Description
The hydraulic system consists of oil, an oil filter, two oil pump, and a valve body (valves and solenoid valves). One oil pump is in the transaxle and is mechanically turned by the input shaft of the transaxle. The second pump is turned by an electrical motor and is mounted on the outside of the transaxle housing. ATF passes through the oil filter and gets distributed along the oil channels.
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The valve body is essential to automatic transaxle control and consists of various valves used to control the oil feed from the oil pump. Specifically, these valves consist of pressure regulator valves, oil redirection valves, shift valves, and manual valves. The body also features electronic solenoid valves that ensure smooth gear changes.
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The ATF warmer is mounted on the valve body cover to reduce oil viscosity friction by increasing oil temperature under cold condition, which in turn improves fuel efficiency. It is serial mounted on the entry of the Electronic Throttle Controller (ETC), as shown in the illustration, and minimizes the effects of cabin heating system.
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- Engine coolant is used for circulating heat in order to heat and cool the transaxle oil.
- Rapidly elevates the transaxle oil temperature during the initial cold start of the engine.
- Prevents over heating of the transaxle oil while the vehicle is moving.
- Transaxle oil warm-up and cooling can be done with a single system.
- The water coolant and oil are separate in order to exchange heat.
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- Remove the under cover (A). Tightening torque: 7.8 ~ 11.8 N.m (0.8 ~ 1.2 kgf.m, 5.8 ~ 8.7 lb-ft)
- Drain the coolant of engine & transaxle cooling system. (Refer to «COOLANT»(ref-675057-S24250348822014120400000) )
- Remove the drain plug (A) and reinstall the drain plug after draining ATF totally. Tightening torque: 33.3 ~ 43.1 N.m (3.4 ~ 4.4 kgf.m, 24.6 ~ 31.8 lb-ft)
- Remove the ATF Warmer (B) after removing the hose (A). Tightening torque: 11.8 ~ 13.7 N.m (1.2 ~ 1.4 kgf.m, 8.7 ~ 10.1 lb-ft)
This transaxle has a standard Mechanical Oil Pump (MOP) linked to the input shaft to generates oil pressure when input shaft rotates. Being a hybrid, this transaxle also has an Electric Oil Pump (EOP). Because the hybrid features Auto-Stop which starts and stops the engine as needed. The Auto-Stop feature prevents the Mechanical Oil Pump (MOP) from operating and building enough pressure for the transaxle to operate. When the vehicle comes to a stop with the engine off, Mechanical Oil Pump (MOP) cannot generate sufficient oil pressure during the initial startup (below 5 KPH) or during low speed driving. For these reasons, the Electric Oil Pump (EOP) takes on this role as an additional device that can generate the required oil pressure when the vehicle comes to a stop or during low speed driving. The Electric Oil Pump (EOP) not only supplies oil pressure to the Under Drive Brake (UD/B), but it also feeds the oil pressure to the Engine Clutch (E/C).
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- While low speed driving or engine auto stop, it supplies oil pressure to Under Drive Brake (UD/B) of automatic transaxle.
- To supply oil pressure to Engine Clutch (E/C) when engine power is needed.
Electric Oil Pump (EOP) Operation
Starting & Creep driving (Low speed) Element Operation Description HSG Stop Vehicle moves by motor (EV mode) --> EOP operates in order to supply hydraulic pressure for 1st gear in A/T at the time of vehicle starting Motor Rotation Engine Stop E/Clutch Disengage EOP Rotation A/T 1st gear Auto Stop Element Operation Description HSG Stop EOP operates to supply the hydraulic pressure (in order to be ready to vehicle starting) --> You can hear the EOP operating sound Motor Stop Engine Stop E/Clutch Disengage EOP Rotation A/T D range
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The oil pump main relay is installed within the HEV fusible link box of the engine room. When the Oil Pump Unit (OPU) triggers the oil pump main relay, electric current needed to operate the Electric Oil Pump (EOP) passes through the Oil Pump Unit (OPU) and is supplied to the Electric Oil Pump (EOP).
In general, the Electric Oil Pump (EOP) operation is controlled by TCM via CAN communication, but in case of CAN communication failure, there is a back-up hard wiring between the TCM and Oil Pump Unit (OPU) as shown in illustration below.
