glitch401
4
The oscillator that could makeover the mechanical watch
Author: Laure-Anne Pessina Will the familiar ticking of our watches be a thing
of the past? A group of EPFL researchers has imagined a unidirectional
continuous oscillator which could become a new timebase for the
mechanical watch. This would revolutionise the mechanical concept whose
basis has remained unchanged for centuries. IsoSpring, the name
given to the new oscillator, was recently revealed to the public at the
Journée d'Etude de la Société Suisse de Chronométrie, the annual
conference of the Swiss watch industry. IsoSpring allows one to bypass
the most complicated mechanism of traditional watches. The result will
be more precise watches with increased autonomy which would also be
noiseless. "Our prototype weighs four kilograms but we're already
trying to miniaturise it so as to fit it in a wristwatch; the watch
industry has expressed great interest in the project," says Professor
Simon Henein, holder of the Patek Philippe Chair and director of
Instant-Lab. IsoSpring differs from the pendulum, the spiral-balance
wheel and the tuning fork, the three oscillators used in clocks and
watches. It represents the first conceptual change in the mechanical
watch in 200 years. 60% energy lost in traditional watches Compliant mechanisms "Our concept is in a mechanical
tradition. We do not appeal to high technology and our methods are
accessible to 18th century engineers," points out Simon Henein. Elasticity for elliptical rotation "Our watch is a
departure from chopped up ticking time and a return to continuous time
as seen in nature by the motion of the stars," concludes Simon Henein.
Source: Mediacom
For the first time
in 200 years the heart of the mechanical watch has been reinvented,
thereby improving precision and autonomy while making the watch
completely silent. EPFL researchers have developed an oscillator that
turns continuously in one direction, eliminating one of the crucial
mechanisms of traditional watches.
Mechanical watches depend on a system of gears leading to the
alternating oscillations of the balance wheel and the motion of the
hands. The interface between these gears and the balance wheel is the
escapement. It continues to represent the most difficult challenge to
engineers. Every time the balance wheel changes direction, the entire
gearing mechanism starts and stops yielding the familiar ticking sound.
"This stop and go motion wastes enormous energy, for this reason even
the best escapements are limited to 40% efficiency," explains Simon
Henein.
Due to its
continuous rotation, IsoSpring eliminates the need for an escapement.
Gone are the traditional intermittent mechanisms, now substituted by
smooth motion based on compliant mechanisms. One of Simon Henein's
specialties, compliant mechanisms use the elastic properties of matter
to effect the motion of mechanical components, eliminating friction and
the need for lubrication.
But how does IsoSpring work, exactly? Imagine an ancient sling in which
you use a leather strap to make a stone turn in a circle. If you
replace the strap with an elastic band, the stone will now move in an
ellipse and its speed will no longer be constant; on the other hand, its
period will now be constant so it can be used to measure time
precisely. This principle, discovered by Isaac Newton in the 17th
Century, is the conceptual basis of the new oscillator. The rotation is
maintained by the traditional barrel spring.
© 2014 EPFL
