Patent Publication Number: US-7213302-B2

Title: Door retention device used in process of manufacturing automobile

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a door retention device for retaining a door at least in a fully opened position and a slightly opened state, the device being used in a process of manufacturing an automobile including a first hinge arm secured to one of a body and the door, a second arm secured to the other of the body and the door, and a hinge pin which interconnects the first and second hinge arms for turning movement relative to each other. 
   2. Description of the Related Art 
   In a process of manufacturing an automobile, and particularly at a step of painting a body having a door, it is a conventional practice to paint an interior of the door and an inner portion of the door in a fully opened state of the door and to paint outer surfaces of the body and the door in a slightly opened state of the door. At such a painting step, a door retention device is required, which is used temporarily for retain the door in fully opened position and in a slightly opened position to prevent the door from being turned voluntarily. 
   There is such a conventionally known door retention device, in which a door checker capable of retain a door in two positions, that is, a fully opened position and a slightly opened position, is mounted temporarily between a body and the door in addition to a door hinge for connecting the body and the door to each other, as disclosed, for example, in Patent Document 1. 
   Patent Document 1: Japanese Patent Application Laid-open No. 9-136679 
   A conventional door checker used temporarily in an automobile manufacturing process is relatively expensive because of a large number of exclusive parts, and moreover operations of mounting and demounting of the body checker to and from the body and the door are troublesome. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished with such circumstance in view, and accordingly, it is an object of the present invention to provide an inexpensive door retention device used in an automobile manufacturing process, wherein a door can be retained at least in a fully opened position and a slightly opened position by the combination of a smaller number of exclusive parts with a door hinge interconnecting a body and the door in the automobile manufacturing process, and moreover, the mounting and demounting of the body checker to and from the body and the door can be achieved easily. 
   To achieve the above object, according to a first aspect and feature of the present invention, there is provided a door retention device for retaining a door at least in a fully opened position and a slightly opened position, the device being used in a process of manufacturing an automobile including a first hinge arm secured to one of a body and the door, a second hinge arm secured to the other of the body and the door, and a hinge pin which interconnects the first and second hinge arms for turning movement relative to each other, characterized in that the door retention device comprises a torsion spring which is mounted to the first hinge arm and which includes a movable arm portion and a torsion shaft for exhibiting a torsional repulsion force in accordance with the swinging of the movable arm portion, and a cam formed on the second hinge arm, the cam being provided with a first positioning recess and a second positioning recess in which the movable arm portion is brought into engagement in the fully opened position and the slightly opened position, and a projection disposed between the first and second positioning recesses and adapted to apply a load to the movable arm portion in accordance with the turning of the door, the torsion spring being capable of being mounted and demounted in a non-loaded state to and from the first hinge arm in the fully opened position of the door. 
   According to a second aspect and feature of the present invention, in addition to the first feature, a roller capable of being rolled on the projection is added to the movable arm portion. 
   According to a third aspect and feature of the present invention, in addition to the first or second feature, the torsion spring is comprised of the torsion shaft, a U-shaped stationary arm portion extending from one end of the torsion shaft, and the U-shaped movable arm portion extending from the other end of the torsion shaft in a direction opposite from the stationary arm portion, and first and second cutout grooves are formed in a surface and a back of the first hinge arm, respectively, so that the torsion shaft and the stationary arm portion are brought into engagement in the first and second cutout grooves, respectively. 
   With the first feature of the present invention, it is possible to construct the door retention device capable of retaining the door in the fully opened position and the slightly opened position, as required, in the automobile manufacturing process, only by mounting the torsion spring utilizing a door hinge originally required for connection of the door to the body, and to provide such a structure extremely easily and inexpensively. Moreover, in the fully opened position, the movable arm portion can be brought into engagement in the first positioning recess in the cam in a non-loaded state. Therefore, not only the mounting of the torsion spring to the first hinge arm but also the demounting or removal of the torsion spring from the first hinge arm can be achieved easily, which can contribute to an enhancement in productivity of the automobile. 
   With the second feature of the present invention, when the door has been turned from the fully opened position in a closing direction or from the slightly opened position in an opening direction, the roller added to the movable arm portion rides on the projection of the cam, so that a repulsion force of the torsion shaft in a torsional direction attains a maximum value. However, the roller rolls on the projection, whereby the door can be smoothly turned. 
   With the third feature of the present invention, the torsion spring can be formed easily from a single spring wire material, and the mounting and demounting or removal of the spring to and from the first hinge arm can be conducted easily. 
   The above and other objects, features and advantages of the invention will become apparent from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of essential portions of an automobile provided with a door retention device according to the present invention.  FIG. 2  is an enlarged sectional view taken along a line  2 — 2  in  FIG. 1 , showing a door in a fully opened position.  FIG. 3  is a view corresponding to  FIG. 2 , but showing the door in a slightly opened position.  FIG. 4  is a sectional view taken along a line  4 — 4  in  FIG. 2 .  FIG. 5  is a sectional view taken along a line  5 - 5  in  FIG. 2 .  FIG. 6  is a perspective view of the door retention device.  FIG. 7  is a view for explaining how to mount a torsion spring in the door retention device. 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
   The preferred embodiment of the present invention will now be described with reference to the accompanying drawings. 
   Referring first to  FIGS. 1 ,  2 ,  5  and  6 , at a step of assembling an automobile, a door D is turnably mounted to a body B of the automobile through a pair of upper and lower hinges H, H to open and close a doorway. Each of the hinges H is comprised of a first hinge arm  1  secured to the body B, a second hinge arm  2  secured to the door D, and a hinge pin  3  having an enlarged head portion  3   a  which interconnects the first and second hinge arms  1  and  2  for turning movement relative to each other. 
   As clearly shown in  FIGS. 2 and 6 , the first hinge arm  1  comprises an oblong stationary base portion  8 , and a pair of inner arm portions  9 ,  9  rising from one end of the stationary base portion  8  and opposed to each other. The stationary base portion  8  is integrally formed at its upper and lower side edges with a pair of ribs  8   a,    8   a  which protrude from a surface of the base portion  8  and which are connected to the respective inner arm portions  9 ,  9 . The stationary base portion  8  is secured to the body B by a bolt  14 . The inner arm portions  9 ,  9  have pinholes  10 ,  10  (see  FIG. 5 ) into which bushes  15 ,  15  are fitted. The inner arm portions  9  are inserted into outer arm portions  6 , so that the bushes  10 ,  10  are aligned with the pair of pinholes  7 ,  7 . 
   The second hinge arm  2  comprises a pair of stationary base portions  5 ,  5 , a pair of outer arm portions  6 ,  6  which rise from edges opposed to the stationary base portions  5 ,  5  and which are opposed to each other, and a connection  6   a  which integrally connects the side edges of the outer arm portions  6 ,  6  to each other. The stationary base portions  5 ,  5  are secured to an end wall of the door D by bolts  12 . The coaxially arranged pinholes  7 ,  7  are provided in tip ends of the outer arm portions  6 ,  6 . The first and second hinge arms  1  and  2  are interconnected for turning movement relative to each other by fitting the hinge pin  3  having the enlarged head portion  3   a  into the pinholes  7 ,  7  and the bushes  15 ,  15 . A slip-off preventing enlarged portion  3   b  is formed at a tip end of the hinge pin  3  by crimping. 
   Reference character C in  FIG. 1  designates a door checker of a sliding type mounted between the body B and the door D after a step of painting the automobile. 
   A general structure of the door hinge H has been described above. According to the present invention, a structure which will be described below is previously added to such a door hinge H. More specifically, as clearly shown in  FIGS. 2 ,  4  and  6 , a first cutout groove  25  is provided in a surface of the stationary base portion  8  of the first hinge arm  1  to extend in parallel to the hinge pin  3 , and a second cutout groove  26  is provided in a back of the stationary base portion  8  to extend likewise in parallel to the hinge pin  3 . The second cutout groove  26  is disposed at a location farther from the hinge pin  3  than the first cutout groove  25 . 
   On the other hand, a cam  20  is formed on the second hinge arm  2  at its upper part, that is, the outer arm portion  6 , as clearly shown in  FIGS. 2 and 5 . The cam  20  is comprised of first and second positioning recesses  20   a  and  20   b  which are located at equal distances apart from an axis of the hinge pin  3  and which are spaced apart from each other in a circumferential direction of the hinge pin  3 , and a projection  20   c  arcuate about the axis of the hinge pin  3  to connect the first and second positioning recesses  20   a  and  20   b.    
   A torsion spring  23  is mounted to such a door hinge H, to retain the door D in a fully opened position F (see  FIG. 2 ) and a slightly opened position S (see  FIG. 3 ), when the body B having the door D mounted thereto has been transported to the painting step. In this case, if the torsion spring  23  mounted only to any one of the pair of upper and lower door hinge H, H, it suffices. 
   The torsion spring  23  is formed from a single spring wire material and comprises a torsion shaft  23   a , a U-shaped stationary arm portion  23   b  extending from one end of the torsion shaft  23   a , and a U-shaped movable arm portion  23   c  extending from the other end of the torsion shaft  23   a . Tip ends of the arm portions  23   b  and  23   c  are shafts  23   b ′ and  23   c ′ parallel to the torsion shaft  23   a . A roller  24  having a guide groove  24   a  around its outer periphery is added to and rotatably fitted over the shaft  23   c ′ at the tip end of the movable arm portion  23   c.    
   The torsion shaft  23   a  is adapted to be disengageably engaged into the first cutout groove  25  in the first hinge arm  1 , and the shafts  23   b ′ at the tip end of the stationary arm portion  23   b  is adapted to be disengageably engaged into the second cutout groove  26 . An end face of the shafts  23   c ′ at the tip end of the movable arm portion  23   c  is adapted to be put into abutment against an upper surface of the first hinge arm  1 . The roller  24  added to the movable arm portion  23   c  is adapted to be brought into engagement with the cam  20  of the second hinge arm  2 . In this case, the cam  20  is designed so that when the door D is in the fully opened position F and the slightly opened position S, the roller  24  is received respectively by the first and second positioning recesses  20   a  and  20   b  with the movable arm portion  23   c  in a non-loaded state, and so that if an attempt is made to turn the door D between the fully opened position F and the slightly opened position S, the projection  20   c  urges the roller  24  to apply a swinging load to the movable arm portion  23   c , thereby generating a repulsion force in a torsional direction in the torsion shaft  23   a.    
   When the automobile is brought into the painting step, the torsion spring  23  is mounted to the door hinge H in the following process: first of all, as shown in  FIG. 7 , in a state in which the door D has been turned to the fully opened position F, the shaft  23   b ′ at the tip end of the stationary arm portion  23   b  is inserted from below into the second cutout groove  26  in the stationary base  8  of the first hinge arm  1 ; thereafter, the torsion spring  23  is rotated about the shaft  23   b ′, whereby the torsion shaft  23   a  is brought into engagement in the first cutout groove  25  in the stationary base  8 ; then, the torsion spring  23  is displaced downwards, until the end face of the shaft  23   c ′ at the tip end of the movable arm portion  23   c  abuts against the upper face of the first hinge arm  1 ; whereby the roller  24  can be brought into engagement in the first positioning recess  20   a  in the cam  20  of the second hinge arm  2  with the movable arm portion  23   c  remaining in a non-loaded state. In this way, when the door D is in the fully opened state, the roller  24  can be brought into engagement in the first positioning recess  20   a  in the non-loaded state of the movable arm portion  23   c  Therefore, before and after the automobile painting step, not only the mounting of the torsion spring  23  to the first hinge arm  1  but also the demounting of the torsion spring  23  can be achieved easily, which can contribute to an enhancement in productivity of the automobile. 
   If an attempt is made to turn the door D from the fully opened state in a closing direction after the mounting of the torsion spring  23 , a swinging load is applied to the movable arm portion  23   c  by a reaction generated at the time when the roller  24  of the movable arm portion  23   c  is about to ride on the projection  20   c  of the cam  20 , whereby a repulsion force in a torsional direction is generated in the torsion shaft  23   a . Therefore, the repulsion force causes the movable arm portion  23   c  to be retained in a state of engagement in the first positioning recess  20   a , whereby the door D can be retained in the fully-opened position F. 
   If the door D is turned from the fully opened position F in the closing direction against the repulsion force, the swinging load is applied to the movable arm portion  23   c  by the roller  24  of the movable arm portion  23   c  riding on the projection  20   c  of the cam  20 , and as a result, the repulsion force of the torsion shaft  23   a  attains a maximum value. However, after the riding of the roller  24  of the movable arm portion  23   c  onto the projection  20   c  of the cam  20 , the door D can be turned relatively smoothly by the roller  24  rolling on the projection  20   c . At that time, the guide groove  24   a  around the outer periphery of the roller  25  is brought into engagement with the projection  20   c , and hence the displacement of the roller  24  on the movable arm portion  23   c  can be prevented. 
   When the door D has reached the predetermined slightly opened position S, as shown in  FIG. 3 , the roller  24  of the movable arm portion  23   b  is brought into engagement in the second positioning recess  20   b  of the cam  20  due to the repulsion force of the torsion shaft  23   a , and hence the door D can be retained in the slightly opened position S. An operation similar to the above-described operation is also achieved when the door D is turned from the slightly opened position S toward the fully opened position F. 
   The state of engagement of the roller  24  with the first and second positioning recesses  20   a  and  20   b  can be maintained easily and reliably by the abutment of the end face of the shaft  23   c ′ of the movable arm portion  23   c  against the upper surface of the first hinge arm  1 . 
   In this embodiment, in the fully opened position F and the slightly opened position S of the door D, there is a slight play, until the roller  24  on the movable arm portion  23   b  in the non-loaded state is put into abutment against the projection  20   c  of the cam  20 , and accordingly a slight play exists in the door D in the turning direction. However, the play of this degree is acceptable at the painting step. 
   As described above, a door retention device used in an automobile manufacturing process according to the present invention can be constructed only by mounting the torsion spring  23  using the door hinge H originally required for connection of the door D to the body B. Therefore, such a structure can be provided extremely easily and inexpensively. 
   After the completion of the painting step, the torsion spring  23  is removed from the door hinge H in the fully-opened state of the door D in a manner reverse to the above-described manner, and for example, a door checker C of a sliding type (see  FIG. 1 ) for retaining the door D at a medium opening degree and in the fully opened position is mounted between the body B and the door D. The cam  20  and the first and second cutout groove  25  and  26  are left in the door hinge H with the torsion spring  23  removed therefrom, but they cannot hinder the usual use of the automobile. 
   The present invention is not limited to the above-described embodiment, and various modifications in design may be made within a scope which does not depart from the subject matter of the invention. For example, the first hinge arm  1  may be secured to the door D, and the second hinge arm  2  may be secured to the body B. It is needless to say that the door retention device of the present invention can be used at any step in the automobile manufacturing process other than the painting step.