As car buffs know, a supercharger is a mechanically driven compressor that increases the pressure of air supplied to an internal combustion engine. It lets the engine take in more oxygen, burn more fuel and produce more power.
Liebherr Components, Nussbaumen, Switzerland, uses a somewhat similar concept to increase the hydraulic performance of its new DPVO215i axial-piston pump. The unit is a high-pressure, variable- displacement pump specially designed for open circuits. The hydraulic pump features inverse-piston technology and boasts a wide, 22° swivel angle. A high swivel angle can increase the range and efficiency of pumps such as these. Robust construction and materials ensure excellent compression strength to handle pressures to 450 bar, and it includes a 100% through-drive option. It can also be combined with all of the company’s standard controllers and is suited for both mobile and industrial hydraulics.
One notable feature is that the DPVO215i has an impeller charge pump, which reduces the risk of cavitation by pre-feeding oil to the piston pump, allowing for a higher suction speed rating and enabling greater volumetric flow. This means that it is possible to achieve the same flow volume with a smaller, more-compact rated size as with a larger unit without an impeller.
The charge pump is designed as a radial and centrifugal pump with an axial impeller. According to Liebherr officials, the operating principle is such that hydraulic fluid is fed in through the suction port into the attached impeller when the drive shaft rotates. That accelerates the oil by centrifugal force and it is pushed to the outside. Oil exits the impeller radially—perpendicular to the drive shaft—at higher velocity and pressure, where it is subsequently fed in a channel to the suction kidney volume of the control plate. Simultaneous delivery of higher fluid flow and pressure results in the axial-piston unit being “charged” to provide more power.
The charge pump also increases the suction pressure of the drive, which facilitates handling of high-viscosity hydraulic fluid without cavitation, and it offers benefits in cold starts with minimal wear.
In a related announcement, Liebherr also introduced the new LH30VO045 medium-pressure axial piston pump. Like the DPVO 215i, it’s designed and manufactured for open circuits in mobile and industrial applications. Pressure range is up to 320 bar.
It includes a wide range of controller options, permitting broad suitability in many stationary and mobile applications. These include load-sensing control (LS0-DA), which offers a pressure cut-off or pressure restriction; and an electro-proportional pressure control (DE) with a negative characteristic curve. In addition to the LS0-DA and DE, other controllers include remote pressure control (DF) controller, now available with electro-proportional control (VE/VK, VK additional controller cut-off at control signal loss) and DA, which expands the functional scope of the other controllers.