Schematic Diagram - Electric-Hydraulic Actuator: Notes

The latest innovation in electro-hydraulic control provides the system with pre-emptive and response within 165 milliseconds. The axial piston pump with innovative centrifugal pressure control eliminates the need for an accumulator and solenoid valve.

The electro-hydraulic actuator is powered by an electric motor and consists of:

• A barrel with pistons
• A pump-lid with suction and discharge ports
• A swash plate and pressure regulating valves.

Rotary motion is converted to linear motion by the angular swash plate. As the barrel rotates, the pistons start to reciprocate inside the barrel. Hence the oil from the suction port is delivered to the discharge port, creating a flow. As the flow to the coupling piston increases, the pressure on this working side also increases.

The pressure, in turn, is controlled by the pressure-regulating valves. The valves are located on the circumference of the barrel. Pressure is regulated because of the force balance between the centrifugal force from the arms and the oil pressure acting on the ball.

When the required pressure is built up, the centrifugal force will be greater than the hydraulic force and the valves will remain closed. The valves remain open when the pressure is reduced.

The level of pressure conveyed by the pump depends on the required torque. For instance, High Pressure (HP) is delivered under traction or high-slip conditions, while much lower pressure is provided when making tight curves, for example to park the vehicle or when driving at high speed.

The transfer case is equipped with an innovative electro-hydraulic clutch control for optimum All Wheel Drive (AWD) performance, with pre-emptive clutch actuation.

Electro-hydraulic axial pump with centrifugal pressure control for pre-emptive and response within 165 milliseconds.