Abstract: An electric heating element is proposed, which has a contact unit formed from at least one PTC component and contact plates resting on either side thereof and a casing, whereby for ensuring a good contact pressure in the end product in the unpressed state of the heating element the contact plates (12, 13) are curved and rest with their convex side on the PTC components (14), the casing (2) is made from dimensionally stable light metal and in the unpressed state has an inner wall (17, 18) with a finite radius of curvature (r1) facing in convex manner the contact arrangement (12, 13, 14) and which is larger than the radius of curvature (r2) of contact plates (12, 13).

Abstract: A sensor (1) for detecting frost deposits, particularly on evaporators of refrigeration plants or the like is proposed, in which between the spaced heat source (3) and heat sensor (4) is provided a thermal connection (2) made from a material, whose thermal conductivity coefficient is of the same order of magnitude as that of frost.

Abstract: Thermal protective switches (1) that are used for limiting the temperature of electrical appliances by automatic opening of the circuit should only reset themselves again after a large change in temperature. In this respect, when the load (9) is overheated, the contact (5') fixed to the bimetallic strip (5) is moved clear of the counter-contact (4) into its open position so that the current through the contact assembly is interrupted. If the fault is not put right there is continuous switching or hunting and there is a danger of the contacts of the thermal protective switch becoming welded to each other. For this reason, for stopping the contacts closing again, the design is such that in the open position the contact assembly, is shunted by the PTC resistor (6). The parts are kept in the open position until the load (9) is turned off by hand.

Abstract: An electric heater, especially for small electric appliances, such as hair roller heaters, egg boilers, or the like, and a method of making same utilizes at least one heating element having contact-making zones on opposite planar parallel surfaces thereof, electrical connection elements in the form of essentially planar contact plates, a contact plate being placed on each of the opposite surfaces, and a holding member having a heat conducting, electrical insulating layer upon a surface thereof. The holding member is bent into a U-shape so as to hold the contact plates clamped fast to the heating elements between legs of the U-shape of the holding member and with the insulating layer disposed on an inner surface of the U-shape between the plates and holding member. In accordance with a preferred embodiment, the insulating layer is of a resilient material having a heat-conductive additive distributed therethrough and the heating elements are formed of PTC material.

Abstract: A continuous flow or flash electric water heater, for example for use in a coffee making machine, includes a compound heating structure made up of at least two elongated generally parallelepyred shaped massive heating bodies of a material having a high thermal conductivity, such as brass. Each body has at least one heat input face and a longitudinal passage for flow of water to be continuously heated. The bodies are positioned side-by-side with the passages parallel to each other and with a heat input face of each body facing a heat input face of the next adjacent body. At least one flat PTC electric heating element is positioned between each four of facing heat input faces and a casing made up of two elongated channel-like casing halves, each U-shaped in cross section and having two side flanges, houses the heating structure and forces the bodies together with the heating elements therebetween.

Abstract: An electrical resistance water heating device, particularly intended for use in coffee or other beverage preparation machines, includes a solid metal heating plate having planar upper and lower surfaces. A fluid throughflow duct is formed between the upper and lower surfaces and includes at least two elongated, spaced, side-by-side branches having corresponding ends interconnected by a connecting conduit to form a continuous fluid flow path from a water inlet to a water outlet. An elongated slot is formed between each pair of side-by-side branches and at least one plate-shaped planar PTC heating element is accomodated within each elongated slot with each of the opposing surfaces thereof directed toward a respective one of the pair of side-by-side branches between which the duct is formed. The spaces between the heating element and walls of the slot are filled with a hardenable electrically insulative filling of good heat conductivity.

Abstract: A combined water heating and vessel support plate for supporting the vessel of a beverage preparation device includes a heating slab having a water flow-through duct constituted by longitudinal apertures in a plurality of prismatic (preferably rectangular) heating-plate segments which are clamped together side-by-side with PTC ceramic electrical resistance heating elements interposed between them. The duct is completed by connecting the apertures externally by tubes or by duct-incorporating end caps on the heating plate to form a continuous flow path from an inlet to an outlet. Various clamping arrangements, preferably with some resilience, are described, as are the use of inter-segment filling materials and electrically insulating materials with good heat-conducting properties, also the selection and positioning of the heating elements to achieve a desired heating effect. The top surfaces of the segments are coplanar and form a flat vessel support surface for heating a vessel placed thereon.

Abstract: Electrical resistance heating element comprising at least one heating conductor in the form of an element which is provided at opposite surfaces with an electrical contacting means and is made of a material having a positive temperature coefficient of electrical resistance (PTC element), and further comprising two substantially plane contact plates, the contact plates being held together with the PTC element interposed between them to form a single unit acting as a contact arrangement, and a sleeve of electrically insulating, heat conductive material having an inner space whose internal cross-section is adapted to the cross-section of the contact arrangement, the contact arrangement being inserted into the inner space in the sleeve under a pressure perpendicular to the plane of the contact plates. The sleeve consists of elastomeric material.

Abstract: A refractory, granular electrically insulative composition useful as an embedding composition for electric heating coils comprises fused and granulated, possibly ground, difficultly fusible, ceramic and possibly oxide-ceramic material having polyalkylsiloxane, e.g. polymethylsiloxane, or polyarylsiloxane admixed in a proportion of from 0.5 to 5.0% added weight. Use of the composition is suitable with tubular heaters which have been produced with it and which, after manufacture and before being brought into use, have been subjected to a heat treatment at a temperature of at least 65.degree. C, for a period of at least 10 minutes. An electrical heating element comprises a housing which is embedded in the composition wherein the ceramic and possibly oxide-ceramic material has been ground.