Electricity: magnetically operated switches – magnets – and electr – Permanent magnet-actuated switches – Thermomagnetic
Patent
1982-03-01
1983-11-08
Broome, Harold
Electricity: magnetically operated switches, magnets, and electr
Permanent magnet-actuated switches
Thermomagnetic
335146, H01H 61013
Patent
active
044145209
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates in general to thermostats and in particular to a new and useful thermostat utilizing a magnet.
Thermostats are known which have a heat sensitive body of ferromagnetic material and a movable magnet cooperating therewith. Biasing means are provided which act between a movable first contact designed as a contact tongue and the magnet. The spring means are arranged to exert a force on the contact tongue with a contact making action against a second contact in one position of the magnet, and a contact opening action away from the second contact in another position of the magnet.
Due to an aspiration towards a safe and reliable contact, such thermostats have a tendency to become complicated and thereby expensive, delicate and/or space requiring structure.
The object of the invention is to provide a thermostat of the kind indicated by way of introduction, which is characterized by a very simple and thereby cheap, reliable and compact structure, while maintaining a very safe and reliable capacity for contact making.
SUMMARY OF THE INVENTION
The object of the invention is achieved by providing the thermostat with a spring tongue acting as the spring means which, in a bent condition, is biased between the contact tongue, near a contact portion thereof, and the magnet.
Accordingly, another object of the invention is to provide a thermostat which comprises a housing, a heat sensitive body of ferromagnetic material connected to the housing and having reduced magnetic attraction with increased temperature, magnet means including a permanent magnet movably mounted to the housing from an attracted position with respect to the body to a spaced position with respect to the body, the magnet means including an outwardly extending level element, a fixed contact connected to the housing, a movable contact movably mounted to the housing and biasing means engaged between the movable contact and the lever element for biasing the magnet means toward its spaced position with respect to the body, the biasing means connected to the movable contact to bias the movable contact against the fixed contact with the magnet means in its attracted position, and to bias the movable contact away with the magnet means in its spaced position.
The invention and its advantages will now be described with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a top plan view of one embodiment of the thermostat in accordance with the invention;
FIG. 2 is a side sectional view of the embodiment of FIG. 1 taken along line II--II of FIG. 1;
FIG. 3 is a front sectional view of the embodiment of FIG. 1 taken along the line III--III;
FIG. 4 is a back sectional view of the embodiment of FIG. 1 taken along the line IV--IV;
FIG. 5A is a perspective view of the movable contact tongue with biasing spring according to one embodiment of the invention; and
FIG. 5B is a view similar to FIG. 5A of another embodiment of the invention .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The thermostat has a two part housing 1, 2. The housing contains a magnet holder 3 with a magnet 4. A wall of the housing contains a plate 5 of ferromagnetic material, which at a certain temperature, the so called Curie point, loses its magnetic properties. The housing further contains a movable contact tongue 6 with terminal tags 7 and 8 extending into the housing. The terminal tag 8 is connected to the contact tongue 6 and the portion of the terminal tag 7 located in the housing forms a contact cooperating with the contact tongue 6.
Between a pin 9, extending downwardly from the magnet holder 3 through an opening 6a in the contact tongue, and the contact tongue 6 a snap spring 10 is biased. With reference to FIGS. 5A and 5B the snap spring can either form part of the contact tongue or projection 6 or be a separate spring. In the latter case the spring 10 contains a slit 11, that receives a tongue 12 integral with the contact tongue 6.
The end of the snap spring 10 most remote f
REFERENCES:
patent: 2537682 (1951-01-01), Ljungfeldt
patent: 3760310 (1973-09-01), Carson
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