Heating device for curved surfaces
View Patent ↗A composite heating device for homogeneous heating of surfaces, especially curved surfaces, such as in particular for homogeneous heating of steering wheels, the composite heating device having a heating element and a multipart thermally conductive layer that includes at least two thermally conductive portions with different thermal conductivities, a first portion of the thermally conductive portions being in contact with the heating element. Steering wheel integrating such a composite heating device.
1. A composite heating device for homogeneous heating of a surface, wherein the composite heating device comprises a heating element and a multipart highly thermally conductive layer comprising at least two highly thermally conductive portions with different thermal conductivities, wherein a first portion of said at least two highly thermally conductive portions is in contact with the heating element, and wherein the heating element is small in surface as compared to the multipart highly thermally conductive layer, representing 2 to 40% of the surface of the multipart highly thermally conductive layer.
2. The composite heating device as claimed in claim 1 , wherein the first portion is the thermally conductive portion having highest thermal conductivity, the thermal conductivity of the first portion expressed in W/(m·K) being at least 100% above that of the other portion(s).
3. The composite heating device as claimed in claim 1 , wherein the first portion is made from a material which is the same than that of a further of the thermally conductive portion(s), the thermal conductivity of the other portion(s) having microstructures within said portion, the microstructures being selected from any one or more of voids, slits, cuts, holes and inclusions.
4. The composite heating device as claimed in claim 1 , wherein the first portion is made from a material which is different from that of a further of the thermally conductive portion(s), the thermal conductivity of the other portion(s) having microstructures within said portion(s), the microstructures being selected from any one or more of voids, slits, cuts, holes and inclusions.
5. An article having a curved surface to be heated, comprising a composite heating device as claimed in claim 1 .
6. The article as claimed in claim 5 , wherein the article is a steering wheel having a rim wherein the heating element of the composite heating device is arranged at the bottom part of the steering wheel's rim.
7. The steering wheel as claimed in claim 6 , wherein the heating element and the multipart thermally conductive layer are arranged symmetrically with respect to the vertical plane of the steering wheel's rim.
8. The steering wheel as claimed in claim 6 , wherein the heating element and the multipart thermally conductive layer are arranged asymmetrically with respect to the vertical plane of the steering wheel's rim.
9. The steering wheel as claimed in claim 6 , comprising a number of composite heating devices fixed at different locations of the rim of the steering wheel, wherein the size, power, orientation and positioning of each heating element and/or the size, orientation and positioning of each of their thermally conductive portions provide homogenous heating of the steering wheel.
10. The steering wheel as claimed in claim 6 , wherein at least one thermally conductive portion of the multipart thermally conductive layer is part of a sensor.
11. The steering wheel as claimed in claim 10 , wherein the sensor is a capacitive sensor arranged for hands-off detection.
12. The steering wheel as claimed in claim 11 , wherein the multipart thermally conductive layer is also electrically conductive.
13. The steering wheel as claimed in claim 12 , wherein the multipart thermally conductive layer serves as a first electrode for the hands-off detection.
14. The steering wheel as claimed in claim 12 , wherein the multipart thermally conductive layer serves as a screen electrode for hands-off detection.
15. The steering wheel as claimed in claim 14 , wherein a further first electrode is applied above said multipart thermally conductive layer with an intermediate insulating layer.
16. The composite heating device as claimed in claim 1 , wherein the surface of the heating element is between 5 and 30% of the surface of the multipart highly thermally conductive layer.
17. The composite heating device as claimed in claim 2 , wherein the thermal conductivity of the first portion is at least 250% above that of the other portion(s).
18. The composite heating device as claimed in claim 2 , wherein the thermal conductivity of the first portion is at least 350% above that of the other portion(s).