US3609622A - Thermostatic device and means for mounting same - Google Patents

Abstract

A thermostatic device including a housing containing a bimetallic disc or strip which engages a cruciform-shaped member, the cross arm of which engages a pair of pins which bear against leaf-spring-type movable contact arms while the stem of the cruciform-shaped member can form reset means providing a simple means for resetting the disc. Mans for mounting the thermostatic device include a plate supporting a plurality of springs, each spring in turn urging a housing of the thermostatic device in a direction away form the plate of the device so that when the plate is secured to a surface the temperature of which is to be sensed, the springs urge the thermostatic housing into contact with the surface.

Description

United States Patent [72] Inventors John Pringle [54] THERMOSTATIC DEVICE AND MEANS FOR 112, 337, 338, 339, 340, 348, 354, 363, 365, 367, 375, 380; ZOO/168C [56] References Cited UNITED STATES PATENTS 3,470,517 9/1969 Ohlemacher et a1 337/348 3,164,701 1/1965 Kirchhubel 337/354 X 2,538,080 1/1951 Bolesky 337/354 X FOREIGN PATENTS 286,193 8/1965 Australia 337/363 Primary Examiner-Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorneys-Harold Levine, Edward J. Connors, Jr., John A.

Haug, James P. McAndrews and Gerald B. Epstein ABSTRACT: A thermostatic device including a housing containing a bimetallic disc or strip which engages a cruciformshaped member, the cross arm of which engages a pair of pins which bear against leaf-spring-type movable contact arms while the stem of the cruciform-shaped member can form reset means providing a simple means for resetting the disc. Mans for mounting the thermostatic device include a plate supporting a plurality of springs, each spring in turn urging a housing of the thermostatic device in a direction away form the plate of the device so that when the plate is secured to a surface the temperature of which is to be sensed. the springs urge the thermostatic housing into contact with the surface PAT-ENTEDSEP28 |97l 3509522 sum 2 OF 3 I THERMOSTATIC DEVICE AND MEANS FOR MOUNTING SAME This invention relates to an assembly for a thermostat.

In some circumstances there is a need for a double pole single throw thermostat, so that both lines of a device a heater for example, can be isolated from the electrical source. According to one type of prior art thermostat, a bridge member interconnects a pair of transverse bridge members which carry contacts thereon cooperable with fixed contacts, the transverse bridge members being spring loaded by means of helical wire springs. However, these are subject to certain failings, one of the main problems being the difficulty of obtaining a substantially simultaneous break of the contacts, so that one contact will tend to pit much more than the other. A second objection is that the device described is unnecessarily complex, and yet a third objection is that the cost of the contacts (which are usually of silver or other expensive material) is high because of the use of four contacts in a single switch. The instant invention overcomes the above-noted shortcomings and accordingly comprises the apparatus hereinafter described, the scope of the invention being indicated in the following claims.

It is an object of the present invention to provide a two pole single throw thermostat having contacts which break simultaneously upon actuation of a thermostatic disc. Another object is the provision of a device which is relatively inexpensive, easy to assembly and of a relatively simple, uncomplicated nature, yet reliable in operation and easily calibrated. Yet another object is the provision of a thermostatic assembly comprising a plurality of thermostatic switches each of which is in firm thermal contact with a surface, the temperature of which is to be sensed.

In the accompanying drawings in which one of the various possible embodiments of the invention is illustrated,

FIG. 1 is a top plan view of a device made according to the present invention with the cover removed;

FIG. 2 is a bottom plan view of the FIG. 1 device with the thermostatic disc and disc retaining cap removed;

FIG. 3 is a cross-sectional elevation taken on lines 33 of FIG. 1 but including the cover, disc and cap;

FIG. 4 is a cross-sectional elevation taken on lines 4-4 of FIG. 3, also including the cover, disc and cap;

FIG. 5 is a plan view of an assembly showing the thermostatic device mounted on a support plate;

FIG. 6 is a front elevation of the FIG. 5 assembly;

FIG. 7 is a side elevation of the FIG. 5 assembly; and

FIG. 8 is a plan view of the support plate shown in FIGS. 5-7.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Turning now to the drawings, and especially FIGS. 5-8, support plate 10 is substantially rectangular in form but has a pair of parallel opposite upturned flanges, 11,12, the plate being provided with a pair of openings 14,16, through which is positioned cylindrically shaped disc- retaining cups 20,20 respectively, of disc-type thermostats. It will be understood that more than two openings could be provided if it were desirable to mount more thermostatic switches. Support plate 10 is provided with two pairs of apertures rm and bJz for each of the thermostats, each pair of apertures having extending between it a wire or leaf spring 18 which engages an out-turned flange 24 on the disc-retaining cap 20 of the thermostat. Spring 18 then urges the thermostat disc-retaining cap through the opening so that when the support plate 10 is clamped to a surface (not shown) which is to be sensed, the disc-retaining caps are urged by the respective springs into contact with the surface with a pressure which is a function of the deflection of the springs and can therefore be maintained within accurately defined limits. Reference may be had to FIG. 7 wherein flange 24 is shown in dotted lines showing the movement possible for such adjustment. Face 38 of the disc-retaining cap being adjacent to the disc constitutes the sensing medium, and since this will be urged into' contact with the surface the temperature of which is to be sensed by spring means 18 it follows that the disc will tend to occupy a position with a minumum air gap. If desired, for even quicker response to temperature changes, an aperture may be provided in face 38 to facilitate heat transfer from the surface to be sensed to disc 34.

The two switches are interconnected by a small bus bar 26 which in this embodiment is of L-shape and which is of small thickness so that differential movement can take place between the two housings of the two thermostats. This arrangement then makes possible a simple assembly wherein a single contact single throw thermostat 30 can be used for normal control of a heating means while the double-contact single-throw out of circuit both lines leading to an element for example. The double-contact thermostat can conveniently be of the type which, having snapped open circuit cannot be placed back into circuit except by depression of a reset button.

The double-contact single-throw thermostat in this embodiment incorporates a number of improvements over previous thermostats. This thermostat is a disc-operated thermostat wherein a concave disc 34 is retained in a disc-retaining cap 20 which is of cylindrical form having a stepped portion 36 near a flat face 38 and adjacent cylindrical walls 40 which terminate in flared flange 25 and outwardly extending radial flange 24 at the mouth of the cap. Indexing groove means 55 may conveniently be provided in flange 25 to facilitate assembly. The disc is in contact with the top end 42 of a stem of a cruciform-shaped member 44, the bottom end 46 projecting through cover 66 and constituting a reset button.

The cross portion 48a, 48b of the cruciform-shaped member 44 engages the upper ends of a pair of matched pins 52a,52b which are freely slidable in respective apertures 54a,54b, the lower ends of the pins engaging leaves of leafspring-type movable contact arms 56a,56b respectively. These arms have on each a contact 57a,57b respectively which engages and disengages a corresponding fixed contact 58a,58b in housing 50. The movable distal ends of the arms, however, carry silver or other low resistance metal contact members 57a, 57b which engage corresponding fixed contact members 58a,58b respectively on the housing, and the two conductors are broken each by a mating contact as the switch operates. By utilizing the matched pin arrangement it becomes possible to get substantially simultaneous opening of the two contacts, and this in turn greatly reduces the damage to contacts. Adjustment is achieved by merely changing the length of the pins. Alternative adjustment can be made by bending the leaf spring members by biasing overlying terminal members 60a,60b respectively mounted in rectangular parallelopiped housing 50. Further, stationary contact members 6la,6lb which mount stationary contacts 58a, 58b respectively, can be bent to effect desired calibration. Similarly, the dimension between the upper end of the stern part of the cruciform member and the upper ends of the pins can be exactly adjusted by having matched pins which are of length chosen to suit a particular switch. Cover 66 of electrically insulating material encloses the switch area.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above apparatus without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A two pole thermostatic switch comprising a base of electrically insulating material, three generally parallel bores extending through a portion of the base, a slot communicating with the three bores, the bottom wall of the slot forming a stop element, a thermostatic disc mounted in the base, cap means received on the base retaining the disc in place; primary mo tion transfer means comprising a cruciform-shaped member having an elongated stem with two opposite ends and a cross arm intermediate the two ends, the cross arm having two distal end portions, the cruciform member slidably mounted in the base in the slot with the stem in one of the bores, the stop element limiting movement of the cross arm with one end of the stem engageable with the disc; two movable contact arms mounted on the base and extending into a switch cavity formed in the base, and movable toward and away from respective stationary contact arms mounted in the base; two matched supplementary motion transfer pins slidably mounted in the other two bores in the base and extending between a respective distal end portion of the cross arm and a respective contact arm and adapted to transfer motion from the disc through the cruciform member to the respective movable contact arm.

2. A switch according to claim 1 in which a cover encloses the switch cavity, a hole is provided in the cover and the other end of the elongated stern of the cruciform extends therethrough to serve as areset button.

3. A switch according to claim 1 in which the switch cavity is formed within a portion of the base which is generally a rectangular parallelopiped while the disc is located on a portion of the base which is generally cylindrical.

4. A switch according to claim 1 in which an elongated terminal member overlies and is biased against each movable contact arm and extends into the switch cavity to permit calibration of each pole by bending the distal portion of the terminal member to change the bias of the portion against the movable contact arm.

Claims (4)

1. A two pole thermostatic switch comprising a base of electrically insulating material, three generally parallel bores extending through a portion of the base, a slot communicating with the three bores, the bottom wall of the slot forming a stop element, a thermostatic disc mounted in the base, cap means received on the base retaining the disc in place; primary motion transfer means comprising a cruciform-shaped member having an elongated stem with two opposite ends and a cross arm intermediate the two ends, the cross arm having two distal end portions, the cruciform member slidably mounted in the base in the slot with the stem in one of the bores, the stop element limiting movement of the cross arm with one end of the stem engageable with the disc; two movable contact arms mounted on the base and extending into a switch cavity formed in the base, and movable toward and away from respective stationary contact arms mounted in the base; two matched supplementary motion transfer pins slidably mounted in the other two bores in the base and extending between a respective distal end portion of the cross arm and a respective contact arm and adapted to transfer motion from the disc through the cruciform member to the respective movable contact arm.

2. A switch according to claim 1 in which a cover encloses the switch cavity, a hole is provided in the cover and the other end of the elongated stem of the cruciform extends therethrough to serve as a reset button.

3. A switch according to claim 1 in which the switch cavity is formed within a portion of the base which is generally a rectangular parallelopiped while the disc is located on a portion of the base which is generally cylindrical.

4. A switch according to claim 1 in which an elongated terminal member overlies and is biased against each movable contact arm and extends into the switch cavity to permit calibration of each pole by bending the distal portion of the terminal member to change the bias of the portion against the movable contact arm.

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