The global drive towards net zero and sustainable energy sources is accelerating the shift from fossil fuel to electric-driven machines. Some European companies are already setting conditions for electric-driven equipment on their tender requirements. Large machines are more complex to convert because of the high-power demand. Nevertheless, as electric technology develops, the ground engineering sector is making progress in transitioning the industry to electric power.
Soilmec is among the leading ground engineering companies with a history of over 50 years in designing, manufacturing, and distributing equipment. In line with global trends toward sustainability, Soilmec has embarked on creating a zero local emission line of machines, choosing the microdrilling machine SM-13e as the first in this range. This machine is typically used in soil consolidation work, anchorage, and tunnel construction.
Parker Hannifin supplied several components for the SM-13e, including the GVM210 series motors and GVI-G650 inverters. This project aimed to meet the functional requirements for speed and power while significantly reducing operating costs and improving performance, relative to the diesel-powered machine.
The challenges to making electric ground engineering machines
Ground engineering machines work in extreme conditions. Construction sites are exposed to the elements and dusty conditions associated with earth moving. Additionally, drilling through rocky ground results in high vibrations. Sensitive electronic components are vulnerable to failure unless designed for these conditions.
In the case of the Soilmec SM-13e ETECH machine, the functional requirements created some specific challenges. The SM-13e required four electric motors, each with an inverter. Two of these motors are mounted on top of the mast in the rotary head. The elevation is particularly challenging because cooling systems must supply the motor at heights up to 10 meters without interfering with the machine’s operation.
Two motors in the rotary head drive the rotational movement, and the other drives the push-pull movement of the drilling head. The control of the rotary’s motors must be highly synchronised, making the inverter and motor design and control critical for machine operation. The rotational speed can vary from a high of 130 rpm to a low of 1 rpm. The push-pull motor also has a wide speed range from 50 m/min to 0.08 m/min.
The electric technology behind the SM-13e
Parker supplied several components for Soilmec’s electrified microdrilling machine, including motors and inverters. The design of the SM-13e utilised the following technologies:
- GVM210300 motor: The SM-13e has four of these motors, which offer speeds of up to 9800 rpm with a peak torque rating of 710 Nm. One of these motors interfaces directly to a hydraulic pump without any coupling. The other motors connect to gearboxes.
- GVI-G650 inverter: Each of the four motors in the solution has an inverter for motor control. These inverters have switching frequencies of 1, 2, 4, 8, 12, or 16 kHz and a peak current of 320A.
- QDC-050-B hydraulic cooler: This cooler provides high power density and efficiency for a maximum cooling capacity of 26kW at 40°C. Parker’s thermal management system uses this cooler to manage the temperature of the motors, inverters, and the hydraulic coil using a specially designed pressurised tank system.
- P2075L hydraulic variable piston pump: This pump can operate at high altitudes, making it a critical element of the solution for keeping the elevated motors cool.
The SM-13e solution was designed with maximum flexibility in mind. There are three operating modes – Normal, Eco, and Boost. The Normal mode delivers standard operational performance, and the Eco mode allows for conserving energy when power demands are lower and elongating battery life. The boost mode enables short periods of maximum performance.
The machine also comes with different options for electrical supply. The simplest configuration requires a constant electrical supply via a cable. The SM-13e can also be delivered with one main battery and works without cable connection, or with two batteries so that a backup battery can be charged while the machine is operating.
The GVI inverters and GVM PMAC motors from Parker were among the core components in the SM-13e’s design. (Photo Credit: Parker)
A collaborative approach
Soilmec has more than fifty years of experience in the ground engineering sector, having developed small and large machines for a wide variety of applications. As a result, the company’s engineers bring a wealth of knowledge and experience about how the new electric equipment must work to meet their customers’ needs. Complementing this, Parker Hannifin has been developing technology and components for machines for more than 100 years. With expertise covering all aspects of mobile equipment, its engineers can provide insights about the individual components as well as how they work together in an electric machine.
In developing the Soilmec SM-13e machine, Parker and Soilmec engineers worked together in a collaborative approach. They went through several iterations of refining the requirements, selecting components, and designing a system that works as an integrated whole. As a result, the first Soilmec SM-13e machine is already delivering excellent results in the field.
The benefits of electric ground engineering machines
Electric machines, like the SM-13e, deliver significant benefits to ground engineering companies. Firstly, they enable users to reduce their carbon footprint substantially. The SM-13e is much more efficient than the diesel equivalent. As the energy source is electrical, the CO2 and other greenhouse gas (GHG) emissions are vastly reduced. At the same time, electric machines are much quieter than internal combustion engines. In contrast to endothermic machines, electric motors are off when the utilities are active, but the machine is not drilling. This drastically reduces the noise to which the operator is subject as well as the energy consumption of the machine.
Secondly, improved efficiency also delivers a reduction in running costs. Diesel engines tend to run on a time-based service interval. This interval is calculated based on the running time of the machine, including idle time. On the other hand, motors on electric machines can be individually monitored for running time. Thus, maintenance intervals can be significantly extended, resulting in operating costs as much as 56% lower. Additionally, the machine is more available due to reduced downtime, and jobs can progress quicker. Maintenance costs are also reduced because there are fewer maintenance tasks required on an electric motor than on a diesel engine.
Lastly, electric machines offer higher performance than their diesel equivalents. This benefit is due to the constant torque availability from electric motors regardless of speed. This is an attractive benefit for construction companies because the improved performance allows them to complete projects in a shorter time, thus improving their profitability.
Electrification in development
Soilmec and Parker have combined their expertise in ground engineering machines and motion and control technology to develop an electric microdrilling machine, the SM-13e ETECH. This machine is the first in a zero local emission line from Soilmec.
There are several challenges to converting ground engineering machines from fossil fuels to electric, including high vibrations and adverse operating conditions. Nevertheless, the project team designed and built a machine that met all the functional requirements and exceeds the performance of the diesel equivalent. The SM-13e microdrilling machine now offers lower emissions and higher efficiencies, reducing operating costs by up to 56% through optimised maintenance programs. The collaborative approach by Soilmec and Parker has delivered a machine that is fit for purpose and operates as an integrated whole rather than just a change in energy source.
Soilmec’s SM-13e (Photo Credit: Soilmec)
