Liquid heating units, control means for such units and vessels incorporating heating units

Claim 2

A liquid heating unit comprising a submersible electric sheathed heating element having a unitary head which is adapted to be secured within an aperture in a wall of a liquid container, said head having means thereon for connection to a mains supply, a control mechanism being provided within said head for moving control contacts for said heating element between closed and open positions, said control mechanism incorporating a heat sensitive ferrite element and a magnet movable between a first position adjacent said heat sensitive element and a second position in which said magnet operates said contacts with means limiting movement of said magnet between said two positions, a vapor tube connected to said head with its interior in communication with a part of said heat sensitive element within said head whereby said tube can transmit steam to said heat sensitive element from above a normal liquid leveL within the container when said heating element is mounted in an aperture in said container wall whereby to cause actuation of said contacts if the liquid reaches a predetermined temperature, said heat sensitive member also being in close thermal conductive relationship with at least a portion of said heating element whereby to cause actuation of said contacts if said heating element is energized and not covered by liquid.

Claim 3

A heating unit as claimed in claim 1 in which the magnet in the second position actuates the contacts at least partially in a magnetic manner.

Claim 4

A heating unit as claimed in claim 1 including a keeper to which the magnet is attracted in moving to the second position.

Claim 5

A heating unit as claimed in claim 1 in which the magnet moves in a pivotal manner.

Claim 6

A heating unit as claimed in claim 1 in which at least one part of the ferrite element abuts a portion of the head which is normally in heat conducting relationship with a liquid within the container.

Claim 7

A heating unit as claimed in claim 1 in which the chamber is subdivided by a flexible diaphragm into a first sub-chamber containing the ferrite element and the magnet, and a second sub-chamber containing the electrical contacts.

Claim 8

A heating unit as claimed in claim 1 in which the head incorporates a re-setting member adapted to be manually moved in return the magnet to its first position.

Claim 9

A vessel as claimed in claim 1 in which the vessel has a filling opening, and the heating unit, with its head and vapor tube can be assembled into or removed from the vessel via the filling opening.

Claim 10

A vessel for the boiling of liquid including a container for receiving the liquid to be heated, the container having a wall provided with a filling opening, a lid for the filling opening, and an aperture in a lower part of the container wall, a liquid heating unit mounted in sealing relationship with the aperture, the heating unit incorporating a submersible sheathed electrical heating element extending within the container adjacent the bottom thereof, the heating element extending from a unitary head a part of which extends through the aperture in the container wall, the head having within it a chamber containing control mechanism including electrical contacts normally in series with the heating element and adapted to be opened by movement of a magnet by gravity away from a ferrite element when the latter is above its Curie temperature, said magnet having a first position adjacent said ferrite element and a second position in which said magnet operates said contacts with means limiting movement of said magnet between said two positions, a vapor tube extending from a position above the normal liquid level in the container into close relationship with the ferrite element thereby to convey vapor to the ferrite element on boiling of the liquid, a part of a ferrite element being in close thermal conducting relationship with a part of the heating element, whereby the ferrite element will be heated to above its Curie temperature on the one hand by vapor from the liquid when it boils and on the other hand by heat conduction from the element if a part thereof is not fully immersed in liquid within the container.

Claim 11

A vessel for the boiling of liquid including a container for receiving the liquid to be heated, the container having a wall provided with a filling opening, a lid for the filling opening, and an aperture in a lower part of the container wall, a liquid heating unit mounted in sealing relationship with the aperture, the heating unit incorporating a submersible sheathed electrical heating element extending within the container adjacent the bottom thereof, the heating element extending from a unitary head a part of which extends through the aperture in the container wall, the head having within it a chamber containing control mechanism including electrical contacts normally in series with the heating element and adapted to be opened by movement of a magnet by gravity away from a ferrite element when the latter is above its Curie temperature, said magnet having a first position adjacent said ferrite element and a second position in which said magnet operates said contacts with means limiting movement of said magnet between said two positions, a vapor tube extending from a position above the normal liquid level in the container into close relationship with the ferrite element thereby to convey vapor to the ferrite element on boiling of the liquid, a part of a ferrite element being in close thermal conducting relationship with a part of the heating element, whereby the ferrite element will be heated to above its Curie temperature on the one hand by vapor from the liquid when it boils and on the other hand by heat conduction from the element if a part thereof is not fully immersed in liquid within the container.

Claim 12

A liquid heating unit comprising a substantially closed vessel, a submersible sheathed electrical heating element in said vessel, input terminals for connecting the unit to a source of electrical supply, a pair of normally closed contacts electrically connected in series with the heating element and the input terminals, and means for opening the contacts if the heating element is not submerged in a liquid or if the liquid attains a predetermined temperature, said means comprising a ferrite element arranged on the one hand in thermal conductive relationship with the electric heating element and on the other hand so as to be heated by steam produced when the liquid attains the predetermined temperature, a vapor tube extending from above the normal liquid level in said vessel to adjacent the said ferrite element, and a permanent magnet movable at least partially by the influence of gravity from a first position in which it is supported by magnetic attraction by the ferrite element while its temperature is below its Curie point, to a second extreme position in which it operates to open the contacts, and means limiting movement of said magnet between said two extreme positions.

Claim 13

A liquid heating unit comprising a substantially closed vessel, a submersible sheathed electrical heating element in said vessel, input terminals for connecting the unit to a source of electrical supply, a pair of normally closed contacts electrically connected in series with the heating element and the input terminals, and means for opening the contacts if the heating element is not submerged in a liquid or if the liquid attains a predetermined temperature, said means comprising a ferrite element arranged on the one hand in thermal conductive relationship with the electric heating element and on the other hand so as to be heated by steam produced when the liquid attains the predetermined temperature, a vapor tube extending from above the normal liquid level in said vessel to adjacent the said ferrite element, and a permanent magnet movable at least partially by the influence of gravity from a first position in which it is supported by magnetic attraction by the ferrite element while its temperature is below its Curie point, to a second extreme position in which it operates to open the contacts, and means limiting movement of said magnet between said two extreme positions.