EP0725557A1

EP0725557A1 - Heating device

Info

Publication number: EP0725557A1
Application number: EP96200230A
Authority: EP
Inventors: Leonardus Johannes Maria Krul; Maarten Josephus Stottelaar
Original assignee: Atag Keukentechniek BV
Current assignee: Atag Keukentechniek BV
Priority date: 1995-02-02
Filing date: 1996-02-02
Publication date: 1996-08-07
Also published as: NL9500196A

Abstract

The invention relates to a heating device, which comprises: a substrate; a ceramic layer covering the substrate; electric heating means; detection means for detecting the temperature; and a control circuit for controlling the heating means on the basis of the temperature detection, wherein the heating device is distinguished in that the heating means are formed by at least one resistance strip which is arranged on the ceramic layer.

Another property of a heating device according to the present invention is that it contains at least two separate areas which are controlled by the control circuit and which each have at least one resistance strip and detection means.

In a device according to the invention the heating means and the detection means are arranged very close to the surface to be heated and close to each other, whereby the control circuit can bring about very rapidly the required changes in the temperature of the surface to be heated of the heating device.

It is likewise no longer necessary to cause a grill plate formed by the heating device according to the invention to function continuously, since the response time of the temperature control is very short.

Description

The invention relates to a heating device, which comprising: a substrate; a ceramic layer covering the substrate; electric heating means; detection means for detecting temperature; and a control circuit for controlling the heating means on the basis of the temperature detection.
Such a heating device is known wherein the heating means and the detection means are placed at a distance from the surface of the heating device to be heated. The substrate is herein usually manufactured from metal wherein uniform conduction of heat to the surface to be heated is achieved through the metal substrate.
The distance of the heating means and the detection means to the surface to be heated has the drawback that only after a relatively long time has elapsed can the control circuit bring about required changes in the temperature of the surface to be heated by controlling the amount of power running to the heating means. In particular cases therefore, such as use of the heating device as grill plate in the catering sector and large-scale kitchen applications, it is necessary to have the heating device functioning continually while no use is being made thereof for long periods. A high energy consumption is the result.
A further drawback of this existing technology is that the energy consumption of a heating device according to this known art is also very high since the entire substrate and the surface to be heated of the heating device are heated, while heating of only a portion of the surface is necessary. This is particularly the case when such a heating device is used as grill plate in the preparation of food, in particular meat products.
The invention has for its object to obviate the above stated drawbacks, and provides to this end a heating device which is distinguished in that the heating means are formed by at least one resistance strip which is arranged on the ceramic layer.
A heating device according to the invention is further distinguished in that the detection means comprise at least one thermal strip which is arranged on the ceramic layer in the vicinity of the resistance strip.
Another property of a heating device according to the present invention is that it contains at least two separate areas which are controlled by the control circuit and which each have at least one resistance strip and detection means.
In a device according to the invention the heating means and the detection means are arranged very close to the surface to be heated and close to each other, whereby the control circuit can bring about very rapidly the required changes in the temperature of the surface to be heated of the heating device.
It is also no longer necessary to have a grill plate formed by the heating device according to the invention function continuously, since the response time for the temperature control is very short.
A further advantage is that the temperature of separate areas of the surface to be heated can be controlled by the control circuit, whereby no longer the entire surface is heated, which produces considerable energy saving.
The invention will be further elucidated with reference to the figure description following hereinbelow of embodiments of grill plates. In the drawing:

fig. 1 shows a partly cut away perspective view of a grill plate according to the known art;
fig. 2 shows a partly cut away perspective view of a grill plate according to the present invention; and
fig. 3 shows a partly cut away perspective view of a detail of fig. 2.

Reference is made in the figures to the same component with the same reference numeral.
The embodiment of a grill plate according to the known art shown in fig. 1 comprises: a substrate 1 manufactured from metal; a heat conducting protective layer 2; heating means designed as heating element 3; a power cable 4; and a control circuit with a thermostat button 5.
In this embodiment of a grill plate according to the known art the heating element 3 is situated in the substrate. In other embodiments the heating element is pressed against the underside of the substrate. The degree of heating is adjustable using the thermostat button 5 with which the amount of power carried through the power cable 4 is adjusted.
The heating element 3 heats the whole substrate 1, wherein the heat spreads through substrate 1 and therefore heat is likewise conducted to the top surface of the heating device, on which surface preparation of food takes place, in particular the grilling or frying of meat products.
The grill plate shown in fig. 2 comprises: a substrate 1 of steel; a ceramic layer 10 covering the substrate 1; resistance strips 13; a thermal strip 12; and a protective layer 2.
The ceramic layer 10 covers substrate 1 completely, wherein conductor strips 11, thermal strips 12 and resistance strips 13 are arranged on the ceramic layer 10 by means of a screen-printing technique. The strips 11, 12 and 13 on the ceramic layer 10 are further covered by a protective layer 2. The power supplied via the power cable 4 is transmitted through the resistance strips 13 via the conductor strips 11. The amount of this current is controlled by the control circuit (not shown) which is placed behind the control panel 15. The thermal strip 12 provides the control circuit with the data relating to the temperature of the heating device necessary for controlling the current.
Fig. 3 shows in detail the above described construction of the heating device. The substrate 1 is completely covered with a ceramic layer 10 which is arranged on the substrate using a spray technique or using an immersion technique in accordance with the electrophoresis principle. The substrate 1 is manufactured from vitreous steel or stainless steel and the ceramic layer 10 is preferably produced from the enamel material elpor. The strips 11, 12 and 13 are preferably arranged on the enamel layer 10 by means of a screen-printing technique. The conductor strips 11 are formed in this embodiment by the conducting paste palladium-silver, but can likewise be made of conducting pastes of for example silver, gold or nickel. The thermal strip is preferably formed using a PTC paste, wherein it should be noted that other materials can also be used.
In another embodiment (not shown) of the invention, the surface of the heating device for heating is divided into a number of areas, wherein each area is provided with separate conductor strips, resistance strips and one or more than one thermal strip. The control circuit is herein adapted such that it controls the power to each area on the basis of the temperature of the relevant area, and therefore controls the temperature in this area of the heating device. In another embodiment a separate control circuit is provided for each area. In order to obviate the risk of undesired contacts in a heating device containing a number of areas, holes are arranged through the substrate 1 through which wiring is placed for connecting the conducting strips, resistance strips and thermal strips to the control circuit. The connections of the wiring and the strips can be effected herein by means of a soldering technique or by means of conducting epoxy or polyamide glues.
In other embodiments, wherein the enamelled substrate is provided on both sides with conducting strips, resistance strips and thermal strips, the inside of each hole through the substrate is likewise enamelled, wherein the strips run through the enamelled holes to the other side.
The invention is described above in the light of the embodiment of a grill plate, wherein it should be noted that such a heating device can also be applied as part of an apparatus in which moisture present therein must be evaporated quickly, or as part of an apparatus for heating liquid flowing therethrough.

Claims

Heating device, comprising: a substrate; a ceramic layer covering the substrate; electric heating means; detection means for detecting temperature; and a control circuit for controlling the heating means on the basis of the temperature detection, characterized in that the heating means are formed by at least one resistance strip which is arranged on the ceramic layer.
Heating device as claimed in claim 1, characterized in that the resistance strip is arranged on the ceramic layer by means of screen-printing technique.
Heating device as claimed in claim 1 or 2, characterized in that the detection means comprise at least one thermistor.
Heating device as claimed in claim 1 or 2, characterized in that the detection means comprise at least one thermal strip which is arranged on the ceramic layer in the vicinity of a resistance strip.
Heating device as claimed in claim 4, characterized in that the thermal strip is arranged on the ceramic layer by means of screen-printing technique.
Heating device as claimed in any of the foregoing claims, characterized by at least two separate areas controlled by the control circuit and each having at least one resistance strip and detection means.
Heating device as claimed in any of the foregoing claims, characterized by holes through the substrate with a ceramic layer herein on the substrate material, wherein connections are arranged through the holes.
Heating device as claimed in any of the foregoing claims, characterized by at last one opening in the ceramic layer forming a mass point where the substrate is connected to a conductor.
Heating device as claimed in any of the foregoing claims, characterized in that the substrate is manufactured from vitreous steel or stainless steel.
Heating device as claimed in any of one foregoing claims, characterized in that the ceramic layer is manufactured from the enamel elpor.
Heating device as claimed in any of the foregoing claims, characterized in that the ceramic layer is arranged on the substrate using a spray technique.
Heating device as claimed in any of the foregoing claims, characterized in that the ceramic layer is arranged on the substrate using an immersion technique in accordance with the electrophoresis principle.
Heating device as claimed in any of the foregoing claims, characterized in that conducting connections are formed using conducting pastes such as palladium-silver, silver, gold or nickel.
Heating device as claimed in any of the foregoing claims, characterized in that the or each thermal strip is formed using a PTC paste.
Heating device as claimed in any of the foregoing claims, characterized in that connections are effected by means of a soldering technique or by using conducting glues containing epoxy or polyamide.
Heating device as claimed in any of the foregoing claims, characterized by a protective layer over the or each resistance strip and over the detection means arranged on the ceramic layer.
Device for frying or grilling food, in particular meat products, characterized by a heating device as claimed in any of the foregoing claims.
Measuring device for recording rainfall, characterized by a heating device as claimed in any of the claims 1-16, which heats the measuring device in order to rapidly evaporate the water remaining therein after the rain has stopped.
Device for heating liquid flowing therethrough, characterized by a heating device as claimed in any of the claims 1-16.