Abstract:
To be able to firmly fix a seat to a floor when the seat is elevated relative to the floor, a pair of hooks are installed at a hook portion of a base member and the two hooks are made engageable to a pair of strikers on the floor.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a seat supporting apparatus suitable for an automobile seat capable of being freely folded up or erected (or molded down) as well as being attachable and detachable with respect to an automobile floor panel. 
     According to a vehicle such as a van type one, when the number of passengers is large, an auxiliary seat is fixed onto a floor panel of the vehicle and when the number of loaded articles is large, the auxiliary seat is removed to thereby keep the large loading space. As proposed by, for example, Japanese Patent Laid-Open Publication No. 86230/1997 or Japanese Utility Model Laid-Open Publication No. 58453/1993, an attachable and detachable seat of this kind has a basic structure in which a seat supporting member is made attachable to and detachable from a pair of strikers fixed to a floor of a vehicle. Whereas a rear striker is simply attached to and detached from a front hook portion of the seat supporting member, a rear striker is attached to and detached from a ratchet mounted to the seat supporting member and movement of the ratchet is controlled by a pawl. 
     According to the seat supporting apparatus of the above-described conventional examples, whereas when a seat is forwardly tilled or collapsed, the front striker is brought into contact with a U-like groove of the hook portion fixed to a base member and the seat is folded forwardly centering on the point of contact, in erecting the seat, the rear seat is tied to the front seat by using a string or the like to thereby maintain the folded state of the seat. Or, another means for keeping the seat from returning to the original position, newly changing the seat position, moving the gravitational center of the seat forward. 
     Such a means is not favorable for elevating (or collapsing) the seat in a safe state because it cannot firmly prevent the seat from rocking or returning to the original position unexpectedly. 
     SUMMARY OF THE INVENTION 
     Hence, it is the problem of the invention to resolve the disadvantage of the conventional technology, mentioned above. 
     According to the invention, in order to resolve the above-described problem, basically, there is provided means for parallely installing U-like shape and C-like shape hook portions for receiving a pair of strikers at front of the base member and moving a pivot center of the seat from a point of contact between the U-like groove and the first striker to a point of contact between the C-like groove and the second striker in elevating the seat. 
     Specifically, according to an aspect of the invention, there is provided a vehicular seat supporting apparatus having a front hook portion and a rear ratchet capable of freely engaging with a front striker and a rear striker fixed to the floor of a vehicle and suitable for supporting a seat, the seat supporting apparatus comprising a base member supporting the seat and attachable and detachable to and from the rear striker fixed to the floor of the vehicle, the ratchet able to engage with and disengage from the rear striker, and pivoting at the base member&#39;s 2 hook portions in the front having a U-like shape and a C-like shape engageable with and disengageable from a first striker and a second striker in the front, wherein in installing the base member, a center of pivoting the base member is moved from a point of contact between the first striker and the U-like groove to a point of contact between the second striker and the C-like groove. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an embodiment of the invention; 
     FIG. 2 is a sectional view taken along an arrow II—II in FIG. 1; 
     FIG. 3 is a sectional view taken along an arrow III—III in FIG. 1; 
     FIG. 4 is a sectional view showing an example of a pin for supporting parts; 
     FIG. 5 is a side view showing engagement means between a hook portion and a front striker; 
     FIG. 6 is a side view showing the folded-up state of a seat; 
     FIG. 7 is a sectional view taken along an arrow IV—IV in FIG. 5; and 
     FIG. 8 is an enlarged detailed view of the hook portion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown by FIG. 1, in respect of a pair of strikers  2  and  2 ′ separated from each other on a floor  1  of a vehicle, a hook portion  5  on the front side of a member  4  supporting a seat  3  is simply engaged with the striker  2 , further, a ratchet  6  on the rear side is made attachable and detachable to and from the striker  2 ′ and the ratchet  6  and a pawl  7  for operating the ratchet  6  are contained in the central space of the seat supporting member  4 . 
     According to the illustrated embodiment, the seat supporting member  4  is constituted by a lower rail  8  and an upper rail  9  slidable relative to the lower rail  8 . A publicly-known mechanism may be used for locking and unlocking the two rails  8  and  9  and a detailed illustration thereof will be omitted. 
     The upper rail  9  which is made of steel having section substantially in an inverted U-like shape, is slid relative to the lower rail  8  via rollers  10  and balls  11  and in order to lock the two rails  8  and  9 , a lock lever  12 ′ shown by FIG. 3 may be used. 
     In the latched state of FIG. 1, when the pawl  7  is pivoted in the counterclockwise direction against the tension of the spring  13  via a long hole  12  installed to the lower rail  8 , an engaging portion of the pawl  7  is detached from the ratchet  6  and the ratchet  6  can be pivoted without being constrained by the pawl  7 . Under this state, when the seat  3  is folded up around the front striker  2 , the rear striker  2 ′ causes the U-like groove of the ratchet  6  to rotate in the counterclockwise direction, and engagement between the striker  2 ′ and the ratchet  6  is released and an unlatched state is established. Under the unlatched state, the U-like groove is maintained in a downward direction receiving tension of the spring  13 . Therefore, in the latching process in which the ratchet  6  is engaged with the striker  2 ′, the seat  3  is moved down as it is, the striker  2 ′ is pressed to the U-like groove directed downwardly, the ratchet  6  is pivoted in the clockwise direction against the tension of the spring  13  and the engaging portion of the pawl  7  is locked to the ratchet  6  by the tension of the spring  13  to thereby provide the latched state. 
     The lower rail  8  has a structure in which portions each having a section substantially in an inverted L-like shape are separate from and facing outward from each other to thereby constitute a section substantially in a T-like shape. The lower rail  8  is provided with vertical wall portions  14  separate from and opposed to each other. The ratchet  6  and the pawl  7  are arranged in a space between the vertical wall portions  14 . 
     Lower portions of the vertical wall portions  14  are curled to inner sides to thereby produce a circular arc portion  15 . 
     As shown by FIG. 4, a pin  16  attached with the ratchet  6  and the pawl  7  disposed between the vertical wall portions  14  opposed to each other and other parts, is provided with a large diameter portion  17  between the vertical wall portions  14  and stepped difference portions between the large diameter portion  17  and small diameter portions are brought into contact with inner wall faces of the vertical wall portions  14  to thereby maintain the separation between the two vertical wall portions  14 . Both ends of the pin  16  are calked. 
     An explanation will be given of a preferred example of the hook portion  5  constituting a principal portion of the invention referring to FIG.  5  through FIG.  8 . 
     The front striker  2  is provided with a first and a second striker  21  and  22 , and the front edge of the hook portion  5 , comprising a plate, is installed with a U-like groove  23  for receiving the first striker  21  and a C-like groove  24  for receiving the second striker  22 . 
     On one side of the hook portion  5 , a first hook  25 , comprising a plate, is arranged to pivot along with a pin  26  and on the other side of the hook portion  5 , a second hook  27  in a plate shape is arranged to pivot along with a pin  28 . A connecting lever  29  is arranged on a side the same as the side of the second hook  27  and the lever  29  is fixed to the pin  26 . A front end of the lever  29  can freely be brought into contact with the second hook  27  and movement of the second hook  27  is transmitted to the first hook  25 . A latch releasing operational lever  30  is arranged on a side the same as the side of the first hook  25  and one end of the operational lever  30  is fixed to the pin  28 . As a result, movement of the operational lever  30  in the counterclockwise direction pivots the second hook  27  in the counterclockwise direction along with the pin  28  and the movement pivots the first hook  25  and the pin  26  in the clockwise direction via the lever  29 . 
     As shown by FIG. 8, the first and the second hooks  25  and  27  are respectively coupled to end portions of a spring  31 . The central coiled portion of the retaining spring  31  is made to dispose at a constant position. 
     In a state of using the seat  3  shown by FIG. 5, the first striker  21  is fitted into the U-like groove  23 , the rear striker  2 ′ is engaged with the ratchet  6  and the seat  3  is fixed to the floor  1 . 
     When the seat  3  is folded, that is, elevated, engagement between the ratchet  6  and the pawl  7  is released, the rear portion of the seat is lifted, the ratchet  6  is released from the rear striker  2 ′ and the rear portion of the seat is further lifted. 
     In lifting the seat, the seat  3  is pivoted centering on the point of contact between the first striker  21  and the U-like groove  23 , thereafter, the second striker  22  is brought into contact with the C-like groove  24 , thereafter, while shifting the point of contact between the first striker  21  and the U-like groove  23 , the center of pivot of the seat is moved to a point of contact between the second striker  22  and the C-like groove  24  and the seat  3  is pivoted centering on the point of contact. Such a movement of the pivoting center accompanied by slippage, engages the groove of the second hook  27  to the striker  22  and engages the groove of the first hook  25  with the first striker  21  and by pushing down the operational lever  30 , there is produced the latched state shown by FIG.  6 . 
     In order to release the latched state shown by FIG. 6, one end of the operational lever  30  is lifted, the pin  28  and the second hook  27  are pivoted in the counterclockwise direction and engagement between the C-like groove  24  and the second striker  22  is released. Movement of the second hook  27  is transmitted to the first hook  25  via the lever  29 , engagement between the first striker  21  and the first hook  25  is released and the seat  3  can be moved to a horizontal position shown by FIG.  5 . At this occasion, the center of pivoting the seat  3  is moved from the second striker  22  to the first striker  21  and slight slippage of the seat  3  is permitted. 
     As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.