How hydraulic systems evolved to meet electrification requirements

Hydraulic systems used in electromechanical machinery require greater emphasis on efficiency, modularity, and other design factors.

Hydraulic systems are crucial for the operation of mobile off-highway machinery. With increasing electrification in this sector, hydraulic technology will continue to play a vital role.

However, to meet the demands of electromechanical machinery and its end users, it is necessary to rethink the design of some hydraulic components and systems.

With the continued growth of electrification, improving the efficiency of hydraulic systems will be a particularly important aspect in the future. Improving the efficiency of hydraulic systems can reduce the power drawn from batteries, thereby ensuring longer operating times, and also helps to reduce the overall battery volume required by the machine.

1. Has the trend towards electrification prompted any changes in hydraulic design?

Electric motor control brings a dynamic performance and low-speed torque level that is not achievable with power take-off shafts (PTOs) or diesel engines. When the pump accelerates at much higher speeds than before, wear unprecedented in past customer applications occurs. The connection between the motor and pump—typically a splined connection—has performed over time, and much experience has been gained from it. Improvements have been made to the sealing of the motor and pump, as well as the lubrication of the connection between them, extending service life and minimizing maintenance requirements.

Electrification is a good way to recognize a major shift that the hydraulic industry must undertake, which can be summarized as a shift from over-designed drivetrains to drivetrains designed for energy demands. Historically, large machine drivetrains were designed based on the most demanding conditions, such as the maximum gradient to be traversed, the weight of the machine, the maximum pressure of the pump and motor, and their displacement. You would determine the size of the drivetrain based on the maximum power or torque required. This wasn’t a major issue when using internal combustion engines (ICE).

The problem with electrification is the cost of the machine, which is related to battery size. If your drivetrain is inefficient, you’ll have to install a larger battery, which means the battery will cost more, and therefore the machine will cost more. Thus, we shift from a world where machine efficiency is unrelated to the total cost of ownership to a world where the total cost and price of a machine are affected because if your drivetrain is inefficient, you’ll have to install a larger battery.

2. With the further development of electrification, what other changes might occur in hydraulic system design?

This concept of efficiency applies not only to each hydraulic component but also to the entire transmission system, which will revolutionize both electromechanical and traditional machinery.

With diesel systems, you have an unlimited energy supply, so efficiency isn’t as critical. But with batteries, this is no longer the case; the efficiency of the entire system must be maximized. The energy conversion efficiency from battery to shaft by the motor and inverter is very high. However, we still need to improve hydraulic efficiency, even if it’s just by five to ten percentage points; it doesn’t need to reach 100%. This will have a significant impact on battery size, cost, and weight, thus affecting the overall energy consumption of the machine.

3. What are the biggest challenges in integrating fluid dynamics and electrification technologies, and how can these challenges be overcome?

We face a highly uneven regulatory environment. The pace of electrification is asymmetrical across different regions. There are currently varying dynamics regarding zero-emission regulations. More realistic and structured regulations may be needed to allow the market to naturally push these technologies to the forefront, as only in this way will the necessary infrastructure be built. Let the market lead us into a zero-emission future.

There are also emerging industry standards surrounding functional safety and cybersecurity. Most products today do not take these factors into account. Therefore, when we look to future designs, this will require some truly comprehensive design changes, especially in the electronics that control and drive these electrified systems.