Air stream heater

Description

BACKGROUND OF THE INVENTION

This invention relates to the art of air stream heaters used for the targeted supply of a hot air stream.

In prior art air stream heaters, a wire coil serves as a heating source for the hot air, the coil being able to be heated up to a maximum of 700° C., thereby heating up the air stream to the desired temperature. The air stream has a maximum volume of 2 m³/h and the max. air pressure is 1 bar (15 psi). On account of the restricted load capacity of the glowing wire coil this type of air stream heater has a limited service life (approx. 250 hrs.).

SUMMARY OF THE INVENTION

The air stream heater of the invention has a completely new concept. The technical values are therefore fundamentally different:

1. Service life of over 1000 hours.

2. Maximum heated air volume 6 m³/h.

3. Max. pressure 2.5 bar (38 psi).

The invention provides an air stream heater, wherein a bush made of copper or brass (5) is located in a metal housing (4) and in the axial boring of the bush a heating cartridge (6) is arranged and on the outer casing of the latter a spiral groove is arranged.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevational view, partly in section, of the air stream heater of the invention; and

FIG. 2 is an enlarged fragmentary sectional view further illustrating the air stream heater of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, in the centrical longitudinal axis of a metallic square housing (4) there is a boring in which a cylindrical bush (5) is arranged, the latter being made of brass or copper. In the inner longitudinal boring of this bush (5) there is a heating cartridge (6). In the outer wall of the bush (5) there is a spiral groove (3). Arranged in the wall at the front end of the housing (4) is a heat detector, which is for the purpose of temperature control of the air stream (2). The rear opening of the housing (4) is sealed by a cap (14) which is provided with a centrical boring (9) and on the rear face of which a protective cable (10) with an electric plug (11) are fastened. The electrical cables of the heat detector and the hearing cartridge (6) are conducted through the boring (9). The annular metal seal (8) at the rear end of the bush (5) prevents the escape of the air stream (2) out of the housing (4). The elbow union (12) is for the purpose of connecting a compressed air line.

The air stream heater of the invention operates in the following manner. The first step is to connect a compressed air line with a pressure controller, a pressure gauge with the elbow union (12) and the electric plug (11) with an electronic temperature controller. The function of the temperature controller is to set the desired temperature of the hot air stream. The compressed air controller provides a pressure setting of the hot air stream. The heat detector signals the temperature of the housing (4) to the electronic temperature controller and the latter transmits the on and off switching signals to the heating cartridge (6). The latter transfers the heat to the bush (5). The inflowing compressed air (2) flows through the spiral groove (3), is heated up in the process and leaves as a heated air stream through the nozzle (1).