| 摘要 |
When additional heat exchangers, such as oil coolers and turbocharged air coolers, are mounted in front of or within the normal coolant heat exchanger or radiator of an internal combustion engine, a variable speed fan drive may be employed to blow air through all of the heat exchangers to cool the various fluids flowing through those heat exchangers. Since the different fluids usually have different desired operating temperature ranges for optimum engine performance, controlling the variable speed fan drive only in response to the temperature of the engine coolant can result in overheating of at least one of the other fluids. This is avoided by temperature sensing the different fluids and effectively determining which one of them has the highest relative temperature in its operating range. The fan drive is then controlled in response to the sensed temperature of that particular fluid. In this way, all of the fluids will be maintained within their desired operating temperature ranges. If the condenser of an air conditioning system is also positioned in front of the engine coolant radiator, the compressor discharge pressure in the system may be monitored and if it exceeds a preset maximum allowable level the fan is automatically driven at full speed to maximize the air pulled in through the condenser, and of course through all of the other heat exchangers, to quickly decrease the refrigerant temperature and thus the discharge pressure. |
