Belgium-based Mazaro is bracing up to roll out two futuristic technologies – Reversible Variable Transmission (RVTs) and Single Stage Variable Transmission (SVT) – that promises to drive enhanced efficiencies in automatic transmissions.
The automotive industry across the globe has been witnessing significant developments in the area of transmissions, driven by an ever-growing need for greater fuel economy, lower emissions and improved driving experience. From three speed gearboxes to 10-speed gearboxes, variation in ratios as well as different types of clutch systems supporting these advanced gears, developments in transmissions are all aimed at ensuring an efficient power transfer from the engine to the wheel.
Destelbergen, Belgium-based Mazaro has developed two futuristic transmission technologies – Reversible Variable Transmissions (RVTs) and Single Stage Variable Transmissions (SVT) that claims to make drivelines more efficient, and help perform better. Auto Tech Review caught up with Filip De Mazière, Director & Development Engineer, Mazaro, to understand how this new transmission technology will shape the future of mobility.
Various automotive transmission technologies currently prevailing in the market, including automatic transmissions, dual clutch transmissions (DCT) and manual transmissions use gears to alter the ratios in various steps, which ensures the engine delivering its best efficiency in a region. The region becomes smaller owing to use of increased number of gears, but leads to substantial shifting that can result in a significant drop in efficiency levels, while shifting gears. Continuously variable transmissions (CVT) serve as an alternative since it can ensure the engine delivers its best efficiency in more driving conditions. However, CVTs leverage a belt or rollers instead of gears with much larger friction than gears and with slip, nullifies the positive effect of their continuous ratio variation.
REVERSIBLE VARIABLE TRANSMISSIONS
Reversible Variable Transmissions (RVT) have been designed for combustion engines and hybrids. Irrespective of the driving conditions, RVTs ensure the engine always runs on its best efficiency curve. These transmissions run with an exceptionally high efficiency even while changing the ratio. The transmission ratio is continuously changing in a real driving scenario that goes a long way in reducing energy consumption as well as emissions, Mazière pointed out.
RVTs run silent and have no gears inside – these transmissions can change the ratios without any torque dip. Power is transmitted by rolling steel wheels with a special shape so that no slip occurs in the rolling contacts, Mazière explained. In RVTs, all components with friction losses such as gears, clutches, synchronisers, torque converter, the CVT-belt or toroidal slipping wheels have been eliminated and are replaced solely by traction wheels, which do not slip. These transmissions transfer power without any slipping components that explains their higher efficiency, claimed Mazière.
RVTs offer speed ratios down to zero, which effectively means that it enables precise manoeuvring because the vehicle is speed controlled independent from the slope and independent from any obstacle on the ground. This technology is practical for lift trucks, container handlers, tractors and airplane tow tractors. RVTs brings in extra efficiency thanks to its unique hydraulic actuation system, consuming no more than 0.1 % of a vehicle’s entire energy consumption, Mazière noted.
RVTs also drive substantial fuel-savings. Simulations undertaken by the company indicate a fuel saving of around 13 % for a RVT-equipped city bus in a standardised on-road test (SORT) driving cycle as compared to a 6-speed automatic transmission. A RVT-equipped vehicle drives off with its engine at idle speed, even with maximum torque at the wheels, thanks to its infinite torque amplification and there is no need to rev up the engine before launching. Mazière cited an example of a city bus driving away with a silently running engine with low emissions. This technology helps accelerate with the engine at all times at maximum speed.
These RVTs offer acceleration with constantly maximum power, while stepped transmissions accelerate with the engine in the proximity of maximum power. The technology helps accelerate with the engine all the time at its speed corresponding to it maximum power. For instance, a diesel engine has a max torque of 300 Nm at 1,500 rpm and a max power of 100 kW at 4,500 rpm. During a full throttle acceleration, the RVT keeps the engine running all the time at 4,500 rpm and the engine continuously supplies 100 kW of power. Equipped with a stepped gear transmission, the engine speed changes from about 3,000 to 4,800 rpm, while the transmission shifts up each time. In this case, the engine power varies between some 60 and 100 kW.
On the fun-to-drive front, Mazière said cruising at constant speed happens with the engine at low and quiet speed. Once the throttle is pressed, the engine immediately revs up to deliver the requested power. There is no power-eating torque converter (that makes accelerations sluggish) in RVTs, the company claims.
Mazaro claims that on a hill, irrespective of the slope and vehicle load, the throttle pedal defines the speed. There is no risk for rolling back as well as no need to dissipate energy by pushing the brakes for slow driving, explained Mazière. In any case the vehicle speed is controllable by the throttle pedal, a feature that is appreciated by material handling equipment manufacturers.
SINGLE STAGE VARIABLE TRANSMISSION
Based on the same technology as the RVT, Mazaro has also developed the Single Stage Variable Transmission (SVT) for electric vehicles. SVT is a simple construction that ensures uninterrupted, step-less traction and silent operation of EVs. Driver and passenger do not notice that there is a transmission in their e-vehicle when an SVT is installed, but they will experience fierce acceleration, climbing capabilities and high top speed without any gear noise or fast spinning motor noise, Mazière stated.
As electric motors can work down to zero speed and in reverse, electric vehicles only need a transmission with a variable ratio without reverse. The SVT is shorter than the RVT and also has an even higher efficiency. The current SVT version has a measured efficiency map, which is almost equal for any operational condition. Mazière said irrespective of the speed, the ratio or the transmitted torque, efficiencies are measured between 94.5 % and 95.5 %. Mazaro is currently developing a newer version with an expected efficiency map ranging between 96 % and 98 %. This is higher than any other transmission system, claimed the company.
Mazaro is aware of the price-sensitive nature of the Indian market and is already engaged in discussions with some Indian companies for carrying out production in India. The company believes production of RVTs and SVTs in India will ensure these transmissions enter the market at a competitive pricing. Both these pioneering transmission technologies claims to significantly reduce the total cost of ownership. Mazaro is yet to take a call on the commercial roll-outs of RVTs and SVTs (globally as well as in India) – it is fine-tuning these transmission technologies and is bullish about launching these technologies in 2021.
TEXT: Suhrid Barua