Optima V6-2.7L VIN 8 (2006)
Power Steering Pressure Control Valve: Description and Operation
EPS SOLENOID
SOLENOID VALVE
A solenoid valve is provided in the gear box to control the flow of power steering oil. The solenoid valve is composed of a releasing spring, a piston
and a plunger.
The input current is varying from 0A to 1A according to the vehicle speed and is controlled by EPS control module. When the ignition switch is
turned on, current is sent to the solenoid valve to push up the plunger and accordingly the piston contacting the plunger is pushed up while overcoming
the spring force. As the vehicle speed increasing the current flow to the solenoid decreased pulling down the piston bottom by the releasing spring
force.
When the piston is pushed up, it closes the oil passing hole, therefore the power steering oil pressure is delivered into the cylinder without any
interruption. But when the hole is opened as the piston is pulling down, some of the oil coming from the rotary valve is drained into reservoir via the
hole inside the rotary valve.
NOTE: When it is necessary to remove the EPS gear box, be sure to disconnect the connector to avoid damage.
EPS GEAR BOX
OPERATION
LEFT TURN (COUNTERCLOCKWISE)
The power steering oil pump generates the oil pressure and the oil enters into the rotary valve. And the torsion bar is twisted by the force between the
steering wheel rotation and the resistance of the tire to the ground.
At a high speed of vehicle, the oil passing the rotary valve comes into the solenoid valve through the lower hole and goes out through the upper hole
flowing the connecting space of piston. At this time the piston is back away due to the spring force overcoming the solenoid plunger. The oil flows
through the space between the piston and side wall.
And then the oil flows again into the rotary valve and finally drained to reservoir through the drain hole between the rotary valve and the torsion bar.
Therefore the oil Dump pressure does not affect to the steering effort.