Patent ID: 8113440

Claim:
A heating apparatus connectable to an engine cooling system of a vehicle, the cooling system including a cooling fluid and a heat exchanger for transferring heat from the cooling fluid to an airstream for heating a passenger compartment of the vehicle, the heating apparatus comprising: a liquid heat generator fluidly connectable to the engine cooling system, the liquid heat generator having a hydrodynamic chamber operable for selectively heating the cooling fluid present within the hydrodynamic chamber, and an inlet passage fluidly connected to the hydrodynamic chamber; a manifold comprising a cavity fluidly connected to manifold inlet passage, a first manifold discharge passage, and a second manifold discharge passage, the manifold inlet passage fluidly connectable to a discharge passage of the heat exchanger, the first manifold discharge passage fluidly connectable to the engine cooling system, and the second manifold discharge passage fluidly connected to the inlet passage of the hydrodynamic chamber; and a control valve comprising a spool slideably disposed within the manifold cavity, the spool moveable between a first position for establishing a fluid path between the manifold inlet passage and the first manifold discharge passage, and a second position for establishing a fluid path between the manifold inlet passage and the second manifold discharge passage, the spool comprising a bypass piston and a modulating piston slideably disposed within the bypass piston, the bypass piston defining at least one orifice for selectively connecting the manifold inlet passage fluidly to the first manifold discharge passage when the spool is positioned in the first position, the modulating piston being selectively movable relative to the bypass piston between a first position, in which the modulating piston substantially blocks a fluid path through the at least one orifice, and a second position, in which the fluid path through the at least one orifice is at least partially open.