FLEXIBLE AND STRETCHABLE ELECTRIC HEATER BASED ON ELECTRICALLY CONDUCTIVE TEXTILE MATERIAL AND METHOD OF MANUFACTURING SAME

Abstract

An electric heating member, in particular for automotive application, includes an electrically conductive, flat-shaped textile member of uniform thickness and a layer of flexible, polymeric plastic material that is adhesively bonded to a surface of the textile member. The electrically conductive textile member is formed by at least two electrically conductive textile member parts that are arranged side by side and are electrically separated. At least one of the at least two textile member parts is electrically connected to electric terminals that are connectable to an electric heater power supply unit. The electric heating member is particularly intended to be used for heating a vehicle steering wheel.

Claims

1. An electric heating member, comprising: an electrically conductive, flat-shaped textile member of uniform thickness having a planar upper surface and a planar opposite lower surface arranged in parallel to the upper surface, a layer of flexible, polymeric plastic material that is adhesively bonded to one out of the upper surface and the lower surface of the textile member, thus covering a major part of the respective surface, wherein: the electrically conductive textile member is formed by at least two electrically conductive textile member parts that are arranged side by side and are electrically separated by a kiss cutting process with regard to a direction that is perpendicular to an extension direction of the textile member parts, and wherein at least one of the at least two textile member parts is electrically connected to electric terminals that are connectable to an electric heater power supply unit.

2. The electric heating member as claimed in claim 1, wherein the textile member is formed by a plurality of more than two textile member parts that are arranged side by side and are electrically separated with regard to a direction that is aligned perpendicular to an extension direction of the textile member parts such that each adjacently arranged two textile member parts are mutually electrically separated.

3. The electric heating member as claimed in claim 1, wherein each textile member part of the plurality of more than two textile member parts is meander-shaped.

4. The electric heating member as claimed in claim 1, further comprising an adhesive layer that is adhesively bonded to the one of the surfaces of the textile member that is arranged opposite of the plastic material layer.

5. The electric heating member as claimed in claim 1, wherein the electrically conductive textile member is made for the most part from polyamide, polyester, or a combination of both.

6. The electric heating member as claimed in claim 1, wherein the electrically conductive textile member comprises warp and weft yarns, and wherein the two or the more than two electrically conductive textile member parts are aligned such that extension directions of the two or the more than two textile member parts form an acute angle with the warp yarns or the weft yarns that lies in a range between 15° and 75°.

7. A method of manufacturing an electric heating member, the method including at least the following steps: providing an electrically conductive, flat-shaped textile member of uniform thickness having a planar upper surface and a planar opposite lower surface arranged in parallel to the upper surface, adhesively bonding a layer of flexible, polymeric plastic material to one out of the upper surface and the lower surface of the textile member, thus covering a major part of the respective surface in a direction perpendicular to the respective surface, and separating by a kiss cutting process the electrically conductive textile member into two or more electrically conductive textile member parts that are arranged side by side and are electrically separated with regard to a direction that is aligned perpendicular to an extension direction of the textile member parts such that each two adjacent textile member parts are mutually electrically separated.

8. The method as claimed in claim 7, further comprising a step of adhesively bonding an adhesive layer to the one of the surfaces of the textile member that is arranged opposite of the plastic material layer.

9. The method as claimed in claim 7, wherein the step of adhesively bonding a layer of flexible, polymeric plastic material is carried out using one out of a printing process, a commabar process or a slot die process.

10. An electric heating member as claimed in claim 1, installed in a vehicle steering wheel.

11. An electric heating member as claimed in claim 1 and comprising an antenna member of a capacitive sensing device for automotive application.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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:

[0044] FIG. 1 schematically illustrates a possible embodiment of an electric heating member in accordance with the invention in a sectional side view in various stages of manufacturing,

[0045] FIG. 2 schematically illustrates the electric heating member pursuant to FIG. 1 at the end of manufacturing,

[0046] FIG. 3 is a plan view on a detail of the electric heating member pursuant to FIG. 1,

[0047] FIG. 4 shows a schematic representation of the electrically conductive, flat-shaped textile member of the electric heating member pursuant to FIG. 1 in a plan view,

[0048] FIG. 5 schematically shows a vehicle steering wheel with a capacitive hands-off detection system using the electric heating member pursuant to FIG. 1, and

[0049] FIG. 6 is a flow chart of a method of manufacturing the electric heating member pursuant to FIG. 1.

DETAILED DESCRIPTION

[0050] FIG. 1 schematically illustrates a possible embodiment of an electric heating member 10 in various stages of manufacturing, in a lateral sectional view. A flowchart of a method of manufacturing the electric heating member 10 pursuant to FIG. 1 is shown in FIG. 6, and steps of the method will be described with reference to FIG. 1 or FIG. 2 and FIG. 6, respectively. The electric heating member 10 is intended for use in a heatable vehicle steering wheel. As will be described later, the electric heating member 10 is also intended to be used as an antenna member of a capacitive hands-off detection system for the vehicle steering wheel.

[0051] In one step 60 of the method, an electrically conductive, flat-shaped textile member 12 of uniform thickness t and width w is provided (FIG. 1, middle). The electrically conductive textile member 12 has a planar upper surface 14 and a planar opposite lower surface 16 arranged in parallel to the upper surface 14 (FIG. 1, above). The textile member 12 is woven, comprising warp and weft yarns, and may be made for the most part from polyester, in particular polyethylene terephthalate (PET). Electrically conductive material such as copper or aluminum may be attached to the upper surface 14 and/or the lower surface 16, for instance by a PVD method like vacuum deposition, with a predetermined material area weight for achieving an appropriate electric resistance of the electrically conductive textile member 12.

[0052] In a next step 62 of the method, a layer of flexible, polymeric plastic material 26 is adhesively bonded to the lower surface 16 of the textile member 12, thus completely covering the lower surface 16 in a direction 28 perpendicular to the lower surface 16 (FIG. 1, middle). The polymeric plastic material 26 may be formed by polyurethane (PU). The adhesive bond may be established by a printing process, a commabar process or a slot die process.

[0053] In a following step 64 of the method, the electrically conductive textile member 12 is separated into a plurality of electrically conductive textile member parts 22 that are arranged side by side. By applying a kisscut process with specific, predetermined settings, by which the textile member 12 is cut from an outside to the polymeric plastic material layer 26, the electrically conductive textile member parts 22 are electrically separated with regard to a direction 30 that is aligned parallel to the lower surface 16 and perpendicular to an extension direction 24 of the textile member parts 22 such that each two adjacent textile member parts 22 are mutually electrically separated. In FIG. 1, the extension direction 24 of the textile member parts 22 is arranged perpendicular to the plane of the drawing. The electrically conductive textile member 12 is thus formed by the plurality of electrically conductive textile member parts 22 (FIG. 1, below; illustration is turned upside down compared to upper and middle illustration).

[0054] The electrically conductive textile member parts 22 may be meander-shaped, as is illustrated in FIG. 3 for a plurality of eight electrically conductive textile member parts 22, or they may have a straight, rectangular shape. It shall be noted that gaps between adjacent textile member parts 22 are highly exaggerated in FIG. 3 for clarity purposes. In reality, the gap between adjacent electrically conductive textile member parts 22 is just large enough for electrical separation, so that the width w of the electrically conductive textile member 12 in the direction 30 parallel to the lower surface 16 and perpendicular to the extension direction 24 of the textile member parts 22 is virtually uninterrupted and unaffected. The electrically conductive textile member parts 22 are electrically connected to electric terminals (not shown) that are connectable to an electric heater power supply unit for providing electric heating power.

[0055] With reference to FIG. 2 and FIG. 6, in a further step 66 of the method, an adhesive layer 32 is adhesively bonded to the upper surface 14 of the textile member 12 that is arranged opposite of the plastic material layer 26. For improved ease of handling, a free surface of the adhesive layer 32 is covered with a paper liner 34 in another step 68. FIG. 2 schematically illustrates the electric heating member 10 pursuant to FIG. 1 at the end of manufacturing, in a ready-for-use state. The paper liner 34 is to be removed prior to or during an installation of the electric heating member 10.

[0056] FIG. 4 shows a schematic representation of the electrically conductive, flat-shaped textile member 12 of the electric heating member 10 pursuant to FIG. 1 in a plan view, omitting the separation into the electrically conductive textile member parts 22. Gaps between adjacent warps 18 and wefts 20 are again highly exaggerated for clarity purposes.

[0057] The left part of FIG. 4 illustrates a situation as if the plurality of electrically conductive textile member parts were aligned such that extension directions of the plurality of electrically conductive textile member parts run in parallel to the warp yarns 18. As the warp 18 and waft yarns 20 are not elastic per se, they would provide high mechanical resistance against an outer force F applied in parallel to an extension direction of the warps 18 and wefts 20, respectively, resulting in little elongation and, thus, low stretchability. This is not a preferred solution.

[0058] The preferred solution for an orientation of the electrically conductive, flat-shaped textile member 12 of the electric heating member 10 pursuant to FIG. 1 is shown in the right part of FIG. 4. Here, the plurality of electrically conductive textile member parts 22 is aligned such that extension directions 24 of the plurality of electrically conductive textile member parts 22 form an acute angle a with the warp yarns 18 that lies in a range between 15° and 75°. In this specific embodiment, the acute angle a is 45°. As the warp 18 and waft yarns 20 do not have to be elongated, they provide low mechanical resistance against an outer force applied in parallel to the extension direction 24 of the plurality of electrically conductive textile member parts 22. This results in a larger elongation of the electrically conductive, flat-shaped textile member 12, and, thus, to an increased stretchability.

[0059] FIG. 5 schematically shows a heatable vehicle steering wheel 46 of a passenger car with a capacitive hands-off detection system 36 using the electric heating member 10 pursuant to FIG. 1.

[0060] The capacitive hands-off detection system 36 includes a capacitive sensing device 38, a sense electrode 40 and a guard electrode, which is formed by the electric heating member 10. The capacitive hands-off detection system 36 is configured for detecting a presence of none, one or both of a driver's hands on the vehicle steering wheel 46. The phrase “being configured to”, as used in this application, shall in particular be understood as being specifically programmed, laid out, furnished or arranged.

[0061] In an installed and operational state, the sense electrode 40 and the guard electrode (i.e. the electric heating member 10) are arranged in parallel to each other, and are wound around and arranged on a major part of a rim 48 of the vehicle steering wheel 46. The electrically conductive sense electrode 40 and the electrically conductive guard electrode are proximal arranged to each other and are electrically mutually insulated.

[0062] The vehicle comprises a steering wheel electric heater power supply unit 50, which in this specific embodiment is fed by a starter battery of the vehicle. The electric heater power supply unit 50 includes a heating power source 52 and a controllable pulse-width modulation (PWM) switching unit 54 for controlling a provision of electric heating power to the electric heating member 10. The provision of electric heating power from the heating power source 52 is controllable by an electronic control unit 42 via the PWM switching unit 54, as is well known in the art.

[0063] The electronic control unit 42 and an AC decoupling circuit 44 form further parts of the capacitive hands-off detection system 36. The AC decoupling circuit 44 electrically connects the electric heater power supply unit 50 and the electric heating member 10 for providing electric power to the electric heating member 10 for heating the vehicle steering wheel 46.

[0064] Due to its flexibility and stretchability, the electric heating member 10 is easy to install even in the complex 3-D installation to the vehicle steering wheel 46. The electric heating member 10 provides uniform heating and, due to its uniform thickness t and uninterrupted and unaffected width w, shows in an installed state an as low as possible visibility and tactility.

[0065] 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.

[0066] 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.