BACKGROUND

Conventional automotive vehicles typically include a heating system for supplying warm air to a passenger compartment of the vehicle. The heating system includes a control system that allows a vehicle operator to regulate the quantity and/or temperature of air delivered to the passenger compartment to achieve a desirable air temperature within the passenger compartment. Cooling fluid from the vehicle's engine cooling system is commonly used as a source of heat for heating the air delivered to the passenger compartment.

The heating system typically includes a heat exchanger fluidly connected to the vehicle's engine cooling system. Warm cooling fluid from the engine cooling system passes through the heat exchanger and gives up heat to a cool air supply flowing through the heating system. The heat energy transferred from the warm cooling fluid to the cool air supply causes the temperature of the air to rise. The heated air is discharged into the passenger compartment to warm the interior of the vehicle to a desired air temperature.

The vehicle's engine cooling system provides a convenient source of heat for heating the vehicle's passenger compartment. One disadvantage of using the engine cooling fluid as a heat source, however, is that there is typically a significant delay between when the vehicle's engine is first started and when the heating system begins supplying air at a preferred temperature. This is particularly true when the vehicle is operated in very cold ambient conditions or has sat idle for a period of time. The delay is due to the cooling fluid being at substantially the same temperature as the air flowing through the heating system and into the passenger compartment when the engine is first started. As the engine continues to operate, a portion of the heat generated as a byproduct of combusting a mixture of fuel and air in the engine cylinders is transferred to the cooling fluid, causing the temperature of the cooling fluid to rise. Since, the temperature of the air being discharged from the heating system is a function of the temperature of the cooling fluid passing through the heat exchanger, the heating system will produce proportionally less heat while the engine cooling fluid is warming up than when the cooling fluid is at a preferred operating temperature. Thus, there may be an extended time between when the vehicle's engine is first started and when the heating system begins producing air at an acceptable temperature level. The time it takes for this to occur will vary depending on various factors, including the initial temperature of the cooling fluid and the initial temperature of the air being heated. It is preferable that the temperature of the cooling fluid reach its preferred operating temperature as quickly as possible.

Another potential limitation of using the engine cooling fluid as a heat source for the vehicle's heating system is that under certain operating conditions the engine may not be rejecting enough heat to the cooling fluid to enable the air stream from the vehicle's heating system to achieve a desired temperature. This may occur, for example, when operating a vehicle with a very efficient engine under a low load condition or in conditions where the outside ambient temperature is unusually cold. Both of these conditions reduce the amount of heat that needs to be transferred from the engine to the cooling fluid to maintain a desired engine operating temperature. This results in less heat energy available for heating the air flowing through the vehicle's heating system.

Accordingly, it is desirable to develop a heating system capable of intermittently providing additional heating of an engine's cooling fluid to improve the heating efficiency of the vehicles' passenger compartment heating system.

SUMMARY

Disclosed is hydrodynamic heater operable for generating a stream of heated fluid. The hydrodynamic heater includes an inlet port for receiving a stream of fluid from an external source and an outlet port for discharging a stream of heated fluid from the hydrodynamic heater. The hydrodynamic heater includes a stator and a rotor positioned adjacent the stator. The stator and rotor together define a hydrodynamic chamber operable for heating a fluid. The rotor is mounted to a drive shaft and rotatable relative to the stator. The hydrodynamic chamber operates to heat fluid present within an interior of the hydrodynamic chamber. The hydrodynamic chamber includes an inlet port located proximate a center of the interior region of the hydrodynamic chamber and an outlet port located along an interior wall of the hydrodynamic chamber. The hydrodynamic chamber inlet port is fluidly connected to the inlet port of the hydrodynamic heater. A fluid bypass passage may be fluidly connected to both the inlet and outlet ports of the hydrodynamic chamber. An inlet fluid metering device may be connected in series with the fluid bypass passage and the inlet port of the hydrodynamic chamber. Heated fluid from the hydrodynamic chamber may be discharged from the outlet port of the hydrodynamic heater to the fluid bypass passage. An outlet fluid metering device may be connected in series with the fluid bypass passage and the outlet port of the hydrodynamic chamber. Power for rotating the drive shaft and rotor relative to the stator may be provided by an external power source.

