Thermostatic control

A thermostatic control has a power element, the integral cup shaped portion of which functions as a range lever adjusted by direct contact with a cam member. The cup element amplifies motion as well as transmitting motion. The normally deflecting portion of the diaphragm part of the power element is held stationary. This arrangement eliminates the necessity of a separate lever range and a bias spring and a lever pivot interface and results in energy spring. A molded drive lever provides the following functions: (1) drive switch mechanism lever; (2) a cut-in adjustment; and (3) a cut-out adjustment. The latter two functions are obtained without effect on the trip points of the load-controlling switch.

BRIEF SUMMARY OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvement in motion transmission mechanism 
particularly for such mechanism incorporated in thermostatic control 
switches. An object of the invention is to provide a low cost and a highly 
reliable and accurate thermostat. 
2. Description of the Prior Art 
Thermostats of this type are described in U.S. Pat. Nos. 2,314,191; 
2,314,240; 3,135,849; and 3,241,381. The thermostats described in such 
patents include a thermal responsive power element operating in response 
to changes in vapor pressure brought about by changes in temperature. The 
mechanisms of these patents require a multiplicity of separately acting 
levers and springs to drive the operating lever of the snap action 
mechanism in opposite directions. None of these or any other patents now 
known to applicant teach that the operating lever is a fundamental part of 
the power element and also determines the range adjustment. Furthermore, 
in these and other patents known to the applicant the cup of the power 
element is stationary whereas in this invention the flexible member or the 
displacement diaphragm is held stationary and the cup is movable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The basic components of the thermostatic control embodying the present 
invention are described in detail in Kuhn et al U.S. Pat. No. 3,241,381. 
Only those components which vary in their structural details from those so 
described will be described herein. A molded base 10 provides the mounting 
for the various components of this thermostat. A thermo-responsive power 
element 12 has an integral cupshaped portion 14 which forms a wall of the 
diaphragm chamber of the power element. This cup-shaped portion 14 
functions as both a motion amplifier and as a range lever, thus 
eliminating some of the levers found in the prior art. 
A flexible diaphragm 16 is suitably secured in sealed relation to the 
cup-shaped portion 14 to form an enclosed diaphragm chamber. A capilliary 
tube 18 is mounted in a tube guide 20, which tube guide can be either on 
the bottom of the molded base 10 or within the base 10. The inner end of 
the capilliary tube 18 is sealed to an opening in the central portion of 
the diaphragm 16. The tube 18 is secured to the molded base and forms the 
support for the diaphragm 16 and for the entire power element 12. The 
thermo-responsive power element 12 and the capilliary tube 18 are charged 
in the customary manner with a vapor pressure forming gas such as Freon 
F-22 or F-12 or methyl chloride all in accordance with the teachings of 
Kuhn et at U.S. Pat. No. 3,241,381 and Smith U.S. Pat. No. 2,751,935. The 
cup-shaped portion 14 is fulcrumed on the interface between an adjustable 
cam 22 (see FIGS. 4 and 6). The cam 22 is movably adjusted by a knob 24 to 
determine the range within which "cut-in" and "cut-out" takes place. 
In performing its function as a range lever the portion 14 is provided with 
spaced upstanding ears 26 to which is pivoted a molded combination lever 
28 (see FIG. 5). The combination lever 28 has spaced integral upstanding 
flanges 30 which are provided with apertures into which pivot studs 32 on 
the ears 26 seat to form a pivotal connection between the portion 14 and 
the combination lever 28. As the portion 14 is moved upwardly due to the 
downward portion of the diaphragm 16 against its relatively fixed center 
portion as held by the capillary tube 18, the combination lever 28 will 
swing upwardly about a lost motion adjustment 36 which is factory set and 
calibrated to balance the point at which the expansion and contraction of 
the power element will cause a flapper spring 38 to move over dead center 
to snap closed or snap open the contacts of the switch as taught by the 
prior art made of record herein. 
The calibration of the lost motion adjustment 36 can be made by a cut-in 
screw 40 and a cut-out screw 42 or by a single screw 44 (see FIG. 3) 
having spaced parallels and opposed surfaces which have an interface 
connection with knife-like pivots 46 on the combination lever 28 (see 
FIGS. 3 and 5). 
The arrangement just described eliminates the necessity of a separate range 
lever and energy spring and a biased spring and lever pivot interface. 
This elimination results in energy saving as well as making a more 
reliable and accurate operating unit. The molded combination lever 28 
provides the following functions: 
1. to drive the switch mechanism; 
2. a cut-in adjustment; and 
3. a cut-out adjustment. 
Also this arrangement because of fewer parts lowers the manufacturing cost 
of the thermostat and makes it more reliable and accurate than those of 
the prior art.