High efficiency, good process performance, low heat generation and low noise levels are the advantages of servo pumps. Many applications with widely varying volume flows and the associated fluctuating power requirements, such as presses or injection molding machines, benefit from the dynamic and precise speed control of a fixed displacement pump using a servo drive. Baumüller has many years of experience in equipping machines with servo pumps and has been able to further optimize the technology in cooperation with mechanical engineers.

The big advantage of the servo pump is the lower life cycle costs thanks to the good energy balance. Depending on the cycle step, the volume and pressure control of the pump can be precisely adapted to the respective requirement by adjusting the motor speed. During process-related cycle breaks of the hydraulic consumers, the drive is shut down and does not consume any energy. During pressure control phases, the motor only rotates at minimum speed and even then consumes very little energy. This in turn is due to the energy-efficient components, as both the compensated fixed displacement pump and the servomotor have very good efficiency levels not only at the nominal point, but also in the partial load range.

Use the leakage current

In addition to energy efficiency, another important factor in life cycle costs is maintenance. To make the pump even more efficient, Baumüller has added connections to both the motor and the fixed displacement pump in the new version, allowing the pump's leakage current to be used for permanent lubrication of the gearing. Grease lubrication of the internal gearing is therefore no longer necessary. As the connection holes are provided on both sides, the motor can be installed vertically or horizontally depending on the application. The motor position is flexible and adapts to the machine design.

The hydraulic pump can now be attached directly to the engine with gearing. This eliminates the need for a coupling and bellhousing, which has the advantage of a shorter installation length and consequently a smaller machine footprint. By eliminating components, the machine manufacturer benefits from lower storage costs and reduced susceptibility to servicing.

Software features

Baumüller has included controller-integrated software in the package for its servo drives. The current version of the servo pump software V2+ brings improvements in the areas of process monitoring, process optimization and process safety. For example, service intervals can be planned with the speed monitoring and slip speed compensation feature. If leakage increases, monitoring the leakage characteristic curve enables automatic speed readjustment. If measured values are outside the tolerance, the operator is informed and the pump can be replaced in good time. Baumüller has also integrated a pressure sensor monitoring system that initially optimizes sensor values and indicates the need to replace the sensor if the inaccuracy increases.

A new software feature also avoids the risk of thermal overload and thus premature pump wear, especially with long pressure holding times. The thermal pump utilization is calculated from the speed and pressure using the temperature model. When a critical threshold value is reached, for example, a bypass valve can be activated to prevent overheating.