Increasing concerns over climate change has put a heightened focus on reducing CO2 emissions from heavy vehicles and mobile equipment. Two ways to lower emissions from construction and agricultural machinery, according to most experts, are to minimize idling periods and to embrace demand-based control of auxiliary actuators.
According to engineers at Bucher Hydraulics, Grand Rapids, Mich., one solution is the electrification of traditionally diesel-powered hydraulic systems. The company has introduced the Smart PowerPack S, which lets operators control a wide range of hydraulic systems with higher efficiency, greater precision, significant noise reduction and zero emissions.
For example, truck-mounted loading cranes are today powered by the diesel engine, as are other auxiliary units such as water pumps, air-conditioning compressors and add-on equipment for municipal work functions.
In conventional PTOs (power take-offs), hydraulic pumps are connected to the truck engine mechanically via a gearbox, a PTO shaft or a V-belt, and they almost always run continuously. Power losses in these systems are significant, usually around 50 to 75%, which is incidentally the reason why truck-mounted loading cranes are often equipped with large oil coolers.
In addition, diesel engines for trucks are optimized for driving at around 50 mph, where they operate efficiently at low speed and high load. To generate the high flow rate required in stationary use (for instance, loading with a crane) the engine speed must increase. This is not only noisy, but also inefficient, as the engine then works at an unfavorable operating point with poor combustion and high specific fuel consumption.
To reduce fuel consumption and thus CO2 and other harmful emissions, vehicle and equipment manufacturers are looking to remove power-take offs from their products. Compressors, fans, steering and hydraulic pumps will be driven electrically using the “power on demand” principle, with no direct connection to the engine. In essence, this electrohydraulic power take-off, or “eh-PTO” will connect directly to the vehicle battery.
Electrification of hydraulic power take-offs enables the use of power-on-demand exactly when it is needed. Hydraulics cannot be eliminated, as it is indispensable for linear movements with high force. However, the hydraulic system must become more efficient to prevent costly power losses.
Bucher Hydraulics has developed the new Smart PowerPack S (SPP S) for utility vehicles with precisely this goal in mind. The SPP S is an intelligent electrified power unit that offers greater control and efficiencies over traditionally diesel-powered hydraulic systems.
A key component that enables higher performance from the product is the Bucher AX pump. It has 24 pistons and is specially designed for variable-speed applications. The large number of pistons keeps pulsations low. A wide speed range from 0 to 3,600 rpm allows full performance of the electric drive across a wide range of demands. Unlike conventional pumps which have a minimum speed limit, the AX pump can operate from zero speed without any breakaway effect.
With an overall efficiency between 92 and 94%, it far exceeds the values of conventional pumps. The system also includes a smart hydraulic block, which generates information on the actual flow demand and integrates pressure-relief functions.
The unit has an operating flow range of 2.27 to 14.38 lpm (0.6 to 3.8 gpm) and an operating pressure range of 17.2 to 230 bar (250 to 3,300 psi) with an integrated five-liter fluid reservoir. The electronically variable pressure-balanced hydraulic pump is part of the intelligent flow-on-demand system, which also includes a single power input connection, an integrated Negative Bypass Control cartridge valve, a Bucher electro-proportional pressure relief valve, and an integrated pressure sensor.
Electronics components that make up the power pack include a 2-in-1 brushless dc motor rated for 56 Vdc with a nominal power output of 3.3 kW. It has an integrated motor controller and onboard thermal protection. The system uses inverters from Bucher Hydraulics Mobile Drives. These calculate the speed set-point internally, which keeps installation costs low.
Onboard digital controls include analog and digital I/O, CANBus interfaces, and a serial data port. The integrated seven-inch customizable color touchscreen provides adaptive application performance readouts as well as system and remote control battery level indication.
The SPP S features intelligent all-in-one hydraulic and electronics connections with application auto-recognition capability, and an IoT system allows for continuous monitoring of system conditions, performance and diagnostics. Bluetooth connectivity engages the unit with tablets and other handheld control devices.
The Smart PowerPack is available in various sizes. In addition to the AX pump for high performance, the modular system also includes various external and internal gear pumps, thus covering a wide range of tasks. There is no power decline when multiple actions are performed simultaneously, with smooth transitions between actions. And it is cross-functional: one PowerPack is designed to suit multiple applications.
According to Bucher engineers, the product can be freely combined with nearly all commercially available hydraulic control systems. Potential applications for the SPP S include dump beds and trailers, truck-mounted cranes, scissor lifts, and construction and landscaping equipment.