This application claims the benefit of priority under 35 U.S.C. § 119 of German Utility Model Application 20 2015 102 449.5 filed May 12, 2015, the entire contents of which are incorporated herein by reference.
The present invention relates to a cartridge type heater.
Cartridge type heaters are electric heaters, in which the electric heating element, which may be embodied, e.g., by a resistance wire wound on a carrier and by a coiled resistance wire, is arranged in the interior of a jacket pipe made of metal, which protects the heating element from environmental effects. The heat transport from the electric heating element to the metal jacket may be guaranteed here, for example, by a filling material, e.g., magnesium oxide or Micanite plates, which is provided at least between the electric heating element and the jacket pipe, has good thermal conductivity and is, furthermore, electrically insulating if resistance wires are used.
It is desirable for many applications that the jacket pipe be grounded by connecting it to a protective ground via a protective ground wire. The connection is brought about according to the state of the art especially by welding or soldering the protective ground wire to the jacket pipe made of metal. Especially in the case of metals that lend themselves poorly to welding or soldering, e.g., in the case of jacket pipes made of titanium or aluminum, clamping of the protective ground wire on the jacket pipe is also resorted to in some cases, but this makes possible only an error-prone and relatively reliable electrical contacting.
The same problem arises in case of cartridge type heaters for low voltage or protective voltage, in which the jacket pipe consisting of metal functions as a return conductor and must therefore be connected to an electrical conductor, even though these cartridge type heaters do not require a protective ground.
An object of the present invention is to provide a cartridge type heater, whose jacket pipe consisting of metal can be connected to a conductor, e.g., a protective ground wire, in a simple and reliable manner. This object is accomplished by a cartridge type heater of the present invention.
The cartridge type heater according to the present invention has, just as the prior-art cartridge type heaters as well, a jacket pipe consisting of metal and an electric heating element, which is arranged within the jacket pipe consisting of metal. The electric heating element may be embodied, e.g., as a resistance wire wound on a carrier or as a coiled resistance wire, and a filling material preferably establishes the heat-conducting contact between the electric heating element and the jacket pipe. It should be noted that the term “jacket pipe” does not imply a limitation to a pipe with a circular cross section, so that the jacket pipe may also have another cross section, especially an oval, polygonal or flat cross section.
It is essential for the present invention that at least one terminal lug connected in one piece to the jacket pipe consisting of metal is present. A considerably improved contact behavior is attained due to this measure.
In a preferred embodiment of the present invention, the terminal lug may be arranged at an end of the jacket pipe. It may have, in particular, at least one section that projects over the edge of the jacket pipe consisting of metal; as an alternative or in addition, the terminal lug may have at least one section in which it is formed by a section of the edge area of the jacket pipe consisting of metal, which said latter section is separated by recesses passing through the pipe wall of the jacket pipe from a section of the jacket pipe consisting of metal, which said latter section is located adjacent in the circumferential direction and from a section of the jacket pipe consisting of metal, which latter section is adjacent against the circumferential direction. The section located adjacent in the circumferential direction and the section located adjacent against the circumferential direction may be directly connected to one another, i.e., pass over into one another or considered to be a single section.
In another preferred embodiment of the present invention, the terminal lug is not arranged at the edge, but centrally in a section of the wall surface of the jacket pipe consisting of metal. This can be embodied by punching the terminal lug out of the wall surface or by cutting it out, for example, with a laser. The terminal lug may subsequently be bent, so that it is positioned at an angle to the wall surface of the jacket pipe. Another possibility of embodying a terminal lug arranged centrally in a section of the wall surface of the jacket pipe consisting of metal and being positioned at an angle to the wall surface is to form the terminal lug internally in one piece with the wall of the jacket pipe.
Consequently, a structure, which is connected in one piece to the jacket pipe and with which a conductor, for example, a protective ground wire can be connected for protective grounding in a more simple manner than with the otherwise unstructured jacket pipe, is provided with the terminal lug in all the variants explained above. This connection can be achieved, for example, by crimping, riveting or screwing, but it is especially advantageous if the terminal lug is configured, at least in its terminal-side end section, as a flat plug or round plug.
Moreover, an electric connection, which would have to be established, and thus a potential source of error, is eliminated by the terminal lug configured in one piece with the jacket pipe in all embodiments, but especially in the embodiment of the connection of a flat plug or round plug.
The present invention is described in detail below with reference to the attached figures. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
Referring to the drawings, the same reference numbers are used for identical parts of identical embodiments.
The terminal lug 14 has a section 14a, which projects over the edge 11a of the jacket pipe 11 consisting of metal. Further, the terminal lug 14 has a section 14b, in which it is formed by a section of the edge area 11b of the jacket pipe 11 consisting of metal, which said section 14b is separated by recesses 15a, 15b passing through the pipe wall of the jacket pipe 11 consisting of metal from a section 11c of the jacket pipe 11 consisting of metal, which said section 11c is adjacent in the circumferential direction, and from a section 11d of the jacket pipe 11 consisting of metal, which said section 11d is adjacent against the circumferential direction.
The terminal lug 24 has a section 24a, which projects over the edge 21a of the jacket pipe 21 consisting of metal. Further, the terminal lug 24 has a section 24b, in which it is formed by a section of the edge area 21b of the jacket pipe 21 consisting of metal, which said section is separated by recesses 25a, 25b passing through the pipe wall of the jacket pipe 21 consisting of metal from a section 21c of the jacket pipe 21 consisting of metal, which said section 21c is located adjacent in the circumferential direction, and from a section 21d of the jacket pipe 21 consisting of metal, which said section 21d is located adjacent against the circumferential direction. The terminal lug 24 is configured as a male part of a flat connection.
The other end 32b of the electric heating element 32 is electrically connected, e.g., likewise welded, crimped or pressed, to the jacket pipe 31 consisting of metal. The jacket pipe 31 consisting of metal is consequently used in the cartridge type heater 30 as a return conductor.
A terminal lug 34, which is made integrally in one piece with the jacket pipe 31 consisting of metal and is formed by a material section that projects over the edge 31a of the jacket pipe 31 consisting of metal, is arranged at the end of the jacket pipe 31 consisting of metal, which said end faces the supply line 33. As an alternative, the terminal lug 34 could also be defined by incising two grooves, each of which passes through the wall of the jacket pipe consisting of metal and starts from the edge of the jacket pipe consisting of metal, so that the terminal lug would have no section projecting over the edge of the jacket pipe consisting of metal.
Further, the cartridge type heater 40 also differs from the cartridge type heaters 10, 20, 30 in that it has a terminal lug 44, which is arranged centrally in a section of the wall surface of the jacket pipe 41 consisting of metal and which is at an angle of >0°, namely, approximately at right angles in the example being shown, to the wall surface of the jacket pipe 41 consisting of metal.
Thus, the terminal lug 44 projects from the wall surface of the jacket pipe 41 consisting of metal in this example. The terminal lug 44 is configured as a male part of a flat connection here. Further,
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Number | Date | Country | Kind |
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20 2015 102 449 U | May 2015 | DE | national |
Number | Name | Date | Kind |
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3307135 | Simmons | Feb 1967 | A |
8022339 | Schlipf | Sep 2011 | B2 |
20140319126 | Li et al. | Oct 2014 | A1 |
Number | Date | Country |
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72 47 690 | Aug 1973 | DE |
85 31 701 | Feb 1986 | DE |
20 2007 010 865 | Oct 2007 | DE |
S55 33443 | Mar 1980 | JP |
Entry |
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German Search Report dated Apr. 4, 2016. |
Number | Date | Country | |
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20160338148 A1 | Nov 2016 | US |