US2498988A - Thermostatic control mechanism - Google Patents

Description

Feb. 28, 1950 W. C. EDEN El' AL THERMOSTATIC CONTROL MECHANISM Filed Aug. 2, 1946 W/LL/AM C. EDE/V 1N VEN TORS RLro/v w BONDURANT www@ ATTORNEYS 'Patented Feb. 28, 1950l THERMO-STATI() CONTROL MECHANISM william c. Eden. am cleveland, and Carlton W. Bondurant, Euclid, Ohio Application August 2, 1946, Serial No. 688,152

` s claims. (ci. zoo- 137) 1 This invention relates. to improvements in thermostatic control mechanism. While the in- .vention is susceptible of more or less general ap'- plication, the illustrated embodiment is intended primarily for regulating means for heating liquid .in a container so as to maintain its temperature constant within close limits. The mechanism may be set however to operate at any selected temperature within a given range.

One of the objects of the invention is the provision of mechanism of the character stated which shall be of simple construction and yet sensitive and accurate in operation.

Another object is the provision of means to prevent damage to the working parts in the event that the apparatus is subjected to a temperature considerably higher or lower than that at which the mechanism is intended to operate.

Another object is the provision of mounting means for an electric switch and a switch operating lever which shall maintain those parts in the same relative position throughout a considerable range of temperature adjustment.

Other objects and features or novelty will appear as we proceed with the description of that embodiment of the invention which, for the purposes of the present application we have illustrated in theaccompanying drawing, in which Fig. 1 is a plan view partly in horizontal sectionfshowing our control mechanism attached to a side wall of a liquid container.

Fig. 2 is a vertical sectional view taken substantially on the line 2-2 of Fig. 1.

Fig. 3 is an outer end view, partly in section approximately on the line 3-3 of Fig. 2.

Fig. 4 is a view partly in section approximately on the line 4-4 of Fig. 2.

Fig. 5 is an inner end view of the unit looking in the direction indicated by the line 5-5 of Fig. 2, and

Fig. 6 is a wiring diagram.

In the drawing III represents a side wall of a liquid container, the contents of which are to be maintained at a selected temperature, generally a temperature above room temperature. The apparatus includes a casing for the control mechanism, and this casing preferably is formed partially of a casting which provides an upper wall 2 having a bore I8 which extends into the interior of the casing. At one end post I'l is counterbored to receive an end of a tube I9 which constitutes one element of the thermostat. Tube I9 and post I'I are held together by suitable means such as a snug iit and a line of solder 2U.

In mounting the apparatus upon a liquid container, a hole is bored through a side wall of the container and the post I1 is projected through that hole. A nut 2I is then applied to the threaded post, a packing ring 22 being disposed between the casting and the container wail. When the nut is turned up tightly the apparatus will be securely fastened to the container and the latterwil be sealed against the egress of liquid.

The other extremity of tube I9 is open when the parts are assembled, and the rod 24 of the thermostat may be inserted through it. This rod is threaded at one end as shown at 25 in Fig. 1 to receive a nut 26. This nut is turned down more or less, depending upon the particular use intended for-the unit, and is then soldered to the tube as indicated at 21.

The casting II, I2 comprises a pair of spaced i webs 28 which join the walls II and I2, and at their inner ends are widened to form bearing blocks 29. These blocks are bored to take a pintle 30, upon which is pivotally mounted between the blocks a bell crank lever 3| having a long arm 32 and a bifurcated short arm 33. One end of rod 24 enters the casing and is iiattened as shown at 25. A short pin 34 projects through the bifurcations 33 of the bell crank and the ilattened end 25 of the rod to form a pivotal connection between these two parts.

On the pintle30 outside the blocks 29 there are pivotally mounted the side walls of a sheet metal bracket 35 which is U-shaped in cross-section, as clearly indicated in Fig. 3, the cross member of the U being relatively short, as indicated at 36 in Fig. 2. Bracket 35 provides the mounting means i'or a switch housing 31 which may be secured to the parallel walls of the bracket by fastenings 3B. A considerable space is provided between the housing 31 and the cross member 36 of the bracket.

The long arm 32 of the operating lever vworks l within this space, and the free end of the arm is beveled oil at 39 in order to increasethe possible throw of the lever. The tube I9 is formed of metal with a high coefficient of expansion, brass` for example, while the rod 24 has a relatively low coeiiicient of expansion; being formed for example of Invar. An increase in temperature expands the-tube I9 and exerts a pull on the rod 24, which swings bell crank lever 3'I clockwise,

causing it topress on a button projecting from the switch housing. This pressure opens the switch. The switch being open, a decrease intemperature contracts tube I9 which causes rod 24 to push against the short arm of the bell crank.

moving the latter counterclockwise or away from 42 can move bracket 35 counterclockwise is limitedtby abutment means in the form of a pin 44,- which is threaded in wall I I and 'engages the cross member 36 of the bracket. We cover wall I I with A cable containing conductors 66 and 66 may .enter the casing from one side through an opening I6.' and a cable containing- conductors 68 and 10 may enter from the opposite side through the other opening I5. The casting is providedwith tapped holes 11 to receive'setscrews for securing these cables in place.

The walls of the casing, other than the walls II and I2 formed by the casting. may be of sheet metal attached to the casting by fastenings 15 or otherwise. In order to hold the block 51 in position lips 96 and 61 are struck up from certain of the sheet metal walls of the casing.

The operation of the unit, it is believed, will be obvious to those skilled in the art. The unit '.may be employed in various connections, one

a sheet metal plate 46 attached to the wall by fastenings 46 and provided with graduation marks 41 surrounding a hole 46 in the plate through which the pin 44 projects. Above the plate 45 there is secured to a reduced diameter outer portion of pin 44 a turn button 49 with a. pointer 5I) which passes over the graduation marks 41 in swinging from one position to another. 'Ihe turn button may be secured to the pin 44 by a setscrew 5|. A spring 62 surrounding the pin and compressed between -the turn button and the plate 45 serves to exert a pull on the pin suillcient to prevent any lost motion when the direction of rotation of the pin is reversed. The spring also adds friction tending to prevent accidental movement of the turn button. 'I'he graduation marks 41may indicate degrees of temperature. A pin 63 set into, the wall II serves to limit the movement of the turn button to an arc somewhat less than 360. Adjustment of the turn button 49 moves the switch button "toward or away from the long arm 32 of the operating lever, and thus regulates within a limited range the temperature at which the switch is opened or closed. Obviously the arm 32 of the lever may swing a considerable distance tc the left, as viewed in Fig. 2, without aiecting the switch in any way, while movement to the right from the illustrated position after operating the switch merely swings the whole bracket and switch assembly away from abutment 44 against the action of spring 42. Hence possible damage to the working parts because of excessively hot or cold climates, such as might be encountered in shipment of the unit, is effectively prevented. Connections for electrical conductors entering the switch housing $1 are indicated at 55 and 56.

For convenience in making the necessary electricalconnections we provide a block 51 of insulation having three sockets 56, 59 and 6B within which are mounted metal sleeves 6I for the reception of wires, these sleeves being perforated and threaded to take setscrews 62 for mechanically and electrically joining the wires in the respective sleeves.

In Fig. 6 we have shown a wiring arrangement by means of which control of a gas heater may be effected. The mechanism may be used however to perform other duties. 65 and 66 are conductors which may be connected with line wires, v65 being mounted in socket 58. Conductors 61 and 68 extend from the terminals 55 and 56 of the switch housing to the sockets sa and so, while conductors 69 and 1I! extend from sockets 59 and 6I! through a solenoid 1I which, when energized, acts through an armature 12 to open a valve 13 in a gas conductor 14 which may feed a gas burner for heating the liquid in the container in connection with which the apparatus is employed.

particular application being the maintenance'of a desired temperature of water in chicken scalding pans or tanks. The disposition of the control casing in a horizontal position with the regulating knob on top is especially convenient in a unit of this character.

The formation of the casing partially as a casting having two walls upon which the moving parts of the unit may be mounted, and embodying a post by which the unit may be mounted upon the container with which it is to be used,

is a valuable feature of the invention. The provision in this same casting of openings through which the necessary electrical conductors may enter the casing is also useful and important. Furthermore the whole assembly may be completed before the remaining walls of the casing are attached to the casting, the block 51 being mounted in the sheetl metal part of the casing before the latter is secured to the casting.

'I'he relative lengths of the tube I9 and rod 24 are so selected, and the nut 26 so adjusted, that at the middle of the desired range of temperatures for a particular purpose the long arm 32 of the operating lever will stand substantially parallel to the rod and tube. At that position any movement of the rod 24 in either direction will produce maximum movement of the lever. Since .to the changing angularity of the short arm of the lever with respect to the rod 24 as the pointer 50 moves in one direction 'or the other from the central position illustrated in Fig. 1. Over and under runs of temperature in service or shipment do not strain the switch or other operating parts, and when normal operating temperature is reestablished the switch is returned .to its preadjusted position.

Having thus described our invention, we claim:

l. In thermostatically operated control mechanism, an electric switch, an operating lever therefor, a common pivotal mounting for said switch and lever, an abutment to prevent movement of said switch toward said operating lever, and yieldable means acting upon said switch exclusively for holding it againstsaid abutment, whereby movement of said operating lever toward said switch and beyond the point of switch operation will swing said switch about said pivotal 'Y s,4os,oes

s. mounting against the action of said yieldable means.

2. In thermostatically operated control mechanlsm, an electric switch, a housing therefor, a`

sheet metal bracket having parallel walls between which said housing is mounted. a bell crank operating lever having a long-arm disposed between said parallel walls, said bracket and lever being independently mounted to swing about a common axis, means for holding said bracket against movement in one direction, thermostatic means for rocking said lever to operate said switch, -a

-pivotal connection between s aid thermostatic means and said lever for positively moving the latter in either direction, and adjustment means functioning independently oi said lever for moving said bracket through a limited arc about said axis 3. In a thermostatica'lly operated control mechanism, an electric switch, a housing therefor, a sheet metal bracket of U-shaped cross-section between the parallel walls oi which said housing is mounted, said housing being spaced from the cross member of the bracket, a bell crank operating lever having a long arm disposed between said parallel walls, said bracket and lever being independently mounted to swing about acommon axis, an abutmentA to limit movement oi' said bracket toward said long arm, yieldable means for holding the cross member of said U-shaped bracket against said abutment, thermostatic means for rocking said lever to operate said switch, pivotal connection between said thermostatic means and said lever i'or positively moving the latter in either direction, and means independent of said lever for adjusting said abut ment and thereby moving said bracket through a limited arc about said axis, whereby movement of said long arm beyond the point of switch operation will swing said bracket about said common axis against the action of said yieldable means.

WILLIAM C. EDEN.

CARLTON W. BONDURANT.

REFERENCES CITED 'The following references are of record in the tile of this patent:

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