The mobile hydraulics industry is in the middle of a mass paradigm shift—a major shift towards electrohydraulic pumping units—with many factors contributing to this change. One of the biggest is lowering emissions and fuel consumption of mobile equipment to meet government mandated emissions regulations. The challenge is that most mobile hydraulic systems use a diesel engine directly coupled to the hydraulic pump sized to run at worst-case scenario: full pressure and flow for all hydraulic functions at the same time. In the real world, however, machines may only see average use of 20% power available. As a result, equipment manufacturers are moving toward electrohydraulic solutions that decouple the hydraulic pump from the internal-combustion engine—and often eliminate the engine altogether.
Electrohydraulic pumping units hold potential to be radically more efficient than traditional hydraulic systems. It has been documented by many companies that electrohydraulic systems can be as much as 80% more efficient than their traditional counterparts. Some key features make this possible, and one of the simplest is power-on-demand functionality. In simple terms, the electrohydraulic motor-pump unit only spins when pressure and flow are needed for work functions. When no work is needed, the electrohydraulic motor-pump unit uses no energy. This represents a huge gain in efficiency compared to keeping an engine and pump idling. Component lifespan is also increased—especially with bearings and seals.
Rob Kindt
Another big advantage to electrohydraulic motor-pump units is the ability to control the direction and amount of hydraulic flow simply by controlling direction and speed of the electric motor. This concept is already well-established in industrial hydraulic applications, such as injection molding machines. These systems eliminate the need for directional and proportional valves in the motion axis in which they are used. Reducing the number and complexity of components in a hydraulic circuit also simplifies troubleshooting
Greater efficiency and control aren’t the only advantages to electrohydraulic pumping units. Because these units need not be driven by a gas or diesel engine, the space and weight otherwise required for an engine, cooling system, and other support systems can be replaced by a much more compact and lighter package driven by high-energy battery packs. The advantage becomes even greater with an integrated electrohydraulic package—consisting of an electric motor, controller, and hydraulic pump combined into one compact unit.
As recently as 10 years ago, electrohydraulic motor-pump units were considered cost-prohibitive for most mobile equipment applications because the return on investment did not justify their high initial cost. However, as more companies develop and install electrohydraulic solutions, their initial cost is dropping. Today’s integrated electrohydraulic solutions now receive serious consideration price-wise, especially when total cost of ownership is considered.
Rob Kindt is chief marketing officer at Hydrapulse Inc., El Dorado Hills, Calif. Contact him via LinkedIn.
