ROBUST PRINTED HEATER CONNECTIONS FOR AUTOMOTIVE APPLICATIONS

Abstract

An electric heating device, in particular for automotive application, includes a dielectric, planar, flexible carrier, at least one electrically resistive conductor line fixedly attached onto a surface of the flexible carrier and, at least for each end of the conductor line, an electrically conductive terminal line. The terminal lines abut and are electrically connected to a respective end of the conductor line, wherein the terminal lines have a width (w.sub.T) that is narrower than a width (w.sub.R) of the conductor line. At least one electrically conductive shunt member is attached to at least one out of at least a portion of at least one of the terminal lines and a portion of the at least one conductor line for at least partially electrically shunting the respective portion.

Claims

1. An electric heating device, in particular for automotive application, comprising: at least one electric heater member that includes: a dielectric, planar, flexible carrier, at least one electrically resistive conductor line of uniform thickness (t) that is fixedly attached onto a surface of the flexible carrier, at least for one end of the at least one electrically resistive conductor line an electrically conductive terminal line, being attached onto the surface of the flexible carrier, and abutting and being electrically connected to the respective end of the at least one electrically resistive conductor line, wherein the electrically conductive terminal lines have a width that is narrower than a width of the at least one electrically resistive conductor line, and at least one electrically conductive shunt member, being attached to at least one out of at least a portion of at least one of the electrically conductive terminal lines and a portion of the at least one electrically resistive conductor line for at least partially electrically shunting the respective portion.

2. The electric heating device claimed in claim 1, including an electrically conductive adhesive layer that is arranged between the portion of the terminal line or the portion of the at least one electrically resistive conductor line and the at least one electrically conductive shunt member for providing an appropriate attachment as an electrically conductive adhesive bond.

3. The electric heating device as claimed in claim 1, including a plastic film and an adhesive layer that are arranged on top of the at least one electrically conductive shunt member, and wherein the plastic film is adhesively attached by the adhesive layer to the flexible carrier at opposite sides of the portion of the terminal line or at opposite sides of the portion of the at least one electrically resistive conductor line for providing an appropriate attachment for the at least one electrically conductive shunt member.

4. The electric heating device as claimed in claim 1, wherein the at least one electrically conductive shunt member is attached to at least the portion of the terminal line or the portion of the at least one electrically resistive conductor line by means for establishing at least one material bond joint.

5. The electric heating device as claimed in claim 1, wherein the at least one electrically conductive shunt member is attached to at least the portion of the terminal line or to the portion of the at least one electrically resistive conductor line by means for establishing at least one force/form fit joint, form fit joint or combined force/form fit joint.

6. The electric heating device as claimed in claim 1, wherein the at least one electrically conductive shunt member is formed as at least one out of a strip of an electrically conductive textile, a strip of copper film and a strip of plastic foil with an attached electrically conductive layer comprising cured electrically highly conductive ink.

7. The electric heating device as claimed in claim 1, wherein the at least one electrically conductive shunt member is formed as a strip of an electrically conductive textile having a textile carrier and a continuous electrically conductive layer attached to a surface of the textile carrier and extending over a major part of an area of the surface, wherein the continuous electrically conductive layer comprises at least one material out of a group formed by copper, nickel, silver, manganese and a combination of at least two of these.

8. The electric heating device as claimed in claim 1, wherein the portion of the terminal line or the portion of the at least one electrically resistive conductor line completely overlaps the at least one electrically conductive shunt member in a direction perpendicular to the surface of the flexible carrier.

9. The electric heating device as claimed in claim 1, wherein a sheet resistance of the at least one electrically conductive shunt member is lower than a sheet resistance of the portion of the electrically conductive terminal line or of the portion of the at least one electrically resistive conductor line.

10. The electric heating device as claimed in claim 1, wherein the flexible carrier is a foil that is substantially made from a plastic material selected from a group of plastic materials formed by polyethylene terephthalate, polyimide, polyetherimide, polyethylene naphthalate, polyoxymethylene, polamide, polyphthalamide, polyether ether ketone, and combinations of at least two of these plastic materials.

11. The electric heating device as claimed in claim 1 wherein the at least one electrically resistive conductor line comprises a cured electrically resistive ink.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein:

[0045] FIG. 1 schematically illustrates a possible embodiment of an electric heating device in accordance with the invention in a perspective exploded view,

[0046] FIG. 2 schematically illustrates an alternative embodiment of an electric heating device in accordance with the invention in a plan view, and

[0047] FIG. 3 schematically illustrates another alternative embodiment of an electric heating device in accordance with the invention in a perspective view.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0048] FIG. 1 schematically illustrates a possible embodiment of an electric heating device 10 in accordance with the invention in a perspective exploded view. The electric heating device 10 is intended and configured to be used for heating on demand a vehicle seat arm rest (not shown) of a passenger car.

[0049] The electric heating device comprises an electric heater member 12. The electric heater member 12 includes a dielectric, planar, flexible carrier 14, which in this specific embodiment is formed as a plastic foil that has a thickness of 50 μm and that is completely made from polyetherimide (PEI).

[0050] The electric heater member 12 further comprises an electrically resistive conductor line 16. The electrically resistive conductor line 16 is fixedly attached onto a surface of the flexible carrier 14, for instance by applying a screen printing process for disposing an electrically resistive ink in the shape of the electrically resistive conductor line 16 and curing the electrically resistive ink. The electrically resistive ink comprises a major part of copper and nickel, so that the electrically resistive conductor line 16 comprises cured electrically resistive ink.

[0051] In this specific embodiment, the electrically resistive conductor line 16 in a cured state has a uniform thickness t of about 10 μm, and typically is between 5 μm and 15 μm. FIG. 1 shows line end portions 18, 20 of the electrically resistive conductor line 16, which are electrically connected to a middle portion (not shown) of the electrically resistive conductor line 16. The middle portion of the electrically resistive conductor line 16 is formed as a meander extending across a major part of the surface of the flexible carrier 14.

[0052] Line ends 22, 24 of the electrically resistive conductor line 16 are formed to extend outwardly away from and perpendicular to the line end portions 18, 20 of the electrically resistive conductor line 16 to form a connecting region of the electric heater member 12. The line ends 22, 24 of the electrically resistive conductor line 16 and the line end portions 18, 20 in that region have an identical width w.sub.R.

[0053] Furthermore, the electric heater member 12 includes two electrically conductive terminal lines 28, 30, which are attached onto the surface of the flexible carrier 14. The two electrically conductive terminal lines 28, 30 may be attached onto the surface of the flexible carrier 14 by applying a screen printing or an inkjet printing process for disposing an electrically conductive ink in the shape of the electrically conductive terminal lines 28, 30 and curing the electrically conductive ink. The electrically conductive ink comprises a major part of silver, so that the electrically conductive terminal lines 28, 30 comprise cured electrically conductive ink.

[0054] In this specific embodiment, the electrically conductive terminal lines 28, 30 have a uniform thickness t of about 10 μm, and typically have a thickness between 5 μm and 15 μm. Each one of the electrically conductive terminal lines 28, 30 abuts and is electrically connected to one of the line ends 22, 24 of the electrically resistive conductor line 16. The terminal lines 28, 30 have a uniform width w.sub.T that is narrower than the uniform width w.sub.R of the electrically resistive conductor line end 22, 24 in that region. For adapting the width w.sub.R of the electrically resistive conductor line end 22, 24 to the width w.sub.T of the terminal lines 28, 30, a tapered transition region 32 is formed in which the width w.sub.R of the electrically resistive conductor line ends 22, 24 linearly decrease to the width w.sub.T of the terminal lines 28, 30.

[0055] Furthermore, the electric heating device 10 includes two pairs of electrically conductive shunt members 34-40. The first pair of electrically conductive shunt members 34, 36 comprises two electrically conductive terminal shunt members. The second pair of electrically conductive shunt members 38, 40 comprises two electrically conductive conductor line shunt members.

[0056] It is noted herewith that the terms “first”, “second”, etc. are used in this application for distinction purposes only, and are not meant to indicate or anticipate a sequence or a priority in any way.

[0057] A sheet resistance of the electrically conductive shunt members 34-40 is lower than a sheet resistance of the portion of the electrically conductive terminal line 28, 30 and is lower than a sheet resistance of a bended transition portion 26 of the electrically resistive conductor line 16.

[0058] In this specific embodiment, the electrically conductive shunt members 34-40 are formed as strips of electrically conductive textile 42. The electrically conductive shunt members 34, 36 of the first pair are shaped straight. The electrically conductive shunt members 38, 40 of the second pair are bend-shaped for adaptation to the shape of the bended transition portion 26 between the line end portion 18, 20 and the line ends 22, 24 of the electrically resistive conductor line 16. Although a shape of the two pairs of electrically conductive shunt members 34-40 is different, they are identically structured. Each electrically conductive shunt member 34-40 has a band-shaped textile carrier that is completely made from polyester. A down-facing surface of each electrically conductive shunt member 34-40 is equipped with an attached continuous layer of electrically conductive material consisting of nickel. In this specific embodiment, the nickel layer has been applied to the down-facing surface by using a physical vapor deposition (PVD) process, namely by vacuum evaporation deposition. Alternatively, it may have been attached by another PVD process or galvanically by employing an electroplating process. The nickel layer extends over a major part of more than 90% of the area of the down-facing surface.

[0059] In an operational state, each electrically conductive terminal shunt member 34, 36 of the first pair of electrically conductive shunt members 34, 36 is attached to one of the electrically conductive terminal lines 28, 30 that, in turn, completely overlaps the electrically conductive shunt member 34, 36 in a direction perpendicular to the surface of the flexible carrier 14. An electrically conductive adhesive layer 44 is arranged between each electrically conductive terminal line 28, 30 and one of the first pair of electrically conductive shunt members 34, 36 for providing an appropriate attachment as an electrically conductive adhesive bond. In this way, the respective electrically conductive terminal line 28, 30 for connecting to an electric power source (not shown) is at least partially electrically shunted by the electrically conductive shunt member 34, 36.

[0060] Further, in the operational state, each electrically conductive terminal shunt member 38, 40 of the second pair of electrically conductive shunt members 38, 40 is attached to one of the bended transition portions 26 between the line end portions 18, 20 and the line ends 22, 24 of the electrically resistive conductor line 16, respectively. Each bended transition portion 26 completely overlaps the respective electrically conductive shunt member 38, 40 in a direction perpendicular to the surface of the flexible carrier 14. An electrically conductive adhesive layer 44 is arranged between each bended transition portion 26 and one of the electrically conductive shunt members 38, 40 for providing an appropriate attachment as an electrically conductive adhesive bond. In this way, the respective bended transition portion 26 between the line end portion 18, 20 and the line ends 22, 24 of the electrically resistive conductor line 16 is at least partially electrically shunted by the electrically conductive shunt member 38, 40. Without the electrically conductive shunt members 38, 40, a current density, and thus a local heat flux density, would be concentrated at an inside of the bended transition portion 26 of the electrically resistive conductor line 16, potentially generating a hot spot when the electric heating device 10 is put into operation.

[0061] In the specific embodiment pursuant to FIG. 1, the electric heating device 10 in accordance with the invention comprises only one electrically resistive conductor line 16. It will be readily acknowledged by those skilled in the art that the invention is also applicable to electric heating devices with a plurality of two or more electrically resistive conductor lines.

[0062] FIG. 2 schematically illustrates an alternative embodiment of an electric heating device 50 in accordance with the invention in a plan view. In order to avoid unnecessary repetitions, only differences with respect to the first embodiment pursuant to FIG. 1 will be described. For features in FIG. 2 that are not described, reference is made herewith to the description of the first embodiment.

[0063] The alternative embodiment of an electric heating device 50 also includes two pairs of electrically conductive shunt members 52-58. The first pair of electrically conductive shunt members 52, 54 comprises two electrically conductive terminal shunt members. The second pair of electrically conductive shunt members 56, 58 comprises two electrically conductive conductor line shunt members.

[0064] In this alternative embodiment, the electrically conductive shunt members 52-58 are formed as strips of copper film 60 having a uniform thickness of 15 μm. The electrically conductive shunt members 52, 54 of the first pair are shaped straight. The electrically conductive shunt members 56, 58 of the second pair are bend-shaped for adaptation to the shape of the bended transition portion 26 between the line end portion 18, 20 and the line ends 22, 24 of the electrically resistive conductor line 16.

[0065] In an operational state, a plastic film 62 with an adhesive layer comprising a pressure-sensitive adhesive is arranged on top of each one of the electrically conductive shunt members 52-58. The plastic films 62 are adhesively attached by the adhesive layer to the flexible carrier 14 at opposite sides of the electrically conductive terminal lines 28, 30 and at opposite sides of the bended transition portion 26, respectively. The plastic films 62 provide an appropriate attachment of the electrically conductive shunt members 52-58 to the electrically conductive terminal lines 28, 30 and to the bended transition portion 26 of the electrically resistive conductor line 16, respectively. The attachment can be established by temporarily applying an appropriate mechanical load to the electrically conductive shunt members 52-58.

[0066] FIG. 3 schematically illustrates another alternative embodiment of an electric heating device 70 in accordance with the invention in a perspective view. In order to avoid unnecessary repetitions, again only differences with respect to the first embodiment pursuant to FIG. 1 will be described. For features in FIG. 3 that are not described, reference is made herewith to the description of the first embodiment.

[0067] The alternative embodiment of an electric heating device 70 also includes two pairs of electrically conductive shunt members 72-78. The first pair of electrically conductive shunt members 72, 74 comprises two electrically conductive terminal shunt members. The second pair of electrically conductive shunt members 76, 78 comprises two electrically conductive conductor line shunt members.

[0068] In this alternative embodiment, the electrically conductive shunt members 72-78 are formed as strips of plastic foil 80 made from polyester with an attached electrically conductive layer comprising cured electrically highly conductive ink and having a uniform thickness of 10 μm. The electrically conductive shunt members 72, 74 of the first pair are shaped straight. The electrically conductive shunt members 76, 78 of the second pair are bend-shaped for adaptation to the shape of the bended transition portion 26 between the line end portion 18, 20 and the line ends 22, 24 of the electrically resistive conductor line 16.

[0069] In an operational state, each electrically conductive terminal shunt member 72, 74 of the first pair of electrically conductive shunt members is attached to one of the electrically conductive terminal lines 28, 30 with the electrically conductive layer facing the respective electrically conductive terminal line 28, 30.

[0070] Further, in the operational state, each electrically conductive shunt member 76, 78 of the second pair of electrically conductive shunt members is attached to one of the bended transition portions 26, respectively, with the electrically conductive layer facing the respective bended transition portion 26.

[0071] An appropriate attachment of the electrically conductive shunt members 72-78 to the terminal lines 28, 30 or to the bended transition portion 26 of the electrically resistive conductor line 16, respectively, is achieved by means for establishing form fit joints.

[0072] In this specific embodiment, the form fit joints are established by rivets 82 that are positioned at ends of each of the electrically conductive shunt members 72-78. The rivets 82 may be formed as metallic rivets or as rivets made from plastic material. In other embodiments, a combined force/form fit joint may be established for the attachment by applying a clinching method at ends of each of the electrically conductive shunt members 72-78, as is well known in the art.

[0073] In other alternative embodiments of the electric heating device, an appropriate attachment of the electrically conductive shunt members 72-78 to the terminal lines 28, 30 or to the bended transition portion 26 of the electrically resistive conductor line 16, respectively, may be achieved by means for establishing material bond joints 84 that are positioned at ends of each of the electrically conductive shunt members 72-78. The material bond joints 84 may be established by soldering.

[0074] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0075] Other variations to be disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality, which is meant to express a quantity of at least two. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.