New Ultra Power micro gearbox from maxon
Inspired by the development of specialised gearboxes for NASA’s Mars 2020 project and the European Space Agency’s ExoMars mission, maxon have introduced a new standard to their miniature gearboxes - now with increased efficiency and improved performance.
Pioneering technological advances, such as those made in connection with Formula 1, eventually filter down into everyday motoring. At maxon, these revolutionary advances occur while working on aerospace projects and are then introduced into the industrial sector. The new ultra-power micro gearboxes were born from maxon’s research and technology developed for the European Space Agency’s Mars project 'ExoMars' and NASA's 'Mars 2020' project. There was a need to ensure the highest possible efficiency even in the extreme environmental conditions found in Space.
The efficiency of the ultra-power micro gearboxes is the relationship between output and input power. Significantly reducing the friction produced in any mechanical system naturally leads directly to optimisation of the DC motor. In the new GPX planetary gearbox UP series, a technical repositioning means that the planetary wheels, which in traditional planetary gearboxes are on plain bearings directly on the carrying axle, are now sited above the ball - or needle bearings. In mechanical engineering rms this is referred to as a 'transition from sliding friction to rolling friction'.
Looking at a maxon GPX32 UP gearbox in three-stage construction as an example, a maximum efficiency of around 90% can be achieved. Comparable miniature gearheads achieve around 70%. Compared with conventional design, we can say that by means of the engineering advances mentioned above, an increase in efficiency by a factor of 30% is accomplished.
This also directly affects further parameters of the DC motor system: Given the same input power, ie. using the same motor and the same motor control system, the gearhead can deliver 30% more torque. Or put another way: the same output power will require 23% less input power for the drive. This results in a much longer potential action time until the next charge cycle, particularly for battery-driven applications.
As a result of the reduction in the input power required, the used motor can in addition be operated at a more favourable operating point. This factor also improves the efficiency of the motor, and with it the whole DC motor and drive system.
As an alternative, smaller and/or lighter motors and electronics can be used, with advantages not only in terms of weight but also in terms of cost.
Significantly longer gearbox service life
As mentioned above, friction in the planetary wheel - axle system could be considerably reduced. At the same time heat generation from operating the drive is noticeably reduced because there is less friction power. Particularly in applications where temperatures should not exceed a certain level (eg. medical power tools), there is improved power output.
The durability of the lubricant plays an important part in terms of wear and tear on the gearboxes' mechanical components. The greater the thermal stress, the more quickly its lubricating properties are lost, and the earlier and more serious therefore the abrasive behaviors in the mechanical system. The abraded metal particles also lead to an agglutination of the lubricant, potentially resulting in a breakdown in its lubricating action.
If the heat feed is checked, then in otherwise identical operating conditions a longer service life can be achieved. This effect is an outstanding feature of the GPX UP gearbox: the service life is five times greater compared with similar traditional maxon gearboxes and compared with competitors' models currently on the market it is 11 times greater.
As an alternative to longer service life, as a result of significant improvements in the torque to diameter ratio (power density), much smaller and lighter gearboxes can be used.
The advantages of the new design are not only producing improvements in the gearbox specification's individual parameters. Further new applications for the GPX UP gearboxes can also be seen, in particular the so-called Force-Feedback applications.
With these applications the advantages of the engineering of the GPX UP gearbox version come into play. The use of mounted planetary wheels makes smooth inverse rotation of the gearboxes possible in normal operation and, if necessary, can provide operator feedback. Quantifiable and tangible mechanical feedback is conveyed to the force and torque elements. To achieve this, the gearbox needs to be reversible, ie. the torque and changes to the torque which are in contact with the output side, need to be conveyed proportionally to the DC motor side.
To demonstrate this application: In electronic flight control (Fly-by-Wire), the pilot's steering movements are not transmitted to the actuators mechanically or hydraulically, as in conventional systems, but electronically. But with this the operator initially loses all tangible feedback on their steering movements. With the deployment of a drive in the control column, the electronically transmitted feedback is mechanically conveyed to the pilot's hand. Inverse rotation is particularly necessary in normal operation, because the additional DC motor installed should not hinder the movements of the control column.
A similar process applies to the innovative surgery robots in the micro- and telesurgery range. Here it is also crucial that the operator receives direct and tangible feedback about the movements they have performed or healthy tissue that should be left untouched. Reversible drives are also in demand in plant construction. In setting mode the axles need to be movable from the output side, without current.
The new GPX UP gearboxes combine a range of important product advantages: More power, more torque, improved efficiency, considerably longer service life, reduction in heat generation, less weight in the drive system as well as the additional reversibility function in multistate gearboxes.
Taking only the first two factors into account, we might refer to them as ultra-power gearboxes. But with the other properties listed here, we can easily coin a new title : Ultra Performance.
Ultra Performance GPX gearboxes from maxon are already available in GPX22 UP und GPX32 UP diameters, and like all 'X-series' they are customisable and available to order online. The GPX42 UP gearbox version will follow in mid-2020. In addition customisable gearheads in the Ultra Performance series are now available in sizes with diameter Ø 8 – 58 mm.
For further information please contact maxon motor Australia tel. +61 2 9457 7477.
© 2020 by maxon motor Australia
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