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US3676998A - Balance for a time piece - Google Patents

Balance for a time piece Download PDF

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Publication number
US3676998A
US3676998A US68696A US3676998DA US3676998A US 3676998 A US3676998 A US 3676998A US 68696 A US68696 A US 68696A US 3676998D A US3676998D A US 3676998DA US 3676998 A US3676998 A US 3676998A
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US
United States
Prior art keywords
balance
phi
rim
cross
initial
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US68696A
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English (en)
Inventor
Andre Simon-Vermot
Charles-Andre Grossenbacher
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Les Fabriques dAssortiments Reunies SA FAR
Original Assignee
Les Fabriques dAssortiments Reunies SA FAR
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Les Fabriques dAssortiments Reunies SA FAR filed Critical Les Fabriques dAssortiments Reunies SA FAR
Application granted granted Critical
Publication of US3676998A publication Critical patent/US3676998A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance

Definitions

  • ABSTRACT A balance for a timepiece in which the cross-sectional shape of the balance rim is fixed so that the cross-sectional area and the perimeter of such area are related and definable in terms of a single common variable. Fixed relationship between this common variable and the mean radius of the balance rim is established by virtue of the initial instantaneous power available to oscillate the balance at the desired initial amplitude and frequency.
  • Optimum balance dimensions are obtained from these corresponding values by selecting that value of mean radius which, for the corresponding value of cross-sectional area of the balance rim, produces a maximum value of moment of inertia for the balance with a decrease in amplitude after 24 hours within predetermined limits.
  • timepiece balances have been constructed, in large part, so as to provide as large a size and consequent moment of inertia as would be allowed within the space available for the balance.
  • the shape of the balance rim has been arbitrament of inertia.
  • an increase in density of the balance or of its rim is normally employed to allow a decrease in the mean radius and/or cross-section of the balance rim.
  • the optimum conditions according to this invention demand that when the density is increased, the mean radius of the balance rim must also be increased.
  • the related values of mean radius and cross-sectional area of the balance rim are then, chosen so as to provide a maximum moment of inertia which, for the instantaneous power available after 24 hours and with the balance in the most unfavorable position (in a vertical plane), will not cause a decrease in oscillatory amplitude which exceeds a predetermined value (preferably 40).
  • FIG. 1 is a graph illustrating a certain relationship in connection with a particular embodiment of the invention
  • FIG. 2 is a plan view of a balance wheel according to the present invention.
  • FIG. 3 is an enlarged view partly in section illustrating certain dimensional details of one embodiment of the invention.
  • FIG. 4 is a .view similar to FIG. 3, but illustrating a modified form of the invention.
  • FIG. 3 illustrates an embodiment of the invention wherein the rim 16 is of square cross-section dimensioned as shown and with the rim exhibiting a mean radius R as illustrated.
  • the modification according to FIG. 4 illustrates a rim 16' of circular cross-section.
  • a is a constant term independent of oscillatory speed and proportional to the weight P of the balance rim, the radii r of the pivots for the balance, and the coefficient of friction 1; acting on such pivots,
  • a 1; rP is a constant term independent of oscillatory speed and proportional to the weight P of the balance rim, the radii r of the pivots for the balance, and the coefficient of friction 1; acting on such pivots
  • the second term is a viscous damping term due to air friction drag on the oscillating balance and is therefore proportional to the instantaneous angular velocity (I: of the balance and the surface area S of the balance rim; and,
  • the third tenn is a quadratic term due to non-linear effects of air friction on the balance rim and arms and which also is proportional to the surface area S.
  • Equation l c K R,,,4 p Equation l c K R,,,4 p
  • R is the mean radius of the balance rim A is the cross-sectional area of the balance rim p is the density of the balance material g is the acceleration due to gravity 1 is the coefficient of friction at the balance pivots r is the balance pivot radius p is the dimensional girth of the balance rim cross-section K, and K are constants determined experimentally.
  • the instantaneous power required to impart an amplitude 41 to the balance at a frequency w is as follows;
  • Equation (1 1) may be further simplified to the form:
  • the instantaneous available power may be derived on the basis of the Airy formula:
  • Equation l 7 From the equation for energy consumption Since instantaneous power then - a 500K +5 10%? 5 Cw 0 l fl? Equation (8) of course, will be recognized as the generalized form of Equation l 7).
  • the B of the mainspring is used as the lett-hand cut-off point for the I versus R, curve and the maximum value of I to the right of this cut-off point yields the most eflicient balance dimensions producing a loss of amplitude within the prescribed limits.
  • the metals and alloys which may be used are for instance:
  • the frequency A/h refers -to alternances per hour whereas the symbol D refers to the outside diameter of the balance wheel.
  • a timepiece of the type having an energy source providing an initial instantaneous available power P, and a balance comprising a hub and a rim oscillated at an initial amplitude 1b, and frequency to by said energy source, the improvement comprising,
  • a timepiece with a balance-hairspring assembly exhibiting a moment of inertia (I)
  • drive means having an initial instantaneous available power P, for oscillating said balance at a given frequency and with a given initial amplitude d), and having after 24 hours of operation an instantaneous available power P for oscillating said balance at said given frequency and with an amplitude said balance having a rim of fixed cross-sectional shape disposed at an average radius R, from said assembly at a given frequency m with a given initial amplitude 1b,, and having after 24 hours of operation an available power P for oscillating said assembly at said given frequency and at an amplitude 4: which is less than P,, said balance having a rim of fixed cross-sectional shape such that its mean radius R,, from its center of oscillation and its cross-sectional area (A) are functionally related according to where C,,s A the cross-sectional area of said rim C ,,s perimeter of said rim cross-section s radial thickness of

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Sorption Type Refrigeration Machines (AREA)
  • Springs (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
US68696A 1967-06-02 1970-09-01 Balance for a time piece Expired - Lifetime US3676998A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH783467A CH534377A (fr) 1967-06-02 1967-06-02 Mouvement de pièce d'horlogerie

Publications (1)

Publication Number Publication Date
US3676998A true US3676998A (en) 1972-07-18

Family

ID=4331148

Family Applications (1)

Application Number Title Priority Date Filing Date
US68696A Expired - Lifetime US3676998A (en) 1967-06-02 1970-09-01 Balance for a time piece

Country Status (3)

Country Link
US (1) US3676998A (fr)
CH (2) CH534377A (fr)
FR (1) FR1567632A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100054090A1 (en) * 2006-12-21 2010-03-04 Franck Orny Mechanical oscillator for timepiece
CN102902193A (zh) * 2011-07-29 2013-01-30 劳力士有限公司 具有优化的枢转的平衡摆轮组件

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH301863A (fr) * 1952-09-22 1954-09-30 Renfer Erwin Balancier pour pièce d'horlogerie.
CH339868A (fr) * 1957-07-11 1959-07-15 Roamer Watch Co Sa Balancier pour mouvement d'horlogerie
CH356719A (fr) * 1959-08-22 1961-08-31 Schild S A Fabrique D Ebauches Balancier pour pièce d'horlogerie
GB918620A (en) * 1959-09-25 1963-02-13 Straumann Inst Ag Improvements in clockwork and like mechanisms

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH301863A (fr) * 1952-09-22 1954-09-30 Renfer Erwin Balancier pour pièce d'horlogerie.
CH339868A (fr) * 1957-07-11 1959-07-15 Roamer Watch Co Sa Balancier pour mouvement d'horlogerie
CH356719A (fr) * 1959-08-22 1961-08-31 Schild S A Fabrique D Ebauches Balancier pour pièce d'horlogerie
GB918620A (en) * 1959-09-25 1963-02-13 Straumann Inst Ag Improvements in clockwork and like mechanisms

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100054090A1 (en) * 2006-12-21 2010-03-04 Franck Orny Mechanical oscillator for timepiece
US8240910B2 (en) * 2006-12-21 2012-08-14 Complitime S.A. Mechanical oscillator for timepiece
CN102902193A (zh) * 2011-07-29 2013-01-30 劳力士有限公司 具有优化的枢转的平衡摆轮组件
CN102902193B (zh) * 2011-07-29 2015-11-25 劳力士有限公司 具有优化的枢转的平衡摆轮组件

Also Published As

Publication number Publication date
DE1773523A1 (de) 1971-06-16
CH783467A4 (fr) 1970-07-31
DE1773523B2 (de) 1972-07-27
FR1567632A (fr) 1969-04-08
CH534377A (fr) 1970-07-31

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