US2786990A

US2786990A - Control and indicating system for electric heating means

Info

Publication number: US2786990A
Application number: US504603A
Authority: US
Inventors: Russell F Garner
Original assignee: Robertshaw Fulton Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1955-04-28
Filing date: 1955-04-28
Publication date: 1957-03-26
Anticipated expiration: 1974-03-26
Also published as: CH345700A; GB786239A; DE1125094B; FR1151543A; NL206565A; NL92738C; BE547217A

Description

March 26, 1957 R. F. GARNER 2,786,990

CONTROL AND mnxcxrmc SYSTEM FOR ELECTRIC HEATING MEANS Filed April 28, 1955 L2 pvmwozz. 102 RUSSELL I. GARNER H18 ATTORNEY United States Patent CONTROL AND INDICATING SYSTEM FOR ELECTRIC HEATING MEANS Application April 28, 1955, Serial No. 504,603

11 Claims. or. 340-222 This invention relates to thermostatic control systems for electric heating means and more particularly to apparatus for indicating the relative position of the thermostat.

It is an object of this invention to indicate when a desired temperature condition is achieved.

Another object of this invention is to indicate when a thermostatic switch is in an on position.

Another object of this invention is to control an electrical indicating device by a switch means having a single operative connection with the thermostat.

In the preferred embodiment of the system, a pair of incandescent lamps are connected in parallel circuit to a source of electrical energy. A novel switching means comprising a pair of flexible switch arms which control energization of the parallel circuit and a third switch arm cooperating with one of said arms to control energization of one of said lamps is operatively connected to .a thermostat of a thermostatic control switch to be moved between open and closed positions in response to movement of the thermostat.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing which is a schematic showing of a control and indicating system embodying this invention.

Referring more particularly to the drawing, the control and indicating system is shown as comprising a cupshaped casing and provided with a cover 12 for the open end thereof which carries a centrally disposed threaded bushing 14. An adjusting screw 16, preferably provided with left-hand threads, is cooperable with the bushing 14 and carries on its exterior end the usual handle or dial 18 by means of which the adjusting screw 16 can be rotated.

Thermally responsive means in the form of an expansible and contractible diaphragm element 20 is carried on the interior end of the adjusting screw 16 and has an operating button 22 projecting therefrom. The interior of the diaphragm 20 is in communication with a capillary tube 24 which extends exteriorly of the cover 12 for communication with the usual bulb element 26 to be located in a medium requiring thermostatic control. As is well known, the temperature responsive means contains a fiuid which expands upon the bulb being heated and serves to actuate the diaphragm 20 sufficiently to operate the parts to be described.

The button 22 abuts a depression 28 formed in the face of a main actuating lever 30 of a snap-action means. The main actuating lever 30 is provided at one end with a knife edge 32 which is cooperable with a support 34 "ice projecting from the casing 10. The opposite end of the lever 30 is also provided with a knife edge 36 around which one end of a coil spring 38 is hooked.

A main control lever 40 of generally H-shaped configuration is provided with a knife edge 42 formed in the center wall thereof for receiving the opposite hooked end of the coil spring 38. The lower legs are each provided with a knife edge 46 for cooperation with suit able supports 48. Pairs of fixed contacts 50 are car ried by the casing 10 to be respectively cooperable with a double pole insulated contact bridge 52 carried by each of the upper legs of the main control lever 40. The

switch

50, 52 may be suitably connected in an electric circuit to control energization of a heating means. The assembly forms a snap-action means of well-known type and further description is hence unnecessary.

Should the temperature of the bulb 26 increase the diaphragm 20 will expand in a manner well known in the art to cause movement of the button 22 to the left to pivot the lever 30 on the support 34 to cause overcenter snap action movement of the lever 40 and opening of the switch 54 52. A decrease in the temperature of the bulb 26 will cause snap movement of the lever 46 in the opposite direction to cause closing of the switch 56, 52. The dial 18 may be calibrated to various settings and it will be obvious that rotation thereof serves to vary the position of the diaphragm 20 and thus the temperature at which the

switch

50, 52 will be closed. Clockwise rotation of the dial 18 increases the operating temperature of the device. Extreme counterclockwise rotation of the dial 18 places the device in an olf position which is shown in the drawing wherein the diaphragm 20 is in the extreme left position. Thermostatic devices of the character thus far described are well known in the art and further description is deemed unnecessary.

A housing 58 is fixed to one end of the casing 10 by a bracket 60 and encloses a switch means now to be described. A flexible arm 62 has one end extending between two of three insulating blocks 64 to project from the housing 58, the other end carrying a fixed contact 66 and being free for movement. The blocks 64 are attached to the interior surface of the housing 58 by a screw 63 which is suitably insulated from the arm 62 and the switch arms now to be described.

A second arm 70 is fixed between two of the three blocks 64 and has one end projecting from the housing 58, the other end carrying a contact 72 engageable with the contact 66. The

flexible switch arms

70, 62 are positioned to have their inherent bias tending to hold the contacts 7 2, 66 in an open position as shown.

A third and shorter arm 74 is positioned intermediate the

arms

62, 70 and is fixed between two of the blocks 64 to have one end projecting from the housing 58. The free end of the arm 74 is provided with a contact 76 which is engageable with a contact 78 positioned on a medial portion of the arm 70. The arm 74 is positioned with respect to the arm 70 to have its inherent bias tending to hold the contacts 76, 78 in closed position as shown. A stop 80 extends from the end block 64 and serves to limit movement of the arm 74 by its inherent bias as will later be described.

To impart movement to the arm 62, a pin 82 is slidably positioned in a bore 84 in the housing 58 to have one end engaging the arm 62, the other end projecting from the housing 58 to engage one end of a lever 86. The lever 86'is suitably pivoted on the bracket 60 by a pin 88 and has the other end thereof engaging one end of a pin 90. The pin 9% is slidably positioned within a bushing 92 suitably fixed in the wall of the cover 12 to have the other end thereof engaging an extending portion 94 of the lever 30.

Should the lever 39 pivot counterclockwise, the pin 90 will cause the lever 86 to pivot clockwise about the pin 88 to cause movement of the pin 82 toward the arm 62. The pin.82 being in eng gement with the arm 62 forces the arm .62 to flex to the leftcausing engagement of the contacts 66, 72. Further movement of the pin 90 will cause flexing to the left of both

arms

62, 70 with the contacts 66, 72 remaining in aclosed position. This also allows flexing to the left of the arm 74 by its inherent bias which maintains engagement of the contacts 76, 78 in a closedposition as shown. Should still further movement of the

arms

62, 70 occur, the arm 74 will flex further to the left to engage the stop 80 which will prevent further movement thereof and permit opening of the contacts 76, 78 upon still further movement of the arms 7.0, 62.

The end of the arm 62 is connected by the lead wire L1 to a source of electric current. The end of thearm 70 is connected in series with an incandescent lamp 96 by the lead wire L2 which completes the circuit to the source. The arm .74 is connected in series with an incandescent lamp 98 by a lead wire 100 which is connected to the lead wire L2 at terminal 102. Thus, the lamp 98 is in a parallel circuit with the lamp 96. It can be seen thatthe contacts 66, 72 control energization of the parallel circuit and lamp 96, and that the contacts 76, 78 control energization of the parallel branch containing the lamp 98.

Operation As the dial 18 is rotated from the off position as shown to a temperature setting, the lever 30 pivots counterclockwise on the support 34. This movement causes the pin 90 to rotate the lever 86 clockwise on the pin 88 to cause movement of the pin 82. Movement of the pin 82 causes movement of the arm 62 to the left to close the contacts 66, 72 thus completing the parallel circuit to energize the olT-on light 96 and the temperature indicating light 98. This condition is set to occur by adjusting the lever 86 to close the contacts 66, 72 when the lever 30 is halfway between its position when the dial 18 is in an off position and its position when the

contacts

50, 52 snap close.

As the dial 18 is rotated still more to the desired setting, the arm 62 moves still further to the left carrying with it the arm 70 with the contacts 66, 72 in their closed position. This allows movement of the arm 74 by its inherent bias to maintain the contacts 76, 78 in a closed position. As rotation of the dial 18 continues the lever 30 will cause over-center snap action of the lever 40 to close the contacts 59. 52 and permit energization of the heating means. As the dial 18 is rotated slightly past the snap action position, the arm 74 will engage the stop 80 and allow opening of the contacts 76, 78 to deenergize the temperature indicating lamp 98. Thus, when the thermostat is positioned at the desired temperature setting by-the dial 18 the contacts 66, 72 will be closed energizing the on-.ofl lamp 96, and the temperature indicating lamp 98 will not be energized since the contacts 76, 78 are open.

Since the

contacts

50, 52 are now closed, the bulb 26 will be heated by the heating means to cause expansion of the diaphragm 20 moving the button 22 to the left. Movement of the button 22 causes the lever 38 to pivot clockwise on the support 34 to permit counterclockwise Slightly before the 5t), 52, the contact 78 will engage the contact 76 energizing the lamp 98 to indicate that the desired temperature has been reached. Since at this point the arm 74 is still engaging the stop 86 and the

arms

62, 70 are held to the left with the contacts 66, 72 in a closed position by the action of the pins 82, 9t) and the lever 86, the continued movement of the lever 39 to the left to open contacts 59, 52 is less than that required to open contacts 66, 72. Thus, the lamps 9 6, 98 will remain on during the entire on and off cycling of

contacts

50, 52 due to the heating and cooling of the bulb 26 by the heating means. When the dial 18 is rotated to the off position, the lever 30 will be forced to the left by button 22 to allow the

switch arms

62, 70, 74 to assume their original position.

If the dial 18 is turned from a low temperature setting after a heating cycle to a higher setting, the lever86 will again pivot clockwise causing movement of the

arms

62, 70 to the left to open the contacts '76, '78 as "before. When the .desired temperature settingis reached .the contacts 76, 78 will close as before.

If the dial 18 is turned from a higher setting after a heating cycle to a lower setting the

arms

62, 70 will be moved sufiiciently to the right to cause opening of the contacts 66, 72 thus dcenergizing both

lamps

96, 98.

cycling position both lamps will be energized as above described.

It will be noted that since the cycling position of the lever 30 is constant for any temperature setting of the dial 18, the device will operate at any temperature setting withoutadjustment.

Although a preferred embodiment of this invention has been shown and described herein, it is to be understood that the -invention is not limited to the details of construction and arrangement of parts disclosed, but is to be interpreted as claimed.

It is claimed and desired to secure by Letters Patent:

-1. In a control system for an electric heating means, thermally responsive switch means movable between controlling positions in response to variations in a temperature condition for'controlling the supply of electric current to the heating means, electric indicating means, first switch means operatively connected to said thermally responsive switch means to be actuated when said thermally responsive switch means is placed in an operative position, second switch means to be actuated when said thermally responsive switch means is actuated in response to a change in the temperature condition, and means inmeans movable between positions for controlling the operation of said thermally responsive means, electric indicating means, first switch means operatively associated with said manually operable means to be moved between open and closed positions when said manually operable means is moved between said positions, second switch means to be moved between open and closed positions when said thermally responsive means moves between said controlling positions, means including said first switch means for actuating said second switch means between said positions in response to movement of said thermally responsive means between said controlling positions, and circuit means connecting said first and second switch means and said indicating means whereby said first and second switch means cooperate to control the energization of said indicating means.

3. In a control and indicating system for an electric heating means, thermally responsive means movable between controlling positions for controlling the supply of electric current to the heating means, manually operable means for controlling the operation of said thermally responsive means, electric indicating means, first switch means operatively connected to said thermally responsive means and movable between open and closed positions by operation of said manually operable means and for a predetermined distance beyond said closed position by operation of said thermally responsive means, second switch means operatively connected to said first switch means, said second switch means being movable between open and closed positions by movement of said first switch means beyond said closed position, and circuit means connecting said first and second switch means and said indicating means whereby first and second switch means cooperate to control energization of said indicating means.

4. In a control and indicating system for an electric heating means, thermally responsive means movable between controlling positions for controlling the supply of electric current to the heating means, manually operable means for controlling the operation of said thermally responsive means, electric indicating means, first switch means comprising a pair of flexible arms having contact means carried thereon, one of said arms being operatively connected to said thermally responsive means, second switch means comprising a third flexible arm and one of said arms of said first switch means, said second switch means having contact means carried thereon, said first switch means being operatively connected to said manually operable means and said thermally responsive means and movable between open and closed positions by said manually operative means and for a predetermined distance beyond said closed position by said thermally responsive means, said second switch means being movable between open and closed positions by movement of said first switch means beyond said closed position, and circuit means connecting said first and second switch means and said indicating means whereby said switch means cooperate to control the energization of said indicating means.

5. In a control system for an electric heating means, thermally responsive switch means movable between controlling positions fior controlling the supply of electric current to the heating means, manually operable means for adjusting the same for response to a desired temperature condition, electric indicating means, and switch means operatively associated with said thermally responsive switch means and including a plurality of contact means, means for moving one of said contact means between open and closed positions in response to movement of said manually operable means, and means including said one contact means for moving another of said contact means between open and closed positions in response to movement of said thermally responsive switch means, said switch means being operative to control energization of said indicating means.

6. In a control system for an electric heating means, thenmally responsive means, switch means for controlling energization f the heating means in response to move ment of said thermally responsive means, manually operable means for adjusting said thermally responsive means for response to a desired temperature condition, electric indicating means, a lever operatively associated with thermally responsive means, first switch means operatively connected to said lever, second switch means operatively associated with said first switch means, said second switch means being biased to a closed position, said first switch means being movable by movement of said lever in response to operation of said manually operable means to a closed position, said second switch means being movable between open and closed positions by said first switch means in response to movement of said lever by said thermally responsive means, and cir- Cult. means connecting said first and second switch means in parallel circuit to control energization of said indicating means.

7. In a control and indicating device system for an electric heating means having a source of electric energy, the combination comprising a casing having switch means therein for controlling the supply of electric current to a heating means, thermally responsive means operatively connected to said switch means for causing movement thereof in response to temperature variations, manually operable means for adjusting said thermally responsive means for response to a desired temperature condition, first and second indicating lamps connected in parallel circuit, first switch means for connecting said parallel circuit to said source, said first switch means being operatively connected to said thermally responsive means to be moved between open and closed positions in response to operation of said manually operable means and between said closed position and a predetermined position beyond said closed position in response to movement of said thermally responsive means in response to temperature variations, and second switch means in series with said second incandescent lamp and operatively associated with said first switch means to be moved between open and closed positions by movement of said first switch means between said closed and predetermined positions.

8. In a control and indicating device system for an electric heating means having a source of electric energy, the combination comprising a casing having switch means therein for controlling the supply of electric current to the heating means, thermally responsive means operatively connected to said switch means for causing movement thereof in response to temperature variations, manually operable means for adjusting said thermally responsive means for response to a desired temperature condition, first and second indicating lamps connected in parallel circuit, first switch means for connecting said parallel circuit to said source, said first switch means being operatively connected to said thermally responsive means to be moved between open and closed positions in response to operation of said manually operable means and movable in a closed position for a predetermined distance by movement of said thermally responsive means in response to temperature variations, and second switch means in series with said second incandescent lamps and operatively associated with said first switch means to be moved between open and closed positions by movement of said first switch means in said predetermined distance.

9. A control and indicating system as claimed in claim 8 wherein said first switch means are biased to an open position and said second switch means are biased to a closed position.

10. In an indicating device, the combination comprising a housing, first and second indicating lamps connected in parallel circuit, first switch means comprising first and second flexible switch arms mounted within said housing and having contact means carried thereon, and second switch means comprising a third flexible switch arm mounted within said housing and having contact means with said second flexible switch arm, said first switch arm being operative between open and closed positions of said first switch means to control energization of both said lamps in said parallel circuit and for a predetermined distance in said closed position of said first switch means to effect movement of said second switch means between open and closed positions to control energization of said second indicating lamp.

11. In an indicating device, the combination comprising first and second indicating lamps connected in parallel circuit, a first switch arm, a second switch arm biased toward said first switch arm and having contact means therewith, said first switch arm being movable relative to said second switch arm between open and closed positions of said contact means and for predetermined distance with said second switch arm in said closed position ofsaid contact means, a third switch 'arm biased toward said second switch arm and having contact means therewith, said third switch arm :being movable with .said second :switch arm in the closed position :0f the last said contact means, abutment means .engageable by said third switch arm in said predetermined distance of movement of said first and second switch'arrns .to effect opening of the last said icontactmeans, and circuit means connecting said switch arms With said indicating lamps whereby the first said contact means control energization References Cited in the file of this patent UNITED STATES PATENTS 2,433,124 Johnson Dec. 23, .1947 2,467,896 Lee -Apr. 1-9, 1949 2,527,767 Schmidt Oct. 31, 1950 2,641,750 Evans June 9, 195-3