Improvements in and relating to Thermostatic Electric Switches or Pushes.
Year: 1899

page_text: Date of Application, 5th Dec., 1899-Accepted, 20th Jan., 1900
ALL DIE DIECIFICATION.
[Communicated from abroad by the AUTO-PROTECTIVE APPLIANCE COMPANY, of
West Virginia, having its principal place of business at 103, State Street,
Boston, Massachusetts, United States of America, Manufacturers of Ther-
mostatic Push-buttons.]
Improvements in and relating to Thermostatic Electric Switches or
Pushes.
I, GEORGE HARRISON, Chartered Patent Agent, of the Firm of D. Young & Co.,
of 11 & 12, Southampton Buildings, London, W.C., do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu
·larly described and ascertained in and by the following statement:-
.
This invention relates to push-buttons adapted to be operated for ordinary
signaling purposes, and containing thermostatic devices arranged to actuate the
circuit upon an abnormal increase in temperature. It is the object of this inven-
tion to make devices of this kind of an indestructible character. Heretofore,
fusible substances have been employed in the thermostatic portion of the devices
of this character, and when an increase in temperature has caused an operation
of the device, the latter is rendered temporarily useless because of the melting
of the fusible substance and the renewal or repair of the thermostat is necessary
in order to place the device in condition for operation again. This invention
consists in the improvement which shall now be described and claimed.
Of the accompanying drawings, forming a part of this specification:-
Fig. 1 represents a top plan view of a push-button constructed in accordance
with this invention.
67
Fig. 2 represents a plan view of the same, with the cap and button removed.
Fig. 3 represents a section on line 3-3 of Fig. 2.
Fig. 4 represents a section on line 4-4, of Fig. 2.
The same reference characters indicate the same parts in all figures.
Referring to the drawings (Figures 1, 2, 3 and 4), a is a base, which may be
omposed of a suitable insulating substance, such as vulcanized fibre or rubber
r wood, and b is a cap of hemispherical form screwed to the base a in the ordinary
nd well-known manner. C, clare the terminals of the circuit, which are carried
hrough the base a and connected with two metallic contact members d d¹, attached
the base by screws &². The members are composed of spring metal
nd are bent around so as to bring their ends into proximity at two places, the
nds 2. 3, being normally separated, and adapted to be brought in contact by de-
ressing the free spring end 3 upon the end 2, and the ends 4, 5, being normally
parated and adapted to be brought into contact by depressing the free spring
d 5 upon the end 4.
A flanged button e of insulating material projects through the central aperture
the cap and rests upon the free end 3 of the outer member d
D...

page_text: 1
said button inwardly, contact between the ends 2, 3, is produced, and the circuit
closed as usual in push-buttons.
f is a chamber or receptacle composed preferably of metal and attached to the
base a by means of screws fl f¹, blocks ff2 of insulating material being inter-
posed between the base and the edges of the chamber, in order to raise the latter
above the base. The upper wall 6 of the chamber f is convex in form, and the
under wall thereof is concave and made very thin and flexible. The thermo-
static action of the chamber f is produced by placing a suitable volatile substance
or substances, such as a hydro-carbon liquid, within the chamber, the latter being
then sealed tight by securely attaching the upper and lower plates 6, 7 along
their edges. The free end 5 of the inner member is brought up underneath
the chamber f, in contact with its lower wall 7. When the temperature of the
space or apartment in which the push-button is located increases to a sufficient
extent to vaporize the volatile liquid contained in the chamber f, causing its
lower side to bulge downwardly, the end 5 of the contact member d' is brought
into contact with the end 4 of the member d, and the circuit is closed, causing
the actuation of a bell or other alarm device placed in the circuit. When the
temperature again decreases, the lower wall of the thermostat assumes its normal
position, and allows the contacts 4, 5 to separate and break the circuit.
It will thus be seen that the thermostat can at any time be tested by bringing
a source of heat, such as a lighted match, in proximity to the push-button, and
causing the actuation of said thermostat, the latter returning to its normal con-
dition when the source of heat is removed. This feature of indestructibility
gives the device an advantage over devices of similar character employing fusible
substances to keep the contacting members in their normal positions, since as
herein before stated, the melting of said fusible substances makes the thermo-
stat temporarily useless.
In order to provide free access of the outside air to the interior of the casing,
the cap is provided with perforations 61 61.
It is obviously within the scope of the invention to provide other arrangements
of the contacts in accordance with well-known circuit systems. For instance,
the thermostat might be employed to keep a circuit normally closed, instead of
normally open as shown.
The advantage of relative indestructibility obtained by the use of the metallic
thermostat above described, consisting of a flexible-walled metal chamber and
a volatile substance therein, may be obtained by the employment of any other
suitably constructed metallic thermostatic device adapted to be deflected by a
change of temperature.
It is obvious that the thermostatic device may be arranged to be operated by
a decrease in temperature, 80 that its contraction will act on an
electric current to give an alarm. When thus arranged, the device would be
useful as an alarm for incubators, conservatories, etc., where a decrease of tem-
perature below a predetermined degree is to be avoided.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent I declare that what I claim is:-
1. A device of the character specified, comprising a base, circuit terminals
fastened thereto, two contact members each connected to one of the terminals,
a thermostat adapted to operate automatically to move one of said members into
contact with the other member, and a push-piece movable independently of said
thermostat and adapted to be manually operated to engage and move one of said
members into contact with the other member, substantially as described.
2. A device of the character specified, comprising a base, circuit terminals
fastened thereto, inner and outer movable contact members mounted on the base.
a metallic thermostat interposed between the two members and adapted to act
on the inner member, and a push-piece adapted to act on the outer member.

page_text: 3. A device of the character specified, comprising a base, circuit terminals
fastened thereto, a metallic receptacle having a flexible inner wall supported
above the base, said receptacle containing a volatile substance, an outer movable
contact member affixed to the base and having a free end projecting above the
said chamber, and an inner movable contact member affixed to the base and
having a free end projecting below the chamber in contact with the flexible
inner wall.
4. A device of the character specified, comprising a base, circuit terminals
fastened thereto, two contact members each connected to one of the terminals,
a thermostat adapted to operate automatically to move one of said members into
contact with the other member, a push-piece movable independently of said
thermostat and adapted to be manually operated to engage and move one of said
members into contact with the other member, and a perforated cap secured to
the base in which said push-piece is mounted, said cap enclosing the thermostat
and the two members, substantially as described.
5. A device of the character specified, comprising a base, circuit terminals
fastened thereto, inner and outer movable contact members mounted on the
base, a metallic thermostat interposed between the two members and adapted
to act on the inner member, a push-piece adapted to act on the outer member,
and a cap formed with perforations in which the push-piece is mounted, said
cap secured to the base and enclosing the thermostat and the two members.
Dated this 5th day of December 1899.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.