Liquid resistant heating element
An improved heating element, comprising: (a) an electrically insulated resistive heating wire; (b) a flexible substrate that supports the electrically insulated resistive wire: (c) one or more electrical connection for an operational component of the heating element, the electrical connection including at least two wires that are joined together; (d) a spacer controlling spacing between the at least two wires approaching the electrical connection; wherein at least a portion of the electrical connection including the spacer is encapsulated in a shrunken heat shrinkable sheath that includes at least one mass of hot melt adhesive within the sheath so that the electrical connection is insulated from fluid penetration.
1. A heating element, comprising:
i. at least two wires, one of the at least two wires is an electrically insulated resistive heating wire;
ii. a flexible substrate that supports the electrically insulated resistive wire;
iii. one or more electrical connections that join the at least two wires together,
iv. a hollow cylindrical spacer that is received on one or more of the at least two wires via an opening in the hollow cylindrical spacer that receives and surrounds at least a portion of the one or more of the at least two wires, the hollow cylindrical spacer controlling spacing between the at least two wires by forming a gap between the at least two wires;
v. a heat shrinkable sheath that includes at least one mass of hot melt adhesive within the heat shrinkable sheath;
wherein a first wire of the at least two wires is passed through the opening of the hollow cylindrical spacer, the opening has a diameter about equal to an outer diameter of the first wire, and a second wire of the at least two wires is spaced away from the first wire by an outer diameter of the hollow cylindrical spacer; and
wherein the at least two wires and the hollow cylindrical spacer are fully encapsulated in the heat shrinkable sheath and the at least one mass of hot melt adhesive when the heat shrinkable sheath is shrunken so that all portions of the hollow spacer are encapsulated and the one or more electrical connections are insulated from fluid penetration, and the at least one mass of hot melt adhesive extends into the gap between the at least two wires so that the at least one mass of hot melt adhesive fully encapsulates each of the at least two wires independently, eliminating voids in the at least one mass of hot melt adhesive between the at least two wires.
2. The heating element of claim 1 , wherein the heating element is a seat heater or a steering wheel heater for an automotive vehicle.
3. The heating element of claim 1 , wherein the at least two wires are selected from the one or more electrically insulated resistive heating wires and one or more power source wires, one or more negative thermal coefficient terminals, one or more sensor wires, one or more thermostat terminals, one or more control wires, one or more thermostat terminals, one or more power wires, a negative temperature coefficient sensor, a signal wire, a thermostat wire, a signal wire, or any combination thereof.
4. The heating element of claim 1 , wherein the hot melt adhesive is characterized as having a melting or softening temperature in excess of about 45° C.
5. The heating element of claim 1 , wherein the sheath is made from a material selected from a polyolefin, a neoprene, a polytetrafluoroethylene, or any combination thereof.
6. The heating element of claim 1 , wherein an adhesive tape patch seals the electrical connection to the substrate.
7. The heating element of claim 1 , wherein the at least two wires are insulated substantially along their length and exposed at the electrical connection where they are joined together.
8. The heating element of claim 1 , wherein the one or more electrical connections are a plurality of electrical connections and at least one of the plurality of electrical connections is a connection between the one or more electrically insulated resistive heating wires and one or more power source wires, and a second of the plurality of electrical connections is a connection between one or more sensor wires and the one or more power source wires.
9. The heating element of claim 1 , wherein the hollow cylindrical spacer is heat flowable.
10. The heating element of claim 1 , wherein the hollow cylindrical spacer is expandable.
11. The heating element of claim 1 , wherein the hollow cylindrical spacer is made of a same material as the hot melt adhesive.
12. The heating element of claim 1 , wherein the hollow cylindrical spacer is elastomeric and non-rigid.
13. The heating element of claim 4 , wherein the hollow cylindrical spacer has a glass transition temperature that is higher than the melting temperature of the hot melt adhesive, and the hollow cylindrical spacer does not melt or deform due to exposure to the hot melt adhesive.
14. The heating element of claim 1 , wherein the hollow cylindrical spacer is configured to be attached to one or more of the at least at least two wires before, after, or during formation of the one or more electrical connections.