Method for estimating surface temperature
The present disclosure related to a method for estimating a surface temperature of a trim layer. The method comprises determining a first heat transfer rate and a second heat transfer rate. The method comprises calculating a rate of change of the surface temperature based on the first and second heat transfer rates, and optionally one or more additional heat transfer rates. The method comprises updating an estimated surface temperature of the trim layer from a prior program cycle based on the rate of change of the surface temperature and the estimated surface temperature of the trim layer from the prior program cycle.
1. A method for estimating a surface temperature of a trim layer of a vehicle component, the method comprising:
determining a first heat transfer rate to or from the trim layer based on a first temperature applied to the trim layer;
determining a second heat transfer rate to or from the trim layer based on a second temperature applied to the trim layer;
calculating a rate of change of the surface temperature based on the first and second heat transfer rates and optionally one or more additional heat transfer rates; and
updating an estimated surface temperature of the trim layer from a prior program cycle based on the rate of change of the surface temperature and the estimated surface temperature of the trim layer from the prior program cycle.
2. The method according to claim 1 , wherein the first temperature is applied by a material layer adjacent to the trim layer; and wherein the material layer is a spacer layer of a vehicle seat, or a cushion layer of steering wheel and/or gear shifter.
3. The method according to claim 2 , wherein the method comprises:
obtaining the first temperature, and
obtaining the estimated surface temperature of the trim layer from the prior program cycle;
wherein the first heat transfer rate is calculated from a difference between the first temperature and the estimated surface temperature of the trim layer from the prior program cycle, a thermal resistance, a surface area through which heat transfer occurs, or any combination thereof, and
wherein if a prior program cycle value is not available, the estimated surface temperature of the trim layer is substituted with a temperature sensed by a local sensor.
4. The method according to claim 3 , wherein the method comprises:
obtaining an occupancy status of the vehicle component;
wherein the occupancy status influences the thermal resistance utilized in the determination of the first heat transfer rate.
5. The method according to claim 4 , wherein the method comprises:
obtaining the occupancy status of the vehicle component;
wherein the occupancy status determines whether the second temperature is applied by an occupant and/or cabin air.
6. The method according to claim 5 , wherein where the second temperature is applied by the cabin air, the method comprises:
obtaining the second temperature, which is a cabin air temperature, and
obtaining the estimated surface temperature of the trim layer from the prior program cycle;
wherein the second heat transfer rate is calculated from the difference between the second temperature and the estimated surface temperature of the trim layer from the prior program cycle, a thermal resistance, a surface area through which the heat transfer occurs, or any combination thereof.
7. The method according to claim 6 , wherein if a prior program cycle value is not available, the estimated surface temperature of the trim layer is substituted with the temperature sensed by the local sensor.
8. The method according to claim 7 , wherein the thermal resistance is that of free convective air.
9. The method according to claim 5 , wherein where the second temperature is applied by the occupant, the method comprises:
obtaining the second temperature, which is a skin temperature of the occupant, and
obtaining the estimated surface temperature of the trim layer from the prior program cycle;
wherein the second heat transfer rate is calculated from a difference between the second temperature and the estimated surface temperature of the trim layer from the prior program cycle, a thermal resistance, a surface area through which the heat transfer occurs, or any combination thereof.
10. The method according to claim 9 , wherein if a prior program cycle value is not available, the estimated surface temperature of the trim layer is substituted with the temperature sensed by the local sensor.
11. The method according to claim 10 , wherein the thermal resistance is a total thermal resistance between skin of the occupant and the surface, and clothing, if present.
12. The method according to claim 11 , wherein where the second temperature is applied by the occupant, the method comprises:
determining a third heat transfer rate to or from the trim layer based on a third temperature applied to the trim layer; and
wherein the second temperature is applied to one or more first portions of the vehicle component by the occupant and the third temperature is applied to one or more second portions of the vehicle component by the cabin air.
13. The method according to a claim 12 , wherein the method optionally comprises:
obtaining the third temperature, which is the cabin air temperature, and
obtaining the estimated surface temperature of the trim layer from the prior program cycle;
wherein the third heat transfer rate is calculated from a difference between the third temperature and the estimated surface temperature of the trim layer from the prior program cycle, a thermal resistance, a surface area through which the heat transfer occurs, or any combination thereof.
14. The method according to claim 13 , wherein if a prior program cycle value is not available, the estimated surface temperature of the trim layer is substituted with the temperature sensed by the local sensor.
15. The method according to claim 14 , wherein the method comprises:
obtaining a ratio of occupied surface area to unoccupied surface area; and
determining the proportions of the second and third heat transfer rates attributable to the second temperature and attributable to the third temperature.
16. The method according to claim 15 , wherein the skin temperature of the occupant is assumed to be a fixed value within the normal range of human skin temperature and/or dynamically estimated.
17. The method according to claim 5 , wherein the vehicle component includes a steering wheel, a gear shifter, a seat, a headrest, a door panel, an instrument panel, a headliner, a center console, a floor, or any combination thereof.
18. The method according to claim 17 , wherein the material layer thermally communicates with one or more thermal effectors; and
wherein the method comprises determining a heat transfer rate between the one or more thermal effectors and the material layer, based on a temperature of the one or more thermal effectors.
19. The method according to claim 18 , wherein where two or more thermal effectors are employed the one or more additional heat transfer rates are attributable to the second and any additional thermal effector.
20. The method according to claim 5 , wherein the temperature of the one or more thermal effectors are inputs provided by sensors;
wherein the sensors include a negative temperature coefficient (NTC) resistor, a resistance temperature detector (RTD), a thermocouple, a semiconductor-type sensor, or any combination thereof.