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Hydraulic Hybrid Technologies


Alternative power sources

Apr , 25
Alternative power sources

It can be argued that there has been very little innovation in propulsion systems for vehicles in the last 20 years. Although engines and gearboxes have become more advanced and efficient, innovation has been limited to improving existing systems.

Internationally, there is pressure from environmental groups, and governments, to reduce harmful emissions from internal combustion engines and this has mostly resulted in the development of hybrid propulsion systems.

The big drive in personal vehicles is to get to zero emissions through electric engines, but the limitation remains the distance a battery charge can give. Also, to recharge such a bank of batteries takes hours, where it takes minutes to refill the fuel tank on a car or a truck.

Just like with internal-combustion engines, trucks that carry a heavier load need bigger motors and batteries. And this is where there seems to be some interesting developments heading for the market.

Hybrid propulsion systems, typically a combination of an internal-combustion engine and another unit such as an electric motor, have been around for a while. As have engines running on CNG (compressed natural gas). But just like engines running off hydrogen – fuel cells – there is a safety issue around the tanks containing the volatile fuels.

Volvo Trucks has developed a new concept with support from the Swedish Energy Agency. The Volvo Concept Truck is said to reduce fuel costs by as much as 30%. But this is achieved mostly by improving the aerodynamics of the rig and reduced weight.

In 2016 Mercedes-Benz announced the development of their eTruck. This is a solution aimed primarily at the so-called last-mile distribution network. It is a zero-emissions vehicle with a range of 200km per charge. But it is not yet clear when they envisage that this truck will be commercially available.

But, generally, electric trucks would only be used on shorter trips, because there are no recharging stations for such a truck’s batteries.

Interact Analysis, an international research specialist in automation, says 2018 saw quite a few new truck manufacturers going electric (https://www.interactanalysis.com/battery-electric-truck-market/). Volvo will have electric power in two of its model series; DAF will electrify two of its models in partnership with VDL and Cummins; and Freightliner, the US manufacturer owned by Daimler, launched electric versions of two of its trucks.

Daimler will be investing $3,2-billion in an electric truck and research and development and Volkswagen an amount of $1,7-billion, respectively.

Interact Analysis says the global battery electric truck market contracted by 12% in 2018 owing to a decrease in demand from China primarily due to a subsidy reduction. The rest of the global market for electric trucks, however, grew by a strong 63%.

Interact Analysis predicts that just under 180 000 battery electric trucks will be sold in 2019, with most of the demand coming from China. Outside of China, they forecast sales of just more than 50 000 units. This will be 81% more than in 2018. Because of the high cost associated with large battery packs, the heavier truck segments will have a small share of the market while the light- and medium-duty segments will combine to make up 98% of the global battery electric truck market.

However, we are not likely to see any of these 180 000 electric trucks locally any time soon. But that can change any moment now, as a locally developed propulsion unit is now available to the market.

Ducere Holdings is the owner of MISER hydraulic hybrid propulsion technology, which they say will bring the future to transport.

André Reyneke, managing director of Ducere, says it is no secret that the batteries remain the Achilles heel of any electric vehicle. The world is still waiting for the battery that can hold enough energy and last as long as the vehicle itself.

“And while we wait, any system that can improve – in other words, reduce – the current draw from batteries and increase the number of charge/discharge cycles will be welcomed. And we have that system.

He says MISER is an enabler of electric vehicles.

“The best electric vehicles are electric-hydraulic hybrids due to its more efficient regenerative-braking abilities along with the launch-assist, reducing peak battery loads.”

Reyneke says the hydraulic system is significantly more efficient than the typical regenerative ability of an electric drive.

“An electric vehicle is about 30% efficient in regenerative braking mode, where hydraulics achieve around 70% efficiency.”

He says this brings a number of possibilities into play. The more efficient regenerative braking could mean up to a 30% increase in range in a town-drive cycle.

“Our current major project and focus, The MISER Hydraulic Hybrid Propulsion System, keeps us involved at the forefront of today’s automotive hybrid technology – and that’s where we like to be,” he says.

Their first product on the market is MISER-HKS, a retrofit hydraulic hybrid unit, specifically for heavy-duty vehicles.

“The MISER technology is a revolutionary new approach to kinetic-energy recovery, engine optimisation, and storage and reapplication for any form of vehicle. The system complements various other technologies aimed at dramatically improving fuel consumption, vehicle performance and total cost of ownership – while simultaneously reducing carbon emissions.”

Reyneke says the technology enables more efficient energy recovery and engine optimisation than any competing technology.

“MISER achieves this with a hydraulic solution using a combination of braking-energy recovery, engine optimisation and various modes such as torque summing, regenerative braking and launch assist. This provides an efficient medium for the fast storing and release of energy, while at the same time optimising engine performance by keeping the engine on the ideal brake-specific fuel consumption line.

“The MISER transmission is a hydraulic and mechanical, infinitely variable dual-path energy-transfer system with a sophisticated microprocessor control system. It has fewer energy-flow paths, fewer valves and fewer parasitic losses, such as charge pumps, than any existing hydraulic hybrid systems.”

The MISER transmission is a compound-type hybrid drive. In some modes it is a series system (where the engine can charge the storage system with energy for later use) and in other modes it is a parallel system (where the energy is delivered from the engine, or the storage system, or a combination of both). This depends on which of the 13 possible modes the control system selects.

The MISER system can be installed in one of two ways. The first option is the Hybrid Kinetic Energy Recovery System, or HKS for short. It involves the fitment of the energy-recovery components only. Benefits are both regenerative braking and engine optimisation. This is already available to the market.

The second installation involves an addition to the vehicle’s gearbox as well as the fitmentof the Hybrid Kinetic Energy Recovery system. This is called the Hybrid Transmission System – HTS. Several additional advantages include savings specifically advantageous in highway-type driving cycles.

“Our pilot projects at long-haul transport clients are delivering excellent results with MISER-HKS, showing fuel savings in certain drive cycles in excess of 40%.

“The Gerotek Test Facility performed independent tests on the first of the trucks and their results have confirmed ours, proving the efficiency of our technology.

“We have also started our new project that uses a combination of our hydraulic unit, and electric motor and a small internal-combustion engine, specifically aimed at smaller passenger vehicles. We expect the first few vehicles on the road in 2019. We believe that this will be a game changer as it incorporates a new way of thinking.”

Reyneke says they see the immediate market potential of MISER as being aftermarket sales, followed by the new transmission and energy-recovery technology universally fitted to all forms of motorised vehicles and transportation systems over the next eight to ten years.

“Unlike electrical systems that cannot scale due to technology constraints, MISER can comfortably be fitted to a range of vehicles – from a small car up to very large excavator. This gives us a distinct advantage as we can participate in a far wider range of sectors.

“Recent studies have shown that electric vehicles will benefit significantly from using hydraulic hybrids to improve current draw and improve battery charge cycles. While the world’s focus is on pure electric and electric-hybrid vehicles, there is very limited attention on the hydraulic hybrid solution. And this is the field in which MISER aims to be the leader,” says Reyneke.

For further information, or to arrange for an interview with André Reyneke:

Réhann Coetzee
071 816 3959

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