Hydraulic Power Unit for Guaranteed Pressure and Flow Rate

The hydraulic power unit is the central module that supplies a hydraulic system with its core parameters. It consists of a variety of components. The larger and more demanding the hydraulic system, the more complex the hydraulic power unit becomes.

Functions of a Hydraulic Power Unit

The hydraulic power unit supplies the hydraulic system with precisely the required pressure and flow rate needed to operate the consumers. In addition, all components for monitoring and conditioning the hydraulic medium are integrated into the hydraulic power unit.

Components of a Hydraulic Power Unit

The typical components of a hydraulic power unit in complex systems are the following:

• Drive
• Pump
• Tank
• Filter
• Cooling
• Sensors

Drives of a Hydraulic Power Unit

The drive powers the hydraulic pump. Typically, a three-phase electric motor is used for this purpose. It delivers a constant speed at a defined torque with low energy consumption. The use of servo motors for this purpose is rather uncommon. However, if the hydraulic pump is to be operated in both pressure and suction directions, the use of a servo motor can also be a sensible drive for a hydraulic system.

Internal combustion engines or turbines are only common for operating hydraulic systems if the torque for the pump can be taken from an already existing engine. A typical example of this application is the power steering pump in a car, which is intended for steering assistance.

Pumps of a Hydraulic Power Unit

The pump’s design and size depend on the pressure and flow rate required for the operation of the hydraulic system. The smallest hydraulic pumps operate with vane cells, while the most powerful variants of these components are linear piston pumps.

Tank of a Hydraulic Power Unit

The hydraulic medium is introduced into the tank and released back into the hydraulic system via a check valve. The tank itself is unpressurized.

Filters of a Hydraulic Power Unit

The tank is open to the outside. This allows it to compensate for pressure fluctuations when the oil level changes. To prevent air from contaminating the hydraulic oil, it is passed through a filter. The flow itself is also guided through fine filters to prevent damage from abrasive particles (micro-scratching) in the piping system.

Cooling of a Hydraulic Power Unit

Hydraulic systems generate a lot of waste heat. This heat accumulates in the tank and is therefore dissipated via cooling systems. This heat dissipation can be actively supported by switching on fans or even cooling units.

Sensors of a Hydraulic Power Unit

Sensors are used to monitor all critical values around a hydraulic power unit. Typically, pressures and temperatures are recorded. Sensors for electrical conductivity in the hydraulic oil or leakage sensors can also usefully complement a hydraulic power unit.

Maintenance of Hydraulic Power Units

A well-maintained hydraulic power unit significantly contributes to extending the lifespan of the entire system. Replacing filters and hydraulic oil are particularly useful measures for this.