1. Field of the Invention
The present invention relates to a thermal management system, and a method for managing thermal characteristics, for a heat producing system.
2. Background Art
In response to demands for improved fuel economy and reduced emissions, vehicles today are being manufactured with systems designed to increase combustion efficiency and reduce parasitic losses of various vehicle components. One way to increase combustion efficiency in an internal combustion engine is to maintain a high degree of control over the temperature of the combustion in the engine cylinders. The use of an effective vehicle thermal management system can help to achieve this goal. For example, controlling one or more of the engine oil temperature, the engine coolant temperature, and the intake air temperature, can provide an effective means for ensuring that combustion within the engine cylinders takes place within a desired temperature range. Controlling the temperature of the combustion within the engine can help to increase combustion efficiency, and reduce exhaust emissions.
A number of thermal management systems are described in a Society of Automotive Engineers (SAE) Technical Paper, Document Number 2001-01-1732, entitled “Thermal Management Evolution and Controlled Coolant Flow,” copyright 2001. One such system includes a controllable electric pump for circulating engine coolant through an EGR cooler. The electric pump can replace a larger, mechanical pump, thereby providing an overall space savings. Another system described in the SAE paper includes a separate EGR cooling loop having its own coolant loop separate from the engine coolant loop. The EGR cooling loop includes a controllable electric pump, and its own liquid-to-air heat exchanger for dissipating heat from the EGR coolant.
While a vehicle thermal management system can be used to control the temperatures of various vehicle systems, including the temperature of combustion, it would be desirable if the same thermal management system could be used to decrease parasitic losses of various components within the vehicle. For example, a thermal management system may employ the use of one or more electric fluid pumps, electric valves and electric fans. These electric components may replace one or more mechanical components which typically operate in accordance with the speed of the engine. Through the use of electric components, controlled by an electronic controller, it would be desirable if such a thermal management system could optimize the operation of the components to reduce overall power consumption while still providing the functionality necessary for an efficient thermal management system.