Patent Publication Number: US-2022219582-A1

Title: Device for providing fatigue-reducing position of vehicle seat

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2021-0005015, filed Jan. 14, 2021, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates generally to a device for providing a fatigue-reducing position of a vehicle seat. More particularly, the present disclosure relates to a device for providing a fatigue-reducing position of a vehicle seat, the device enabling a seat in a second or third row to be fixedly placed like a hammock in the cabin of the vehicle to provide a fatigue-reducing position in which an occupant may comfortably rest. 
     Description of the Related Art 
     Generally, a vehicle seat is provided with basic components, such as a seat cushion on which the lower part of the body of an occupant is seated, a seatback against which the upper part of the body of the occupant is leaned, and a headrest supporting the neck and the head of the occupant, as well as a variety of seat adjustment devices and a variety of convenience devices disposed inside and outside the seat. In addition, a seat mechanism enabling the position of the seat to be freely changed according to the body shape of the occupant or the situation is further required. 
     The vehicle seat is basically provided with a reclining device for reclining the seatback backward to allow an occupant to rest or sleep thereon. However, there is a drawback in that it is impossible to uniformly distribute the pressure of the body of the occupant only using the reclining device. Thus, there is a drawback in that a fatigue-reducing position may not be established. For reference, the fatigue-reducing position refers to a position in which the angles of support of the buttocks, the thighs, calves, and the like may be changed when the angle of support of the upper body of an occupant is changed to distribute the pressure of the body of the occupant to the maximum extent, so that the occupant may feel comfortable while the fatigue of the occupant is reduced. 
     Accordingly, for autonomous driving vehicles to be released in the future, a solution enabling an occupant to be in a fatigue-reducing position in the cabin of a vehicle during long distance traveling is required. In addition, the provision of a seat mechanism able to provide a comfortable relaxation position is required to allow a user to rest or sleep in the cabin of a vehicle for vehicle camping or the like. 
     The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art. 
     SUMMARY 
     Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art, and the present disclosure is intended to propose a device for providing a fatigue-reducing position of a vehicle seat. The device enables a seat in a second or third row in the cabin of a vehicle to be detached from the originally-mounted position and be fixedly placed like a hammock between a front seat and a package panel to provide a fatigue-reducing position in which an occupant may comfortably rest. 
     In order to achieve the above objective, according to one aspect of the present disclosure, a device for providing a fatigue-reducing position of a vehicle seat is provided. The device may include: a first striker mounted on a front seatback; a first latch unit mounted on a rear seat cushion such that the first striker is fastened thereto in a lockable manner; a second latch unit mounted on a rear surface portion of a rear seatback; a sliding-locking unit mounted on a package panel disposed behind a rear seat in a height adjustable manner; and a second striker provided on a front end of the sliding-locking unit to be fastened to the second latch unit in a lockable manner. 
     The first latch unit may be mounted on a front end of the rear seat cushion or at a lower position on the front end of the rear seat cushion to fasten the first striker in a lockable manner. The second latch unit may be mounted on a top end side of the rear surface portion of the rear seatback. The first striker may be mounted at a position on an upper surface of the front seatback exposed when the headrest is detached from the front seatback or at a top end position on a rear surface of the front seatback. 
     The first striker of the front seatback may be fastened to the first latch unit of the rear seat cushion and the second striker of the sliding-locking unit mounted on the package panel is fastened to the second latch unit of the rear seatback, to place and fix a rear seat between the front seatback and the package panel. The first striker may have a shape of a quadrangular loop and be mounted to a pivot bracket by welding or the like. The pivot bracket may be hinged or fastened to a fixing bracket fixedly mounted on a top end of a rear surface portion of the front seatback to be pivotable in a top-bottom direction. 
     The first latch unit may include: a control lever mounted on a front end of the rear seat cushion to pivot when manipulated by being pulled; a protrusion that protrudes from an inner surface portion of the control lever to pivot along with the control lever when the control lever is pivoted; a pair of first support brackets mounted at inner positions on the front end of the rear seat cushion; a first locking lever including a first pulling end integrally provided on an upper portion thereof and a locking end integrally provided on a rear portion thereof, the first locking lever being axially disposed on the pair of first support brackets via a first rotary shaft; a push bar connected to the first pulling end of the first locking lever; a second locking lever including a catching end integrally provided on an upper portion thereof, the catching end being configured to be restrained by the locking end of the first locking lever, and a first locking recess provided on a lower portion thereof, the first locking recess being configured to receive the first striker inserted thereinto, wherein the second locking lever is axially disposed on the pair of first support brackets via a second rotary shaft; a vertical bent bar connected to the protrusion and the push bar, wherein the vertical bent bar is rotated and pushes the push bar forward when the control lever and the protrusion rotate; and a first return spring connected to the first rotary shaft and the second rotary shaft. 
     A support plate supporting the vertical bent bar may be provided at a side position behind the control lever. The support plate may have a slot by which an angle of rotation and a distance of the vertical bent bar are defined. 
     The second latch unit may include: a pair of second support brackets mounted on a top end of a rear surface of the rear seatback; a third locking lever including a cable connecting end provided on a top portion thereof, connected to a pulling cable, and configured to be pulled, and a stopper end provided on a lower portion thereon, wherein the third locking lever is axially mounted on the pair of second support brackets via a third rotary shaft; a fourth locking lever including a second pulling end integrally provided on an upper portion thereof and a second locking recess provided on a lower portion thereof and receiving the second striker inserted thereinto, wherein the fourth locking lever is axially mounted on the pair of second support brackets via a fourth rotary shaft; and a second return spring connected to the third locking lever and the second pulling end of the fourth locking lever. 
     The sliding-locking unit may include: a rail pipe mounted on the package panel to be arranged in a top-bottom direction; a slider fitted around an outer surface of the rail pipe to be movable vertically; an elastic clamp having a circular tubular structure with one side thereof being open, the elastic clamp being located between an outer surface of the rail pipe and an inner surface of the slider; a pulling plate integrally provided on one end of the elastic clamp and that extends toward an outer diameter portion of the slider; a stopper integrally provided on an outer surface of the slider to define positions of the pulling plate before and after being pulled; and a manipulation cable connected to the pulling plate and configured to be pulled. 
     A friction plate may be provided on an inner surface of the elastic clamp to be in contact with or detached from the rail pipe. When the manipulation cable is manipulated by being pulled, the elastic clamp may be expanded in an outer diameter direction while being pulled, thus realizing an unlocking operation for releasing the elastic clamp to neither press nor be in friction contact with the rail pipe. 
     When a manipulation of pulling the manipulation cable is stopped, the pulling plate may be moved to an original position while the elastic clamp is contracted in an inner diameter direction by elastic restorative force, so that a locking operation in which the elastic clamp is pressed against and in friction contact with the rail pipe is performed. A placing plate protruding forward may be mounted on the slider, and the second striker may be provided on a front end of the placing plate. 
     According to exemplary embodiments of the present disclosure, the following effects may be provided. 
     First, a seat in a second or third row may be detached from the originally-mounted position and be fixedly placed like a hammock in the cabin of a vehicle to provide a fatigue-reducing position in which an occupant may comfortably rest. 
     Second, a seat in a second or third row may be detached from the originally-mounted position and be fixedly placed like a hammock in the cabin of a vehicle so that the angle of the seat cushion of the detached rear seat and the reclining angle of the seatback of the detached rear seat may be adjusted by moving the sliding-locking unit up and down. Accordingly, a variety of fatigue-reducing positions may be provided as intended by the occupant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objectives, features, and other advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating a first striker of a device for providing a fatigue-reducing position according to the present disclosure, the first striker being mounted on a front seatback; 
         FIG. 2  is a perspective view illustrating a first latch unit of the device for providing a fatigue-reducing position according to the present disclosure, the first latch unit being mounted on a rear seat cushion; 
         FIG. 3  is an enlarged perspective view illustrating portions of the device for providing a fatigue-reducing position according to the present disclosure, in which the first latch unit and the first striker are fastened to each other; 
         FIGS. 4A to 4C  are side views illustrating a process of fastening the first latch unit and the first striker among the components of the device for providing a fatigue-reducing position according to the present disclosure; 
         FIG. 5  is a view illustrating a second latch unit among the components of the device for providing a fatigue-reducing position according to the present disclosure, the second latch unit being disposed on a rear seatback; 
         FIG. 6  is a perspective view illustrating a sliding-locking unit having a second striker among the components of the device for providing a fatigue-reducing position according to the present disclosure, the sliding-locking unit being mounted on a package panel behind the rear seat; 
         FIG. 7  is an enlarged perspective views illustrating the fastening of the second latch unit and the second striker among the components of the device for providing a fatigue-reducing position according to the present disclosure; 
         FIGS. 8A to 8C  are side views illustrating a fastening process of the second latch unit and the second striker among the components of the device for providing a fatigue-reducing position according to the present disclosure; 
         FIGS. 9 and 10  are side views illustrating the rear seat arranged in a fatigue-reducing position by the device for providing a fatigue-reducing position according to the present disclosure; 
         FIG. 11  is a cross-sectional view illustrating a locked position of the sliding-locking unit among the components of the device for providing a fatigue-reducing position according to the present disclosure; and 
         FIG. 12  is a cross-sectional view illustrating an unlocked position of the sliding-locking unit among the components of the device for providing a fatigue-reducing position according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, combustion, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). 
     Although exemplary embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes may also be performed by one or plurality of modules. Additionally, it is understood that the term controller/control unit refers to a hardware device that includes a memory and a processor and is specifically programmed to execute the processes described herein. The memory is configured to store the modules and the processor is specifically configured to execute said modules to perform one or more processes which are described further below. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.” 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
     In the accompanying drawings,  FIG. 1  is a perspective view illustrating a first striker  11  of a device for providing a fatigue-reducing position according to the present disclosure, the first striker  11  being mounted on a front seatback  10 ,  FIG. 2  is a perspective view illustrating a first latch unit  100  of the device for providing a fatigue-reducing position according to the present disclosure, the first latch unit  100  being mounted on a rear seat cushion  20 , and  FIG. 3  is an enlarged perspective view illustrating portions of the device for providing a fatigue-reducing position according to the present disclosure, in which the first latch unit  100  and the first striker  11  are fastened to each other. In  FIG. 3 , a protective cover  130  illustrated in  FIG. 2  is omitted. 
     As illustrated in  FIG. 1 , the first striker  11  may be mounted at a position on the upper surface of the front seatback  10  exposed when the headrest is detached from the front seatback  10  or the top end of the rear surface of the front seatback  10 . Particularly, a fixing bracket  12  is fixedly mounted on the top end of the rear surface of the front seatback  10 . A pivot bracket  13  may be hinged or fastened to the fixing bracket  12  to be pivotable in the top-bottom direction. The first striker  11  has the shape of a quadrangular loop and is mounted to the pivot bracket  13  by welding or the like. Thus, when the first striker  11  is turned while being pushed forward, the first striker  11  may be moved to a non-use position (i.e. a parking position) in which both the first striker  11  and the pivot bracket  13  are brought into close contact with a rear surface portion of the fixing bracket  12 . In contrast, when the first striker  11  is turned while being pulled backward, the first striker  11  is deployed to a use position to be fastened to the first latch unit  100 . 
     As illustrated in  FIGS. 2 and 3 , the first latch unit  100  allowing the first striker  11  mounted on a rear surface portion of the front seatback  10  to be fastened in a lockable manner may be mounted on the front end of the rear seat cushion  20 . Particularly, the first latch unit  100  may be mounted at a lower position on the front end of the rear seat cushion to fasten the first striker  11  in a lockable manner. 
     As one component of the first latch unit  100 , a control lever  101  to be manipulated by a user may be pivotably mounted at a predetermined position on the front end of the rear seat cushion  20 . In addition, a protrusion  102  is integrally provided on the inner surface of the control lever  101  such that the protrusion  102  pivots along with the control lever  101  when the control lever  101  is pivoted. 
     A pair of first support brackets  105  may be mounted at inner positions on the front end of the rear seat cushion  20  such that the first support brackets  105  are spaced apart from each other in the transverse direction. A first locking lever  110  may be rotatably mounted at a front position on the inner surface of each of the first support brackets  105 , and a second locking lever  120  may be rotatably mounted at a rear position on the inner surface of each of the first support brackets  105 . 
     The first locking lever  110  is configured such that a first pulling end  112  is integrally formed and a locking end  113  is integrally formed on the rear portion. The first locking lever  110  may be rotatably mounted at a front position on the inner surface of each of the first support brackets  105  via a first rotary shaft  111 . The second locking lever  120  is configured such that a catching end  122  configured to be restrained by the locking end  113  is integrally formed on the upper portion thereof and a first locking recess  123  configured to receive the first striker  11  inserted thereinto is formed in the lower portion of the second locking lever  120 . Thus, the second locking lever  120  may be rotatably mounted at a rear position on the inner surface of the first support brackets  105  via a second rotary shaft  121 . 
     In particular, a push bar  104  may be connected to the first pulling end  112  of the first locking lever  110 . In addition, a vertical bent bar  103  is connected to the protrusion  102  and the push bar  104 . When the control lever  101  and the protrusion  102  rotate, the vertical bent bar  103  is also rotated and pushes the push bar  104  forward. In addition, as illustrated in  FIGS. 4A to 4C , a first return spring  106  is connected to the first rotary shaft  111  and the second rotary shaft  121 . The first return spring  106  provides elastic restorative force to the first locking lever  110  and the second locking lever  120  so that the first locking lever  110  and the second locking lever  120  rotate and return to the original positions. 
     Particularly, a support plate  107  that supports the vertical bent bar  103  may be formed at a side position behind the control lever  101 . The support plate  107  may include a slot  108  by which the angle of rotation and the distance of the vertical bent bar  103  are defined. Thus, as illustrated in  FIG. 4A , when the control lever  101  is not manipulated, the first locking recess of the second locking lever  120  is arranged in an upwardly-inclined position such that the first striker  11  may not be smoothly inserted into the first locking recess  123 . 
     In contrast, when the control lever  101  is pushed upward by the user, as illustrated in  FIG. 4B , the protrusion  102  and the vertical bent bar  103  rotate downward and, at the same time, the vertical bent bar  103  pushes the push bar  104  forward. Subsequently, the push bar  104  pulls the first pulling end  112  of the first locking lever  110  in the forward direction and, at the same time, the first locking lever  110  rotates in the forward direction about the first rotary shaft  111 . Consequently, the catching end  122  of the second locking lever  120  is unlocked from the locking end  113  of the first locking lever  110 . 
     At the same time, the second locking lever  120  may be rotated downward about the second rotary shaft  121  by elastic restorative force of the first return spring  106 . Consequently, the first locking recess of the second locking lever  120  may be arranged in a forwardly-open position such that the first striker  11  is inserted thereinto. Then, as illustrated in  FIG. 4B , the first striker  11  mounted on the front seatback may be inserted more easily into the first locking recess of the second locking lever  120 . 
     As illustrated in  FIG. 4C , after the first striker  11  is inserted into the first locking recess of the second locking lever  120 , when the user releases the control lever  101 , the first locking recess of the second locking lever  120  is arranged in an upwardly-inclined position. Consequently, the first striker  11  may be in a locked position in which the first striker  11  is not separated from the first locking recess. 
     In the accompanying drawings,  FIG. 5  is a view illustrating a second latch unit  200  among the components of the device for providing a fatigue-reducing position according to the present disclosure, the second latch unit  200  being disposed on a rear seatback  30 ,  FIGS. 6 and 7  are views illustrating a sliding-locking unit having a second striker  62  among the components of the device for providing a fatigue-reducing position according to the present disclosure, the sliding-locking unit being mounted on a package panel  50  behind the rear seat, and  FIGS. 8A to 8C  are side views illustrating a fastening process of the second latch unit  200  and the second striker  62  among the components of the device for providing a fatigue-reducing position according to the present disclosure. 
     As illustrated in  FIGS. 5 and 6 , the second latch unit  200  may be mounted on the top end side of the rear surface portion of the rear seatback  30 , and may fasten the top end of the rear surface of the rear seatback  30  to the package panel  50  disposed behind the rear seat. The second latch unit  200  may include second support brackets  210 , a second return spring  220 , a third locking lever  230 , a fourth locking lever  240 , and the like. 
     In particular, the second support brackets  210  may be mounted at inner positions on the top end of the rear surface of the rear seatback  30 . The third locking lever  230  is configured such that a cable connecting end  232  connected to a pulling cable  231  is formed on the upper portion thereof such that the pulling cable  231  may be pulled and a stopper end  233  configured to stop the rotation of the fourth locking lever  240  in the forward direction is formed on the lower portion thereof. The lower end of the third locking lever  230  is rotatably mounted on the rear end side of the pair of second support brackets  210  via the third rotary shaft  234 . 
     The fourth locking lever  240  is configured such that a first pulling end  241  may be integrally formed on the upper portion thereof and a second locking recess  242  configured to receive the second striker  62  inserted thereinto may be formed in the lower portion thereof. The fourth locking lever  240  may be rotatably mounted on the front end side of the pair of second support brackets  210  via a fourth rotary shaft  243 . In particular, the second return spring  220  may be connected to a middle portion of the third locking lever  230  and the first pulling end  241  of the fourth locking lever  240 . 
     Thus, as illustrated in  FIG. 8A , the second locking recess  242  of the fourth locking lever  240  is usually arranged in a downwardly-open position, i.e. in a position in which the second striker  62  may not be inserted thereinto. In contrast, when a user-manipulatable lever (not shown) connected to the pulling cable  231  is pulled, the pulling cable  231  pulls the cable connecting end  232  of the third locking lever  230 , and thus, the third locking lever  230  may rotate in the forward direction about the third rotary shaft  234 . 
     At the same time, since the third locking lever  230  is connected to the first pulling end  241  of the fourth locking lever  240  via the second return spring  220 , when the third locking lever  230  is rotated, the second return spring  220  may be pulled forward to pull the first pulling end  241  of the fourth locking lever  240  forward. Then, as illustrated in  FIG. 8B , since the fourth locking lever  240  is rotated in the forward direction, the second locking recess  242  is arranged in a backwardly-open position, and thus, the second striker  62  may be inserted thereinto. 
     As illustrated in  FIG. 8C , when the user releases a lever (not shown) connected to the pulling cable  231 , the fourth locking lever  240  may be rotated to the original position by elastic restorative force of the second return spring  220  to arrange the second locking recess  242  in a downwardly-open position. Consequently, the second striker  62  may be locked into the second locking recess  242 . 
     Referring to  FIGS. 6 and 7 , a package panel  50  may be mounted on the rear portion of the rear seat to divide the rear seat from a trunk room, and a sliding-locking unit  60  may be mounted on the package panel  50  in a height-adjustable manner. Particularly, the second striker  62  configured to be inserted into the second locking recess  242  of the fourth locking lever  240  in a lockable manner may be formed on the front end of the sliding-locking unit  60 . 
     As a component of the sliding-locking unit  60 , a rail pipe  61  arranged in the vertical direction may be mounted on a rear surface portion of the package panel  50 . In addition, a slider  63  having the shape of a hollow pipe may be fitted around the outer surface of the rail pipe  61  to allow the hollow pipe to be movable vertically. In particular, the second striker  62  may be mounted on a placing plate  69  mounted on the slider  63  and may protrude forward while being arranged in the transverse direction of the placing plate  69 . 
     As illustrated in  FIGS. 11 and 12 , an elastic clamp  64  may be disposed between the outer surface of the rail pipe  61  and the inner surface of the slider  63 . The elastic clamp  64  may have a circular tubular structure with one side thereof being open. Particularly, a friction plate  67  may be attached to the inner surface of the elastic clamp  64 . The friction plate  67  is configured to be in friction contact with or detached from the outer surface of the rail pipe  61 . 
     In addition, a pulling plate  65  that extends toward the outer diameter portion of the slider  63  may be formed integrally on one end of the elastic clamp  64 . Particularly, an open area is formed in a specific position of the outer diameter portion of the slider  63 . Stoppers  66  respectively having a plate shape are formed on both sides of the open area. The pulling plate  65  may be disposed between the stoppers  66  such that the pulling plate  65  may be pulled. 
     In addition, a first end of a manipulation cable  68  may be connected to the pulling plate  65 , and a second end of the manipulation cable  68  may extend through the stoppers  66  and be connected to the user-manipulatable lever (not shown). Thus, positions of the pulling plate  65  before and after being pulled using the manipulation cable  68  may be defined by the stoppers  66 . Accordingly, when the manipulation cable  68  is manipulated by being pulled, the elastic clamp  64  is expanded in the outer diameter direction while being pulled, so that the friction plate  67  of the elastic clamp  64  is detached from the outer surface of the rail pipe  61 , as illustrated in  FIG. 11 . In other words, the friction plate  67  moves to an unlocked position, in which the friction plate  67  is neither pressing nor in friction contact with the rail pipe  61  any further. 
     As described above, when the unlocking position in which the friction plate  67  is neither pressing nor in friction contact with the rail pipe  61  any further, the slider  63  moves to a height-adjustable position in which the slider  63  is movable vertically along the rail pipe  61 . In contrast, when the pulling manipulation of the manipulation cable  68  is released, as illustrated in  FIG. 12 , the pulling plate  65  may be moved to the original position by elastic restorative force of the elastic clamp  64  and, at the same time, the elastic clamp  64  is contracted in the inner diameter direction, and thus, the friction plate  67  of the elastic clamp  64  may be pressed against and in friction contact with the outer surface of the rail pipe  61 . In other words, the elastic clamp  64  may be locked to the rail pipe  61 . 
     When the rail pipe  61  is locked due to the pressing against and the friction contact with the friction plate  67 , the slider  63  remains in a fixed position instead of moving up or down along the rail pipe  61 . A typical reclining device  40  may be disposed on the lower portion of the rear seatback  30 , i.e. at a lower position on the rear seatback  30  that is a boundary to the rear seat cushion  20 . Since the reclining device  40  is implemented using a known mechanism for adjusting the reclining angle of the rear seatback  30 , a detailed description thereof will be omitted. 
     Hereinafter, an operation flow of the device for providing a fatigue-reducing position according to the present disclosure having the above-described configuration will be described. In the device for providing a fatigue-reducing position according to the present disclosure, the first striker  11  of the front seatback  10  may be fastened to the first latch unit  100  of the rear seat cushion  20  and the second striker  62  of the sliding-locking unit  60  mounted on the package panel  50  may be fastened to the second latch unit  200  of the rear seatback  30 , such that a rear seat may be placed and fixed between the front seatback  10  and the package panel  50 . 
     First, the rear seat may be detached from a floor panel, to which the rear seat has been fitted. Afterwards, the first striker  11  mounted on the top end of the rear surface of the front seatback  10  may be inserted into the first locking recess of the second locking lever  120  of the first latch unit  100  mounted on the front end of the rear seat cushion  20 . In this regard, when the user manipulates and pushes the control lever  101  upward, as illustrated in  FIG. 4B , the protrusion  102  and the vertical bent bar  103  are rotated downward and, at the same time, the vertical bent bar  103  pushes the push bar  104  forward. 
     Subsequently, the push bar  104  pulls the first pulling end  112  of the first locking lever  110  in the forward direction and, at the same time, the first locking lever  110  rotates in the forward direction about the first rotary shaft  111 . Consequently, the catching end  122  of the second locking lever  120  may be unlocked from the locking end  113  of the first locking lever  110 . At the same time, the second locking lever  120  is rotated downward about the second rotary shaft  121  by elastic restorative force of the first return spring  106 . Consequently, the first locking recess of the second locking lever  120  may be arranged in a forwardly-open position such that the first striker  11  is inserted thereinto. 
     Then, as illustrated in  FIG. 4B , the first striker  11  mounted on the front seatback may be inserted, more easily, into the first locking recess of the second locking lever  120 . As illustrated in  FIG. 4C , after the first striker  11  is inserted into the first locking recess of the second locking lever  120 , when the user releases the control lever  101 , the first locking recess of the second locking lever  120  may be arranged in an upwardly-inclined position. Consequently, the first striker  11  may be in a locked position in which the first striker  11  is not separated from the first locking recess. 
     Accordingly, as illustrated in  FIG. 9 , the front end of the rear seat cushion  20  may be connected to the top end of the rear surface of the front seatback  10 . Afterwards, the second striker  62  may be inserted into the second locking recess  242  of the second latch unit  200  mounted on the top end of the rear surface of the rear seatback  30 . In this regard, when the user pulls the lever (not shown) connected to the pulling cable  231 , the pulling cable  231  pulls the cable connecting end  232  of the third locking lever  230 , and thus, the third locking lever  230  may rotate in the forward direction about the third rotary shaft  234 . 
     At the same time, since the third locking lever  230  is connected to the first pulling end  241  of the fourth locking lever  240  via the second return spring  220 , when the third locking lever  230  is rotated, the second return spring  220  is pulled forward to pull the first pulling end  241  of the fourth locking lever  240  forward. Then, as illustrated in  FIG. 8B , since the fourth locking lever  240  is rotated in the forward direction, the second locking recess  242  may be arranged in a backwardly-open position, so that the second striker  62  may be inserted thereinto. 
     Subsequently, when the user releases the lever (not shown) connected to the pulling cable  231  after having inserted the second striker  62  into the second locking recess  242  of the second latch unit  200 , the fourth locking lever  240  may be rotated to the original position by elastic restorative force of the second return spring  220  and thus, the second locking recess  242  may be arranged in a downwardly-open position. Consequently, the second striker  62  may be locked into the second locking recess  242 . 
     As illustrated in  FIG. 9 , the top end of the rear seatback  30  may be connected to the top end of the package panel  50 . In particular, as illustrated in  FIG. 11 , as the friction plate  67  of the elastic clamp  64  remains in pressing (e.g., in a pressing state), while being in friction contact with, the rail pipe  61 , the slider  63  remains fixed instead of moving up or down along the rail pipe  61 . As illustrated in  FIG. 9 , the second striker  62  mounted on the placing plate  69  extending from the slider  63  remains in position without moving. 
     As described above, as the front end of the rear seat cushion  20  is connected to the top end of the rear surface of the front seatback  10  and the top end of the rear seatback  30  is connected to the top end of the package panel  50 , the rear seat cushion  20  and the rear seatback  30  are arranged in the fatigue-reducing position like a hammock such that an occupant may comfortably lie thereon. 
     The fatigue-reducing position may be changed as intended by the user by adjusting the forward and backward movement of the front seat, the tilting angle of the rear seat cushion, the reclining angle of the rear seatback, and the like, as well as by the upward or downward (e.g., vertically) movement of the sliding-locking unit. For example, when the fatigue-reducing position illustrated in  FIG. 9  is changed to the fatigue-reducing position, i.e. when the front seat is moved forward and the rear seatback  30  is further inclined in response to the reclining device  40  being manipulated, as illustrated in  FIG. 10 , the height of the sliding-locking unit  60  is adjusted. 
     In this regard, when the user pulls the manipulation cable  68  by manipulating the lever, the pulling plate  65  connected to the manipulation cable  68  is pulled and, at the same time, the elastic clamp  64  is spread and expanded in the outer diameter direction, the friction plate  67  of the elastic clamp  64  is detached, i.e. unlocked, from the outer surface of the rail pipe  61 , as illustrated in  FIG. 11 . Thus, when the friction plate  67  stops pressing against or being in friction contact with the rail pipe  61 , i.e. the locking may be removed, the slider  63  may move vertically along the rail pipe  61 . In other words, the slider  63  is in a height-adjustable position. 
     Accordingly, since the slider  63  is locked as described above after the slider  63  is moved downward from the position illustrated in  FIG. 9  to the position illustrated in  FIG. 10 , a change to the fatigue-reducing position in which the front seat is moved forward and the rear seatback  30  is more inclined backward by the manipulation of the reclining device  40  may be performed more easily. 
     As set forth above, a seat in a second or third row in the cabin of a vehicle may be detached from the originally-mounted position and be fixedly placed like a hammock between a front seat and the package panel. The tilting angle of the seat cushion of the detached rear seat and the reclining angle of the seatback of the detached rear seat may be adjusted by moving the sliding-locking unit up and down. A variety of fatigue-reducing positions may be provided as intended by the occupant.