US544363A

US544363A - Thermostatic instrument

Info

Publication number: US544363A
Authority: US
Publication date: 1895-08-13
Anticipated expiration: 1912-08-13

Description

(No Model.)

MARTIN. THERMOSTATIG INSTRUMENT.

No. 544,363. Patented Aug. 13,1895.

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UNITED STATES PATENT OFFICE.

'MORRIS MARTIN, OF MALDEN, MASSACHUSETTS.

' I'HERMOSTATIC INSTRUMENT.

SPECIFICATION forming part of Letters Patent N0. 544,363, dated August 13, 1895.-

Applieation filed June 5, 1893. Serial No. 476,609- (No model.)

dust and corrosion in the normal or inactive condition of the instrument and are exposed to the'direct action of the heat when in operation, thereby rendering instruments of this class more sensitive and reliable. The terminals referred to in thermostats of this class as now commonly constructed are inclosed in or concealed by a hood secured to the base of the instrument to prevent it being accidentally detached therefrom, and the said hood is now commonly made whole orsolid, without perforations or openings, to protect the contact members or terminals of the instrument from dust, corrusion, (he. The hood referred to has been provided with small perforations or holes to permit of the passage of heat to the inexpansible member of the thermostat, but in practice this construction has been found objectionable on account of the liability of the holes being closed, as when the ceiling of the room is whitewashed or painted, and because the holes, if not accidentally closed, permit of the entrance of dust into the hood, which collects on the terminals of the instrument and thereby prevents the electric circuit being closed when the instrument is operated by a rise in temperature, as by the breaking out of a fire.

In accordance with my present invention, the thermostatic instrument is provided with a hood-passively connected to the instrument, as will be described, and normally inclosing and protecting the active terminal of the instrument,'but which is rendered active to expose the said terminals by a rise in temperature. The hood is preferably composed of two parts or members, one part of which is firmly secured to the instrument and the other part of which is secured to the first part, preferably by a fusible connection or material. The stationary part or member of the hood is preferably provided with a substantially large opening, normally closed by the movable part or member, preferably made as a plate or disk. The plate or movable member of the hood when subjected to heat is released from the main or stationary portion of the hood, as will be described, and exposes the contact members Within the shell to the direct action of the heat, thereby rendering this class of instruments more sensitive and reliable in action.

The particular features in which my invention consists will be pointed out in the claims at the end of this specification.

Figure l is an under side View of a thermostatic instrument embodying my invention, showing the same as ready to be placed in operative position; Fig. 2, an under side view of the instrument shown in Fig. 1 with the plate or movable'member of the hood removed; and Fig. 3 a sectional detail, to be referred to.

The thermostatic instrument herein shown consists essentially of an expanding member a of any usual or well-known construction, preferably two metal strips having diderent rates of expansion, and a contact screw or terminal ct, with which the expanding member a co-operates when acted upon by heat.

The expanding member a is shown as secured to a metal post a and the terminal a is also secured to a metal post a both of which are supported by a metal plate a, secured, as by screws (1 to a base or support a of insulating material, the metal posts a a being insulated from the plate a and the latter being provided with arms a 0. through which are extended binding-posts a a, insulated from the plate a and electrically connected to the posts a a respectively. The thermostat just described isand may be of the well-known form and construction now commonly used on the Well-known Watkins automatic firealarm system.

In accordance with my present invention the contact members a a are normally protected from dust, corrosion, &c., by a hood, preferably composed of two parts b b, which may be of the construction herein shown.

The part b is herein shown asasubstantially annular rim or ring having diametically-oppositc notches b b to fit over the arm a a of the plate a. The part b is herein shown as a disk or circular plate having an annular flange or lip 12 which projects beyond or overlaps the edge of the openingin the rim or ring I), and is removably secured to said rim or ring by fusible materialsuch as solder, Wax, the. (Indicated in Fig. 3 by the heavy black line U.) The opening in the ring or rim 1') is preferably made substantially large, so that when uncovered by the plate or disk 11 a substantially large inlet is altorded for the passage of heated air to the contact member or terminal a.

In the normal or inactive condition of the instrument the movable member of the hood is secured to the stationary member by the fusible material, and the contact members a a are protected from dust, moisture, &c.; but when the temperature of the vicinity in which the instrument is placed rises above a certain or predetermined point the fusible material melts and permits the movable member to uncover the stationary member, thus exposing the expanding member a to the direct action of the heat, the said movable member in the present instance acting by gravity to uncover the opening in the stationary member of the cover.

My improved instrument enables the contact members or terminals to be thoroughly protected from dust, dirt, moisture, &1'C., when placed in operative position, and yet enables the instrument to respond to a substantially low temperature, as the active member of the thermostat is exposed to the direct action of the heatafter it has risen to a predetermined point. I prefer to construct the hood substantially as herein shown, but I do not desire to limit my invention inthis respect, as it is evident the hood may be made of other forms and constructions without departing from the spirit of my invention. For instance, the hood may be made in one piece, as now commonly constructed, and held in place by a fusible material. Furthermore, I do not desire to limit my invention to the use of a fusible material,

as the hood may be made of material expansible by heat and adapted at a normal tenr perature to cover the instrument, but at an abnormal temperature to expand and uncover the instrument, the expansion of the hood exposing the active terminal of the instrument to the direct action of heat.

It will be noticed that the hood for the instrument fits over and incloses, but does not form part of the instrument,anddoes not operate any part of the said instrument, but protects the instrument in the manner above set forth, and is passively connected thereto. The hood, while protecting the instrument from dust, &c., as described, is acted upon by the heat to expose the instrument to the action of the heat, and therefore can be used with any form of thermostat which is constructed in such manner as to be liable to be rendered inoperative or defective by dust, paint, whitewash, dzc.

I claim- 1. The combination with a thermostatic instrument, of a protective hood inclosing the instrument and passively oo-operating therewith and responsive to a rise in temperature to expose the said instrument without directly etlfecting the operation of the same, for the purpose specified.

2. The combination with a thermostatic in strument, of a protective hood independent of and disconnected from the active parts of the said instrument but normallycovering the same, and a fusible material to secure the said hood in operative position and operated by heat to permit the hood to expose the active parts of the said instrument without directly effecting the operation of the same, for the purpose specified.

3. The combination with a thermostatic instrument, of a protective hood inclosing the said instrument and passively cooperating therewith, the said hood having a movable member rendered active by an increase in temperature to expose the instrument to the action of heat but not to operate the same, substantially as described.

t. The combination with a thermostatic instrument, of a protective hood inclosing the said instrument and having a movable member independent of the thermostatic instrument and capable of movement without operating the said instrument, and a fusible mate rial governing the action of the movable member of the said hood, substantially as described.

5. The combination with a thermostatic instrument provided with circuit terminals or members, one of which is expansible, of a protective hood passively cooperating with the said instrument and consisting of a stationary member inclosing the instrument, and a movable member fusibly connected to the stationary member and capable of movement independent of the thermostatic instrument, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

MORRIS MAFL'IIN.

W itncsses:

J AS. I-I. CHURCHILL, J. MURPHY.

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