US2192633A - Surface thermostat - Google Patents

Description

Manch s, 1940. v o. BEAM 2,192,633

SURFACE THERMOSTAT y,

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1NVENTOR V/L y/wv 0. en/V BY ff... /...M @f 7M ATTORNEY5 Patented Mar. 5, 1940 UNITED ISTATES SURFACE THERMOSTAT Vilynn .0. Beam, Cleveland Heights, Ohio, assignor to The Bryant Heater Company, Cleveland, Ohio, a corporation of Ohio Application October 8, 1937, Serial No. 168,001

' 4 Claims.

This invention relates to a thermostat and especially to a thermostat of the surface type adapted to be clamped or otherwise positioned in proximity to a pipe or other member conveying or containingwater or the medium whose temperature is to be controlled.

The principal object of the invention is to provide a thermostat of the type mentioned which is highly efficient but simple in construction, ruglo ged, and easily applied to a hot Water pipe or similar member.

The invention may be further briefly summarized as consisting in certain novel details of construction and combinations and arrangements of parts which will be described inthe specification and set forth in the appended claims.

In the accompanying sheet of drawings,

Fig. 1 is a front view of a thermostat embodying my invention;

Fig. 2 is a vertical sectional view of the same;

Fig. 3 is a rear view of the same; and

Fig. 4 is a detail sectional View substantially along the line 4 4 of Fig. 2.

In this instance, the thermal responsive means consists of two bi-metal thermal elements which are arranged and which function in a novel manner to operate a switch which can function in different ways, as, for example, to control a valve which supplies gas or other fuel to the heat- 0 ing equipment.

In this case, the device includes a housing l0. in which is supported a suitable switch II adapted to control a circuit represented by conductors I2 which are shown as extending into the bottom of 'the housing. The switch members located in the case but not shown are operated through the medium of a vertically movable pin I3 extending up through the top of lthe case of the switch II. A switch of simple construction may be employed, such switch consisting of a movable contact blade engaged by the pin I3 and adapted to be moved toward or from a vstationary contact. Generally the switch is biased toward closed position and is opened by the depression of the pin I3, this method of operation being utilized when the switch is employed for the purpose of controlling a valve which in turn controls the supply of fuel to the burner or burners of the heating 50 equipment. However, there may be employed a reverse action switch normally biased toward open position and closed by the depression of the pin .s I3. A thermostat with a switch of this kind may be utilized, for example, in aunit heater to start a fan at a predetermined high temperature or to open the fan circuit when the temperature drops to a predetermined point.

The pin I3 is operated through the medium of a bell crank I4 pivoted at I5 on a suitable part of the switch and provided with an arm Ma eX- 5 tending horizontally over the pin I3 and with an arm Mb extending vertically.

The rear of the housing I0 is open and secured to it by screws I6 or otherwise is an adapter block I1 constituting in effect a part of the housing, 10 the outer face of the adapter block being rounded or otherwise shaped so as to engage the pipe or other heated member to which the device may be secured by a strap (not shown) which may be attached to the adapter by any suitable means 'l5 such as screws I8 engaging tapped holes in opposite sides of the adapter.

Although in some instances a single b-meta thermal element may answer the requirements by providing sufiicient movement toactuate the 20 switch, it is desirable, for obvious reasons, to have the thermostat small in size, in which event a single long bi-metal thermal element is not-feasible. I obtain compactness and the desired small size and still secure the required switch operat- 25 ing movement without complicated movement magnifying means by utilizing two bimetal elef ments which operate in a manner such that the effect of the movement of one is to enhance the movement of the other. ments are shown at I9 and 20 respectively in substantially parallel relation within the adapter I1.

At their lower ends these elements are riveted or otherwise secured at 2I (Fig. 3) to a support consisting in this instance of two blocks 22 one of 35 which spaces the elements apart, and the support or blocks 22 are in turn connected to the adapter by a thin metal torsion strip 23 fastened between its ends by the rivets or screws 2I to' the support 22' and at its ends fastened by screws y) 23h to opposite sides of the adapter.

The upper end of the rearmost and longer thermal element I9 bears against the rear end of a pin 24 which is secured ,to the upper end of arm Mb of the switchoperating bell crank Il. The upper end of the inner and shorter thermal element 20 is normally held stationary, being connected tothe forward end of an adjustable shaft 25 screwed into or otherwise fixed in a shaft 23 which is in threaded relation with the boss Illa on the front wall of the housing I0 and provided at-its outer end with a suitable adjusting knob 21 cooperating `with a dial or scale 28 (Fig. 1). The shaft 25 extends freely through' a hole in the upright arm Mb of the bell crank I4 and its inner These two bi-metal ele-'- 30` or rear end may be connected to the upper end of the thermal element 20 in any suitable way, but in this instance the upper middle part of the thermal element has a notch constituting a yoke which fits into an annular groove near the rear end of shaft 25. By turning the knob 21, the shafts 25 and 26 are turned and moved endwise, thus rocking the thermal element assembly to the right or left to a position at which it will function to actuate the switch at a different temperature than that at which the switch is operated with the thermal element in a different position corresponding to a different position of the adjusting knob 21. A sufficiently coarse pitch thread is employed on the shaft 26 and in the boss Illa so that with a limited movement 0f the adjusting knob 21.. a suiiicient endwise movement is imparted to the shaft 25 to give the thermostat a substantial operating range.

In operation, when the device is clamped to a pipe, such as a hot water pipe, substantially the temperature of the pipe is transmitted to the two thermal elements by conduction and convection. As the temperature rises, the upper end of the thermal element I9 is moved to the left as the same is viewed in Fig. 2, and this movement is imparted to the pin 24. At the same time the inner element 20 is exed, but since its upper end is normally held stationary by the shaft 25, the effect of the flexing of this element is to rock the thermal element assembly (this being permitted by the torsion strip mounting thereof) so as to increase the inward movement of the upper end of the thermal element I9. The two increments of movement, one due to the flexing of the element I9 by its temperature rise and the other due to the rocking of the assembly by the flexing of the element 20 by reason of its temperature rise, are suicient to move the pin 24 inwardly far enough to rock the bell crank I4 to open the switch II (or to close it as the case may be). As the temperature falls and the thermal elements I9 and 2U are cooled, the reverse action takes place.

To adjust the temperature at which the switch II is tripped, the knob 21 is turned to the right or left, depending upon whether the switch is to function at a higher or a lower temperature, the adjustment of the knob serving to rock the thermal element assembly and thus vary the normal position of the upper end of thermal element I9 with respect to the pin 24.

Thus it will be seen that the objects of the invention are attained t0 a high degree. Additionally, it might be mentioned that the thermostat may be mounted in any desired position as it functions in precisely the same manner regardless of how it is positioned, which is not the case with other surface thermostats in use at the present time employing mercury switches and therefore required to be very carefully and accurately mounted in either a horizontal or a vertical position.

While I have shown the preferred construction, I do not desire to be conned to the precise details shown and described but aim in my claims to cover all modifications which do not involve a departure from the spirit and scope of the invention.

Having thus described my invention, I claim: 1. A thermostat comprising a housing, a thermal element, a torsion strip support therefor, a switch in said housing, and means for transmitting movement from the thermal element to the switch'.

2. A surface thermostat comprising a housing having a portion adapted to be clamped to a pipe or the like,'a thermal element adjacent said portion, a torsion strip 4support therefor, a switch in said housing, means for transmiting movement from the thermal element to the switch, and adjustable means for varying the normal position of the thermal element.

3. In a thermostat of the character described, a housing, a circuit controlling switch therein, and a thermal element assembly comprising a base, a torsion strip supporting the same, two bi-metal thermal elements projecting from the base and having corresponding ends xed thereto, switch operating means between the free end of one of said elements and the switch, and normally stationary but adjustable means engaging the second thermal element.

4. In a thermostat of the character described, a housing, a circuit controlling switch therein, a bi-metal thermal element, a torsion strip mounted at its ends only in said housing, said bi-metal thermal element being attached to said torsion strip intermediate the ends thereof, and means between the free end of said thermal element and said switch for actuating the switch.

VILYNN o. BEAM.

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