Transfer Case Oil Cooling System, Function - GF28.55-P-1002AVJ
Model 253 with transmission 725.096
View of transmission oil cooling circuit
Function requirements for oil cooling system in general
- Circuit 87 ON
- Internal combustion engine running
- Vehicle driving
Oil cooling system in general
In order to keep the operating temperature of the transfer case constantly low, the oil pump (10) integrated into the transfer case is used.
The transmission oil temperature can be lowered by the oil cooling system and can help prevent damage to the transfer case due to overheating.
Transmission oil heat exchanger
The transmission oil heat exchanger is designed as a plate-type oil cooler. Its operating principle enables it to have a compact design and provide high efficiency when cooling the transmission oil as well as when heating the transmission oil during the warm-up phase.
Function sequence for oil cooling system
The function sequence is subdivided into the following steps:
- Function sequence for oil cooling system
- Function sequence for coolant supply control
Function sequence for oil cooling system
The transmission oil is sucked in through the oil intake fitting with oil screen (6) by the oil pump (10) in the transfer case and pumped to the transmission oil heat exchanger. The transmission oil heat exchanger forms the interface between the transfer case oil circuit and the coolant circuit. The waste heat of the transmission oil is absorbed by the coolant within the transmission oil heat exchanger (plate-type oil cooler).
The transmission oil flows from the transmission oil heat exchanger back to the transfer case.
Function sequence for controlling flow of coolant to heat exchanger to meet requirements
Circulation pump 3 low temperature circuit (M43/8) is actuated to meet requirements depending on the oil temperature of the automatic transmission and the oil temperature of the transfer case. It pumps the coolant for cooling to the automatic transmission and the transfer case. To gather information on the transmission oil temperature in the transfer case, the all-wheel drive control unit (N45) reads in the transmission oil temperature sensor (B91) over a direct line. The transmission oil temperature then sends the information over the suspension FlexRay (Flex E) to the powertrain control unit (N127). The powertrain control unit also receives the transmission oil temperature of the automatic transmission from the fully integrated transmission control unit (Y3/8n4) and other information of the ME-SFI [ME] control unit (N3/10) over the drive CAN (CAN C1). The powertrain control unit then regulates the low-temperature circuit switchover valve (Y73/1) and circulation pump 3 low-temperature circuit over the drivetrain LIN (LIN C3) to match the received information.
| Overview of system components, automatically controlled all-wheel drive (4MATIC) | GF28.00-P-9998AVJ |