Pump operation
- Pump housing
- Shaft
- Rotor
- Vane
- Pump ring
- Rear guide plate
- Front guide plate
- Inlet port
- Outlet port
- Pump mounting
- Overflow valve
- Flow control valve
- Restrictor
The pump element comprises a rotor with a number of slots, a vane for each slot, a pump ring and two end plates with inlet and outlet ports for the hydraulic fluid.
The oval shape of the pump ring causes an increase and decrease in the volume between the pump ring and the rotor. Inlet ports lead to the areas where the volume increases and outlet ports from the areas where the volume decreases, producing a pump effect.
There are ten pump cells between the ten vanes. The volume decreases and increases twice per revolution. Besides being forced outwards by centrifugal force, the vanes are also pressed outwards towards the pump ring by the pressurized hydraulic fluid entering the slots inside the vanes.
The adapted combination of the restrictor (13) and the flow control valve (12) makes it possible to obtain a constant flow from the pump, irrespective of the engine/pump speed. The overflow valve (11) protects the pump from harmfully high pressure, e.g. steering wheel at full lock.
A certain amount of hydraulic fluid must pass through the valve for the control valve to be able to operate, but not when the steering wheel is at full lock. Continuous fluid circulation also helps to cool the pump.
The pump delivers a maximum pressure of approximately 10 MPa (100 bar) and a maximum flow of approximately 6 liters per minute.