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The fourth industrial revolution has made data and automated systems management more powerful and practical than ever. However, despite the increased availability of advanced control systems, hydraulics generally aren't as optimized as possible. The efficiency of fluid power systems sits at an average of 21%, remaining quite low. Fortunately for engineers that work with hydraulic drives, there are methods they can use to improve the function of these systems.
1. Apply Active Damping
Unwanted oscillation in hydraulic systems is bad for efficiency. When working with a system that is experiencing significant amounts of movement, you can use damping to minimize it and increase system efficiency.
Two types of damping exist, active and passive. Passive damping relies on friction and isn't as energy-efficient as active damping. As a result, active damping will be the better option in most cases. Engineers can manage active damping systems with a motion controller. While in use, these systems reduce the amount of inefficient movement in a hydraulic drive, increasing its overall efficiency.
Systems that are especially prone to oscillation — primarily those with a low friction-to-mass ratio or those with a tendency to absorb input energy as potential energy — will benefit the most from active damping systems.
2. Take Advantage of Valveless Designs
Conventional hydraulic systems don't drive oil directly to the mover. Instead, they rely on intermediary valves that adjust the flow of oil from the reservoir to the actuator. While popular, these designs aren't the most efficient possible.
Valveless hydraulic system designs that send oil directly to the actuator as it's needed can dramatically improve the fuel and energy efficiency of systems. Compared to those that rely on valves, these systems can reduce fuel consumption by as much as 40% and drive efficiency. The addition of other design features, like microstructured surfaces, can further increase performance.
3. Implement Advanced Control Algorithms
Many state-of-the-art hydraulic systems use valve control, and engineers can efficiently control them with the right algorithm in place. This setup makes selecting the correct control algorithms — ones you can use with hydraulic power and take into account the quirks of these systems — essential in running hydraulic drivers efficiently.
When it comes to control algorithms, engineers have options. Many hydraulic systems use the classic proportional-integral-derivative or proportional-integral control, which continuously adjusts from proportional to integral control as the actuator moves towards its desired position. However, these control systems aren't the most efficient options available.
More advanced control systems — including simple adaptive control and adaptive PID control schemes — can yield performance boosts over PID systems and may be a better fit for individual machines.
Cutting-edge control systems that take advantage of machine learning or AI technology may also be a possibility. AI algorithms drive electro-hydraulic actuators, and companies already use them in some applications. These machines can be a good fit for systems prepared to collect, process, and analyze the massive amounts of data that AI algorithms depend on.
4. Maximize Idle and Off Time
Hydraulic systems left running when not needed are highly wasteful in terms of energy. It's possible to use a hydraulic control system to maximize idle and off time, ensuring that the system does not cycle when the actuators don't need to be active.
Intelligent pump controls that can deactivate a hydraulic pump system or cycle the hydraulic fluids can lower a system's average power demand. Over time, this will make the system more efficient than it would be if left fully operational, even when not use.
5. Consider Thermal Control Systems
While the design and components included in a hydraulic system can vary, every piece in a machine — except hydraulic reservoirs — will generate heat while the system is in use. Most systems depend on hydraulic oil maintaining a certain level of viscosity to keep the system adequately lubricated. Temperature can change this viscosity — increasing the likelihood of boundary lubrication and possibly reducing efficiency.
As a result, lack of thermal regulation can be as detrimental to the functioning of a hydraulic system as poor control methods or oil contamination. For this reason, managing the temperature of hydraulic oil is critical to the efficient function of a hydraulic system.
Equipping hydraulics with thermal regulation systems that monitor the inflow temperature of hydraulic oil can help engineers keep this substance as close to the optimal operating temperature as possible.
Optimizing Performance When Incorporating Hydraulic Drives
The rise of industry 4.0 has made it possible to use data to optimize many machines and industrial systems. However, hydraulic systems — despite their continued widespread use — often remain highly inefficient. Fortunately, it's possible for engineers working with or implementing hydraulic systems to improve their efficiency. Advanced control systems, thermal regulation and active damping systems can all help improve the efficiency of new and existing hydraulic drives.
Image Credit: Simon Speed / CC0