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RELATED APPLICATION DATA 
   The present invention is based upon Japanese priority application No. 2005-113340, which is hereby incorporated in its entirety herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to improvement of a door checker for an automobile connected between a body and a door of the automobile for holding the door at a predetermined opening-degree position. 
   2. Description of the Related Art 
   A conventional door checker of this type is, as disclosed in the Japanese Patent Publication No. 3-13392, provided with a case fixed to one of a body and a door of an automobile, a check lever movably penetrating the case and connected to the other of the body and the door, a shoe holder which is held by the case and capable of advancing/retreating to/from the check lever, a shoe held by the shoe holder and sliding on the check lever with relative movement of the case and the check lever, and a check spring for springing back the shoe holder to the check lever side within the case so that the shoe is brought into pressure contact with the check lever, and a detent notch to be engaged with the shoe is formed on the check lever so that the door is stopped/held at a specified opening degree by an engaging force between the detent notch and the shoe. 
   In the above conventional door checker, the opening degree for holding the door can be set only in several stages, and thus the door can not be often held at an opening degree desired by a user. 
   SUMMARY OF THE INVENTION 
   The present invention has been achieved in view of the above circumstances and has an object to provide a door checker for an automobile which can easily set an opening degree for holding the door in a large number of steps so that the door can be held at the opening degree desired by the user. 
   In order to achieve the above object, according to a first feature of the present invention, there is provided a door checker for an automobile, comprising: a case fixed to one of a body and a door of the automobile; a check lever movably penetrating the case, oscillatably axis-supported by the other of the body and the door, and provided with a rack on one side face; a pinion meshed with the rack and rotatably housed in the case; a movable shoe housed in the case so that the movable shoe can be engaged with and disengaged from a tooth portion of the pinion; and a check spring for biasing the movable shoe in the direction of engagement with the pinion, wherein the door is held at an arbitrary opening degree by an engaging force of the movable shoe with the pinion due to a biasing force of the check spring. 
   With the first feature of the present invention, since the pinion in the case is rotated by the rack of the check lever according to the opening-degree change of the door so as to be engaged with any tooth portion of the pinion, the number of steps which can hold the door by the engaging force can be set to be large with ease depending on the number of rack teeth, and thus the door can be held at the opening degree desired by the user. 
   According to a second feature of the present invention, in addition to the first feature, shoe pushing-up means is provided in the case so as to separate the movable shoe from the pinion with relative movement of the case and the check lever. 
   With the second feature of the present invention, since the shoe pushing-up means is provided in the case so as to separate the movable shoe from the pinion with relative movement of the case and the check lever, when the door is swung from the held position, the contact between the movable shoe and the pinion is cut off, thereby preventing noise caused by the contact. 
   According to a third feature of the present invention, in addition to the first or second feature, a rotational axis of the pinion is arranged in parallel with an axis for oscillatably connecting the check lever to the other of the body and the door. 
   With the third feature of the present invention, since the rotational axis of the pinion is arranged in parallel with the axis of the check lever, the meshed state between the rack and the pinion of the check lever can be always kept normal even if a relative angle between the check lever and the case is changed according to the movement of the door, and thus the engagement state between the pinion and the movable shoe is not changed. Therefore, a force for holding the door can be always stabilized irrespective of the opening degree of the door. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an essential part of an automobile equipped with a door checker according to a preferred embodiment of the present invention. 
       FIG. 2  is a plan view of the door checker shown in the state where the door is not held. 
       FIG. 3  is a plan view of the door checker shown in the state where the door is held. 
       FIG. 4  is a sectional view along  4 - 4  line in  FIG. 2 . 
       FIG. 5  is an enlarged sectional view along  5 - 5  line in  FIG. 2 . 
       FIG. 6  is a sectional view along  6 - 6  line in  FIG. 5 . 
       FIG. 7  is an exploded perspective view of the door checker. 
       FIG. 8  is a sectional view along  8 - 8  line in  FIG. 3 . 
       FIG. 9  is a sectional view along  9 - 9  line in  FIG. 8 . 
       FIG. 10  is a view for explaining an operation of a cam plate of shoe pushing-up means in the above door checker. 
       FIG. 11  is another view for explaining the operation of the cam plate. 
       FIG. 12  is a door opening/closing load character diagram of the door checker. 
       FIG. 13  is a view, corresponding to  FIG. 9 , of another preferred embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The above-mentioned object, other object, characteristics, and advantages of the present invention will become apparent from preferred embodiments, which will be described in detail below by reference to the attached drawings. 
   First, in  FIG. 1 , a door D is swingably mounted to a body B of an automobile so as to open/close an entrance thereof with a vertical pair of hinges H and H, and a door checker C of the present invention is mounted between the hinges H and H between the body B and the door D. 
   As shown in  FIGS. 2 to 7 , the door checker C has a case  1  fixed to an inner surface of an end wall of the door D with a bolt  2 . The case  1  is constituted by a case body  1   a  having a box shape with one end opened and a cover  1   b  fixed to the end wall of the door D with the bolt  2  while covering the opened end. Provided on the cover  1   b  and the case body  1   a  are a through hole  3  opened on the end wall of the door D and coaxially aligned through holes  4  and  5 . A base end of a check lever  6  penetrating these three through holes  3 ,  4  and  5  is connected to a bracket  7  through an axis  8  so that the check lever  6  and the bracket  7  are capable of mutual rotational movement. The bracket  7  arranges the axis  8  in parallel with a pivot shaft Ha of the hinge H, and is fixed to the body D with a bolt  9  (See  FIG. 1 ). 
   The check lever  6  comprises a core plate  6   a  made of a steel plate extending over the entire length in its longitudinal direction, and an outer skin  6   b  made of a synthetic resin to be mold-bonded to a circumferential surface of the core plate  6   a . At a free end of the check lever  6 , full-open stopper means  12  for defining an open limit of the door D is provided. This full-open stopper means  12  comprises a stopper plate  13  penetrated by the free end of the check lever  6 , a stopper pin  15  which is press-fit into a pin hole  14  provided at the free end of the check lever  6  so as to support a back surface of the stopper plate  13 , and a cushion member  16  made of rubber and supported on the front surface of the stopper plate  13 . When the door D is largely opened, an end wall of the case  1  is received by the stopper plate  13  through the cushion member  16 , so that the full-open position of the door D is defined. 
   One side face of the check lever  6  in parallel with the axis  8  is divided into a non-holding section E corresponding to a section from the full-closed position of the door D to a predetermined small opening degree, and a holding section F corresponding to a section from the end of the non-holding section E to the full-open position of the door D. Projectingly provided on a side surface of the holding section F are a rack  17  and a pair of guide ribs  18  and  18  arranged on opposite sides of the rack  17 . Opposite side edges of the core plate  6   a  rise so that they bite into the guide ribs  18  and  18 . A side surface of the non-holding section E of the check lever  6  is a flat surface having the same level as a bottom surface of the rack  17 , and the pair of guide ribs  18  and  18  extend to the side surface of this non-holding section E. Both outer portions of both the guide ribs  18  and  18  on the side surface of the check lever  6  are formed on a pair of flat rail surfaces  19  and  19  which are slightly lower than the bottom surface of the rack  17 . 
   Provided in the case  1  are a pinion  20  capable of being meshed with the rack  17 , a pivot  21  for rotatably support the pinion  20 , a pair of friction plates  22  and  22  arranged on opposite outer sides of the pinion  20  and penetrated by the pivot  21 , a pair of cam plates  23  and  23  arranged outside of these friction plates  22  and  22  and rotatably supported by the pivot  21 , a pair of set springs  25  and  25  made of rubber, arranged outside of both the cam plates  23  and  23  with washers  24  and  24  therebetween and penetrated by the pivot  21 , and a pair of support plates  26  and  26  fitted to opposite ends of the pivot  21  to contact with the inner opposite surfaces of the case  1  while compressing the set springs  25  and  25 . The friction plates  22  and  22  are brought into pressure contact with the pinion  20  and the cam plates  23  and  23  by a compression reaction of the set springs  25 . The friction plates  22  are molded from a friction material such as rubber, cork, brake lining material, clutch facing material, etc. 
   The support plates  26  and  26  are constituted so that movement of the check lever  6  in the longitudinal direction is limited by a bottom wall of the case body  1   a  and the cover  1   b , but the movement of the check lever  6  in the direction orthogonal to the longitudinal direction is not prevented by the case  1 . The check lever  6  side on the outer circumferential face of each of the cam plates  23  is formed into an arc surface  23   a  with the pivot  21  as its center. When the pinion  20  is in the non-holding section E of the check lever  6 , the arc surface  23   a  rides on the rail surface  19  of the check lever  6  so as to break off contact of the pinion  20  with the check lever  6  (See  FIGS. 2 ,  5  and  6 ); and when the pinion  20  is moved to the holding section F of the check lever  6 , the arc surface  23   a  is raised from the rail surface  19  by meshing with the rack  17  (See  FIGS. 3 and 8 ). 
   Further provided in the case  1  are a fixed shoe  30  slidably supporting the side surface of the check lever  6  opposite to the rack  17 , a movable shoe  31  opposed to the fixed shoe  30  with the pinion  20  and the check lever  6  therebetween, and a check spring  32  made of rubber for springing back the movable shoe  31  toward the pinion  20  and the cam plates  23  and  23 . 
   The fixed shoe  30  is fixed within the case  1 , while the movable shoe  31  is capable of sliding on the inner surface of the case  1  so that it can advance/retreat to/from the fixed shoe  30 . A projection  31   a  is integrally formed on the movable shoe  31  so as to apply a rotational resistance to the pinion  20  by being engaged between tooth portions  20   a  and  20   a  of the pinion  20 . 
   Moreover, a pair of peak portions  23   b  and  23   b  arranged so as to hold the projection  31   a  therebetween are provided on each of the cam plates  23 . Both the peak portions  23   b  and  23   b  are formed with their top portion protruding higher than the tooth portion  20   a  of the pinion  20 , and a valley portion between both the peak portions  23   b  and  23   b  is made deep so as not to prevent the engagement of the projection  31   a  between the tooth portions  20   a  and  20   a  of the pinion  20 . 
   Furthermore, the cam plate  23  is provided with a pair of stopper claws  23   c  and  23   c  which are brought into contact with the inner surface of the case  1  so as to limit a rotational angle around the pivot  21  of the cam plate  23  to a constant value. When the cam plate  23  is rotated till each of the stopper claws  23   c  is brought into contact with the inner wall of the case  1 , an inclined surface of one of the peak portions  23   b  separates the projection  31   a  of the movable shoe  31  from the tooth portion  20   a  of the pinion  20 . At this rotation limit of the cam plate  23 , a repulsive force of the check spring  32  generates a component force f 2  with which the projection  31   a  goes down the inclined surface of the peak portion  23   b  because the peak portion  23   b  holds the projection  31   a  at the middle of the inclined surface (see  FIG. 11 ). 
   In the above embodiment, the friction plate  22 , the cam plate  23  and the set spring  25  constitute shoe pushing-up means L for separating the movable shoe  31  from the pinion  20  with relative movement of the case  1  and the check lever  6 . 
   Next, operation of this preferred embodiment will be described. 
   As shown in  FIGS. 2 ,  5  and  6 , when the door D is between the non-holding section from the full-closed position to a predetermined small opening degree, that is, when the pinion  20  is in the non-holding section E on the side face of the check lever  6 , the cam plate  23  separates the pinion  20  from the check lever  6  by being received by the rail surface  19  of the check lever  6 . Therefore, when the door D is opened/closed in the non-holding section, the cam plate  23  smoothly slides on the rail surface  19  of the check lever  6 , so that an opening/closing load of the door D is small (see a line a in  FIG. 12 ). Thus, the door D can be smoothly opened/closed. 
   When the door D is moved from the non-holding section to the holding section, the pinion  20  is moved to the holding section F of the check lever  6 , and the pinion  20  is forced to rotate by meshing with the rack  17 . However, the projection  31   a  of the movable shoe  31  engaged between the tooth portions  20   a  and  20   a  of the pinion  20  resists the rotation of the pinion  20 , so that the opening load of the door D is increased as shown by a line b′ in  FIG. 12 . At this stage, the arc surface  23   a  of the cam plates  23  and  23  is raised from the rail surface  19 , and the meshed state is ensured without backlash of the pinion  20  and the rack  17 . 
     FIGS. 3 ,  8  and  9  show the state where the door D is held at an intermediate opening degree of the holding section. In this state, the fixed shoe  30  and the movable shoe  31  clamp therebetween the check lever  6  and the pinion  20  meshed with the rack  17  due to pressure by a spring-back force of the check spring  32 , the pinion  20  is strongly meshed with the rack  17 , and the projection  31   a  of the movable shoe  31  is strongly engaged between the tooth portions  20   a  and  20   a  of the pinion  20 . Therefore, the engaging force generates an opening/closing load of the door D (see a load peak portion b′ in  FIG. 12 ), and the door D cannot be opened/closed unless the load is exceeded. 
   At this time, the cam plates  23  and  23  receive the projection  31   a  of the movable shoe  31  between the pair of peak portions  23   b  and  23   b.    
   When the door D is swung from this state in the opening direction or the closing direction within the holding section so as to move the case  1  with respect to the check lever  6  and correspondingly the pinion  20  is rotated, for example, in the direction of an arrow A, the pinion  20  rotates the cam plate  23  in the same direction through the friction plates  22  and  22 . Therefore, as shown in  FIG. 10 , the cam plate  23  immediately scoops up the projection  31   a  of the movable  31  with the inclined surface of one of the peak portions  23   b  and separates the projection  31   a  from the tooth portion  20   a  of the pinion  20 , and then, as shown in  FIG. 11 , one of the stopper claws  23   c  is brought into contact with the inner face of the case  1  to stop the rotation of the cam plate  23 . Therefore, even if the door D is further swung and the pinion  20  is rotated by the rack  17 , no contact is generated between the pinion  20  and the projection  31   a , so that noise caused by the contact can be prevented. A swing load of the door D at that time is shown by a line c in  FIG. 12 , and the swing load is determined by a friction force between the pinion  20  and each of the friction plates  22 . 
   When the swing of the door D is stopped again at another intermediate opening degree, a force f acts on the projection  31   a  of the movable shoe  31  engaged with the inclined surface of one of the peak portions  23   b  as shown in  FIG. 11 . That is, by the spring-back force of the set spring  25 , the force f exerted by the projection  31   a  of the movable shoe  31  on the inclined surface of one of the peak portions  23   b  of the cam plate  23  is divided into a component force f 1  perpendicular to the inclined surface of the peak portion  23   b  and a component force f 2  facing the direction of the inclined surface of the peak portion  23   b . The latter component force f 2  tries to guide the projection  31   a  to a space between the tooth portions  20   a  and  20   a  of the pinion  20 . Thus, when the projection  31   a  begins to slide down the inclined surface, the projection  31   a  swiftly slides down the inclined surface by an inertia force of the movable shoe  31  to be engaged between the tooth portions  20   a  and  20   a  of the pinion  20  and enters a state similar to the initial state as shown in  FIG. 9 . Therefore, the door D can be held at the another intermediate opening degree by the strong engaging force between the projection  31   a  and the tooth portions  20   a  and  20   a  of the pinion  20  by the spring-back force of the check spring  32 . 
   When the door D is swung in the closing direction, the pinion  20  is rotated in the direction opposite to the arrow A, and the same effect as stated above is generated except that the inclined surface of the other of the peak portions  23   b  of the cam plate  23  contributes to scooping-up of the projection  31   a.    
   As described above, in the holding section of the door D, the pinion  20  is rotated by the rack  17  of the check lever  6  according to the change in opening degree of the door D, and the projection  31   a  of the movable shoe  31  can be engaged between any tooth portions  20   a  and  20   a  of the pinion  20 , so that the number of steps holding the door D by the engaging force can be set to be large with ease depending on the number of teeth of the rack  17 . Therefore, the door D can be held at an opening degree desired by a user. 
   The rotational axis of the pinion  20 , that is, the pivot  21  is arranged in parallel with the axis  8  supporting the check lever  6 , and thus even if the relative angle of the check lever  6  and the case  1  is changed according to the movement of the door D, the meshed state between the rack  17  in the check lever  6  and the pinion  20  in the case  1  is not disturbed, and the engagement state between the pinion  20  and the movable shoe  31  is not changed in the case  1 . Therefore, irrespective of the opening degree of the door D, the door holding force can be always stabilized. 
   Next, another preferred embodiment of the present invention will be described referring to  FIG. 13 . 
   In this preferred embodiment, even when the pinion  20  is moved in the holding section F of the check lever  6 , the arc surface  23   a  of the cam plate  23  is kept in contact with the rail surface  19  so that an excessive pressure does not act on the meshed portion between the pinion  20  and the rack  17 . Also, the tip end shape of the tooth portion  20   a  of the pinion  20  is formed into a circle inscribed with three curves of involute curves m and m on opposite side faces and a tooth tip end circle n, thereby smoothly carrying out engagement/disengagement of the projection  31   a  of the movable shoe  31  between the tooth portions  20   a  and  20   a . The other components are the same as those in the previously-described embodiment, and the same reference numerals are given to portions corresponding to those in the previously-described embodiment in the drawing so as to omit duplicated explanation. 
   The present invention is not limited to the above-described embodiments, and various changes in design may be made without departing from the subject matter of the present invention. For example, the rack  17  to be meshed with the pinion  20  may be formed over the entire area of the check lever  6 . Further, the case  1  may be fixed on the body B side and the bracket  7  of the check lever  6  may be mounted on the door D side. Furthermore, a coil spring, disk spring, etc. may be used as the check spring  32  or the set spring  25 .

Summary:
A door checker for an automobile includes: a case fixed to one of a body and a door of the automobile; a check lever movably penetrating the case, oscillatably axis-supported by the other of the body and the door, and provided with a rack on one side face; a pinion meshed with the rack and rotatably housed in the case; a movable shoe housed in the case so that the movable shoe can be engaged with and disengaged from a tooth portion of the pinion; and a check spring for biasing the movable shoe in the direction of engagement with the pinion. The door is held at an arbitrary opening degree by an engaging force of the movable shoe with the pinion due to a biasing force of the check spring. Thus, it is possible to easily set a large number of steps in an opening degree for holding the door.