 5. A ceramic pin 95, having a circular body portion, is provided at one end with an oval or elliptically shaped configuration 96 reciprocal to the shape of the opening 93 and adapted to project into the opening. The oval-shaped section or end zone of the pin engaging in a correspondingly shaped opening in the switch arm 24 prevents rotative movement between the switch arm and the pin and avoids any lateral or longitudinal displacement of the pin relative to the switch arm 24'.

Figures 7 and 8 illustrate another form of connection between the adjustable switch arm and an adjusting means. In thisforrn, a contact-carrying switch arm ormember 24" equipped with a contact 50' is formed with a V-shaped depression 100 providing an apex zone 102. A ceramic or lava pin 104 similar in character to the pin 72 is provided at its lower end with a wedge-shaped configuration 105 which terminates in a rectilinear edge 106, nesting or engaging in the apex zone or depression 102 of the t -shaped configuration or recess in contact-carrying arm 24". The upper end zone of pin 104 is of semispherical configuration, substantially the same as the zone 70 of pin 72, and is adapted for engagement in the socket of the manipulating means 60 of the character shown in Figure 1.

Thus, engagement of the ceramic or lava pin 104 within the V-shaped depression 100, as shown in Figures 7 and 8, prevents any lateral displacement of the pin with respect to the contact-carrying switch member and prevents relative rotation of pin 104 with respect to switch member 24". The arrangement shown in Figures 6 through 8 may be embodied in the switch shown in Figure 1 in lieu of pin 72 and switch member 24.

The several forms of the invention provide means for preventing rotation of the switch member engaging pin relative to the switch member so that there is no relative angular movement, displacement or lost motion between the switch member and the pin which would cause wear of the parts with consequent impairment of the accuracy of operation of the construction. While several forms of the invention are disclosed herein, it is to be understood that the principles of the invention embrace the utilization of cooperating configurations of the .pin and switch member at their zones of engagement of a character preventing lateral displacement and rotation of the pin relative to the switch member.

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

I claim:

1. 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 arms for completing a circuit through said switch arms, a thermostat element disposed to be influenced by heat from the heating element, a member of insulating material disposed between the thermostatic element and one of said switch arms, a manually adjustable element having a socket formed therein, a pin formed of insulating material having one end engageable in the socket formed in said manually adjustable element, said pin being formed at its other end with a zone of noncircular cross section, the second of said switch arms being formed with a noncircular recess adapted to receive the noncircular end portion of the pin whereby said pin is restrained against rotation during adjusting movements of the manually adjustable element.

2. 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 arms for completing a circuit through said switch arms, a thermostat element disposed to be influenced by heat from the heating element, a member of insulating material disposed between the thermostatic element and one of said switch arms, a manually adjustable element having a socket formed therein, a pin formed of insulating material having one end engageable in the socket formed in said manually adjustable element, said pin being formed at its other end of a noncircular configuration in cross section, the second of said switch arms being formed with a zone of noncircular shape adapted to receive the noncircular end zone of the pin whereby said pin is restrained against rotation during adjusting movements of the manually adjustable element.

3. Switch mechanism having a relatively movable switch member, cooperating contacts for completing a circuit, one of said contacts being carried by the switch member, a manually adjustable element, a pin formed of insulating material having one end engageable with the manually adjustable element, said pin being formed at its other end with a zone of noncircular cross-sectional configuration, said switch member being formed with a noncircular depression to receive the end portion of noncircular cross-sectional configuration of the pin whereby said pin is restrained against rotation during adjusting movements of the manually adjustable element.

4. In combination, switch mechanism including a support, a contact-carrying switch arm mounted upon the support, a second contact arranged for cooperation with the contact carried by said arm, a bimetallic element carried by the support, means disposed between the bimetallic element and said second contact whereby fiexure of the bimetallic element under temperature change causes relative change in position of said second contact, a relatively movable element, a pin formed of insulating material disposed between said rotatable element and said first-mentioned switch arm, the configurations of the pin and switch arm at their zone of engagement being of noncircular reciprocal shape resisting rotative movement of the pin during relative movement of said element, said pin being disposed to transmit relative motion of the relatively movable element to the contact-carrying arm to adjust the initial position of the contact carried thereby for chang ing the thermic operating range of the switch mechanism.

5. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, and a strut member of insulating material having a spherically shaped end portion engaging the rotatable element, other end of said strut having a rectangular end portion, said second switch member having a recess engaged by the rectangular end portion of the strut member whereby rotational movement of said strut member relative to said second switch member is restrained 6. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit throngthe switch members, thermoresponsive means arranged to be moved upon variations in temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, and a strut member of insulating material engaging the rotatable element and said second switch member, an end zone of said strut member being formed with a noncircular cross-sectional configuration, said second switch member being formed with a zone of noncircular shape reciprocal to the shape of the noncircular end zone of the strut member and adapted to receive the noncircular cross-sectional configuration of the strut member whereby rotational movement is prevented between said strut member and said second switch member.

7. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, and a strut member of insulating material engaging the rotatable element and said second switch member, an end zone of said strut member being formed with a noncircular cross-sectional configuration, said second switch member being formed with a recess of noncircular shape to receive the noncircular end zone of the strut member.

8. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, and a strut member of insulating material engaging the rotatable element and said second switch member, an end zone of said strut member being formed with a wedge-shaped configuration, said second switch member being formed with a depressed portion to receive the wedge-shaped configuration whereby rotational movement is prevented between said strut member and said second switch member.

9. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, a strut member of insulating material engaging the rotatable element and said second switch member, and a socket formed in said rotatable element, one end of said strut member being formed with a spherically shaped portion engaging the socket in said element, the other end zone of the strut member being formed with a polygonally shaped portion, said second switch member being formed with a mating configuration to receive the polygonally shaped portion of the strut member.

10. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, a strut member of insulating material engaging the rotatable element and said second switch member, and a socket formed in said rotatable element, one end of said strut member being formed with 8 a spherically shaped portion engaging said socket, the other end zone of the strut member being formed with a rectangularly shaped portion, said second switch member being formed with a rectangularly shaped opening to receive the rectangularly shaped portion of the strut member.

11. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, a strut member of insulating material engaging the rotatable element and said second switch member, and a socket formed in said rotatable element, said socket having a spherically shaped surface portion, one end of said strut member being formed with a spherically shaped portion engaging the spherically shaped surface portion of said element, the other end zone of the strut member being formed with an oval-shaped portion, said second switch member being formed with an oval-shaped opening to receive the oval-shaped portion of the strut member.

12. Circuit-controlling means including, in combination, switch mechanism having two relatively movable switch members, cooperating contacts carried by said members for completing a circuit through the switch members, thermoresponsive means arranged to be moved upon variations in ambient temperature, means for transferring movement of said thermoresponsive means to one of said switch members, manually operable means for regulating the position of the second switch member, said manually operable means including a rotatable element, a strut member of insulating material engaging the rotatable element and said second switch member, and a socket formed in said rotatable element, said socket having a spherically shaped surface portion and a conically shaped surface portion, one end of said strut member being formed with a spherically shaped portion engaging the spherically shaped surface portion of said element, the other end zone of the strut member being formed with a polygon-ally shaped portion, said second switch member being formed with a similarly shaped opening to receive the polygonally shaped portion of the strut member.

References Cited in the file of this patent UNITED STATES PATENTS 2,321,338 Ulanet June 8, 1943 2,405,003 Woodman July 30, 1946 2,473,081 Vaughan June 14, 1949 2,478,503 Richmond Aug. 9, 1949 2,557,810 Bletz June 19, 1951

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