The single most counterintuitive fact in home and vehicle energy is that a heat pump does not create heat. It moves it. Understanding that one sentence is enough to understand why heat pumps are central to electrifying buildings and cars — and a 2020 Denso patent makes the cycle concrete.
The mechanism is a loop. A refrigerant fluid is compressed, which makes it hot; it gives up that heat to wherever you want warmth; it then expands and turns cold; and in its cold state it absorbs heat from the outside air or ground before being compressed again. The compressor, run by electricity, is the only energy input, and the heat being delivered is mostly heat that already existed outside, simply relocated.
That relocation is why a heat pump can be more than 100 percent 'efficient' in the everyday sense: for each unit of electricity the compressor uses, it can deliver three or four units of heat, because most of the heat is pumped, not generated. A resistance heater, by contrast, is capped at one unit out per unit in. Denso's grant US10661631B2, simply titled "Heat pump cycle," describes a refrigerant loop engineered for the demanding case of a vehicle cabin.
The vehicle case is instructive because it is hard. A car heat pump has to work across a wide temperature range, switch between heating and cooling, and not drain an EV's battery with a power-hungry resistance heater in winter. The patent's reversing and routing of refrigerant is exactly the kind of detail that determines how much winter range an EV keeps — a real-world consequence of an abstract thermodynamic cycle.
Read this 2020 grant as a baseline. The heat-pump patents that follow it through the decade keep wrestling with the same cycle under harder conditions — colder climates, lower-GWP refrigerants, industrial temperatures. But the core never changes: move heat, do not make it. Once you see the loop, every later improvement is legible as a refinement of this one idea.