Patent Publication Number: US-2021188362-A1

Title: Vehicle seat

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to U.S. Provisional Patent Application No. 62/951,525, filed on Dec. 20, 2019. The contents of the provisional application are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a vehicle seat detachably attached to a floor of a vehicle. 
     BACKGROUND ART 
     Conventionally, there is a vehicle seat detachably attached to a floor of a vehicle. For example, there is a vehicle seat that includes a lock mechanism detachably attached to a striker provided on a floor of a vehicle so as to lock the vehicle seat to the floor (see, JP2006-69499A). 
     In such a conventional vehicle seat, if an object other than the striker abuts against a particular part of the lock mechanism by accident, the lock mechanism may be activated by mistake in a state where the vehicle seat is detached from the floor. 
     SUMMARY OF THE INVENTION 
     In view of such a problem of the prior art, a primary object of the present invention is to provide a vehicle seat that can prevent a lock mechanism from being activated by mistake in a state where the vehicle seat is detached from the floor. 
     To achieve such an object, one embodiment of the present invention provides a vehicle seat ( 1 ) detachably attached to a floor (F) of a vehicle (V), including: a seat body ( 3 ) configured to support an occupant; and a lock mechanism ( 6 ) disposed below the seat body, detachably attached to a first striker (S 1 ) provided on the floor, and including a first lock part ( 34 ) that has a first lock groove ( 35 ) configured to be engaged with the first striker, and a cover ( 23 ) configured to be displaced between an exposing position to expose the first lock groove and a covering position to cover at least a part of the first lock groove. 
     According to this arrangement, by displacing the cover to the covering position, it is possible to prevent an object other than the first striker from abutting against a particular part of the lock mechanism by accident. Therefore, it is possible to prevent the lock mechanism from being activated by mistake in a state where the vehicle seat is detached from the floor. 
     Preferably, the lock mechanism further includes a second lock part ( 38 ) that has a second lock groove ( 39 ) configured to be engaged with a second striker (S 2 ) provided on the floor, a lever ( 25 ) disposed at the second lock part and configured to be displaced between an activated position and an inactivated position, and a connecting member ( 26 ) connecting the cover and the lever, and when the second striker is engaged with the second lock groove, the second striker pushes the lever to displace the lever from the inactivated position to the activated position, and thereby, the lever pulls the cover via the connecting member to displace the cover from the covering position to the exposing position. 
     According to this arrangement, it is possible to displace the cover from the covering position to the exposing position by an attachment operation of the vehicle seat. Therefore, it is possible to more securely prevent the lock mechanism from being activated by mistake in the state where the vehicle seat is detached from the floor. 
     Preferably, the lock mechanism further includes an urging member ( 24 ) configured to urge the cover to the covering position, and when engagement of the first striker with the first lock groove and engagement of the second striker with the second lock groove are released, the cover is displaced from the exposing position to the covering position by an urging force of the urging member. 
     According to this arrangement, it is possible to displace the cover from the exposing position to the covering position by a detachment operation of the vehicle seat. Therefore, it is possible to more securely prevent the lock mechanism from being activated by mistake in the state where the vehicle seat is detached from the floor. 
     Preferably, the cover is configured to rotate between the exposing position and the covering position, and the lever is configured to rotate between the activated position and the inactivated position. 
     According to this arrangement, it is possible to displace the first and levers in small spaces. 
     Preferably, a rotational direction of the cover from the covering position to the exposing position is the same as a rotational direction of the lever from the inactivated position to the activated position. 
     According to this arrangement, it is possible to efficiently transmit rotation from the lever to the cover by a simple action. 
     Preferably, the cover includes a first upper arm ( 44 ) extending upward from a rotational center of the cover, the lever includes a second upper arm ( 48 ) extending upward from a rotational center of the lever, a first end in a longitudinal direction of the connecting member is connected to the first upper arm, and a second end in the longitudinal direction of the connecting member is connected to the second upper arm. 
     According to this arrangement, it is possible to stably activate the first and levers. 
     Preferably, the lever is disposed in front of the cover, and the connecting member is composed of a cable extending in a fore and aft direction. 
     According to this arrangement, it is possible to displace the connecting member in a small space and to make the configuration of the connecting member simple. 
     Preferably, in a state where the lever is disposed in the inactivated position, the lever extends in a direction crossing a direction along which the second striker engages with the second lock groove. 
     According to this arrangement, it is possible to more securely prevent the lock mechanism from being activated by mistake in the state where the vehicle seat is detached from the floor and to more securely displace the lever from the inactivated position to the activated position when the second striker is engaged with the second lock groove. 
     Preferably, the vehicle seat further includes a slide rail ( 4 ) configured to slidably support the seat body, wherein the connecting member is disposed below the slide rail. 
     According to this arrangement, it is possible to protect the connecting member by the slide rail, and thereby to prevent the connecting member from being damaged or deformed by an outside force. 
     Preferably, the vehicle seat further includes: a slide rail ( 4 ) configured to slidably support the seat body; and a rail cover ( 5 ) configured to cover at least a part of the slide rail, wherein the connecting member is disposed inside the rail cover. 
     According to this arrangement, it is possible to protect the connecting member by the rail cover, and thereby to prevent the connecting member from being damaged or deformed by an outside force. 
     Preferably, the cover is formed in a bag shape and configured to cover an entirety of the first lock groove in a state where the cover is disposed in the covering position. 
     According to this arrangement, it is possible to securely prevent the object other than the first striker from abutting against the particular part of the lock mechanism by accident in the state where the cover is disposed in the covering position. 
     Preferably, the cover is formed in a plate shape and configured to cover only a part of the first lock groove in a state where the cover is disposed in the covering position. 
     According to this arrangement, it is possible to make the configuration of the cover simple. 
     Thus, the present invention provides a vehicle seat that can prevent a lock mechanism from being activated by mistake in a state where the vehicle seat is detached from the floor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a right side view of a vehicle seat attached to a floor of a vehicle according to an embodiment of the present invention; 
         FIG. 2  is a right side view of the vehicle seat detached from the floor according to the embodiment of the present invention; 
         FIG. 3A  is a left side view of a rear part of a lock mechanism in a state where a latch member is disposed in a release position; 
         FIG. 3B  is a left side view of the rear part of the lock mechanism in a state where the latch member is disposed in an engagement position; 
         FIG. 4  is a right side view of the vehicle seat in the middle of being attached to the floor according to the embodiment of the present invention; 
         FIG. 5A  is a right side view of a rear part of a lock mechanism in a state where a cover is disposed in an exposing position according to another embodiment of the present invention; and 
         FIG. 5B  is a right side view of the rear part of the lock mechanism in a state where the cover is disposed in a covering position according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     In the following, a vehicle seat  1  according to an embodiment of the present invention will be described with reference to  FIGS. 1 to 4 . Arrows Fr, Re, Up, and Lo, which are appropriately attached to the drawings, indicate the front side, rear side, upper side, and lower side of the vehicle seat  1 , respectively. Directional terms (for example, front, rear, upper, lower, right, and left) will be used based on a viewpoint of an occupant (not shown) sitting on the vehicle seat  1 . 
     (Vehicle Seat  1 ) 
     As shown in  FIGS. 1 and 2 , the vehicle seat  1  is detachably attached to a floor F of a vehicle V such as an automobile. A pair of left and right first strikers S 1  (only the right first striker S 1  is shown in the drawings) and a pair of left and right second strikers S 2  (only the right second striker S 2  is shown in the drawings) are provided on the floor F. Each second striker S 2  is disposed in front of each first striker S 1 . Each of the front and rear strikers S 1 , S 2  has a U-shape. In the drawings, only a half of each of the front and rear strikers S 1 , S 2  are shown. 
     The vehicle seat  1  includes a seat body  3  configured to support the occupant, a pair of left and right slide rails  4  (only the right slide rail  4  is shown in the drawings) configured to slidably support the seat body  3 , a pair of left and right rail covers  5  (only the right rail cover  5  is shown in the drawings) configured to cover a rear part of each slide rail  4 , and a pair of left and right lock mechanisms  6  (only the right lock mechanism  6  is shown in the drawings) disposed below the seat body  3  and detachably attached to each of the front and rear strikers S 1 , S 2 . Hereinafter, the above components of the vehicle seat  1  will be described in order. 
     (Seat Body  3 ) 
     As shown in  FIGS. 1 and 2 , the seat body  3  includes a seat cushion  8  on which the occupant sits and a seat back  9  disposed above the seat cushion  8 . The seat cushion  8  includes a pair of left and right side frames  11  (only the right side frame  11  is shown in the drawings) extending in the fore and aft direction and a pair of front and rear connecting frames (not shown) extending in the lateral direction so as to connect the pair of left and right side frames  11 . The seat back  9  is attached to a rear end of the seat cushion  8  via a pair of left and right hinge members  12  (only the right hinge member  12  is shown in the drawings). The seat back  9  is configured to rotate with respect to the seat cushion  8  between an upright position (see  FIG. 1 ) to extend upward from the rear end of the seat cushion  8  and a folded position (see  FIG. 2 ) to be folded onto the seat cushion  8 . 
     (Slide Rails  4 ) 
     As shown in  FIGS. 1 and 2 , each slide rail  4  is disposed right below each side frame  11  of the seat cushion  8  and extends in the fore and aft direction. Each slide rail  4  includes an upper rail  14  and a lower rail  15 . The upper rail  14  is fixed to a lower end of each side frame  11  of the seat cushion  8 . The lower rail  15  supports the upper rail  14  such that the upper rail  14  is slidable in the fore and aft direction. 
     (Rail Covers  5 ) 
     As shown in  FIGS. 1 and 2 , each rail cover  5  extends in the fore and aft direction. Each rail cover  5  includes an upper plate  17  disposed horizontally and a side plate  18  extending downward from an outside end in the lateral direction of the upper plate  17 . The upper plate  17  is interposed between each side frame  11  of the seat cushion  8  and the upper rail  14  of each slide rail  4 . The side plate  18  covers the rear part of each slide rail  4  from outside in the lateral direction. 
     (Lock Mechanisms  6 ) 
     As shown in  FIGS. 1, 2, 3A and 3B , each lock mechanism  6  includes a base member  21  extending in the fore and aft direction, an elastic member  22  attached to a rear part of the base member  21 , a cover  23  rotatably attached to the rear part of the base member  21 , an urging member  24  interposed between the base member  21  and the cover  23 , a lever  25  rotatably attached to a front part of the base member  21 , a connecting member  26  connecting the cover  23  and the lever  25 , a latch member  27  and a lock member  28  rotatably attached to the rear part of the base member  21 , and a spring member  29  interposed between the latch member  27  and the lock member  28 . 
     As shown in  FIGS. 1 and 2 , the base member  21  of each lock mechanism  6  is disposed right below each slide rail  4 . The base member  21  includes an inner plate  31  extending in the fore and aft direction and an outer plate  32  attached to a rear part of the inner plate  31  from outside in the lateral direction. An upper end of the inner plate  31  is attached to a lower end of the lower rail  15  of each slide rail  4 . An upper end of the outer plate  32  is engaged with a lower end of the side plate  18  of each rail cover  5 . 
     In a rear part of the base member  21 , a first lock part  34  is formed by both of the inner plate  31  and the outer plate  32 . The first lock part  34  has a first lock groove  35  configured to be engaged with each first striker S 1 . The first lock groove  35  extends vertically and is opened downward. The first lock part  34  is provided with a stopper  36  disposed at a front edge of the first lock groove  35 . In a front part of the base member  21 , a second lock part  38  is formed by the inner plate  31 . The second lock part  38  has a second lock groove  39  configured to be engaged with each second striker S 2 . Arrows X shown in  FIGS. 1, 2, and 4  show a direction (hereinafter referred to as “engagement direction X”) along which each second striker S 2  is engaged with the second lock groove  39 . The second lock groove  39  extends horizontally and opened forward. That is, the first and second lock grooves  35 ,  39  are opened to different directions. 
     As shown in  FIGS. 1 and 2 , the elastic member  22  of each lock mechanism  6  is attached to an outer face of the base member  21  by an attachment plate  41 . The elastic member  22  is made of rubber or elastomer, for example. The elastic member  22  is configured to cover an upper part of the first lock groove  35  from outside in the lateral direction. 
     The cover  23  of each lock mechanism  6  is made of steel and formed in a plate shape, for example. The cover  23  is disposed at the first lock part  34 . The cover  23  is attached to the outer face of the base member  21  via a first rotation axis  43  so as to rotate around the first rotation axis  43 . The cover  23  includes a first upper arm  44  extending upward from the first rotation axis  43  (namely, the rotational center of the cover  23 ) and a first lower arm  45  extending downward from the first rotation axis  43 . The cover  23  is configured to rotate between an exposing position (see  FIG. 1 ) to expose the entirety of the first lock groove  35  and a covering position (see  FIG. 2 ) to cover a lower part of the first lock groove  35  by the first lower arm  45  from outside in the lateral direction. In a state where the cover  23  is disposed in the covering position, the first lower arm  45  abuts against the stopper  36 . 
     The urging member  24  of each lock mechanism  6  is composed of a coil spring, for example. A first axial end of the urging member  24  is attached to the base member  21  and a second axial end of the urging member  24  is attached to the first upper arm  44  of the cover  23 . The urging member  24  is configured to urge the cover  23  to the covering position (see  FIG. 2 ). 
     The lever  25  of each lock mechanism  6  is made of steel and formed in a plate shape, for example. The lever  25  is disposed at the second lock part  38 . The lever  25  is attached to the outer face of the base member  21  via a second rotation axis  47  so as to rotate around the second rotation axis  47 . The lever  25  includes a second upper arm  48  extending upward from the second rotation axis  47  (namely, the rotational center of the lever  25 ) and a second lower arm  49  extending downward from the second rotation axis  47 . The lever  25  is configured to rotate between an activated position (see  FIG. 1 ) to expose the entirety of the second lock groove  39  and an inactivated position (see  FIG. 2 ) to cover a center part of the second lock groove  39  by the second lower arm  49  from outside in the lateral direction. In a state where the lever  25  is in the inactivated position, the lever  25  extends in a direction crossing the engagement direction X. 
     The connecting member  26  of each lock mechanism  6  is composed of a cable, for example. The connecting member  26  extends in the fore and aft direction along the outer face of the base member  21 . The connecting member  26  is disposed below each slide rail  4 . A rear end (a first end in the longitudinal direction) of the connecting member  26  is connected to the first upper arm  44  of the cover  23  via a first attachment  51 . A front end (a second end in the longitudinal direction) of the connecting member  26  is connected to the second upper arm  48  of the lever  25  via a second attachment  52 . A center part in the longitudinal direction of the connecting member  26  is inserted into a tube  53  extending in the fore and aft direction. 
     As shown in  FIGS. 3A and 3B , the latch member  27  of each lock mechanism  6  is attached to an inner face of the base member  21  via the first rotation axis  43  so as to rotate around the first rotation axis  43 . A latch groove  55  is provided on a front face of the latch member  27 . The latch member  27  is configured to rotate between a release position (see  FIG. 3A ) to release the engagement of the latch groove  55  with each first striker S 1  and an engagement position (see  FIG. 3B ) to engage the latch groove  55  with each first striker S 1 . The latch groove  55  extends in the fore and aft direction and opened forward, in a state where the latch member  27  is disposed in the engagement position. An abutting face  56  is provided on the rear face of the latch member  27  so as to be adjacent to the latch groove  55 . A recess  57  is provided on the rear face of the latch member  27  so as to be adjacent to the abutting face  56 . 
     The lock member  28  of each lock mechanism  6  is attached to the inner face of the base member  21  via a third rotation axis  59  so as to rotate around the third rotation axis  59 . A protrusion  60  is provided on a rear face of the lock member  28  so as to be engaged with the recess  57  of the latch member  27 . The lock member  28  is connected to an operation member (not shown) such as a lever or a button via a wire cable  61 . 
     The spring member  29  of each lock mechanism  6  is composed of a coil spring, for example. The spring member  29  urges the latch member  27  to the release position (see  FIG. 3A ). 
     (Attachment/Detachment Operation of Vehicle Seat  1 ) 
     In the following, attachment/detachment operation of the vehicle seat  1  will be described in detail. Incidentally, the actions of the pair of left and right lock mechanisms  6  during the attachment/detachment operation of the vehicle seat  1  are similar to each other. Hereinafter, the action of only one lock mechanism  6  will be described. 
     As shown in  FIG. 2 , in a state where the vehicle seat  1  is detached from the floor F, the cover  23  is disposed in the covering position by an urging force of the urging member  24 . Thereby, the cover  23  covers the lower part of the first lock groove  35  to prevent the first striker S 1  from abutting against the abutting face  56  of the latch member  27  (i.e. to prevent the lock mechanism  6  from being activated). Also, in the state where the vehicle seat  1  is detached from the floor F, the lever  25  is disposed in the inactivated position. Also, in the state where the vehicle seat  1  is detached from the floor F, the seat back  9  is disposed in the folded position. Also, in the state where the vehicle seat  1  is detached from the floor F, the latch member  27  is disposed in the release position (see  FIG. 3A ) by an urging force of the spring member  29 . 
     When a worker such as an occupant performs the attachment operation of the vehicle seat  1 , as shown in  FIG. 4 , the worker first engages the second striker S 2  with the second lock groove  39  along the engagement direction X. When the second striker S 2  is engaged with the second lock groove  39  in this way, the second striker S 2  pushes the lever  25  to rotate the lever  25  from the inactivated position to the activated position. Thereby, the lever  25  pulls the cover  23  via the connecting member  26 , and the cover  23  rotates from the covering position to the exposing position against the urging force of the urging member  24  to allow the first striker S 1  to abut against the abutting face  56  of the latch member  27  (i.e. to allow the lock mechanism  6  to be activated). Incidentally, a rotational direction of the cover  23  from the covering position to the exposing position is the same as a rotational direction of the lever  25  from the inactivated position to the activated position (see dotted arrows in  FIG. 4 ). 
     Next, the worker lowers the rear part of the vehicle seat  1 . Thereby, as shown in  FIG. 3A , the first striker S 1  is engaged with the first lock groove  35  and abuts against the abutting face  56  of the latch member  27 . When the worker further lowers the rear part of the vehicle seat  1 , as shown in  FIG. 3B , the first striker S 1  pushes the latch member  27  to rotate the latch member  27  from the release position to the engagement position against the urging force of the spring member  29 . Thereby, the recess  57  of the latch member  27  is engaged with the protrusion  60  of the lock member  28  to hold the latch member  27  in the engagement position. In this way, the lock mechanism  6  is activated. 
     Next, as shown in  FIG. 1 , the worker rotates the seat back  9  from the folded position to the upright position. Thereby, the attachment operation of the vehicle seat  1  to the floor F is completed. 
     When the worker performs the detachment operation of the vehicle seat  1 , the worker first rotates the seat back  9  from the upright position to the folded position. 
     Next, the worker operates the operation member (not shown) connected to the lock member  28  via the wire cable  61 . When the operation member is operated in this way, the operation member pulls the lock member  28  via the wire cable  61 . Thereby, as shown in  FIG. 3A , the engagement of the recess  57  of the latch member  27  with the protrusion  60  of the lock member  28  is released to rotate the latch member  27  from the engagement position to the release position by the urging force of the spring member  29 . In this way, the lock mechanism  6  stops being activated. 
     Next, as shown in  FIG. 4 , the worker raises the rear part of the vehicle seat  1 . Thereby, the engagement of the first striker S 1  with the first lock groove  35  is released. 
     Next, as shown in  FIG. 2 , the worker releases the engagement of the second striker S 2  with the second lock groove  39 . Thereby, the second striker S 2  stops pushing the lever  25 , and the lever  25  stops pulling the cover  23  via the connecting member  26 . Thereby, the cover  23  rotates from the exposing position to the covering position by the urging force of the urging member  24  to prevent the first striker S 1  from abutting against the abutting face  56  of the latch member  27  (i.e. to prevent the lock mechanism  6  from being activated). Also, when the cover  23  rotates from the exposing position to the covering position as described above, the cover  23  pulls the lever  25  via the connecting member  26  to rotate the lever  25  from the activated position to the inactivated position. Thereby, the detachment operation of the vehicle seat  1  is completed. 
     (Effect) 
     In the present embodiment, the cover  23  is configured to rotate between the exposing position to expose the first lock groove  35  and the covering position to cover the lower part of the first lock groove  35 . Accordingly, by rotating the cover  23  to the covering position, it is possible to prevent an object other than the first striker S 1  from abutting against the abutting face  56  of the latch member  27  by accident. Therefore, it is possible to prevent the lock mechanism  6  from being activated by mistake in the state where the vehicle seat  1  is detached from the floor F. Thereby, it is possible to prevent a situation where the first striker S 1  abuts against the latch member  27  that has already rotated from the release position to the engagement position when the vehicle seat  1  is attached to the floor F. Also, it is possible to protect the first lock groove  35  by the cover  23  and thereby to prevent the first lock groove  35  from being damaged or broken. 
     Also, the first striker S 1  cannot be appropriately engaged with the first lock groove  35  unless the second striker S 2  is engaged with the second lock groove  39 . Thereby, it is possible to urge the worker to engage the first striker S 1  to the first lock groove  35  after engaging the second striker S 2  to the second lock groove  39 . That is, it is possible to urge the worker to attach the vehicle seat  1  to the floor F with a correct procedure. 
     Also, when the second striker S 2  is engaged with the second lock groove  39 , the second striker S 2  pushes the lever  25  to rotate the lever  25  from the inactivated position to the activated position, and thereby, the lever  25  pulls the cover  23  via the connecting member  26  to rotate the cover  23  from the covering position to the exposing position. Accordingly, it is possible to displace the cover  23  from the covering position to the exposing position by the attachment operation of the vehicle seat  1 . Therefore, it is possible to more securely prevent the lock mechanism  6  from being activated by mistake in the state where the vehicle seat  1  is detached from the floor F. 
     Also, when the engagement of the first striker S 1  with the first lock groove  35  and the engagement of the second striker S 2  with the second lock groove  39  are released, the cover  23  rotates from the exposing position to the covering position by the urging force of the urging member  24 . Accordingly, it is possible to rotate the cover  23  from the exposing position to the covering position by the detachment operation of the vehicle seat  1 . Therefore, it is possible to more securely prevent the lock mechanism  6  from being activated by mistake in the state where the vehicle seat  1  is detached from the floor F. 
     Also, the connecting member  26  is disposed below each slide rail  4 . Accordingly, it is possible to protect the connecting member  26  by each slide rail  4 , and thereby to prevent the connecting member  26  from being damaged or deformed by an outside force. 
     Also, the cover  23  is formed in a plate shape and configured to cover only a part of the first lock groove  35  in the state where the cover  23  is disposed in the covering position. Accordingly, it is possible to make the configuration of the cover  23  simple. 
     (Modification) 
     In the present embodiment, the connecting member  26  is disposed below each slide rail  4 . In another embodiment, as shown in  FIGS. 5A and 5B , the connecting member  26  may be disposed inside each rail cover  5 . According to this arrangement, it is possible to protect the connecting member  26  by each rail cover  5 , and thereby to prevent the connecting member  26  from being damaged or deformed by an outside force. 
     In the present embodiment, the cover  23  is formed in a plate shape and configured to cover only a part of the first lock groove  35  in the state where the cover  23  is disposed in the covering position. In another embodiment, as shown in  FIGS. 5A and 5B , the cover  23  may be formed in a bag shape and configured to expose the entirety of the first lock groove  35  in a state where the cover  23  is disposed in the exposing position (see  FIG. 5A ) and to cover an entirety of the first lock groove  35  in a state where the cover  23  is disposed in the covering position (see  FIG. 5B ). According to this arrangement, it is possible to securely prevent the object other than the first striker S 1  from abutting against the abutting face  56  of the latch member  27  in the state where the cover  23  is disposed in the covering position. 
     In the present embodiment, the connecting member  26  is composed of a cable. In another embodiment, the connecting member  26  may be composed of a member other than a cable (for, example, the connecting member  26  may be composed of a bent wire made of steel or a rod). In this case, the lever  25  may push the cover  23  via the connecting member  26  to displace the cover  23  from the covering position to the exposing position. 
     In the present embodiment, the first and levers  23 ,  25  rotate. In another embodiment, the first and levers  23 ,  25  may slide in the fore and aft direction. 
     In the present embodiment, the cover  23  exposes the entirety of the first lock groove  35  in the state where the cover  23  is disposed in the exposing position (see  FIG. 1 ). In another embodiment, the cover  23  may not expose the entirety of the first lock groove  35  in the state where the cover  23  is disposed in the exposing position. For example, the cover  23  may expose most of the first lock groove  35  in the state where the cover  23  is disposed in the exposing position. 
     Concrete embodiments of the present invention have been described in the foregoing, but the present invention should not be limited by the foregoing embodiments and various modifications and alterations are possible within the scope of the present invention.