Principle / MAP-controlled Thermostats

When the engine runs at full load, the higher operating temperature will bring adverse effects (such as ignition delay due to detonation trend). Therefore, full load operation will effectively reduce the coolant temperature through the MAP thermostat.

Volkswagen 1.4T engine cooling system thermostat (coolant regulator) is shown below.

The thermostat is installed in the channel of the coolant circulation, changing the flow route and flow of the coolant according to the temperature of the coolant. When the temperature of the coolant reaches the opening temperature of the thermostat, the valve begins to open and the cooling system starts to run. When the temperature of the coolant increases, the opening degree of the thermostat continues to increase until the maximum.

MAP-controlled thermostat is also called electronic automotive thermostat and MAP thermostat. When the engine runs at full load, the higher operating temperature will bring adverse effects (such as ignition delay due to detonation trend). Therefore, full load operation will effectively reduce the coolant temperature through the MAP thermostat.

1-Heating cartridge; 2-Main valve; 3-Rubber parts; 4-Bypass valve; 5-housing; 6-Plug; 7-Working element housing; 8-Main spring; 9-Working piston; 10-Cross bar; 11-Bypass spring

The function and basic mechanical structure of the MAP thermostat are basically the same as that of the conventional thermostat. The MAP thermostat is integrated with a heating element in the expansion element (wax component) and forms a unit with the thermostat housing. The thermostat housing is made of die-casting aluminum alloy, and the inner part of the thermostat is also integrated with an electrical interface used to connect the expansion element to the heating element. The cooling system reads the temperature of the coolant and the engine through the temperature sensor, and then connects to heating cartridge power in the MAP thermostat based on the temperature characteristic curve stored in the ECU. The cartridge determines the opening degree of the thermostat according to the current.

Compared with the conventional thermostat, the MAP thermostat can be open at a predetermined time through heating cartridge and determine the degree of opening of the thermostat according to the current engine load condition, which can ensure that the engine is maintained in an optimal working state.