Patent ID: 7380728

Claim:
A heating device for a motor vehicle that includes an internal combustion engine and an engine coolant circuit, the heating device comprising: a housing defining a heat generation chamber, a rotor mounted in the heat generation chamber for rotation on a drive shaft, a cooling jacket defining a cooling chamber in heat exchange relationship with the heat generation chamber, the cooling chamber being adapted for circulating the engine coolant and including a coolant inlet and a coolant outlet, wherein the cooling chamber has a portion that extends in a radial direction of the heating device to substantially the same extent as the heat generation chamber and is axially adjacent to the heat generation chamber, and a pump wheel driven by the drive shaft, wherein the pump wheel is arranged in said portion of the cooling chamber and is configured to circulate coolant within the cooling chamber, wherein the cooling jacket comprises cooling ribs that form cooling ducts for the coolant, wherein the cooling ducts run radially outward in approximate spirals from the pump wheel, and wherein the pump wheel is arranged longitudinally in a center of the spirals.