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By: DonCorson [AHCI Moderator] | PM
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New Developments in Timepiece Regulators – SSCStudy Day 2014Date: Oct 22, 2014,00:10 AM - (view entire thread)
New Developments in Timepiece Regulators – SSC Study Day
2014
The Société Suisse de Chronométrie (SSC), hosted a study day in
September dedicated to the “Vectors of Innovation in Watchmaking –
Materials, Design and Calculation” The conference was held at the new SwissTech Convention
Center on the campus of the Swiss Federal Institute of Technology in Lausanne (EPFL).
There were many presentations including subjects such as developments in colored ceramic
materials, the characterisation of the elastic properties and deformation of the nickel-phosphor
materials used in the LIGA process, measurements of acoustic elements (read; repetition gong) using
a Doppler laser, etc..
For me, the two most interesting presentations had to do with new implementations of the regulating
organ of mechanical watches, the Genequand regulator and the IsoSpring regulator. The
Genequand regulator is an implementation of John Harrison’s grasshopper escapement for clocks
(1730) using flexible elements instead of pivots. This escapement is combined with a new pivotless
oscillator with very high quality factor, greatly increasing the autonomy. It is also entirely implemented
in silicon.
The following report presents my own explanation of the presentation of the IsoSpring regulator by
Professor Simon Henein [1]. This regulator is based on a different concept than the oscillator
systems used as the time base for today’s watches and pendulum clocks. This regulator has been
dubbed "IsoSpring", but I would prefer to call it "Orbital", as it is based on the physics of celestial
movement, the orbits of the planets as described by Kepler and proven by Newton. These concepts
lead to an orbital regulator that does not require an escapement. It does not chop the time into short
periods, ticks, but produces a continuous controlled movement.
Professor Henein started the presentation with a quick, but in depth, history of modern escapements,
mechanisms that is used in all mechanical clocks and watches made today. We remember that one
of the main requirements for a precise, practically usable time base is that its oscillating frequency be
independent of the amplitude of oscillation. This property, known as isochronism, makes the
timekeeping independent of the fluctuations of the energy source. The isochronism principle was
discovered by Galileo and implemented first by Christiaan Huygens, in 1656 for clocks with the
pendulum and in 1675 with the balance-hairspring (in parallel with Hooke) for watches. With these
improvements the accuracy of clocks went from an error of 15 minutes a day to about 15 seconds a
day, a tremendous improvement of almost two orders of magnitude.
Subsequent advances were less spectacular, the chronometer escapement bettering the
timekeeping, the Swiss anchor escapement and certainly the introduction of draw on the anchor
bettering the reliability. From that time (1800) to now the advances have been small and incremental,
many tiny improvements that all together have lead to the level of timekeeping and reliability that we
see today. But these regulators are all based on simple oscillation, the movement of a mass with a
restoring force, be it gravity in the case of a pendulum or a spring in the case of a balance wheel.
That balancee wheel must continually stop and change direction.
The novelty of the IsoSpring orbital regulator is that it is based on the orbits of the planets around the
sun, yielding unstopped rotation. The basic concept goes back to 1687 when Isaac Newton
published the Principia Mathematica. His most famous result was to show that the celestial
movements could be explained by a few simple principals and to prove the laws of Kepler governing
the elliptical orbits of the planets around the sun, the sun being at one of the focus points of the
ellipse.
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New MovementDevelopments, theGenequand Regulator- >> There is more happening in the watch
world than we may expect, here an example
announced yesterday, the Genequand
regulator. Photo credit CSEM Following is the
press release from Vaucher Manufacture and
the CSEM about the new Genequand
regulator: Fleurier and Neuchâtel, 15
September 2014 - A perfect... Read more..
Author: DonCorson
(8) Latest Reply: Fri, Sep 26, 2014
Approaching Resonance- part 3- >> Approaching Resonance - part 3 Don
Corson, December 2013 This is the third of a
series discussing the behaviour of so called
“resonant” watches. As we have seen these
watches are properly called watches with
coupled oscillators. Click here to read the first
instalment of this series, click here to r... Read
more..
Author: DonCorson
(5) Latest Reply: Wed, Jan 01, 2014
Approaching Resonance– part 2- >> Approaching Resonance – part 2 Don
Corson, November 2013 In the first article of
this series discussing resonance in watches I
set up a simulation of an oscillator such as the
balance wheel / hairspring pair in a mechanical
watch. I was able to determine the basic
parameters of the simulation so tha... Read
more..
Author: DonCorson
(4) Latest Reply: Sun, Nov 17, 2013
BRAND FORUMS (A-M) BRAND FORUMS (N-Z) BRAND BLOGS NEWS & FEATURES SETUP & SUPPORT
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1 of 4 27.10.2014 11:46
In the same paper Newton showed that replacing force of gravity from the sun by a central linear
force of attraction, the orbits remain elliptical and that the period of rotation of the planet is always the
same. It is this isochronism property of orbits that is used by the IsoSpring orbital regulator to create
a constant rotational speed regulator, i.e., the size of the orbit can vary, but the period of rotation
remains constant.
This can be imagined as a kind of sling with elastic bands. If you put a stone in a sling and let it
rotate with differing applied force, the elastics will stretch differently giving different diameters of the
stones trajectory, but the period of rotation will remain the same. Newton proved that this type of
system is isochronous, i.e. that the period of rotation is only dependent on the mass and the rigidity of
the spring holding it.
Of course, the mathematical proof depends on several assumptions, each of which could pose a
problem for a physical realisation. In particular, the assumption of a point mass with zero moment of
inertia is physically impossible. This needs to be taken into account.
The diagram shows a schematic realisation of such a system. The presentation continues with a long
treatment of the error caused by the inertia of the rotating mass on the system. It is shown that this
can be so much that the system could be useless as a timekeeper, but improvements are possible.
Moving on to the physical realisation two different models are described. The figure below shows a
realisation using flexible blades for a slingshot type embodiment. But even when optimised this type
of realisation will have errors caused by the rotational inertia.
WatchTech - New Developments in Timepiece Reg... http://watchtech.watchprosite.com/show-forumpos...
2 of 4 27.10.2014 11:46
A method to eliminate the rotational inertia is to reduce the number of rotating pieces in the
realisation and to use a mass that does not turn. A mass that does not turn is equivalent to a
planet that travels around its orbit without changing its orientation, in which the day and the year have
the same length. Such structures can be made using flexible guidance systems known as compliant
mechanisms. Compliant mechanisms have become quite popular in the last 15 years or so. This
system allows the mass to move with 2 degrees of freedom, x (left-right) and y (forward-back), but not
to rotate. The springs realise a system in which the restoring force always points toward the center.
This type of system is called a central spring.
The figure below shows an implementation of a central spring. We can see the two thin horizontal
blades at the top and bottom that allow the movement in the y direction as well as providing the
restoring force in this direction. Inside that structure we see the vertical blades providing the flexibility
in the x direction as well as that restoring force. It is easy to see that the mass in the middle can
move in x and y directions and which allows a rotational trajectory while movement in the third
direction, z, is not possible.
To power such a regulator, the planet mass must be driven continuously with a circular motion. To
this end, a crank is used. The crank must have a variable length as when more force is used to turn
the crank, the orbit of the mass will be larger, but as we know the period of rotation will remain the
same, except for any residual isochronism error. As the only part that is turning is the crank it is
simple to keep its moment of inertia much less than that of the planet and have a theoretically
excellent isochronism.
More
WatchTech - New Developments in Timepiece Reg... http://watchtech.watchprosite.com/show-forumpos...
3 of 4 27.10.2014 11:46
New Older Posts: visual tour of a service center...
This type of regulator results in a major simplification of the regulating system of a timekeeper. As
there is no escapement the losses of the escapement (over 50%) are eliminated and use of compliant
mechanisms instead of pivots results in a high quality factor (Q). It is hoped that very good results in
terms of power reserve and timekeeping will be obtained in the future using this system. Of course
there is still much to learn about the implementation of this kind of regulator, its reliability and
timekeeping performance in the "real world". This is the subject of ongoing research and
development at the INSTANT-LAB of the EPFL in Neuchâtel.
I would like to thank Prof. Henein and Mr. Vardi of the INSTANT-LAB and the SSC (http://www.ssc.ch)
for their friendly support with this report and allowing me to use some images from the papers of the
Journée d'Etude - Les vecteurs de l'innovatioin en horlogerie 17.09.2014.
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Main Post: New Developments in Timepiece Regulators – SSC Study Day 2014 DonCorson : October 22nd, 2014-00:10
Very interesting study... watercolors : October 22nd, 2014-04:26
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