Abstract:
A transmission wheel comprises a gear having a hole and a pinion having a plurality of teeth and being removably mounted in the hole of the gear. The hole of the gear has at least one chord-shaped stop portion engaging two adjacent teeth of the pinion to prevent relative rotation between the pinion and the gear.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a transmission wheel, to a method for manufacturing the transmission wheel, and to a self-winding wheel train, and more particularly to a transmission wheel which can be manufactured by a simplified process, a method for manufacturing the transmission wheel and a self-winding wheel train having the transmission wheel. 
     2. Background Information 
     FIG. 6 is a schematic top view showing a self-winding train wheel structure. FIG. 7 is a sectional view showing the self-winding train wheel structure shown in FIG.  6 . This self-winding train wheel  500  is structured by an intermediate first transmission wheel  503  to transmit rotation of an oscillating weight  501  to a first reduction wheel  502  which transmits rotation of the intermediate first transmission wheel  503  to a pawl lever  504 , the pawl lever  504  being supported at a shaft in an eccentric position of this first reduction wheel  502  and formed by a draw finger  5041  and a feed finger  5042 , a second reduction wheel &amp; pinion  600  whose rotation is regulated in one direction by the pawl lever  504  to transmit rotation to a ratchet wheel  505 , the ratchet wheel  505  being in engagement with a barrel complete stem  5071  of a barrel complete  507 . The rotation of the ratchet wheel  505  is transmitted to the barrel complete  507  to store power on a spiral spring provided therein. The second reduction wheel &amp; pinion  506  is rotatably supported at a shaft by a barrel complete bridge  551  and a second transmission bridge  552 . The second reduction wheel &amp; pinion  600  is arranged at an underside of the ratchet wheel  505 . This is to reduce the thickness of the timepiece movement. 
     If the oscillating weight  501  rotates due to a movement of a user&#39;s arm, the rotation is transmitted to the first reduction wheel  502  through the intermediate first transmission wheel  503 . Regardless of the rotational direction of the first reduction wheel  502 , the second reduction wheel &amp; pinion  600  rotates in one direction due to action of the draw finger  5041  and feed finger  5042 . The rotation of the second reduction wheel &amp; pinion  600  is transmitted to the ratchet wheel  505  through a second transmission pinion  602 . The rotation of the ratchet wheel  505  winds the spiral spring of the barrel train  507 . 
     FIGS.  8 ( a )- 8 ( b ) are explanatory views showing parts forming a conventional second reduction wheel &amp; pinion. This second reduction wheel &amp; pinion is structured by two members of a gear  601  (FIG.  8 ( a )) and a pinion  602  (FIG.  8 ( b )). The gear  602  has saw-formed teeth  611  for engagement with a pawl lever  504 . The gear  601  has at its center part a hole part  612  for receiving the pinion  602  therein. The hole part  612  is provided with stop parts  613 . Also, the pinion  602  has shaft parts  621 ,  621  at its respective ends. Furthermore, a pinion part  622  is made in a two-stage form. The pinion  602  is provided with teeth  622   a  at the smaller diameter part and teeth  622   b  at the larger diameter part. Furthermore, the small diameter part of the two-staged part is provided with a cutout  623 . This smaller diameter part  622   a  is fitted in the hole part  612  of the gear  601 . The cutouts  623 ,  623  engage the stop parts  613 ,  613  to suppress rotation between the gear  601  and the pinion  602 . Also, the gear  601  and the pinion  602  are freely removable. 
     To manufacture a gear  601 , first a plate material is blanked by pressing to obtain a disk member. Next, teeth  611  are formed in a peripheral edge of this disk member. A hobbling machine is used for forming the teeth  611 . A hole part  612  is formed by a compound dice simultaneously with blanking a disk member. Meanwhile, in the manufacture of a pinion  602 , first a shaft  621  and two-staged pinion  622  are formed by a lathe. Next, the pinion  602  is removed from the lathe and attached on a milling machine to form cutouts  623  by milling. Also, the cutouts  623  may be formed by attaching on a forging machine. The pinion  602  is cut with teeth throughout the pinion part by the hobbling machine. 
     Upon shipping the movement, release of the spiral spring is made to conduct inspection for accuracy of the movement (date difference, for a self-winding watch). Specifically, the ratchet wheel  505  is rotated to make the spiral spring to be fitted in the barrel complete  507  into a fully wound state. One rotation of the barrel complete  507  requires 7 hours. Due to this, the ratchet wheel  505  is wound back by about 3.4 turns in order to obtain rotation of 1 day (24 hours). If the ratchet wheel  505  is wound back, the rotation of the ratchet wheel  507  is transmitted to a not-shown second wheel and third wheel, thus rotating a second hand and minute hand. An hour hand obtains rotation from a hour pinion of the second wheel through an hour wheel. Then, the second hand is measured for deviation at a time of the ratchet wheel  505  is wound back. 
     In the meanwhile, if the ratchet wheel  505  is to be wound back in a state the ratchet wheel  505  and the second reduction wheel &amp; pinion  600  are in engagement with, the pawl lever  504  would be put into an engagement state with the second reduction wheel &amp; pinion  600 , thus making difficult to perform winding back. Due to this, in order to release the engagement between the ratchet wheel  505  and the oscillating weight  501 , the second transmission bridge  552  shown in FIG. 7 is removed to remove the pinion  602  of the second reduction wheel &amp; pinion  600  from the gear  601 . This releases the engagement between the ratchet wheel  505  and the second reduction wheel &amp; pinion  600  and the ratchet wheel  505  is allowed to freely rotate. Thus, accuracy inspection can be effectively conducted. 
     In the conventional second reduction wheel &amp; pinion  600 , the wheel  601  and the pinion  602  are made in a separate structure so that in an inspection process the pinion  602  can be removed from the gear  601 . In an assembling state, engagement is made for the stop parts  613  of the hole part  612  with the cutouts  623  of the pinion  622  to thereby conducting positioning in a rotational direction. Meanwhile, in manufacturing a pinion  602 , a staged pinion  622  is cut with using a lathe and the pinion  602  is relocated onto a milling machine to cut cutout parts  623 . Furthermore, teeth cutting is made including the smaller diameter part  622   a  to be fitted in the gear  601 . Also, the gear  601  together with the hole part  612  is blanked by a press into a disk form, followed by teeth cutting by a hobbling machine. 
     However, there has been a problem that the manufacture of a second reduction wheel &amp; pinion  600  in the above manner results in increase of manufacture process steps. Therefore, it is an object of the present invention to provide a transmission wheel that the manufacture process is to be reduced and method for manufacturing a same transmission wheel and a self-winding train wheel structure. 
     In order to achieve the above object, a transmission wheel according to the present invention has a structure having a pinion removably fitted in a hole part formed in a gear. An engagement part comprised of a string part or a chord-shaped stop portion with which teeth of the pinion engages is formed integral with the hole part of the gear. The pinion is fitted and assembled in the hole part of the gear such that teeth of the pinion and the engagement part are brought into engagement. 
     Conventionally, the gear and the pinion have been positioned with a cutout part and a stop part put in engagement. However, in this invention positioning is conducted utilizing teeth of a gear. That is, the gear is provided with an engagement part in a hole part so that teeth of a pinion is engaged with this engagement part. By doing so, the pinion can be omitted to re-form for a cutout part or the like. 
     A transmission wheel according to the present invention has a structure having a pinion removably fitted in a hole part formed in a gear, the hole part of the gear being formed in a drum form, and a string part or a chord-shaped stop portion of the drum form being given a dimension to abut against nearly a top of two adjacent teeth of the pinion, wherein the pinion is engaged with the gear by abutting the adjacent two teeth against the string part. 
     The gear is provided, in a hole part, with a string part with which teeth of the pinion are engaged through abutment. In this invention, the gear requires only to open a hole part in a drum form having a string part in one part thereof. The pinion does not require re-forming. 
     A transmission wheel according to another embodiment of the invention has a structure arranged at an underside of a ratchet wheel and having a gear and a pinion that are removably fitted, said gear being formed with a hole part generally in a circular form in which the pinion is to be inserted, and the hole part being integrally formed with string parts or chord-shaped stop portions to abut against adjacent two teeth of the pinion, wherein the pinion is engaged with the gear by abutting the adjacent two teeth against the string parts. 
     If the string part is integrally formed with an opening part upon opening thereof, the gear requires only hole opening. If the string part is made in a same size abutable against teeth of the pinion, labor and time for re-forming the pinion is to be omitted. 
     A transmission wheel according to another embodiment of the invention has a structure arranged at an underside of a ratchet wheel and having a gear and a pinion that are removably fitted, said gear being formed with a hole part generally in a circular form in which the pinion is to be inserted, and the hole part being integrally formed with one string part or chord-shaped stop portion to abut against adjacent two teeth of the pinion, wherein the pinion is engaged with the gear by abutting the adjacent two teeth against the string part. 
     This invention is structurally provided with one string part in the hole part so that two teeth of the pinion are abutted against the string part. This also enables full engagement between the gear and the pinion, making unnecessary to re-form a pinion. 
     A transmission wheel according to another embodiment of the invention has the hole part having as the engagement part three or more string parts or chord-shaped stop portions, wherein the gear and the pinion are fitted and assembled such that adjacent two teeth of the pinion are abutted against each of the string part. 
     That is, if adjacent two teeth of the pinion are abutted against the string part and engaged with the gear, the string part may be three or more in number. This makes it possible to engage between the gear and pinion without re-forming the pinion. 
     A method for manufacturing a transmission wheel according to the present invention includes: a pinion manufacturing process of manufacturing a pinion by subjecting a gear forming process to a shaft member having a step part; a gear manufacturing process of manufacturing a gear by opening a hole part at a center part for engagement with the pinion and integrally forming in the hole part an engagement part having a string part or chord-shaped stop portion for engagement with teeth of the pinion; and an assembling process of fitting and assembling the gear and the pinion such that teeth of the pinion are put into engagement with the engagement part. 
     Conventionally, where manufacturing a transmission wheel of a separable structure, a gear and a pinion are made. A cutout part is provided in the pinion cut with teeth to engage between the cutout part and stop part provided in the hole part of the gear. In this invention, however, an engagement part for engagement with pinion teeth is formed integral with a hole part of the gear, omitting the forming process for the cutout part. This simplifies the manufacture process for the transmission wheel. 
     An automatic train wheel structure according to the present invention comprises: a first reduction wheel obtaining rotation from an oscillating weight, and a second reduction wheel supported at a shaft in an eccentric position of the first reduction gear wherein engaged with a gear upon swing only in one direction are a pawl lever to seeing a draw finger and feed finger due to rotation of the first reduction wheel to obtain a rotation force in one direction, and a hole part opened in the gear being removably fitted with a pinion; and a ratchet wheel engaging the pinion of the second reduction wheel to obtain rotation and arranged at an upper side of the second reduction wheel; wherein in an inspection process the pinion is separated from the gear to release mesh between the ratchet wheel and the second reduction wheel, the automatic train wheel characterized by: a hole part opened in the gear of the second reduction wheel is integrally formed with an engagement part that teeth of the pinion engage. 
     When, opening a hole part in the gear of second transmission wheel, an engagement part for engagement with pinion teeth is integrally formed. Other forming than tooth cutting is not made on the pinion. This simplifies the manufacture process for a second transmission wheel, thereby simplifying the structure of the automatic train wheel structure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an explanatory view showing a second reduction wheel &amp; pinion according to Embodiment  1  of the invention. 
     FIG. 2 is an explanatory view showing parts constituting the second reduction wheel &amp; pinion shown in FIG.  1 . 
     FIG. 3 is an explanatory view showing a second reduction wheel &amp; pinion according to Embodiment  2  of the invention. 
     FIG. 4 is an explanatory view showing a second reduction wheel &amp; pinion according to another embodiment of the invention. 
     FIG. 5 is an explanatory view showing a second reduction wheel &amp; pinion according to another embodiment of the invention. 
     FIG. 6 is a schematic top view showing an automatic train wheel structure. 
     FIG. 7 is a sectional view showing the automatic train wheel structure shown in FIG.  6 . 
     FIGS.  8 ( a ) and  8 ( b ) are explanatory views showing parts constituting a conventional second reduction wheel &amp; pinion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereunder, the present invention will be explained in detail with reference to the drawings. Incidentally, the invention is not limited to by the embodiments. 
     (Embodiment 1) 
     FIG. 1 is an explanatory view showing a second reduction wheel &amp; pinion according to Embodiment 1 of the invention. FIG. 2 is an explanatory view showing parts constituting the second reduction wheel &amp; pinion shown in FIG.  1 . This second reduction wheel &amp; pinion  100  is structured by two members of a gear  1  (FIG.  2 ( a )) and a pinion  2  (FIG.  2 ( b )). The gear  1  has saw-formed teeth  11  for engagement with a pawl lever. The gear is opened, at its center part, with a hole part  12  in which a pinion  2  is to be assembled. The hole part  12  is provided with two chord-shaped or string-formed stoppers or stop portions or parts  13 . The stop parts  13  are integrally formed in an opening process for the hole part  12 . The pinion  2  has shaft parts  21  at its respective ends. Furthermore, a pinion part  22  is a in a two-stage form. The pinion  2  is provided with teeth  22   a  at the smaller diameter part and teeth  22   b  at the larger diameter part. This smaller diameter part is fitted in the hole part  12  of the gear  1 . The stop part  13  has a string length nearly equal a spacing between adjacent two teeth  22   a ,  22   b , specifically a spacing between opposite tooth surface tip ends. When fitting the pinion  2  in the gear  1 , the stop part  13  is rendered positioned between adjacent two teeth  22   a ,  22   b . This engages teeth  22   a ,  22   b  of the pinion  2  with stop part  13  thereby suppressing the gear  1  and the pinion  2  from rotating in a circumferential direction. Also, the gear  1  and the pinion  2  are removable. 
     To manufacture the gear  1 , a plate material is first blanked by pressing to obtain a disk member. Next, teeth  11  are formed in a peripheral edge of the disk member. A hobbling machine is used in forming teeth  11 . The hole part  12  is formed by a compound dice simultaneous with blanking the disk member. 
     Also, together with the hole part  12  stop parts  13 ,  13  are integrally formed. Also, in manufacturing the pinion  2 , first the shaft parts  21  and two-staged pinion part  22  are formed by a lathe. Next, teeth are formed on the pinion  2  throughout the pinion part by the hobbling machine. 
     The automatic train wheel using this second reduction wheel &amp; pinion  100  is as shown in FIG.  6  and FIG. 7, omitting explanation thereof. Incidentally, although the above embodiment described on the case with a pinion having 6 teeth, the invention is not limited to this. For example, even in a case of 8 teeth for example, the stop part on the gear side may be determined in string length as an interval of tooth tip faces of adjacent teeth. 
     (Embodiment 2) 
     FIG. 3 is an explanatory view showing a second reduction wheel &amp; pinion according to Embodiment 2 of the invention. The second reduction wheel &amp; pinion  200  according to Embodiment 2 of the invention has only one stop part  13  provided in a hole part  12 . The stop part  13  has a string length almost equal to a spacing between opposite tooth tip faces of pinion teeth  21 ,  21 , similarly to the above. When fitting a pinion  2  in a gear  1 , the stop part  13  is positioned between adjacent two teeth  21 ,  21 . In the case of one stop part  13 , it is satisfactory to suppress rotation in a circumferential direction between the gear  1  and the pinion  2 . The other structures are generally similar to Embodiment 1 and explanation thereof is omitted. 
     (Other Embodiments) 
     Also, as shown in FIG. 4 the stop part  13  may be provided three in number. If provided plurality, the integral formation with the hole part  12  will not increase the processes of manufacture. Also, the stop parts  13  may be provided four or more in number. Also, as shown in FIG. 5 an engagement part  53  may be provided that is in a particular form to engage the teeth of pinion  2 . 
     Industrial Applicability 
     As explained above, the transmission wheel of the invention is provided with an engagement part having a string part in the gear hole part thereof to engage pinion teeth with the engagement part. Accordingly, labor and time is omitted in forming cutout part or the like in the pinion. This simplifies the process of manufacture for the transmission wheel. 
     More specifically, the transmission wheel of the invention has a gear hole part provided with a string part against which adjacent pinion teeth are abutted, making it unnecessary to re-form the pinion. This simplifies the process of manufacturing the transmission wheel. 
     The transmission wheel of the invention has a gear string part integrally formed upon opening the hole part, requiring only opening a hole in the gear. This omits labor and time of re-forming the pinion, simplifying the process of manufacture. 
     The transmission wheel of the invention has a gear provided with a hole part provided with one string part against which two pinion teeth ar abutted. Because this also provides sufficient engagement between the gear and the pinion, the transmission wheel can be manufactured in a simple structure and the pinion is not required to re-form similarly to the above. This simplifies the process of manufacture for the transmission wheel. 
     In the transmission wheel of the invention, a gear provided with a hole part is provided with three or more string parts so that, upon assembling, adjacent two teeth are abutted against each of the string parts. This also makes it unnecessary to re-form the pinion similarly to the above, simplifying the process of manufacture for the transmission wheel. Also, because the gear and the pinion is held by abutment at three points or more, they can be engaged firmly. 
     In the manufacturing method for a transmission wheel according to the invention, an engagement part having a string part with which the pinion teeth are engaged is integrally formed with the gear hole part, thus omitting the process of forming the cutout part. This simplifies the process of manufacturing the transmission wheel. 
     The automatic train wheel structure according to the invention has an engagement part for engagement for pinion teeth which is integrally formed upon opening the opening part in the gear of the second reduction wheel &amp; pinion constituting the automatic train wheel. The pinion is not subjected to nothing other than tooth cutting. This generally simplifies the process of manufacturing the second reduction wheel &amp; pinion and hence the structure of the automatic train wheel structure.