Abstract:
The present invention aims to provide a bearing structure allowing direct adjustment between itself and an opposing bearing even after assembly and a watch equipped with the same. A bearing structure of a watch rotatably supports a forward end portion of a shaft of a wheel with respect to a base body, and includes: a bearing, a bearing support body supporting the bearing and having a male screw portion on an outer peripheral surface concentric with the shaft of the wheel, and an adjustment nut equipped with a female screw portion threadedly engaged with the male screw portion of the bearing support body, regulated in its displacement in the extending directions of the shaft of the wheel by the base body, and adapted to adjust the position of the bearing with respect to the extending direction of the shaft via the bearing support body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a bearing structure rotatably supporting a forward end portion of a wheel shaft with respect to a base body and, to a watch equipped with the same. 
     2. Description of the Related Art 
     Adjustment of the vibration of a balance main body through adjustment of the distance between a balance upper bearing and a balance lower bearing has itself already been proposed (Patent Documents JP-A-2007-178431 and JP-A-2007-178432). 
     However, in Patent Documents JP-A-2007-178431 and JP-A-2007-178432, in order to adjust the distance between the balance upper bearing and the balance lower bearing, there is effected, at a portion of a balance bridge spaced apart from the balance upper bearing, the adjustment of the distance between the balance bridge and a base body such as a main plate, so that the adjustment is not effected directly; thus, not only is the adjustment rather difficult but also it requires an installation space or an adjustment space. Further, in the case of Patent Document JP-A-2007-178431, there are two adjustment portions, so that the adjustment is so much the more difficult. Further, in this case, it is actually only possible to perform the adjustment on one side. 
     SUMMARY OF THE INVENTION 
     It is an aspect of the present invention to provide an object of the present invention to provide a bearing structure allowing direct adjustment of the distance between itself and an opposing bearing even after assembling and a watch equipped with the same. 
     There is provided, according to the present invention, a bearing structure rotatably supporting a forward end portion of a wheel shaft with respect to a base body, comprising a bearing, a bearing support body supporting the bearing and having a male screw portion on an outer peripheral surface concentric with the wheel shaft, and an adjustment nut equipped with a female screw portion threadedly engaged with the male screw portion of the bearing support body, regulated in its displacement in the extending direction of the wheel shaft by the base body, and adapted to adjust the position of the bearing with respect to the extending direction of the shaft via the bearing support body. 
     In the bearing structure of the present invention, there are provided “a bearing support body supporting the bearing and having a male screw portion on an outer peripheral surface concentric with the wheel shaft, and an adjustment nut equipped with a female screw portion threadedly engaged with the male screw portion of the bearing support body, regulated in its displacement in the extending direction of the wheel shaft by the base body, and adapted to adjust the position of the bearing with respect to the extending direction of the shaft via the bearing support body,” so that, solely by turning the adjustment nut concentric with the wheel shaft, it is possible to displace the bearing itself of the wheel shaft in the extending direction of the shaft via the bearing support body, making it possible to adjust the bearing to an appropriate position, and to adjust the distance between a pair of bearings supporting both ends of the wheel to an appropriate distance, whereby it is possible to appropriately support the rotation of the wheel by the bearing structure. 
     Here, the female screw portion of the adjustment nut is threadedly engaged with the male screw portion concentric with the wheel shaft, so that the adjustment nut is positioned concentrically with the wheel shaft, whereby it is possible to minimize the requisite space for the arrangement and operation of the adjustment nut. While the bearing and the bearing support body are typically formed as separate components, they may also be, in some cases, formed as an integral unit (inclusive of an identical object) or as components that are normally inseparably fixed to each other. 
     In the bearing structure of the present invention, the bearing support body is typically biased in one way of the extending direction of the shaft by an elastic member to thereby suppress rattling; however, in some cases, it is also possible to make the screw pitch of the female screw portion of the adjustment nut somewhat different from that of the male screw portion of the bearing support body, thereby suppressing rattling of the bearing support body. 
     In a typical bearing structure according to the present invention, the bearing support body is fit-engaged with a hole portion of the base body; the bearing support body is equipped with a flange-like portion protruding radially outwards in a region situated on the wheel shaft base portion side of the hole portion of the base body and facing one end surface of a peripheral wall of the hole portion of the base body; between the one end surface of the peripheral wall of the hole portion of the base body and the opposing surface of the flange-like portion of the bearing support body, there is arranged an elastic member exerting a force causing the two surfaces to separate from each other; and one end surface of the adjustment nut is in contact with the end surface of the end surfaces of the peripheral wall of the hole portion of the base body which is on the opposite side of the one end surface. 
     In this case, under the action of the elastic force of the elastic member, one end surface of the adjustment nut is pressed against the end surface of the end surfaces of the peripheral wall of the hole portion of the base body which is on the opposite side of the end surface facing the elastic member, so that in accordance with rotation in one direction or the opposite direction of the adjustment nut, the bearing support body is displaced in the extending direction of the shaft with respect to the base body, thereby effecting positioning of the bearing in that direction. In the case in which the elastic member is provided, it is possible to absorb impact by the elastic member, thus providing a high impact resistance. 
     In another typical bearing structure according to the present invention, the bearing support body is fit-engaged with a hole portion of the base body; the bearing support body is equipped with a flange-like portion protruding radially outwards in a region situated on the wheel shaft forward end portion side of the hole portion of the base body and facing one end surface of a peripheral wall of the hole portion of the base body; between the one end surface of the peripheral wall of the hole portion of the base body and the opposing surface of the flange-like portion of the bearing support body, there is arranged an elastic member exerting a force causing the two surfaces to separate from each other; one end surface of the adjustment nut is in contact with the one end surface of the end surfaces of the peripheral wall of the hole portion of the base body; and displacement of the adjustment nut toward the forward end of the shaft is regulated. 
     In this case, “the elastic member exerts a force to cause one end surface of the peripheral wall of the hole portion of the base body and the opposing surface of the flange-like portion of the bearing support body to separate from each other”, and “one end surface of the adjustment nut is in contact therewith, and displacement of the adjustment nut toward the forward end of the shaft is regulated,” so that displacement of the adjustment nut in the extending direction of the shaft is actually prohibited, so that, in accordance with the rotation in one direction or in the opposite direction of the adjustment nut, the bearing support body is displaced in the extending direction of the shaft with respect to the base body, thereby effecting positioning of the bearing in that direction. 
     Typically, in this bearing support structure, the adjustment nut is equipped with a large diameter portion and a small diameter portion, and a protrusion protruding radially inwards from the base body is engaged with a step portion of the large diameter portion and the small diameter portion of the adjustment nut, thereby effecting the above-mentioned regulation. 
     In this case, the regulation of the displacement of the adjustment nut toward the forward end of the shaft can be effected easily and reliably. Here, as long as it can be held immovably with respect to the base body in the regulating state, the protrusion may be a swaged portion obtained by swaging a part of the base body, a holding ring fitted onto the base body, or some other means of the same effect. 
     In still another typical bearing structure according to the present invention, the bearing support body is fit-engaged with a hole portion of the base body; the adjustment nut is equipped with a flange-like portion protruding radially inwards; between the nut side end surface of the bearing support body facing the flange-like portion of the adjustment nut and the surface of the flange-like portion facing the nut side end surface, there is arranged an elastic member exerting a force causing the two surfaces to separate from each other; and the adjustment nut is regulated in its displacement in the extending direction of the shaft by the flange-like portion of the base body and a holding ring fitted onto the base body. 
     In this case, “the elastic member exerts a force causing the nut side end surface of the bearing support body and the surface of the flange-like portion of the adjustment nut facing the same to separate from each other,” and “the adjustment nut is regulated in its displacement in the extending direction of the shaft by the flange-like portion of the base body and a holding ring fitted onto the base body,” so that, in accordance with the rotation of the adjustment nut in one direction or the opposite direction, the bearing support body is displaced in the extending direction of the shaft, thereby effecting positioning of the bearing in that direction. 
     Typically, in the bearing structure of the present invention, the adjustment nut has a driver groove in the end surface thereof. However, as long as there is a deformed portion engaged so as to be rotated, it is also possible to provide some other portion (deformed portion) instead of the driver groove. 
     In this case, the forward end of a screwdriver is fitted into the driver groove to rotate the adjustment nut, so that the adjustment can be effected easily, and the requisite occupation space for adjustment can be substantially minimized. 
     Typically, in the bearing structure of the present invention, the bearing has a bearing cap jewel and a bearing hole jewel. 
     In this case, the bearing can rotatably support the shaft with respect to both an axial force and a radial force. It should be noted, however, that the bearing may also be a thrust bearing or a journal bearing rotatably supporting the shaft with respect to solely one of the axial force and the radial force. 
     Typically, in the bearing structure of the present invention, the wheel consists of a watch component. However, if so desired, it may also be a component of some other machine or apparatus. 
     Typically, in the bearing structure of the present invention, the wheel consists of a balance with hairspring or an escape wheel &amp; pinion of a watch. 
     In this case, it is possible to adjust the rotation of the balance with hairspring or the escape wheel &amp; pinion constituting the core of the movement of the watch to an appropriate condition, and the operation of the watch can be easily set to an appropriate condition. 
     The watch of the present invention is equipped with a bearing structure as described above. While the bearing structure is typically provided solely at one end side of a wheel, if so desired, it may also be provided on either side. In this case, after the assembly, the position in the axial direction of the wheel can be adjusted to an optimum position (in terms of the positional relationship with respect to other wheels). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory sectional view of a part of a watch according to a preferred embodiment of the present invention having a balance structure according to a preferred embodiment of the present invention; 
         FIG. 2  is a partially cutaway explanatory perspective view of the balance structure portion of the watch of  FIG. 1 ; 
         FIG. 3  is an explanatory plan view of the balance structure portion of the watch of  FIG. 1 ; 
         FIG. 4  is an explanatory sectional view of a part of a watch according to a preferred another embodiment of the present invention having a balance structure according to another preferred embodiment of the present invention; 
         FIG. 5  is an explanatory sectional view of a part of a watch according to still another preferred embodiment of the present invention having an escape wheel &amp; pinion structure according to still another preferred embodiment of the present invention; and 
         FIG. 6  is a partially cutaway explanatory perspective view of a part of the watch of  FIG. 5  including the escape wheel &amp; pinion structure of  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
     Embodiments 
       FIGS. 1 through 3  partially show a watch  3  according to a preferred embodiment of the present invention having a balance structure  2  equipped with a balance upper bearing structure  1  as a bearing structure according to a preferred embodiment of the present invention. In the drawings, the case back side of the watch  3  is on the upper side as in the case of normal assembly and dismantling; in the following, the terms “upper side” and “lower side” mean the “upper side” and “lower side” as seen in the drawings. 
     The watch  3  is equipped with a main plate  7 . The main plate  7  is equipped with a hole portion  7   a , to which a balance lower bearing structure  10  is mounted. On the other hand, a balance bridge  20  as a base body is detachably fixed to a bridge stand  7   b  of the main plate  7 . A balance upper bearing structure  1  is incorporated into the balance bridge  20 . 
     The balance structure  2  is composed of a balance main body  30 , the balance upper bearing structure  1 , and a balance lower bearing structure  10 . 
     As can be seen from  FIGS. 2 and 3  as well as  FIG. 1 , the balance main body  30  as a wheel includes a balance staff  31  as a shaft, a balance wheel  32 , a collet  33 , a hairspring  34 , a stud support  35 , a double roller  36 , etc.; further, it includes what the balance main body  30  should usually have such as a body of regulator  37  and a regulator pointer  38 . Since the structure of the balance main body  30  and the functions of the parts thereof themselves are well known in the art, a detailed description thereof will be omitted here. 
     As can be seen from  FIG. 1 , the balance lower bearing structure  10  is of the same structure as in the prior art; it includes a lower outer bearing frame  11  fitted to the hole portion  7   a , an inner bearing frame  12 , a hole jewel  13 , a lower cap jewel  14 , and a cap jewel support fastener  15 . 
     One end portion  20   a  of the balance bridge  20  is fixed to the bridge stand  7   b  of the main plate  7 , and another end portion  20   b  thereof is equipped with a hole portion  21 . More specifically, in an upper surface  20   c  (case back side surface) of the end portion  20   b , the balance bridge  20  is equipped with an annular groove portion  22  around the hole portion  21 , and is equipped with a cylindrical portion  23  defining the inner peripheral side of the annular groove portion  22  and an annular flange-like portion  24  protruding radially inwards from a central portion  23   b  of an inner peripheral surface  23   a  of the cylindrical portion  23 , with the hole portion  21  being defined by an inner peripheral surface  24   a  of the annular flange-like portion  24 . 
     The balance upper bearing structure  1  rotatably supporting the balance staff  31  of the balance main body  30  at the upper end portion or an upper tenon portion  31   a  thereof with respect to the balance bridge  20 , has a bearing support body  40 , a bearing  50 , an elastic member  6 , and an adjustment nut  70 . 
     Here, the bearing  50  includes an upper hole jewel  51  and an upper cap jewel  52 , and an inner bearing frame  53  supporting the upper hole jewel  51  and the upper cap jewel  52 , and the bearing support body  40  as a bearing frame includes an upper outer bearing frame  41  and a cap jewel support fastener  42 . In the bearing  50 , the cap jewel support fastener  42  is locked to a lock portion  43  of the outer bearing frame  41 , and the upper hole jewel  51 , the upper cap jewel  52 , and the inner bearing frame  53  are supported between the cap jewel support fastener  42  and the outer bearing frame  41 , and the upper hole jewel  51  and the upper cap jewel  52  are supported between the cap jewel support fastener  42  and the inner bearing frame  53 . Here, the inner bearing frame  53 , the hole jewel  51 , the cap jewel  52 , and the cap jewel support fastener  42  that are on the upper side are respectively formed in constructions similar to those of the inner bearing frame  12 , the hole jewel  13 , the cap jewel  14 , and the cap jewel support fastener  15  that are on the lower side. Further, in this area, the upper outer bearing frame  41  is formed in a construction similar to that of the lower outer bearing frame  11 . 
     The upper outer bearing frame  41  has a cylindrical portion  44  constituting a main body, and the cylindrical portion  44 , which is concentric with the balance staff  31 , extends through the hole portion  21  so as to be movable in the extending directions A 1 , A 2  of the center axis C of the balance staff  31 . The outer bearing frame  41  has a male screw portion  45  on an outer peripheral surface  44   b  of a peripheral wall portion  44   a  situated on the upper side of mainly the flange-like portion  24  of the cylindrical portion  44 , and a flange-like portion  46  extending radially outwards so as to face a surface  24   b  facing the balance wheel  32  of the flange-like portion  24  of the balance bridge  20  from the outer peripheral surface of the peripheral wall portion  44   c  situated on the lower side of the flange-like portion  24  (on the base portion side of the balance staff  31  or the side where the balance wheel  32  exists). 
     The elastic member  6  is arranged between a surface  24   b  of the flange-like portion  24  of the balance bridge  20  and an opposing surface  46   a  of the flange-like portion  46  of the outer bearing frame  41 , and exerts a force causing the two surfaces  24   b ,  46   a  to be separated from each other, biasing the outer bearing frame  41  in the direction A 1  with respect to the balance bridge  20 . The elastic member  6  can effect positioning on the outer bearing frame  41  without involving any rattling; further, when an impact is applied to the balance structure  2 , it mitigates the impact, making it possible to suppress an excessive force from being applied to the tenon portion  31   a  of the balance staff  31 , etc. The elastic member  6  consists, for example, of a belleville spring. However, it is also possible to employ some other type of component as long as it is arranged between the annular surfaces  24   b ,  46   a  and can exert a force causing the two surfaces  24   b ,  46   a  to be separated from each other. 
     The adjustment nut  70  is equipped with a female screw portion  71  threadedly engaged with a male screw portion  45  of the outer bearing frame  41 . Under the action of the elastic member  6 , one end surface  72  of the adjustment nut  70  abuts the surface of the flange-like portion  24  of the balance bridge  20  which is on the opposite side of the surface  24   b , that is, the upper surface  24   c , and is regulated or set in its displacement in the direction A 1  by the flange-like portion  24 . 
     Thus, when the adjustment nut  70  is rotated clockwise around the center axis C, that is, in the direction C 1 , the outer bearing frame  41  is displaced in the direction A 2 . On the other hand, when the adjustment nut  70  is rotated counterclockwise, that is, in the direction C 2 , around the center axis C, the outer bearing frame  41  is displaced in the direction A 1 . That is, in accordance with rotation in the directions C 1 , C 2  of the adjustment nut  70 , the outer bearing frame  41  is displaced in the directions A 2 , A 1  with respect to the balance bridge  20 , and the position of the bearing  50  with respect to the direction in which the axis C extends can be adjusted. 
     A driver groove  75  is formed diametrically in the upper end surface  74  of the adjustment nut  70 . Thus, in the balance upper bearing structure  1 , in the state in which the balance upper bearing structure  1  has been assembled to the watch  3 , the forward end portion of a flatblade screwdriver is engaged with the groove  75 , and, solely by rotating the shaft of the screwdriver clockwise or counterclockwise, the rotating position of the adjustment nut  70  is adjusted, and the position of the bearing  50  itself with respect to the extending directions A 1 , A 2  of the axis C can be adjusted. Thus, the requisite space for the adjustment can be minimized. Further, through the adjustment of the position of the bearing  50  in the directions A 1 , A 2 , the distance between the bearing  50  and the lower bearing structure  10  can be adjusted to an appropriate magnitude that is neither too large nor too small, so that the balance staff  31  of the balance main body  30  of the balance structure  2  can be reciprocated in the directions C 1 , C 2  at a predetermined frequency as designed, whereby it is possible to effect a predetermined time measurement. 
     The engaged portion of the adjustment nut  70  which is engaged with the turning tool to receive rotational torque may consist of some other structure than the groove  75  that diametrically extends across the annular end surface  74 . 
     Next, a watch  3 A according to another preferred embodiment of the present invention having a balance structure  2 A according to another preferred embodiment of the present invention will be described with reference to  FIG. 4 . 
     In the balance structure  2 A of the watch  3 A of  FIG. 4 , the elements, portions, etc. that are the same as the elements, portions, etc. of the balance structure  2  shown in  FIGS. 1 through 3  are indicated by the same reference numerals, and the elements, portions, etc. that are corresponding to but somewhat different from the elements, portions, etc. of the balance structure  2  shown in  FIGS. 1 through 3  are indicated by the same reference numerals with symbol A affixed thereto. 
     In the balance structure  2 A, a cylindrical portion  23 A of a balance bridge  20 A is equipped with a flange-like portion  24 A extending radially inwards from a lower end portion  23   b A of an inner peripheral surface  23   a A thereof, and an inner peripheral end  24   a A of the annular flange-like portion  24 A defines a hole portion  21 A. The cylindrical portion  23 A has a swaged portion  26  extending from an upper end portion  25  thereof. 
     Further, in the balance upper bearing structure  1 A of the balance structure  2 A, an outer bearing frame  41 A has a small diameter lower peripheral wall portion  44   c A and a large diameter cylindrical portion  44 A situated on the upper side of a lower peripheral wall portion  44   c A (the forward end  31   a  side of the balance staff  31 ). The small diameter lower peripheral wall portion  44   c  of the outer bearing frame  41 A is movably fit-engaged with a hole portion  21 A of the balance bridge  20 A. Between the small diameter lower peripheral wall portion  44   c A and the large diameter cylindrical portion  44 A, there is formed a flange-like portion  46 A protruding radially outwards and equipped with a surface  46 A b  facing a peripheral wall portion of the hole portion  21 A, that is, an upper surface  24   c A of the flange-like portion  24 A. The cylindrical portion  44 A has a male screw portion  45 A on an outer peripheral surface, which is concentric with the balance staff  31 . In this example, the bearing support body  40 A is composed of the outer bearing frame  41 A and the cap jewel support fastener  42 . 
     Further, in the balance upper bearing structure  1 A of the balance structure  2 A, an elastic member  6 A in the form of a belleville spring is arranged between an upper surface  24   c A of the flange-like portion  24 A of the balance bridge  20 A and a lower surface  46 A b  of the flange-like portion  46 A of the outer bearing frame  41 A opposed thereto in order to exert a force causing the two surfaces  24   c A,  46 A b  to separate from each other. 
     Further, in the balance upper bearing structure  1 A of the balance structure  2 A, an adjustment nut  70 A is equipped with a large diameter portion  76  and a small diameter portion  77 . A swaged portion  26  as a protrusion protruding radially inwards from the upper end portion  25  of the cylindrical portion  23 A of the balance bridge  20 A, is bent radially inwards by swaging, and is engaged with a step portion  78  of the large diameter portion  76  and the small diameter portion  77  of the adjustment nut  70 A. Thus, the movement of the adjustment nut  70 A in the direction A 2  with respect to the balance bridge  20 A is regulated or set by the swaged portion  26  engaged with the step portion  78 . A lower surface  72 A of the adjustment nut  70 A abuts an upper surface  24   c A of the flange-like portion  24 A of the balance bridge  20 A, and the displacement of the adjustment nut  70 A in the direction A 1  with respect to the balance bridge  20 A is regulated or set by the flange-like portion  24 A. 
     Also in the balance structure  2 A, a turning tool such as a screwdriver is engaged with the driver groove  75  in the upper end surface  74  of the adjustment nut  70 A, and, solely by turning the adjustment nut  70 A in the direction C 1  or C 2 , the outer bearing frame  41 A is displaced in the direction A 2  or A 1  with respect to the balance bridge  20 A to thereby adjust the position in the directions A 1 , A 2  of the balance upper bearing structure  1 A, whereby it is possible to realize a condition suitable for reciprocal rotation of the balance staff  31  of the balance structure  2 A. 
     Next, a watch  3 B according to still another preferred embodiment of the present invention having an escape wheel &amp; pinion structure  2 B according to still another preferred embodiment of the present invention will be described with reference to  FIGS. 5 and 6 . 
     In the escape wheel &amp; pinion structure  2 B of the watch  3 B of  FIGS. 5 and 6 , the elements, portions, etc. that are the same as the elements, portions, etc. of the balance structure  2  shown in  FIGS. 1 through 3  are indicated by the same reference numerals, and the elements, portions, etc. corresponding to, though somewhat different from, the elements, portions, etc. of the balance structure  2  shown in  FIGS. 1 through 3  and of the balance structure  2 A shown in  FIG. 4  are indicated by the same reference numerals with a symbol B affixed thereto (with symbol A omitted where symbol A is affixed to the reference numerals). 
     In the escape wheel &amp; pinion structure  2 B, an escape wheel &amp; pinion main body  90  is supported by a lower bearing structure  10 B and an upper bearing structure  1 B so as to be rotatable in the directions C 1 , C 2  around the center axis C. In an outer bearing frame  11 B, the lower bearing structure  10 B is fitted into a hole  7   a B of the main plate  7 , and the upper bearing structure  1 B is attached to a train wheel bridge  80 . 
     The escape wheel &amp; pinion main body  90  has an escape wheel shaft or escape wheel arbor  91 , an escape wheel  92  integral with the escape wheel shaft  91 , and an escape pinion  93 . The escape shaft  91  has at both end portions thereof thin shaft portions or tenon portions  91   a ,  91   b  rotatably supported by the upper bearing structure  1 B and the lower bearing structure  10 B. The escape wheel  92  is engaged with a body of pallet fork (not shown), and the escape pinion  93  is held in mesh with a wheel constituting a time measurement train wheel (not shown) of the watch  1 B to support the time measurement operation of the watch  1 B, which is well known in itself, so a description thereof will be omitted. 
     In the escape wheel &amp; pinion structure  2 B, the train wheel bridge  80  has on the inner side of the upper surface  81  thereof an annular large diameter recess  82 , an annular small diameter recess  83 , and an circular hole portion  84 , which are concentric. Here, the large diameter recess  82  is defined by a cylindrical peripheral surface  82   a  and an annular bottom surface  82   b , whose center is the center axis C, and the small diameter recess  83  is defined by a cylindrical peripheral surface  83   a  and an annular bottom surface  83   b , whose center is the center axis C. The cylindrical peripheral surface  83   a  is continuous with the inner peripheral edge of the annular bottom surface  82   b . The circular hole portion  84  is defined by a cylindrical peripheral surface  84   a , and the cylindrical peripheral surface  84   a  is continuous with the annular bottom surface  83   b  of the small diameter recess  83 . Thus, the train wheel bridge  80  is equipped with an annular flange-like portion  85 , and an inner peripheral surface  85   a  of the flange-like portion  85  is defined by the peripheral surface  84   a  of the hole portion  84 , with one surface  85   b  of the flange-like portion  85  being defined by the bottom surface  83   b  of the small diameter recess  83 . 
     Further, in the escape wheel &amp; pinion upper bearing structure  1 B of the escape wheel &amp; pinion structure  2 B, a bearing frame  41 B has a small diameter peripheral wall portion  47  and a large diameter cylindrical portion  48  situated on the upper side of the small diameter peripheral wall portion  47  (on the side of a tenon portion  91   a  at the forward end of the escape wheel shaft  91 ). The small diameter peripheral wall portion  47  of the bearing frame  41 B is movably fit-engaged with the hole portion  84  of the train wheel  80 . The large diameter cylindrical portion  48  has a male screw portion  45 B on an outer peripheral surface that is concentric with the escape wheel shaft  91 . In this example, the bearing support body  40 B is composed of the bearing frame  41 B and a cap jewel support fastener  42 B. 
     The male screw portion  45 B is threadedly engaged with an adjustment nut  70 B equipped with a female screw portion  71 B. The adjustment nut  70 B is equipped with a large diameter portion  76 B and a small diameter portion  77 B, and the large diameter portion  76 B is rotatably fit-engaged with the small diameter recess  83  of the train wheel bridge  80 . The height of the large diameter portion  76 B is approximately the same as the depth of the small diameter recess  83 , and is typically somewhat larger than the depth. Thus, the step portion  78 B of the large diameter portion  76 B and the small diameter portion  77 B is approximately the same height as the bottom surface  82   b  of the large diameter recess  82 , and typically protrudes slightly beyond the bottom surface  82   b . Further, the adjustment nut  70 B has at the top portion of the small diameter portion  77 B an annular flange-like portion  79  extending radially inwards, and a lower surface  79   a  of the flange-like portion  79  faces a top surface  48   a  of the large diameter cylindrical portion  48  of the bearing frame  41 B. A lower surface  76 B a  of the large diameter portion  76 B of the adjustment nut  70 B abuts the bottom surface  83   b  of the small diameter recess  83  of the train wheel bridge  80 , and displacement of the adjustment nut  70 B in the direction A 1  is prohibited or set by the train wheel bridge  80 . 
     An annular holding ring  60  is fitted to the large diameter recess  82  of the train wheel bridge  80 . That is, the holding ring  60  is driven into the large diameter recess  82  of the train wheel bridge  80 , and an outer peripheral surface  61  of the holding ring  60  is held in intimate contact with a peripheral surface  82   a  of the large diameter recess  82  of the train wheel bridge  80 . Further, a lower surface  62  of the holding ring  60  is in contact with the step portion  78 B of the adjustment nut  70 B to actually prohibit or set displacement of the adjustment nut  70 B in the direction A 2 . 
     Between the lower surface  79   a  of the flange-like portion  79  of the adjustment nut  70 B and the top surface  48   a  of the large diameter cylindrical portion  48  of the bearing frame  41 , there is arranged a belleville spring  6 B as an elastic member, and the belleville spring  6 B exerts a force causing the surfaces  79   a ,  48   a  to separate from each other. 
     Also in the escape wheel &amp; pinion structure  2 B, a turning tool such as a screwdriver is engaged with the driver groove  75  in the upper end surface  74  of the adjustment nut  70 B, and, solely by turning the adjustment nut  70 B in the direction C 1  or C 2 , the bearing frame  41 B is displaced in the direction A 2  or A 1  with respect to the train wheel bridge  80  to adjust the position of the escape wheel &amp; pinion upper bearing structure  1 B in the directions A 1 , A 2 , whereby it is possible to realize a condition suitable for reciprocating rotation of the escape wheel arbor or escape wheel shaft  91  of the escape wheel &amp; pinion structure  2 B.