Horology: time measuring systems or devices – Escapements – With oscillating or reciprocating means
Patent
1997-09-15
1998-11-17
Miska, Vit W.
Horology: time measuring systems or devices
Escapements
With oscillating or reciprocating means
368142, G04B 1500, G04B 1920
Patent
active
058386416
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention pertains to a a mechanical timepiece with a tourbillon mechanism which is thin-shaped and which can facilitate an adjusting operation during assembly.
BACKGROUND ART
In an ordinary mechanical timepiece that uses a main spring as the power source, uses as the controller a timed annular balance having a hair spring mounted thereon and uses a pallet fork and escape wheel as the escapement, there occurs the dynamic eccentricity error of the center of gravity due to the inevitable non-uniformity of the configuration of the timed annular balance. Also, during the operation, shifting of the center of gravity occurs due to the expansion and contraction of the hair spring. For this reason, it results that where the timepiece vertical attitude, the isochronism of the timed annular balance fluctuates depending on what time position is located upside. As a mechanism for canceling the above-mentioned fluctuation of the isochronism due to the attitude of the timepiece, there is a mechanism which is called "tourbillon".
The tourbillon mechanism is one which was developed by the French A. L. Brequet about 200 years ago for the purpose of causing an increase in the time accuracy of portable timepieces. The tourbillon mechanism is basically arranged to have the escapement and controller loaded on a final stage gear of the speed-up gear train to thereby construct a cage and arranged, by causing this cage itself to rotate at all times, to cancel the fluctuation in isochronism that occurs due to the attitude of the timepiece.
Also, on account of its minute structure, the tourbillon mechanism has its cage portion exposed on a dial side of the timepiece and has its parts elaborately finished to thereby appeal its mysterious movements, thereby also aiming to enhance the commercial value of timepieces with the tourbillon mechanism as that in a region of complex timepiece. One of the reasons for this is because the tourbillon mechanism has in itself the power of appealing its unique technological beauty.
FIG. 8 is a sectional view illustrating a timepiece that uses a conventional tourbillon mechanism. The power of a main spring not illustrated is transmitted to a gear 30 at a terminal end of the speed-up gear train. The rotation of the gear 30 at this terminal end thereof is transmitted to a pinion 31 (pinion) that has been provided at a lower end of a cage 29, whereby the cage 29 is rotated. In this cage 29, there are loaded between a cage upper plate 12 and a cage lower plate 32 an escape wheel 5, a pallet fork 6 that is engaged with the escape wheel 5 and a timed annular balance that is engaged with the pallel fork 6. The cage upper plate 12 and the cage lower plate 32 are connected to each other by cage support columns 11. With a shaft pin 13 provided on the cage upper plate 12 and a shaft pin 33 provided on the cage lower plate 32 being used as the rotating shafts, the cage 29 is rotated. An escape pinion 3 that has been formed coaxially with the escape wheel 5 is meshed with a sun gear 19 that is fixed to a main plate 8. When the cage 29 is rotated, the escape pinion 3 makes a planetary gear movement of its revolving around the sun gear 19 while rotating about its own axis. By this planetary gearing, the rotation of the speed-up gear train is transmitted to the escape wheel 5. The rotating force of the escape wheel 5 is transmitted to the timed annular balance 7 through the pallet fork 6 and thereby serves as a power source for causing rotational vibration of the timed annular balance 7.
Since as mentioned above by the cage 29 being rotated the escape wheel 5, pallet fork 6 and timed annular balance 7 loaded inside the cage 29 are integrally rotated at all times, the fluctuations in isochronism that occur when the timepiece is at four vertical attitudes wherein 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock are located upside are canceled one another, with the result that the isochronism becomes always fixed.
However, in the above-mentioned tourbillon mechanism, since the cage pinion
REFERENCES:
patent: 5608694 (1997-03-01), Grimm et al.
Tanaka Tsuyoshi
Tohkoku Muneo
Miska Vit W.
Seiko Instruments Inc.
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