US2786116A - Thermostat for ice chests - Google Patents

Description

March 19, 1957 E. P. MASSON 2,736,115

THERMOSTAT FOR ICE CHESTS 'Filed May 18, 1954 INVENTOR: EMILE PIERRE MAssON,

HIS A6EN7'5.

My invention has for its object a thermostat for ice chests, characterized by its great simplicity and its high sensitivity, whereby it is far superior to the thermostats generally used for ice chests. This thermostat is designed on the principle of the expansion of water when freezing inside a yielding casing for a suitable cross-section.

It may be noticed as a matter of fact that, for the application considered, it is sufficient to adjust the temperature to a value near freezing point at a suitably selected point inside of the chest and, under such conditions, it seems to be of advantage to benefit by the sudden increase in volume when water is freezing. If it is preferred to select a slightly different temperature for adjustment purposes, it is possible to adjust the temperature of freezing by incorporating a small amount of a suitable liquid such as alcohol or glycerin.

On the other hand, it is possible, with such a thermostat, to modify within certain limits the temperature of adjustment either by shifting the thermostat inside the ice chest or else by inserting heat-insulating screens adapted to make said chest assume according to the case a temperature nearer that of the walls or that of the evaporator.

I will now describe by way of example, reference being made to accompanying drawings, a simple embodiment of my improved thermostat; its small size allows it to be easily housed inside all ice chests. In said drawrngs:

Fig. 1 is an elevational partly sectional view of the thermostat;

Fig. 2 is a cross section through line AB of Fig. 1;

Fig. 3 is a plan view thereof.

In the example illustrated, I resort to a metal tube 1 having an oval cross-section such as that of the tubes used in manometers, folded into U-shape and almost entirely filled with water. The two ends of the tube are fiat and closed by welding, as apparent at 1a. Metal blades 2 are secured to said ends and carry contact-pieces 4 which are insulated by means of sleeves and washers 3 made of insulating material. These contact-pieces cooperate in the clamping of insulated yielding wires 5 to provide connection between the latter and the contactpieces.

The contact-pieces are adjusted in a manner such that they engage each other when at room temperature and that their separation is produced only when the U-shaped tube opens and its arms are spaced by 2 to 3 mm. With a tube of the type illustrated which may assume a height of 70 mm. and a breadth of 60 mm. with an oval crosssection the major axis of which has a length of about 15 mm., the transformation of all the water contained therein into ice opens the arms of the U by about 6 to 8 mm. The separation is thus already performed when only part of the water has frozen. The adjustment is executed once and for all and provides a large safety margin which takes into account slight fortuitous deformations and the nited States Patent ice possibility of a wear of the contact pieces. The sole modification which may appear lies in the fact that when first starting the operation of the ice chest after a stoppage, the time required for the contact pieces to open is not constant; but all the following movements of the thermostat will be executed to either side of the new position of equilibrium thus defined. The system may thus be considered as proof against misadjustment. On the other hand, the stresses relied on are of the magnitude of a few hundred grams, which allows resorting to tungsten contact-pieces the wear of which is small and it is unnecessary to resort to special steps for ensuring a sudden opening. Lastly, the transmission of heat to the water through a metal tube and also the small size of the arrangement ensures a very low calorific inertia.

With a view to protecting the thermostat against shocks or fortuitous contacts, it is of advantage to locate it in side a small metal casing, perforated or otherwise, while leaving a suflicient clearance with reference to the latter so as to allow the U to open to a maximum; only the insulated wires pass out of the casing. The U-shaped tube may be held in position by very weak springs which prevent it from assuming an abnormal position or from being shaken during transportation. Such arrangements are easy to provide and require no special description.

An advantage of the embodiment disclosed resides in that if, for any reason whatever, the tube has been insufiiciently filled with water, it is easy to flatten it over a small further length so as to reduce its free volume to the desired value. Furthermore, the temperature at which the filling has been performed is not critical since the effects of expansion of water are negligible as compared to those arising through the formation of ice.

As already mentioned, it is possible to execute a thermostat for a temperature different from normal freezing point by incorporating to the water glycerin, alcohol or the like.

It is also possible, as disclosed, to modify the temperature of operation of the ice chest by shifting the thermostat inside the latter or by inserting heat-insulating screens in front of said thermostat. This may be performed in any suitable manner and no further description is required for such arrangements.

It should be remarked that the thermostat being at a temperature higher than that of the evaporator, there is no condensation of water to be feared, which condensation would be detrimental to its proper operation.

The direct action of the U-shaped tube on the contactpieces has been disclosed as the simplest embodiment of my invention, but it will be readily ascertained that by reason of the large movement obtained for the ends of the U-shaped tube, the deformations of the U may be transmitted mechanically outside the chest, for instance through a yielding cable.

What I claim is:

l. A thermostat, for use in controlling the electric switching mechanism of a refrigerator including two switch contacts, comprising in combination, a narrow hollow closed metallic tube filled with a body of water and disposed on the interior of said refrigerator, said tube being bent and carrying on one end portion one of said contacts, the other contact being mounted with relation to the second end of said tube, said first end being movable relative to said second end in response to temperature changes prevailing internally of said refrigerator near said tube causing changes of the volume of the body of water inside said tube thereby deforming said tube, whereby said contacts will within a certain temperature range be interengaged and within an other temperature range be disengaged.

2. A thermostat, for use in making and breaking an a electric circuit in response to temperature changes, comprising a closed hollow elongated tube bent to have its ends in a first position spaced apart for a predetermined distance, a body of liquid expanding upon freezing and contracting upon unfreezing disposed on the interior of said tube forcing one end to move relative to the other into a second position of increasing distance between said ends upon freezing of said liquid, said tube being operable to return said ends to said rest position upon unfreezing of said liquid, two contacts for said circuit, one contact being connected to an end of said tube, said contacts being operable to be interengaged in one of said positions and to be disengaged in the other position.

3. A thermostat, for use in making and breaking between two contacts an electric circuit in response to temperature changes, comprising in combination, a closed hollow U-shaped tube, one of said contacts being connected with relation to each end of said tube, one of the ends of said tube being movable relative to the other between a first position wherein said contacts are interengaged and, respectively, a second position wherein said contacts are spaced from each other out-of-engagernent, a body of substance disposed in the interior of said tube having the properties to be liquid above a certain temperature and to be frozen below that temperature and to expand upon freezing and, respectively, to contract upon unfreezing forcing upon expansion generated by freezing the ends of the tube from the first position to the second position, said tube being operable to return said ends upon unfreezing of said substance from the second position to the first position.

4. An element, for use in connection with the interengagement and disengagement of two electric contacts for making and breaking an electric circuit, comprising a closed hollow U-shaped tube, the ends of said tube being connected with relation to said contacts and being movable relative to each other between a first position of spacing apart from each other of said ends and, respectively, a second position of spacing apart of said ends for a distance different from that of said first position, a liquid substance disposed on the interior of said tube, said liquid substance having the properties to expand upon freezing and to contract upon unfreezing and forcing upon freezing the ends of the tube from the first position to the second position, said tube being operable to return said ends upon unfreezing of said substance from the second to the first position.

References Cited in the file of this patent UNITED STATES PATENTS Re 18,154 Hull Aug. 18, 1931 1,475,313 Newhard Nov. 27, 1923 2,187,258 Wood Jan. 16, 1940 2,453,851 Miller Nov. 16, 1948 2,622,923 Cobb Dec. 23, 1952

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