HEATING DEVICE WITH SKIVED FINS AND METHOD FOR PRODUCING A HEATING ROD

Abstract

Disclosed is a heating device comprising a heating resistor, and a heat sink thermally coupled to the heating resistor, wherein the heat sink comprises corrugated fins that are skived fins integral to the heat sink. Also disclosed is a method for producing a heating rod.

Claims

1. A heating device, comprising: a heating resistor; a heat sink thermally coupled to the heating resistor; and skived fins that are integral to the heat sink, wherein the skived fins have a corrugated shape.

2. The heating device according to claim 1, wherein the heat sink is part of a housing in which the heating resistor is arranged.

3. The heating device according to claim 1, wherein that the heat sink is a tube in which the heating resistor is arranged.

4. The heating device according to claim 3, wherein the tube is a flat tube.

5. The heating device according to claim 3, wherein the inner surface of a fin carrying tube wall is convex.

6. The heating device according to claim 1, wherein the skived fins are arranged on opposite sides of the heat sink.

7. The heating device according claim 1, wherein each fin has at least three corrugations.

8. Method for producing a heating rod, comprising: arranging a heating resistor in a tube; and providing the tube with heat sink fins by skiving, wherein the skiving is done with a corrugated blade, whereby corrugated heat sink fins are formed by the skiving.

9. The method according to claim 8, wherein the heating resistor is a ceramic resistor, the tube is a flat tube having broad sides and narrow sides, at least one of the broad sides of the tube has a convex inner surface, and, after arranging the heating resistor in the tube, the tube is compressed, whereby the flat tube is reduced in thickness.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0017] FIG. 1 shows a side view of a heating device;

[0018] FIG. 2 shows a top view of the heating device;

[0019] FIG. 3 shows a front view of the tube housing of the heating device; and

[0020] FIG. 4 shows a mounting frame including a contact plate and a heating resistor of the heating device.

DESCRIPTION

[0021] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

[0022] FIGS. 1 to 3 show a heating device, more precisely the tube housing of a heating device that is provided as a heat sink. The housing is a flat tube 1 comprising heat sink fins 2. The heat sink fins 2 are skived fins integral to the tube 1. This means that the fins 2 were made by skiving from a flat tube. In the skiving process fins were peeled from the flat tube using a sharp and accurately controlled blade tool. The blade tool shaves a small thickness of the tube surface, lifts it up and bends it vertically to form the fins 2 one after another. Two opposite sides of the tube 1 are provided with fins 2. The fins 2 are provided on broad sides of the tube 1. These broad sides are connected by narrow sides which are free from fins. The tube 1 and the fins 2 are a single piece, e.g., of aluminum.

[0023] The fins 2 are corrugated fins and therefore have a wavy shape as can be seen in FIG. 2. Each fin 2 has several corrugations, e.g., four or more corrugations, running from a proximal end, where the fins 2 are connected to tube 1, to a distal end of the fins 2. Corrugated fins are produced by skiving when a corrugated blade is used.

[0024] The flat tube 1 has two opposing broad sides carrying fins 2 and narrow sides connecting the broad sides. As shown in FIG. 3, the width of the tube 1 is larger than the width of the fins 2. On both sides of the fins 2 is a ledge 3 to which a pressing tool can be applied for compressing the tube 1 after a ceramic PTC resistor has been arranged inside the tube 1.

[0025] Inside the tube 1 is a mounting frame 5 holding a contact plate 6 and one or more ceramic heating resistors 8, e.g., PTC heating resistors. The mounting frame 5 is shown in FIG. 4 with only one ceramic heating resistor 8, the other three compartments 9 of the mounting frame 5 are empty for simplicity, but could of course also be filled with heating resistors 8. The mounting frame 5 may be provided with noses 10 for holding the ceramic heating resistors 8 in the compartments 9.

[0026] The heating resistors 8 are electrically contacted by the contact plate 6 which protrudes from the tube 1 forming a terminal for connecting to an electrical power source. The contact plate 6 is electrically insulated from the tube 1. A second contact plate may be provided inside the tube 1, or the tube 1 itself me be used to provide a ground connection for the heating resistors 8.

[0027] The resistors 8 are plate-shaped. They are electrically contacted at their large front and back sides, which each face one of the two fin carrying broad sides of the tube 1. The front and back sides of the resistors 8 are the contact faces of the resistors.

[0028] The heating device can be produced by arranging the heating resistors 8 together with the mounting frame 5 and the contact plate 6 inside tube 1. The tube 1 is then plastically deformed by compressing it. Thereby, thermal contact between the heating resistors 8 and the tube 1 is improved.

[0029] Both broad sides of the tube 1 have an inner surface 4 that is convex. Thus, the inside of the tube 1 bulges towards the contact faces of the resistors 8. Hence, the height of the interior space of the tube 1 decreases from the narrow sides towards the middle. The height of the interior space is measured in a direction from one of the fin carrying broad sides to the opposite fin carrying broad side. The inwardly curved inner surface of the broad sides facilitates the compression process and leads to an improved thermal coupling between tube 1 and resistors 8.

[0030] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

LIST OF REFERENCE SIGNS

[0031] 1 tube [0032] 2 fin [0033] 3 ledge [0034] 4 convex surface [0035] 5 mounting frame [0036] 6 contact plate [0037] 8 resistor [0038] 9 compartment [0039] 10 nose