Description And Operation - Engine Cooling System
| 1 - Radiator | 6 - Electric Coolant Heater |
| 2 - Thermostat Housing | 7 - Exhaust Gas Recirculation (EGR) Cooler |
| 3 - Coolant Control Valve | 8 - Engine Oil Cooler |
| 4 - Pressurized Coolant Bottle | 9 - Water Pump |
| 5 - High Temperature Auxiliary Coolant Pump |
DESCRIPTION: The main engine cooling system consists of the same conventional vehicle cooling system components with an additional high temperature auxiliary coolant pump and electric coolant heater unique for PHEV.
| 1 - Heater Core | 7 - Coolant Control Valve |
| 2 - Engine Radiator | 8 - Check Valve |
| 3 - Cylinder Head | 9 - Electric Coolant Heater Inlet Coolant Temp Sensor |
| 4 - Cylinder Block | 10 - High Temperature Auxiliary Coolant Pump |
| 5 - EGR Cooler | 11 - Electric Coolant Heater |
| 6 - Engine Oil Cooler | 12 - Heater Core Inlet Coolant Temp Sensor |
OPERATION:
The engine cooling system regulates engine operating temperature when the engine is running, provides cooling for the EGR system and engine oil, and provides coolant to the heater core for heating the vehicle cabin. The coolant bottle and cap regulate the cooling system pressure. The centrifugal water pump is used to circulate coolant throughout the system when the engine is running. The thermostat is closed when the engine is cold to block the flow through the radiator allowing the engine to reach operating temperature quickly. The thermostat opens when the engine is near operating temperature to allow flow through the radiator maintaining the proper engine temperature.
When the engine is not running, the Power Inverter Module will operate the electric coolant heater to warm the coolant in the engine cooling system that is circulating through the heater core. The electric coolant heater is connected to a HV cable from the BPCM. The electric coolant heater is provided battery power from a relay and a chassis ground. The PIM controls the operation of the electric coolant heater using a common LIN bus communication line shared with the chiller valve and electric A/C compressor used in the battery cooling system. The coolant control valve and check valve can restrict the flow of coolant pulled from the engine. The coolant in the heater core portion of the system is circulated through the high temperature auxiliary coolant pump and through the heater to the heater core. This allows the coolant to be heated quickly and maintain temperature easier. There is a temperature sensor mounted in the system before the high temperature auxiliary coolant pump and another mounted at the inlet of the heater core used to monitor the cooling system temperature and regulate heating.