OIL PUMP [SKYACTIV-G 1.5 (WITH 4-2-1 EXHAUST SYSTEM)]
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Outline
• The oil pump has a mechanism for feedback control of oil pressure. As a result, an oil pressure increase of more than the set pressure is suppressed and oil pump drive resistance is reduced. In addition, because the set pressure can be changed (oil pressure two-step control) by operating the engine oil solenoid valve, the oil pump drive resistance is reduced even during low speed/low to medium loads.
Purpose, Function
• The oil pump suctions the engine oil in the oil pan through the oil strainer and pumps engine oil into the engine.
Construction
Without coolant control valve
• The oil pump is located under the cylinder block (inside the oil pan).
• With the adoption of the chain drive type oil pump, the diameter of the rotor is reduced. As a result, the oil pump drive resistance has been reduced.
• The oil pump consists of the following parts:
• The relief valve and bypass valve is pushed and opened if oil pressure increases excessively when starting an extremely cold engine. As a result, the engine oil flows and excessive oil pressure increase is suppressed.
• When the relief valve is pushed and opened, engine oil flows. As a result, the oil pressure decreases and the oil pump drive resistance is reduced.
With coolant control valve
• The oil pump is located under the cylinder block (inside the oil pan).
• The oil pump consists of the following parts:
Operation
Without coolant control valve
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• The oil pump adjusts oil pressure in two steps (low oil pressure setting, high oil pressure setting) by switching the oil passage with the operation of the engine oil solenoid valve. For the operation condition of the engine oil solenoid valve, refer to CONTROL SYSTEM. (See
ENGINE OIL CONTROL [SKYACTIV-G 1.3, SKYACTIV-G 1.5].)
Engine oil flow when setting low oil pressure (engine oil solenoid valve ON)
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a. When the engine oil solenoid valve is turned ON, oil pressure is also applied to the upper part of the pilot valve. Because the oil pressure applied to the upper and lower parts of the pilot valve is almost the same, the pilot valve is pressed down by the spring force.
b. Oil pressure is applied to the upper part of the relief valve.
c. When the oil pressure exceeds the relief valve opening pressure, the relief valve is pressed down and engine oil flows (oil pressure decrease).
d. When the oil pressure is less than the relief valve opening pressure, the relief valve closes. As a result, engine oil flow stops (oil pressure increase).
e. Oil pressure is adjusted by repeating Step (c) to (d).
Engine oil flow when setting high oil pressure (engine oil solenoid valve OFF)
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a. When oil pressure exceeds the pilot valve opening pressure, the pilot valve is pressed up and oil pressure is applied to the upper part of the relief valve.
b. Because the relief valve opening pressure is exceeded by applying oil pressure to the upper part of the relief valve, the relief valve is pressed down and engine oil flows (oil pressure decrease).
c. When the oil pressure is less than the pilot valve opening pressure, the pilot valve closes. As a result, the relief valve closes and engine oil flow stops (oil pressure increase).
d. Oil pressure is adjusted by repeating Step (b) to (c).
With Coolant Control Valve
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• When the rotor is rotated by the rotation of the shaft which is the driving shaft, the capacity of the operation chamber formed by the 7 vanes, the slide, and the rotor changes.
• The operation chamber capacity changes from minimum to maximum to minimum until the oil reaches the discharge outlet from the inlet and oil is pumped from the discharge outlet.
• When the engine oil supplied from the engine oil solenoid valve is not supplied, and hydraulic pressure is not applied to the slide in oil pump, the oil pump discharge pressure is at the maximum.
• The slide swings at the fulcrum point according to the high/low hydraulic pressure applied to the oil pump via the engine oil solenoid valve.
• The capacity of the operation chamber changes when the slide swings, therefore the discharge pressure from the pump is suppressed.
By repeatedly performing this operation while the engine is running, the oil pump discharge pressure is controlled.
Hydraulic pressure supplied from engine oil solenoid valve is low
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― Because the swing amount of the slide inside the oil pump is small when the hydraulic pressure from the engine oil solenoid valve is low, the operation chamber capacity is maintained at large. As a result, the oil pump discharge pressure increases.
Hydraulic pressure supplied from engine oil solenoid valve is high
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― Because the swing amount of the slide inside the oil pump is large when the hydraulic pressure from the engine oil solenoid valve is high, the operation chamber capacity is reduced. As a result, the oil pump discharge pressure decreases.
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• The oil discharged from the oil pump flows to the oil gallery and is applied to the slide which composes the operation chamber. Therefore, the swing amount is automatically applied to the slide during pump operation, and the oil pump itself controls the discharge amount using its structure.
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• The bypass valve opens if the hydraulic pressure increases excessively in a case such as when starting an extremely cold engine. Engine oil flows to the oil pan when the bypass valve is open. As a result, excessive hydraulic pressure increase is suppressed.
