Really Double Performances
Hub Motor with Internal Gearbox
wire connection
break pad version
36 holes version

Intellectual Property: Patent of invention
Status: in production
Market Availability: after presentation to the 2014
Padua Expobici
Business Opportunity: Minimal Powertrain AG
Data, Drawings and Pictures: Available

 

Hub Motor with Internal Gearbox
pack 7 pinions. (available 5-7)
wire connection
160mm disc brake
36 holes version

Intellectual Property: Patent of invention
Status: in production
Market Availability: after presentation to the 2014
Padua Expobici
Business Opportunity: Minimal Powertrain AG
Dati, Disegni ed Immagini: Available

 

Hub Motor with Internal Gearbox

Hub Motor with Internal Gearbox

How And What

Really it is impossible to design a motor, of a minimal power, capable to give a sufficient torque to meet the automotive standard, also spending the best electronic technology and the most sophisticated highly performant mechanical knowing for fixed ratio.

The physical reality that the Power is equal to Torque multiplied by the Angular speed imposes also in the light vehicles field insurmountable limits on achievable performance when accelerating and especially uphill.

These, the reasons for the presence in the drivelines or drivetrains of the technical unit called Gearbox, which has the specific function of being able to exploit the maximum Power producible by varying in inverse proportion the above mentioned parameters, for which to the below speeds correspond higher torques and vice versa.

If you think about the growing trend in the number of transmission ratios offered by gear boxes chainrings/pinions-set from the initial fixed one to the current 27-speed of the mountain bikes till to the Continuously Variable transmission, becomes obvious the needing and the contribution of this component.

Furthermore, any engine also has its own performances, graphically illustrated by its characteristic curves determined by testing on a chassis dynamometer.

The parameters thus identified are not constant and therefore Torque, Efficiency, Specific Consumption etc. are related to the number of revolutions even affected by environmental conditions and especially by the use then, also in relation to efficiency and consumption, almost never it can do better than thanks to a good gearbox.

In the electrical machines, said use is indicated by the reference standards, used by the motor manufacturer for example, to declare suitable and guarantee it.

Typically it comes to service codes such as: continuous (S1), temporary / limited in time (S2), cyclic (S3).

Values ​​such as peak torque then – often promotion opportunities on a commercial level – have no technical meaning because they must be considered limited at the starting time (properly called starting torque) and however usable only for a few seconds, unless this regarding, the times and conditions for which the motor can work at that value, without damage and breakage, are been specified. This also applies to the torques defined continuous therefore, to know how much they are really exploitable in time as well as in general understand in which point of the powertrain the data are referred: engine output, driving wheels…, is essential.

It should also be duly said that the maximum torque that the electric motors DC brushless permanent magnet can give with equal voltage, corresponds to their current absorption that is limited to the value of nominal discharge (non-peak or maximum) in the possibilities of  the battery so that, in a motor not coupled to a shiftable gearbox even if it is designed to withstand the joule resulting effect, is fanciful to think that torque values ​​nevertheless really declared, are really obtainable regardless of the evaluation of the electric storage capacity which is coupled.

Quite different is availing of a shiftable gearbox, which in the example of a transmission ratio τ = 0.5, guarantees a double couple at half speed, without the need of a double electric current intensity.

The dual transmission ratio, operable manually as well as automatically as needed, makes these motors PMBLDC type – means Permanent Magnet Brushless Direct Current – with high magnet intensity by using rare earths (NdFeB), category Synchronous Motor, capable of performance unreachable by different solutions having the same power and for the same service time.

Designed for 250W of continuative maximal nominal power and 36V and 48V to meet the law regarding the Pedal Assisted Electric Bicycle, this motor with gearbox inside is available in several versions: for front wheel drive and/or rear wheel drive with sprockets up to 7, for the disc brake or buffer/V-brakes and, it is really valid to realize Minimal Powertrain Hybrid type also in vehicles which typically employ a secondary transmission by chain.

In view of the high torque can be downloaded to the ground, please note that the maximum traction achievable in a two-wheeled vehicle is usually at the rear.