Economical hydraulic cooling circuit for motor vehicle engine - uses continuously running electrically driven coolant pump and higher power pump connected to engine through clutch when temp. is high

摘要

The hydraulic cooling circuit for an internal combustion engine used in a motor vehicle traverses the engine (M) and a heat exchanger (14) and has a pumping system comprising a primary pump (P) which runs continuously and a secondary pump (S) of higher power than the primary pump and operating intermittently in response to engine temperature. The primary pump is driven by an electric motor (18) and may be run at constant speed in conjunction with a variable opening thermostat (13) in the cooling circuit, or at a speed variable with engine temperature. The secondary pump (S) is driven by the engine, through a clutch (22) which is engaged when the engine temperature exceeds a pre-set threshold.