HAWE’s seat-type directional valves avoid leakage otherwise associated with spool-type valves. Individual sections can be controlled by solenoids requiring only 8 W of power.
Lowering the operating costs and energy demand during production is important for both manufacturers and operators of machine tools. These benefits serve as sales features for machine tool builders and users, who, in turn, can promote to their customers.
Designing efficient hydraulic systems requires not only strategic circuit design, but specifying individual components exhibiting high efficiency as well. For example, officials at HAWE Hydraulics USA, Charlotte, N. C., say that specifying hydraulic power units (HPUs) dedicated to specific circuits can save substantial energy because none is needed when the circuit is not active. This is in contrast to a centralized hydraulic system, where multiple circuits are supplied by a single, large HPU. Recently conducted tests for energy efficiency with three different designs of hydraulic systems.
Energy-efficient components
One method HAWE uses to conserve energy is to mount the HPU’s pump submerged in the hydraulic reservoir. Submerging the motor in the oil provides better cooling for the electric motor, which, in turn, allows using a smaller motor — and a smaller motor uses less power than a larger one.
The smaller reservoir also translates to less oil in the hydraulic system. The compact construction often eliminates the need for a separate installation space for the HPU, so it can be integrated directly into the machine. All pressurized components are made of steel, thereby enabling operating pressures of up to 700 bar (10,153 psi).
Another technique is to use seat type valves. Unlike a sliding spool, a seat valve exhibits positive, leak-free shutoff when the valve is closed. With spool valves, the pump constantly has to re-feed the system during operation to compensate for the inherent leakage around the spool. When used in clamping circuits, clamping pressure is safely maintained even with the pump switched off.