GB2122858A

GB2122858A - Electric heater

Info

Publication number: GB2122858A
Application number: GB08315187A
Authority: GB
Inventors: Istvan Szikra
Original assignee: Hutogepgyar
Current assignee: Hutogepgyar
Priority date: 1982-06-08
Filing date: 1983-06-02
Publication date: 1984-01-18
Also published as: GB8315187D0; DE8315832U1; FR2528264B1; IT8321164A1; GB2122858B; DE3319597A1; FR2528264A1; IT8321164A0; HU186068B; IT1161840B

Abstract

The invention relates to an integrated heater and the structural design thereof. According to the invention heating resistors (4, 5) designed for two or more different voltages, are arranged in bores (2) in one single ceramic body so that by means of the properly grouped bores running parallel with the longitudinal axis in the ceramic body, as well as by the suitably shaped rib (3) the heating-resistors for the different voltages are safely separated from each other. The heater may be used in absorptive refrigerators. <IMAGE>

Description

SPECIFICATION Electric heater The invention relates to an electric heater suitable for the operation on two or more different voltages, in particular for absorptive refrigerators with combined operation, 'combined' meaning multiple power source.

Due to the increase of tourism all over the world and extended leisure there is an everincreasing demand for the so-called 'leisure products', e.g. for absorptive refrigerators with a combined operation, i.e. for refrigerators which can be equally operated from the mains, an accumulator, or a gas-bottle. Taking the combined operation and the fact that said refrigerators are mostly used in trailers, into consideration, the prescriptions relating to the security of life and property are most strict. With these equipments reliability and long endurance are of utmost importance. A further requirement lies in that the heater should be arranged in the boiler where it is the most suitable from the point of view of heat transfer; simultaneously-in order to reduce heat losses-the dimensions should be the possibly smallest.

In general, the presently manufactured absorptive refrigerators with a combined operation are made with two heaters: one of them is operated from the mains voltage (e.g. 220 V), the other from an accumulator (e.g. 12 V).

In order to be abie to place properly the heaters, two independent steel tubes are to be welded to the pipe liner of the boiler with two longitudinal welds each.

The installation of two heaters involves several disadvantageous features, so e.g. the unsatisfactory heat transmission, heat loss due to the larger dimensions of the boiler, increased expenditure of material and work in the course of welding, and additional costs of assembly; moreover, the use of two heaters increase the price.

In order to reduce the energy consumption of the refrigerator and its production costs, an integrated heating element which can be operated on two or more different voltages, which complies with the requirements relating to the safety of life and property, which has a long useful life and which can be manufactured in mass production of the highest enconomy would be desirable.

An aim of the invention is to produce a heater with the aid of which said disadvantageous features can be eliminated, and at the same time the advantageous or desirable features can be fully achieved.

According to the invention an electrical heater suitable for operation at two or more different voltages comprises an elongate body of ceramics material and separately energisable heating means for each of said different voltages, the heating means for each of said voltages comprising one or more resistive heating element(s) located within longitudinal bores formed in said elongate body and the bore or bores associated with the heating means for each voltage being separated from the bore or bores associated with the or each of the other heating means by a wall or rib of ceramics material serving electrically to isolate the heating means from one another when energised.

The invention will be described in detail by way of example only with reference to the accompanying drawings, wherein: Figure 1 is a bottom view of the ceramic body of a heater according to the invention; Figure 2 is a sectional view of the heater according to the invention, taken along the lines Il-Il of Figure 1; Figure 3 shows the heater according to the invention in an assembled state, partly in elevation and partly in broken-away section; Figure 4 is a detail B on an enlarged scale and partly in section, showing a terminal assembly of the heater according to the invention, and Figure 5 is a sectional view illustrating the wiring of the heater according to the invention, taken along the line A-A of Figure 3.

In accordance with the invention a cylindrical heater 1 is made of ceramics (e.g. Pyrostat) with excellent electric properties in such a manner that in the direction of the longitudinal axis asymmetrically grouped bores 2 are formed for receiving heating resistors 4, 5. Separation of the high-voltage part 4 (e.g. 220 V) from the parts 5 for the small-voltage (e.g. 1 2 V) is performed by means of the ceramic wall or rib 3.By properly shaping the rib 3, as well as with the aid of the bores 2 running parallel with the longitudinal axis and serving for the arrangement of the heating resistors 4, 5 for the different voltages and by the asymmetrically grouping the international standard prescriptions relating to the leakage path and the air gap, as well as the minimal wall thickness of 3 mm-representing the compliance with the prescriptions relating to the safety of life and property-can be fulfilled. In order to achieve better heat conductivity and to fix the heating spirai means, after having inserted the heating resistors 4, 5 the longitudinal bores are filled up with pulverized alumina 10.

Termination of the heating resistor is performed by means of the nickel wire connection 6 arranged in the bores of the ceramic body 1, i.e.

by means of the flexible lead 7, also made of nickel and provided with an insulation of glassfibre-reinforced silicon-rubber. Prior to the installation into the ceramic body 1, connection between each of the heating resistors 4, 5, and a respective flexible lead 7 made of nickel and provided with the glassfibre-reinforced siliconrubber insulation by means of a nickel wire connection 6 is performed-as it becomes apparent from Figures 4 and 5-by pressing.

The flexible lead 7 made of nickel and being provided with a normal insulation only, is placed into the glassfibre-reinforced silicon-rubber pipe 8-serving as a protective insulation-thereafter the pipe 8 is glued into the ceramic body 1 by means of a ceramic substance 9 which hardens in air; in the course of this process the ends of the ceramic body 1 are also sealed.

Accordingly, the invention relates to an integrated heater and the structural formation thereof, within which the heating resistors for two or more different voltages are located in suitably grouped bores in the ceramic body, running in the direction of the longitudinal axis, as well as with a rib in such a manner that the parts for the different voltages are well separated from each other.

The advantage of the solution according to the invention lies in that instead of the two heaters having been used up to now one single heater can be applied, accordingly production costs can be reduced by about 40.

A further advantage lies in that the boiler ofthe equipment has a simple design, the dimensions are smaller; by the optimal arrangement of the integrated heater and by the proper arrangement of the insulating material energy can be saved. By the installation of the more simply designed boiler and one single heater not only material can be saved but expenditure of labour may be considerably reduced.

A further advantage of the solution according to the invention lies in that it can be applied with or without a switch for the selection of the mode of operation and blocking, respectively, in the absorptive refrigerators.

Claims

1. An electrical heater suitable for operation at two or more different voltages comprising an elongate body of ceramics material and separately energisable heating means for each of said different voltages, the heating means for each of said voltages comprising one or more resistive heating element(s) located within longitudinal bores formed in said elongate body and the bore or bores associated with the heating means for each voltage being separated from the bore or bores associated with the or each of the other heating means by a wall or rib of ceramics material serving electrically to isolate the heating means from one another when energised.

2. An electrical heater as.claimed in claim 1, wherein the bores associated with any heating means comprising more than one heating element are grouped together so as to be separated from the bore or bores associated with the or each of the other heating means by a said wall of ceramic material.

3. An electrical heater as claimed in claim 1 or claim 2, wherein electrical connection to each of the heating means is made at one end of the body of ceramic material, and the point or points of connection for each of the heating means are also separated and electrically isolated from those of the or each of the other heating means by said wall or rib of ceramics material,

4. Electric heater for thermotechnical equipments, in particular absorptive refrigerators with a combined operation, wherein heating resistors designed for operation at two or more voltages are arranged in bores in one single cylindrical ceramic body so that by the suitable grouping of the bores which run in the direction of the longitudinal axis of the body and by means of suitably shaped ribs in the ceramic body the parts for the different voltages are well separated from each other.

5. Electric heater as claimed in claim 4, wherein a glassfibre-reinforced silicon-rubber tube serves as a protective insulation for each of a number of flexible leads made of nickel and forming the terminals for the heating resistors, and each of said tubes is glued into the ceramic body by means of a ceramic substance, which hardens in air.

6. Electric heater as claimed in claim 4 or claim 5, wherein the heating resistorls) associated with each of the different voltages are switched to the desired voltage by means of a separate switch or temperature controller for each of the voltages.

7. Electric heater as claimed in claim 4 or claim 5, wherein the heating resistors associated with each of the different voltages, are switched to the desired voltage by means of a common switch for selecting the mode of operation and blocking, respectively.

8. An electrical heater substantially as shown in and as hereinbefore described with reference to the accompanying drawings.