HVAC system with positive temperature coefficient varying along length of heat rod
In a first aspect, a vehicle HVAC system includes: a housing that defines at least first and second air conduits to a vehicle interior compartment; and at least first and second heat rods that each traverses the first and second air conduits, wherein a first positive temperature coefficient along a length of the first heat rod is greater at the first air conduit than at the second air conduit, and wherein a second positive temperature coefficient along a length of the second heat rod is greater at the second air conduit than at the first air conduit.
1. A vehicle HVAC system comprising:
a housing that defines at least first and second air conduits to a vehicle interior compartment; and
at least first and second heat rods that each traverse the first and second air conduits, wherein a first positive temperature coefficient along a length of the first heat rod is greater at the first air conduit than at the second air conduit, and wherein a second positive temperature coefficient along a length of the second heat rod is greater at the second air conduit than at the first air conduit.
2. The vehicle HVAC system of claim 1 , wherein the first air conduit leads to a driver position, and the second air conduit leads to a passenger position.
3. The vehicle HVAC system of claim 1 , wherein each of the first and second heat rods comprises different stones along its length.
4. The vehicle HVAC system of claim 3 , wherein the different stones abut each other at a divider between the first and second air conduits.
5. The vehicle HVAC system of claim 4 , wherein stones on one half of the first heat rod have a higher positive temperature coefficient than stones on another half of the first heat rod.
6. The vehicle HVAC system of claim 1 , wherein each of the first and second heat rods traverses the first and second air conduits at a right angle with a divider between the first and second air conduits.
7. The vehicle HVAC system of claim 1 , further comprising at least a third heat rod.
8. The vehicle HVAC system of claim 7 , wherein a third positive temperature coefficient along a length of the third heat rod does not vary between the first and second air conduits.
9. The vehicle HVAC system of claim 7 , wherein each of the first, second and third heat rods is controlled individually.
10. The vehicle HVAC system of claim 1 , wherein each of the first and second heat rods is controlled individually.
11. The vehicle HVAC system of claim 1 , wherein:
wherein the first heat rod has different material properties along its length such that a first portion of the first heat rod has a first positive thermal coefficient and a second portion of the first heat rod has a second positive thermal coefficient; and
wherein the second heat rod has different material properties along its length such that a first portion of the second heat rod has a third positive thermal coefficient and a second portion of the second heat rod has a fourth positive thermal coefficient.
12. The vehicle HVAC system of claim 1 , wherein the first heat rod and the second heat rod are substantially parallel to one another.
13. The vehicle HVAC system of claim 1 , wherein each of a first portion of the first heat rod and a first portion of the second heat rod traverses the first air conduit and a second portion of the first heat rod and a second portion of the second heat rod traverse the second air conduit.