Electric Heating Device and Method of Manufacturing the Same

Abstract

An electric heating device includes a housing encompassing a PTC element and strip conductors electrically connected to the PTC element for energizing the same with different polarity. The housing is integrally molded over the PTC element and strip conductors from a polymer ceramic. A method of manufacturing such an electric heating device also is disclosed.

Claims

1. An electric heating device comprising: a PTC element; strip conductors electrically connected to the PTC element for energizing the same with different polarity; and a housing encompassing the PTC element and the strip conductors, wherein the housing is a one-piece housing formed from a polymer ceramic

2. The electric heating device according to claim 1, wherein the housing is surmounted on one side by a contact lug that is electrically conductively connected to the strip conductors.

3. The electric heating device according to claim 2, wherein a contact sheet forms the strip conductor and the contact lug.

4. The electric heating device according to claim 2, wherein at least two conduct lugs are provided and are configured to provide an electrical connection of the electric heating device to a power source.

5. A method of manufacturing an electric heating device including with a housing which encompasses a PTC element and strip conductors electrically connected thereto for energizing the same with different polarity, the method comprising: inserting the PTC element and the strip conductors into a mold cavity; surrounding the PTC element and the strip conductors by a polymer ceramic; and solidifying the polymer ceramic to form the housing.

6. The method according to claim 5, wherein the PTC element is connected to contact sheets forming the strip conductor and a contact lug, and the thus produced assembly is held in place during molding of the housing via the projecting of the contact lug beyond the PTC element.

7. The method according to claim 6, wherein at least two conduct lugs are provided and are configured to provide an electrical connection of the electric heating device to a power source.

8. The method according to claim 6, wherein the housing is injection molded.

9. The method according to claim 5, wherein the housing is injection molded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further details and advantages of the present invention will become apparent from the enclosed description of an embodiment income nation with the drawings, in which drawings

[0018] FIG. 1 is a perspective side view of an embodiment of the present invention; and

[0019] FIG. 2 is a cross-sectional view along lines II-II according to FIG. 1.

DETAILED DESCRIPTION

[0020] In the figures, reference number 2 identifies an electric heating device. The electric heating device 2 has a housing 4 encompassing a PTC element 6 and strip conductors 8. The strip conductors 8 are electrically connected to the PTC element 6 for energizing the same with different polarity. The housing 2 is a one-piece housing formed from a polymer ceramic.

[0021] The polymer ceramic is molded around the PTC element 6 and the strip conductors 8 by a thermoset injection molding process. Thus, the PTC element 6 and the strip conductors 8 are completely sealed within the polymer ceramic Only contact lugs 10 formed by free ends of sheet metal pieces defining the strip conductors 8 project beyond the housing 4.

[0022] The polymer ceramic of the embodiment is an inorganic-organic composite consisting of ceramic fillers of e.g. Al.sub.2O.sub.3 and a matrix of organo silicon polymers—primarily polysiloxanes. The formation of the housing by the polymer ceramic is based on the chemical crosslinking of functionalized resins, which can be further transformed into ceramic-like structures by thermal post-treatment. The polymer ceramics have a high thermal stability and also a low shrinkage, high dimensional stability and dimensional stability. Relevant service properties (e.g. electrical conductivity, thermal conductivity, dielectric properties) and processing parameters can be adapted to the specific application of a heater within a motor vehicle, in which the inventive electric heating device will be employed, by selecting suitable functional fillers and binder systems. The use of polymer-ceramic materials allows cost-effective, simple processing of the material and provides high thermal stability of the housing 4.