Obtaining heat from a car in the winter has never been an instantaneous process when a car is cold. This is because a car with an internal combustion engine uses heat from the engine to warm up the cabin. When the engine is cold no heat can be obtained from it. Thus, to make the interior of a car comfortably warm in a cold winter day, the driver must either endure the low temperature until the engine warms up or remotely start the car in advance to preheat it.
Both options have obvious drawbacks. Sitting in a freezing car is not comfortable so numerous layers of clothing must be worn to stay warm. In addition, drivers entering a cold car dressed in many layers of clothing often do not remove those layers when the cabin warms up. Large winter jackets and layered clothing in general restrict bodily movement. This can cause discomfort and fatigue over the length of a trip. Preheating the car wastes fuel.
Ford Global Technologies, LLC (apparently a subsidiary of Ford Motor Company) recently sought patent protection for a method that heats the cabin of a car virtually instantly (see U.S. patent application publication no. 2022/0305876). Ford claims that its new technology would solve the drawbacks above which drivers in cold climates are familiar with. Before describing its new invention in detail, Ford lists some additional known methods for instantly heating the interior of a cabin but ultimately deems them as being unsatisfactory in some respect.
These methods are: 1) utilizing a conventional resistive type heater in the cabin (akin to a coiled heater wire that becomes red hot when electricity passes through it), and 2) modifying the vehicle’s air conditioning (A/C) system in a way that enables it to generate heat instead of cooling in the cabin (yes, that is correct, an A/C system that generates heat).
In option 2, some modifications must be made to an ordinary A/C device to make it produce heat, but these modifications are known. Basically, the coolant in the A/C system is rerouted to flow in the area that is climate-controlled in a hot state rather than cold (as in a conventional A/C). This idea has been implemented successfully for quite some time in residential central air conditioning systems where the same “A/C unit” provides both heat and cooling for the home.
However, Ford deems these solutions as being impractical or inadequate in the context of a vehicular heating and cooling system because resistive heaters demand more electrical power than a car’s battery and alternator can provide (redesigning the car’s electrical system to handle the increased power demand is costly). In addition, modifying a car’s A/C system to function like a heater does work, but little heat can be obtained from it instantaneously so it would still take a long time for the cabin to warm up.
Interestingly, Ford’s solution to instantaneous heat in the cabin combines the two methods above but importantly it builds upon them in an ingenious way. Ford starts with a modified A/C system as its base (which can provide heating and cooling, as desired). However, and acknowledging that this system cannot provide an appreciable amount of heat instantaneously in cold conditions, Ford’s solution to the problem is to first heat up the A/C coolant fluid in the tubing to a high temperature. Only when the A/C fluid becomes hot is it pumped through tubing inside of the cabin to heat the cabin instantly. The key factor here is that the waiting time for the A/C fluid to become hot is reasonably short.
While Ford’s concept is ingenious and straightforward (in hindsight), its actual implementation in a vehicle is rather complex. Bypass valves must be added to the A/C system to accelerate the heating of the A/C fluid in the tubes. Initially, the bypass valves operate to form a closed loop that makes the A/C fluid flow in and out of the compressor repeatedly while intentionally bypassing the interior of the cabin and the radiator. This is done to reduce heat losses in the cabin and at the radiator.
While the pumping action of the compressor by itself heats up the A/C fluid (by virtue of compressing it), Ford also added a separate resistive type heater close to the A/C tubing to further accelerate the process of heating the A/C fluid. When the A/C fluid becomes sufficiently hot, the bypass valves are operated in a different setting to allow the hot A/C fluid to be pumped through the cabin. Inside the cabin a fan blows air through the hot tubing to warm up the cabin quickly.
Ford has also experimented to optimize the implementation of its system in actual use. Specifically, Ford monitors in real-time the operational status of the engine, transmission and all the components of the A/C system. Based on the monitored information, Ford adjusts the operation of the engine, the operation of the transmission and the operation of the A/C system in a way designed to heat the cabin as quickly as possible. Hopefully, we will see this technology implemented in the near future.