Automatic watch
United States Patent 1 1 1111 3,878,673 Meitinger 1 Apr. 22, 1975 1 AUTOMATIC WATCH 3.010.277 11/1961 Guyot 58/83 R lnventor: Heinz Meitinger, Mutlangen,  
 Germany Bifora-Uhren .I. Bidlingmaier Gmbl-l, Schwabisch Gmund, Germany Filed: Jan. 15, 1974 Appl. No.: 433,527  
 Assignee:  
 Foreign Application Priority Data Jan. 20, 1973 Germany 2302885 U.S. Cl 58/83 A Int. Cl. G04b 5/24 Field of Search 58/82 R, 82 A, 83 R, 83 A References Cited UNITED STATES PATENTS Bornfriend 58/82 A Primary Iiraminer-George H. Miller, Jr. Attorney, Agent, or Firn1Parmelee, Miller, Welsh &amp; Kratz [57] ABSTRACT An automatically rewound watch having a mainspring barrel with exterior teeth in engagement with a control member gear, the control member being a nut axially movable along a threaded shaft which is rotated during rewinding so that the nut moves in a first direction in response to rewinding and in opposite direction in response to unwinding of the barrel, said shaft being axially movable upon the nut engaging a stop member so to disengage a rewinding mechanism coupling.  
 10 Claims, 1 Drawing Figure AUTOMATIC WATCH BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to portable watches and, in particular, to a mechanism for automatically rewinding the mainspring thereof. Usually, the mainspring is housed in a barrel and fixed to a mainspring shaft. The mainspring shaft is operatively connected via a pinion mounted thereon to a blocking gear. Further, there is a rotatably journalled mass, termed a rotor, oscillating upon movement of the watch and coupled to the mainspring to rewind it.  
 2. Prior Art In order to make sure that under all circumstances the watch is wound sufficiently, the rewinding mechanism must be designed in such a manner that under normal conditions, the watch is wound more than necessary so that under less extensive movement, the rewinding will be still sufficient. Overwinding of the mainspring is prevented by a coupling. Frequently, the coupling is provided between the outer mainspring end and the barrel permitting slipping of the spring end with respect to the barrel. The friction torque at which this slipping occurs must be adjusted with utmost care and must be maintained constant for the time of service since, upon decrease of said torque, the winding will be insufficient while upon increase thereof the mainspring will be overwound resulting in an inaccurate operation of the watch due to overswing of the balance.  
 SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic rewinding mechanism in which there are no sensitive components which may lead to trouble, such that the mainspring will be wound but to a given number of turns and thereafter the operative connection between the mechanism and the blocking gear is disabled.  
  According to the invention, the coupling is controlled by a control member responsive to relative rotation of the mainspring barrel and the blocking gear. Relative rotations in a first direction such that the mainspring is unwound will cause movement of the control member in a first direction. Relative rotation in the other, second direction such that the mainspring is rewound will cause movement of the control member in a second direction. At the end of the second path of movement, there is a stop member which, upon engagement of the control member, will disable the coupling between rotor and rewind pinion.  
  Thus, the coupling is provided between the rewind pinion and the rotor gearing, and it is preferred to make use of the one-way coupling which normally is present at this point to prevent rotation of the rotor gearing in case of the blocking gear being actuated manually. In this manner, the design provides a very inexpensive solution.  
  A simple and relatively small design results by using as the control member a nut having teeth at its outer circumference in engagement with teeth provided at the barrel exterior. The nut is carried by the rewind shaft which for this purpose has been threaded. The number of teeth is selected such that the ratio of the number of teeth between the blocking gear andthe rewind pinion is equal to the ratio of the number of teeth between the mainspring barrel and the control nut, i.e.:  
 number of teeth on blocking gear/number of teeth on rewind pinion number of teeth on mainspring barrel/number of teeth on control nut In addition to the standard components usually present in watches of this type, the control nut and the stop member are the only parts to be added while the rewind shaft must be provided with a thread.  
  If the mainspring shaft is rotated by the rewind shaft, the nut is blocked against rotation by engagement of its teeth with those of the barrel so that the nut will travel along the rewind shaft until it arrives at the stop member. The latter may cause an axial movement of the rewind shaft so as to discouple the gearing and to stop further winding. If, on the other hand, the watch is in operation while the rewind shaft is stopped, the barrel rotation drives the nut so that the latter moves along the rewind shaft in the opposite direction, disengages the stop member and permits rewinding again. Accordingly, the actual position of the nut indicates the respective winding status of the main spring, and this position may be displayed, say, via a dial window.  
  In order to prevent jamming of the control member at the stop member in case of the watch being wound by hand, i.e., directly via the blocking gear, it has been found preferable to make the rewind shaft thread terminate a certain distance spaced from the stop member. If the rewind shaft has been already axially shifted, its thread will thereafter disengage from the control nut thread and prevent any further pressure from being exerted thereon, if the rewind pinion is manually rotated.  
  A preferred embodiment of the invention is shown in the attached drawing and will be described in detail hereunder.  
  The drawing is a schematic section view through a watch movement, those parts which are not germane to the invention being omitted for clarity.  
  The rewind pinion 2 is in engagement with the blocking gear or wheel 1 and is operatively connected with the rewind wheel 3 via a one-way coupling mechanism. The latter permits manual rewinding in that the pinion 2 is rotated while the rewind wheel 3 is blocked, because of its being in engagement with the rotor of the automatic rewind mechanism via a conventional reduction gear (not shown). The oneway coupling operates such that the inclined nose 4 at arm 5 is urged downwardly against the bias of spring 6. During rewinding by the automatic rewind mechanism which via wheel 21 and pinion 2 (the latter in engagement with rewind wheel 3) is connected to the coupling, the rewind wheel drives via nose 4, the arm 5 and the pinion 2. Wheel 3 is rotatably journalled about rewind shaft 7. The shaft 7 is provided with a thread and extends through control nut 8 having interiorly the mating thread while it is provided exteriorly with teeth engaging teeth 9 on the circumference of the main spring barrel [0. There is, however, no spring bias transmission to nut 8. The number of teeth 9 on barrel 10 relates to that of nut 8 as the number of teeth of blocking wheel I to that of rewind pinion 2. In the preferred embodiment, barrel l0 and blocking wheel 1 have the same number of teeth, and on the other hand, nut 8 and pinion 2 have the same number of teeth.  
  Due to the equal transmission ratios, nut 8 is driven downwardly if rewind pinion 2 is rotated forwardly while the barrel is stopped, and if pinion 2 is stopped while the barrel 10 rotates under the bias of the main spring therein (not shown), nut 8 is driven upwardly (as seen in the drawing). Thedimensions are chosen such that nut 8 is just in tough with pinion 2 with the main spring being completely-unwound. At the other end of shaft 7, nut 8 arrives atshaft bearing 11 prior to the main springs being completely rewound; this position is shown in the drawing. in further rewinding. torque acts upon shaft 7 and the latter tends to drive nut 8 further downwardly. Since the latter, however. is blocked against the bias of spring 6, wheel 3, however, remains in its axial position because its upward movement is prevented by sleeve 12.  
  Therefore, axial upward movement of shaft 7 results in disengagement of nose 4 and arm 5, hence, the automatic rewinding mechanism is discoupled. The coupling will be enabled again upon a rotation of barrel 10 by an angle corresponding to one turn of nut 8.  
  A display member 13 scans the axial position of nut 8 which corresponds to the winding status of the main spring and the position of member 13 may be seen by the user through a window provided in the watch dial (not shown).  
  The barrel support is designed such that the barrel may be radially shifted after unscrewing of barrel screw 14 so to disassemble the barrel. For this purpose, the barrel screw 14 has a long bolt 23 serving as a bearing form main spring shaft 15 and barrel 10, the bolt extending through shaft 15 into base plate 16. The upper end of shaft 15 is journalled in a slot 18 which extends inwardly from the edge of bridge 17. Rewind pinion 2 and a blocking cone (not shown) are mounted such that the barrel is urged into the bearing of its shaft by the resulting forces.  
  If the thread on shaft 7 terminates at a point 24 somewhat spaced from bearing 1], nut 8 will disengage the thread on shaft 7 once the latter has been lifted. Therefore, the coupling mechanism will always return to the initial operating condition even in case of the main spring being rewound manually, i.e. directly at wheel I. The disengagement of the coupling, on the other hand, is likewise assured somewhat prior to complete rewinding of the main spring.  
  Supplemental parts for the coupling are only sleeve 12 and nut 8, parts which are neither expensive nor cumbersome, and the thread to be cut on shaft 7 which do not contribute to costs of manufacture in any considerable amount. in summary, the cost of manufacture in general will, for the watch according to the invention, be rather less than of a watch having instead a main spring with slip coupling means.  
  The automatic rewinding being controlled by the ratio of the gearing instead of a force and friction dependant coupling. proper operation of the automatic mechanism may be expected over a long service period.  
 What I claim is:  
  1. In a watch having an automatic rewind mechanism, comprising a mainspring fixed at a mainspring shaft and housed in a mainspring barrel, said mainspring shaft having a toothed blocking gear in operative engagement with a toothed rewind pinion, the latter mounted on a rewind shaft and including a rotor oscillating upon movement of the watch, the oscillatory motion of said rotor being transmitted to said mainspring via said rewind pinion and blocking gear in order to wind said mainspring, the improvement comprising coupling means between said rotor and said rewind pinion which coupling means is automatically disengaged after the mainspring is wound to a predetermined extent in order to prevent overwinding, which coupling means comprises:  
 a. a rewind wheel rotatably journalled about the rewind shaft and disposed above and coaxial with the rewind pinion, said rewind wheel being in engagement with the rotor of the automatic rewind mechanism via reduction gear means;  
 b. means cooperative with the rewind wheel and the rewind shaft whereby rotary motion is imparted to the rewind pinion;  
 c. an interiorly threaded nut engaging threads on the rewind shaft, said nut having exterior teeth in engagement with teeth provided on the circumference of the mainspring barrel, said nut being driven downwardly along the rewind shaft when the rewind pinion is rotated while the barrel is stopped and driven upwardly along the rewind shaft when the barrel is rotated under the bias of the mainspring and the rewind pinion is stopped, said nut being at its uppermost position on the rewind shaft when the mainspring is unwound and at its lowermost position on the rewind shaft when the mainspring is wound; and  
 d. a stop member at the lowermost position of the nut on the rewind shaft, whereby upon further winding, torque acting upon the rewind shaft drives the nut downwardly against the stop member resulting in axial upward movement of the rewind shaft, thereby disengaging the coupling between the rotor of the automatic rewind mechanism and the rewind pinion.  
  2. The improvement of claim 1 whereby the means by which rotary motion is imparted to the rewind pinion comprises a nose formed on the top surface of the rewind wheel and alaterally extending arm mounted on the rewind shaft and disposed above the rewind wheel. said arm engaging said nose whereby the oscillatory motion of the rotor is converted via the reduction&#39;gear means to cause rotation of the rewind wheeL-the nose of the rewind wheel driving the arm which in turn causes rotation of the rewind pinion.  
  3. The improvement of claim 1 wherein the nut at its uppermost position on the rewind shaft is just in contact with the rewind pinion.  
  4. The improvement in claim 1 wherein the ratio of the number of teeth between the blocking gear and the rewind pinion is equal to the ratio of the number of teeth between the mainspring barrel and the nut.  
  5. The improvement of claim 1 further including a display member for indicating the axial position of the nut on the rewind shaft, the relative position of the nut on the rewind shaft corresponding to the relative bias of the mainspring.  
  6. The improvement of claim 1 including means for manual operation of the blocking gear in order to wind the mainspring when the coupling between the rotor of the automatic rewind mechanism and the rewind pinion is disengaged.  
  7. The improvement of claim 6 wherein the thread provided on the rewind shaft terminates a predetermined distance from the stop member, said thread disengaging from said nut upon axial upward movement of the rewind shaft.  
  8. The improvement of claim 1 further including a spring disposed between the rewind wheel and the rewind pinion, the rewind shaft being axially.- movable against the bias of said spring.  
  9. The improvement of claim 8 further including means for preventing upward movement of the rewind 6 10. The improvement of claim 9 wherein said means for preventing upward movement of said rewind wheel comprises a sleeve journalled about the upper end of wheel when the rewind shaft moves axially upward 5 the rewind Shaft against the bias of the spring.