Asphalt compactors aren’t known as the most difficult machine to use on the job. Although compactors perform a critical function, especially when regularity specifications are at stake, many contractors leave them to their less experienced operators.
But what if these machines didn’t even need an on-board operator?
Enter Volvo Construction Equipment’s CX01 asphalt compaction concept, a planned ConExpo revelation that had to wait until the recent Utility Expo to be presented to contractors.
“We just wanted to look at what the future of compaction would look like,†said Justin Zupanc, head of the asphalt compaction development team at Volvo CE. Equipment world at the show. “We wanted to create a better driving environment, reduce fuel consumption and exhaust emissions, and increase productivity.”
“A better driving environment” results in the absence of a cabin. Instead, a connected fleet of CX01 single drum units led by an uploaded compaction plan would either be remotely controlled by an operator or controlled autonomously.
Volvo already has an autonomous system on its TA15 haulers, which is currently in customer testing, and there are plans to test a similar system on the CX01, Zupanc said.
The CX01 has no knuckle joint “so there is no point of balance, there is nothing we can stray from,” Zupanc explains. Volvo solved this problem by using a split drum – which has two halves which can be operated independently – maintained in a vertical position by means of a self-balancing control system. (The split drum comes out of its current 9 ton class machine sold in Europe.) To spin, operators can vary the speed of each half of the drum. “You can make a pretty sharp turn,†he says.
And although it is not used when the unit is on asphalt, users would also have the option of rotating the machine.
Rethinking the paving processThe Volvo CX01 compactor prototype has guards and emergency stops at every corner.Equipment world
Volvo says the CX01 – which means experimental compaction unit n ° 1 – provides the means to “fundamentally rethink the paving processâ€. By removing the operator, you also remove their exposure to vibration, noise and dust.
As expected, a fleet of CX01s could be deployed on larger jobs and communicate not only with each other but with other machines on site. Machines could monitor the job, report belt conditions such as density, temperature and passes (which smart compactors already do) and determine when and where to compact. “They can move if an area is already compacted,†Zupanc explains. “All the information is available for the crew and the other machines. You can even send them to the asphalt plant.
The compact design and maneuverability of the machine could also lead to streamlined compaction cycles, lower costs and more agile work patterns, Volvo says. The bearing pattern, weight and number of rollers can be adjusted to match the width, thickness and speed of the paving operation. With Volvo’s existing Co-Pilot system, operators can use a touchscreen to remotely control compactors.
Flexible power
The CX01 has a flexible power system. It has both a 1.7 liter diesel engine and an energy storage system that can operate in diesel only, hybrid or fully electric mode. “The diesel is only there to run the 20 kilowatt generator,†Zupanc explains. The generator in turn powers two 48-volt ultracapacitors placed on either side of the drum, which in turn power three 14-kilowatt electric motors, one for each side of the drum, and another to power the eccentrics of the vibration system.
“You can run it with the diesel engine on, and it still charges the ultracapacitors,†says Zupanc. When the ultracapacitors are charged, the motor can be turned off and the machine becomes fully electric. The motor will restart when the ultracapacitor loads are low. “They charge very quickly, within minutes,†he says. The downside: capacitors do not have the capacity of a lithium-ion battery; the running time is about 20 minutes, depending on your speed.
“We had never used them before and wanted to see how they worked,†says Zupanc, explaining why Volvo was using ultracapacitors on the CX01. “Although they don’t have the capacity of lithium-ion batteries, they are good for vibration and they have a long life cycle. They may not be the right solution as they don’t have that longevity, and who knows, we can pair them with a lithium ion battery down the road. “
Since ultracapacitors need a constant charge, the diesel engine is unlikely to turn off while they are in use.
Volvo is also considering using a coating based on low-friction water-reducing polymers on the surface of the drum. – now theoretical – which could also be used on its other compactors. This would combat the common problem of asphalt sticking to the drum, now solved by using water. The CX01, however, has limited water storage.
Volvo has produced = the following explanatory video on how it envisions using the CX01:
