Abstract:
A simply structured and inexpensive seat slide apparatus, which, in an ordinary front/rear position adjustment of a seat, allows a passenger to operate manually without using a power drive unit; and in walk-in operation only, enables the seat to slide swiftly using the power drive unit.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present invention claims priority under 35 U.S.C. §119 to Japanese Application No. 2005-016595 filed Jan. 25, 2005, which is incorporated herein by reference.  
       FIELD OF INVENTION  
       [0002]     The present invention relates to a seat slide apparatus having a lower rail member firmly fixed to a floor face of a vehicle and an upper rail member mounted with a seat cushion, which is capable of adjusting the position of a seat for the vehicle forward and backward, in particular to a seat slide apparatus arranged so that the upper rail member and the lower rail member are connected to each other via a traction member such as a wire, and by pulling the traction member with a power unit, the upper rail member can be slid on the lower rail member.  
       BACKGROUND  
       [0003]     In one-box type vehicles represented by “minivan” or “cab wagon”, many types of vehicles are equipped with three row seats in the interior. With respect to a seat disposed in the third row, (referred to as “third row seat”), generally passengers get on and off using a rear door. However, when passengers get on the third row seats, the seat disposed immediately before these seats (referred to as “second row seat”) obstructs the path for getting on and off. Therefore, the second row seat is provided with a “walk-in function” for allowing the second row seat to slide (move) forward (or backward).  
         [0004]     As for the “walk-in function”, as disclosed in Japanese Patent Application Laid-Open No. H 06-328973 and Japanese Patent Application Laid-Open No. H 08-126541, conventionally there are well-known arts such that the walk-in function is activated by an operation at the driver&#39;s seat or inclination of a seat back, forward/backward movement of the seat and the like are carried out by means of an electrical control.  
         [0005]     Also, vehicles such as minivan are in a trend such that a variety of seat arrangements are required to respond various mode of use and purpose of users. The followings are typical examples of seat arrangements; i.e., space of cargo room is increased by largely moving the second and third row seat forward and backward respectively; or the second row seat and the third row seats are brought closer to each other and the seat back of the second row seat is inclined forward; thereby, the back face of the second row seat is used as a table and the like.  
         [0006]     In order to achieve various seat arrangements as described above, in many cases, a “long rail” is employed to install the second row seat and the like to the vehicle floor face. Here, the wording “long rail” ordinary means the lower rail in the seat slide apparatus. However, the wording “long rail” sometimes used to indicate the seat slide apparatus itself equipped with a lower rail, which is further longer than the lower rail of a seat slide apparatus used for driver&#39;s seat (passenger seat).  
         [0007]     Since the long rail has a wide movable range, when a passenger slides the seat on the long rail in a wide range by hand (manual operation), the passenger suffers a workload. Accordingly, an arrangement such that a power drive unit is used for the long rail (power seat system) is appropriately employed.  
         [0008]     As for the power seat system, “an arrangement of a combination of a lead screw and a nut”, “an arrangement of combination of a rack and a pinion” or the like, which have been conventionally provided to a seat slide apparatus of an ordinary length, may be employ.  
         [0009]     However, as it reads, since the long rail is structured using a long member, a deflection and/or a deformation are easily generated particularly in the longitudinal direction. Therefore, it is difficult to fit the “lead screw &amp; nut” or “rack &amp; pinion” in full length of the long rail with high precision. Also, in the case where a system of the “lead screw &amp; nut” or the “rack &amp; pinion” is employed and when the driving speed is increased, large noises and vibrations maybe generated resulting in an uncomfortable feeling to the passengers.  
         [0010]     As a solution of the above problems, Japanese Patent Application Laid-Open No. 2004-243811 discloses “a structure for sliding an upper rail member by winding traction member such as a wire.” In this technique, even when a small deflection or deformation is included in a lower rail, the traction member pulls an upper rail member along the deflection/deformation. Therefore, the upper rail member can be slid reliably and satisfactory silence is also achieved. In this point, this technique is a superior technique.  
         [0011]     However, there resides a problem in the technique disclosed in the Japanese Patent Application Laid-Open No. 2004-243811 such that, irrespective of the situation whether the seat is in a walk-in operation or in an ordinary front/rear position adjustment, the upper rail member has to has a constitution to be always slid (moved) at a constant speed. That is, to carry out the ordinary front/rear position adjustment of the seat, since the seat has to be locked (prevention of sliding) at a short pitch (distance) of 20-30 mm, the sliding speed of the upper rail member has to be set to a relatively slow speed. When the walk-in function is activated and the seat is made to slide a long distance under such speed setting, the sliding movement is felt to be too slow.  
         [0012]     Considering the situation where the walk-in function is activated, when the second row seat is caused to slide forward swiftly, the passengers can get into the interior quickly. Therefore, when the walk-in operation is used, the seat has to be made to slide at a fast speed. Particularly, in a rainy situation when a passenger with no umbrella activates the walk-in function to get on the third row seat, it is strongly required for the seat to be slid (moved) at a high speed.  
         [0013]     In the technique disclosed in Japanese Patent Application Laid-Open No. 2004-243811 also, the sliding speed of the seat under the walk-in operation can be increased by electrically controlling the sliding movement. In this case, there arises such a problem that various control devices are additionally required resulting in an increase of manufacturing process and cost. Further, there arises such a problem that the risk of trouble is increased due to the complicated apparatus itself.  
         [0014]     Further, in the technique disclosed in the Japanese Patent Application Laid-Open No. 2004-243811, there resides such a problem that, irrespective of the situation whether the seat is in a walk-in operation or in an ordinary front/rear position adjustment, the seat has to have a constitution to be always slid by a driving force (motor). Generally, it is the second row seat located in the vicinity of the rear door that has to be given with the walk-in function. In many cases, the second row seat is designed for three passengers. That is, to fine adjust the front/rear position of the seat, even in a state when three passengers sit on the seat and the entire weigh is applied to the seat, the seat has to be slid forward/backward by driving a motor and winding a wire cable. To this end, a large diameter (high strength) wire cable has to be wound with a motor of a high output capacity. This inevitably leads to such a problem that the weight and cost of the apparatus itself is increased.  
         [0015]     Furthermore, in the case where the seat is made to slide using a power drive unit in a state passengers sit on the seat, there resides such a problem to the sliding speed of the seat has to be controlled to a low speed in order to ensure the safety of the passenger and to obtain a satisfactory torque of the motor.  
         [0016]     The present invention has been proposed at least in view of the above-described problems. The inventor found the fact that, by combining a manual seat system and a power seat system, and when passengers sit on the seat, the seat is made to slide in a manner of a manual operation by a passenger; and only when no passenger sits on the seat, the seat is made to slide by a power drive unit; thereby a swift walk-in operation can be achieved.  
         [0000]     Patent Document 1  
         [0017]     Japanese Patent Application Laid-Open No. H 06-328973  
         [0000]     Patent Document 2  
         [0018]     Japanese Patent Application Laid-Open No. H 08-126541  
         [0000]     Patent Document 3  
         [0019]     Japanese Patent Application Laid-Open No. 2004-243811  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0020]     An embodiment of the present invention provides a inexpensive seat slide apparatus having a simple structure, which is capable of being operated manually by a passenger without using a power drive unit when carrying out an ordinary front/rear position adjustment of the seat; and only when carrying out the walk-in operation, a swift sliding of the seat can be obtained by using the power drive unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:  
         [0022]      FIG. 1  is a perspective view of a seat slide apparatus  100  in accordance with an embodiment of the present invention.  
         [0023]      FIG. 2  is a side view of the seat slide apparatus  100  shown in  FIG. 1 .  
         [0024]      FIG. 3  is a cross sectional view of the seat slide apparatus  100  taken along the line A-A shown in  FIG. 2 .  
         [0025]      FIG. 4  is a partial plane view of the seat slide apparatus  100  shown in  FIG. 2 .  
         [0026]      FIG. 5  is a side view of an upper rail member  10  in the seat slide apparatus  100  shown in  FIG. 1 .  
         [0027]      FIG. 6  is a side view of the upper rail member  10  shown in  FIG. 5  viewed from the other side.  
         [0028]      FIG. 7  is a perspective view of a power drive unit constituted of a rotation dram  60 , a motor  70  and a clutch  80 , which is included in the seat slide apparatus  100  shown in  FIG. 1 .  
         [0029]      FIG. 8  is a cross sectional view of the power drive unit shown in  FIG. 7  taken along the line B-B.  
         [0030]      FIG. 9  is a block diagram showing forward walk-in operation of the seat slide apparatus  100  in accordance with the present invention.  
         [0031]      FIG. 10  is a block diagram showing backward walk-in operation of the seat slide apparatus  100  in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0032]     First, a seat slide apparatus  100  includes an upper rail member  10  capable of mounting a seat cushion; a lower rail member  20  capable of being firmly fixed to a floor face of a vehicle; a locking unit  30  disposed to the upper rail member  10  for locking and unlocking relative movement of the upper rail member  10  with respect to the lower rail member  20 ; an operation lever  90  connected to the locking unit  30  capable of being manually operated to lock and unlock the locking unit  30  by a passenger; a unlocking device  40  connected to the locking unit  30  for locking and unlocking the locking unit  30  using a power; a traction member  50  for pulling the upper rail member  10 , of which both ends are connected to the front and the rear ends of the lower rail member  20 ; a rotation drum  60  disposed on the rear side of the upper rail member  10  or seat cushion for winding the traction member  50 ; a motor  70  connected to a rotation drum  60  for rotating the rotation drum  60 ; clutch  80  for transmitting driving force of the motor  70  to the rotation drum  60 ; a first switch SW 1  disposed on the surface of an interior wall for activating the unlocking device  40 , the motor  70  and the clutch  80 ; and a second switch SW 2  disposed in a front area of the lower rail member  20  for inactivating the unlocking device  40 , the motor  70  and the clutch  80  after the upper rail member  10  has been slid forward.  
         [0033]     A seat slide apparatus  100  may also comprise an upper rail member  10  capable of mounting a seat cushion; a lower rail member  20  capable of being firmly fixed to a floor face of a vehicle; a locking unit  30  disposed to the upper rail member  10  for locking and unlocking relative movement of the upper rail member  10  with respect to the lower rail member  20 ; an operation lever  90  connected to the locking unit  30  capable of being manually operated to lock and unlock the locking unit  30  by a passenger; a unlocking device  40  connected to the locking unit  30  for locking and unlocking the locking unit  30  using a power; a traction member  50  for pulling the upper rail member  10 , of which both ends are connected to the front and the rear ends of the upper rail member  10 ; a rotation drum  60  disposed on the lower rail member  20  or vehicle floor face for winding the traction member  50 ; a motor  70  connected to a rotation drum  60  for rotating the rotation drum  60 ; a clutch  80  for transmitting driving force of the motor  70  to the rotation drum  60 ; a first switch SW 1  disposed on the surface of an interior wall for activating the unlocking device  40 , the motor  70  and the clutch  80 ; and a second switch SW 2  disposed in a front area of the lower rail member  20  for inactivating the unlocking device  40 , the motor  70  and the clutch  80  after the upper rail member  10  has been slid forward.  
         [0034]     Further, the invention in accordance with claim  3  is the seat slide apparatus  100  according to claim  1  or  2 , further comprising a third switch SW 3  disposed in substantially central area of the lower rail member  20  for inactivating the unlocking device  40 , the motor  70  and the clutch  80  after the upper rail member  10  has been slid backward.  
         [0035]     Owing to the above-described arrangement, the following effects are obtained.  
         [0036]     When the first switch SW 1  disposed on the interior wall surface is turned ON, the unlocking unit  40 , the motor  70  and the clutch  80  are activated. When the unlocking unit  40  is activated, the prevention against the relative movement of the upper rail members  10  with respect to the lower rail members  20  by the locking unit  30  is released and the motor  70  and the clutch  80  are activated. The driving force of the motor  70  is transmitted to the rotation dram  60 , and the rotation dram  60  winds the traction member  50 ; thus the upper rail members  10  are slid (moved) forward. When the upper rail member  10  reaches the second switch SW 2  and comes into contact therewith and the second switch SW 2  is turned ON, the unlocking unit  40 , the motor  70  and the clutch  80  are inactivated; thus, the relative movement of the upper rail members  10  with respect to the lower rail members  20  is locked with the locking unit  30 .  
         [0037]     That is, it is possible for a passenger not only to complete the walk-in operation only by operating the first switch SW 1  to turn ON but also to make the upper rail members  10  to slide forward/backward by manually operating the handle lever  90 .  
         [0038]     Ordinarily, when the walk-in is activated, since the seat is made to slide at a high speed, no passenger sits on the seat, the traction member  50  wound by the rotation dram  60  and the motor  70  for rotating the rotation dram  60  do not have to support the weigh of passengers. Therefore, the traction member  50  is not required to be highly strong nor the motor  70  is not required for a large output. Therefore, the weight and cost for the seat slide apparatus  100  itself can be reduced.  
         [0039]     Furthermore, when the third switch SW 3  for inactivating the unlocking unit  40 , the motor  70  and the clutch  80  are provided in the substantially central portion of the lower rail member  20 , by rotating the motor  70  in reverse, the upper rail members  10  is made to slide (move) backward. When the upper rail member  10  comes into contact with the third switch SW 3  and the third switch SW 3  is turned ON, the unlocking unit  40 , the motor  70  and the clutch  80  are inactivated, the relative movement of the upper rail members  10  with respect to the lower rail members  20  is locked by the locking unit  30 .  
         [0040]     A seat slide apparatus  100  will be described below with reference to an embodiment thereof.  
         [0041]     The seat slide apparatus  100  in accordance with the embodiment is used mainly when a second row seat is installed in a vehicle such as a minivan. As shown in  FIG. 1 , the seat slide apparatus  100  has an upper rail member  10 , a lower rail member  20 , a locking unit  30 , an unlocking unit  40 , a traction member  50 , a rotation dram  60 , a motor  70 , a clutch  80  and the like. Each component element will be described below.  
         [0042]     The upper rail member  10  is disposed at the right and left sides of a seat for a vehicle to allow a seat cushion to be mounted thereon. If the upper rail member  10  is capable of mounting a seat cushion, any upper rail member having any shape or structure may be employed. In this embodiment, as shown in FIGS.  1  to  6 , a steel plate is formed into a substantially right and left symmetrical shape by means of press; and these rails are disposed in positions opposite to each other.  
         [0043]     In this embodiment, in the upper rail member  10 , two cylindrical wire-insertion ports  13  are provided being aligned in the front-rear direction extending upward from a cut formed in the upper face of the upper rail member  10 . The wire-insertion ports  13  are used as ports for inserting inner wires  51  from a rotation dram  60 , which will be described later. Also, below the wire-insertion ports  13 , guide portions  14  are provided communicating with each other. The guide portions  14  are for guiding the inner wires  51  inserted from the wire-insertion ports  13  to the inside of the lower rail member  20  and for changing the direction of the inner wires  51  in a gentle arc shape toward the end portion of the lower rail member  20 . The guide portions  14  are formed in a groove-like shape, and at least for the sliding surface of the groove in which the wire slides, a material such as a resin of a small resistance is preferably employed.  
         [0044]     As shown in  FIG. 1 , in this embodiment, between a pair of upper rail members  10 , a mount plate  11  of a plate-like member is provided for mounting the rotation dram  60 , the motor  70 , the clutch  80  and the like. The dimensions of the width of the mount plate  11  are arbitrarily determined in accordance with the distance between the lower rail members  20 , which will be described later.  
         [0045]     As shown in  FIGS. 2, 3 ,  5  or  6 , on the lower portion of the upper rail member  10 , rollers  12  are pivoted. Owing to the rotational movement of the rollers  12  inside the lower rail members  20  (which will be described later), the upper rail members  10  are allowed to slide smoothly with respect to the lower rail members  20 . To the upper rail members  10 , nuts  15  for mounting a seat are fixed in a manner of welding. A seat cushion is placed on the upper rail members  10  and fastened with bolts to the nuts  15 ; thus, the seat cushion can be mounted and fixed therewith.  
         [0046]     The lower rail members  20  are for firmly fixing the seat slide apparatus  100  to the floor face of the vehicle, and for slidably supporting the upper rail members  10 . If the lower rail members  20  are firmly fixed to the floor face of the vehicle and the upper rail members  10  are allowed to slide, any shape and structure thereof may be employed. In this embodiment, as shown in  FIG. 3 , a copper plate is bent into a substantially C-like shape in cross section having an opening on the top in a manner of press. And a pair of the right and left cylindrical members is disposed at positions opposite to each other. Particularly, in this embodiment, as shown in  FIG. 1 , a long lower rail member  20  called as long rail is employed. Considering the case where a single seat is mounted, the distance between the lower rail members  20  is prescribed to a relatively narrow distance. Needless to say, the distance between the lower rail members  20  is not particularly limited to the above constitution. The distance may be arbitrarily determined in accordance with the width of the seat for the vehicle to be mounted thereon. On the bottom face of the lower rail members  20 , foot members  22  used for firmly fixing the lower rail members  20  to the floor face of the vehicle are fixed in a manner of welding.  
         [0047]     Also, to the both ends of the lower rail members  20 , an end bracket  23  is attached respectively to cover the sectional opening. In a substantially central portion of the end bracket  23 , a slit is formed for allowing a wire end  53  to be hooked, which will be described later. The width of the slit is prescribed to a width slightly larger than the diameter of an inner wire  51  that the wire end  53  cannot pass therethrough, which will be described later.  
         [0048]     The locking unit  30  is for preventing a relative movement of the upper rail members  10  with respect to the lower rail members  20 . If the upper rail members  10  can be prevented from sliding with respect to the lower rail members  20  and fixed thereby, any shape and/or structure of the locking unit  30  may be employed. This embodiment employs the following constitution as shown in  FIG. 2  or  FIG. 4 . That is, a lock lever  31  having projections capable of being inserted and engaged with rocking holes  21  is provided slidably in the vertical direction within the guide portions formed on the upper rail members  10 . The rocking holes  21  are continuously formed in the longitudinal direction inside the lower portion of the lower rail members  20 . The lock lever  31  is connected to the unlocking unit  40 , which will be described later, and to a handle lever  90  that is operated manually by a passenger. As shown in  FIG. 5 , a cylindrical convex member  32  is implanted in the side face of the lock lever  31 , and in a central portion of the handle lever  90 , a pin  91  is provided penetrating the handle lever  90  to rotatably pivot the handle lever  90  with respect to the upper rail member  10 . The handle lever  90  is energized with a coil spring  92  so that the handle lever  90  presses the lock lever  31  via the convex portion  32  to maintain the state that the lock lever  31  is engaged in the rocking holes  21 . When a passenger operates the handle lever  90  manually (manual operation), or when the unlocking unit  40  is activated, the lock lever  31  moves forward/backward with respect to the rocking holes  21  formed in the lower rail member  20 ; thereby the relative movement of the upper rail members  10  with respect to the lower rail members  20  is prevented and released.  
         [0049]     The unlocking unit  40  is for releasing the locking by the locking unit  30 . If the locking by the locking unit  30  can be released, any shape or structure may be employed for the unlocking unit  40 . In this embodiment, as shown in  FIG. 1 , a servomotor  41  including a small size motor and a speed reduction unit (not shown) is connected to the lock lever  31 . It is arranged so that, when the servomotor  41  is activated, the lock lever  31  is moved forward/backward with respect to the rocking hole  21  in the lower rail member  20 . Further, it may be arranged so that the servomotor  41  operates the handle lever  90  for manual operation; thereby the locking can be released.  
         [0050]     The traction members  50  are for pulling the upper rail members  10 . In the present invention, if the upper rail members  10  can be pulled, any shape or structure may be employed for the traction members  50 . In this embodiment, as shown in  FIG. 1  or  FIG. 5 , a wire cable including an outer tube  52  and an inner wire  51  is employed. By twisting a plurality of metal wires, the strength of the inner wires  51  is increased and a cylindrical wire end  53  is provided to the both ends respectively. One end of the inner wires  51  is inserted through the wire-insertion port  13  and the guide portion  14  formed in the upper rail member  10  and guided inside the lower rail member  20 , and the wire end  53  is hooked to the end bracket  23 . The other end of the inner wires  51  is attached to the rotation dram  60  so as to be wound by the rotation dram  60 . The portion of the wire from the wire-insertion ports  13  protruding through the cut in the upper end of the upper rail member  10  to the rotation dram  60 , the inner wire  51  is inserted through the outer tube  52  to protect the inner wire  51  respectively.  
         [0051]     The inner wires  51  are provided to one lower rail member.  20  in the pair of lower rail members  20 , but other lower rail member  20  is not provided therewith. Because, in the seat slide apparatus  100 , it is assumed that the traction member (wire cable) is wound only when the walk-in operation is carried out in a state that no passenger sits on the seat.  
         [0052]     When the motor  70  is activated, which will be described later, the rotation dram  60  rotates to wind the traction member  50 . If the traction member  50  can be wound, any shape or structure may be employed for the rotation dram  60 . In this embodiment, as shown in  FIG. 8 , a cylindrical member, which is formed with a spiral groove on the peripheral surface thereof, is employed. And at the upper and lower end portions of the cylindrical member, hooking concave portions for allowing the wire end  53  to be hooked are formed. To the hooking concave portions, the wire end  53  of two inner wires  51  of which wire ends  53  are hooked to the end brackets  23  provided to the front and rear ends of the lower rail members  20 , and on the spiral groove on the outer periphery of the cylindrical member, the inner wires  51  are wound.  
         [0053]     The motor  70  is connected to the rotation dram  60  to rotate the rotation dram  60 . If the motor  70  is capable of rotating the rotation dram  60  being connected thereto, any shape or structure may be employed. In this embodiment, a general-purpose motor, which is used for opening/closing slide door of a vehicle, may be employed.  
         [0054]     The clutch  80  is for arbitrarily connecting/disconnecting the motor  70  with the rotation dram  60 . When the motor  70  and the rotation dram  60  are connected with each other, the driving force of the motor  70  is transmitted to the rotation dram  60 , and the rotation dram  60  follows the motor  70 . If the motor  70  and the rotation dram  60  can be arbitrarily connected/disconnected with each other, any shape or structure may be employed for the clutch  80 . This embodiment employs a one-way clutch, in which the torque from the motor  70  is transmitted to the rotation dram  60 , but the rotation torque from the rotation dram  60  is not transmitted to the motor  70 . Owing to the above-described constitution, the manual operation in an ordinary front/rear position adjustment area is not suffered from the resistance of the motor  70 . Therefore, the operation can be carried out with the same operation force as that required in the ordinary manual seat slide apparatus  100 . Needless to say, the present invention is not limited to the above constitution, but a general electromagnetic clutch or a mechanical clutch may be employed.  
         [0055]     A first switch SW 1  is disposed on the surface of the interior wall. When a passenger operates the switch to turn ON, the unlocking unit  40 , the motor  70  and the clutch  80  are activated. Although not illustrated, in this embodiment, a push-button switch may be disposed on the console panel of the vehicle, in the vicinity of the rear door, or to the seat provided with the walk-in function.  
         [0056]     A second switch SW 2  is disposed in the vicinity of the front area of the lower rail member  20 . When the upper rail member  10  slides forward (walk-in is activated), the upper rail member  10  presses (operates) the switch SW 2  to inactivate the unlocking unit  40 , the motor  70  and the clutch  80 . In this embodiment, as shown in  FIG. 1 , a limit switch is disposed on the upper face in the forward portion of one lower rail member  10 .  
         [0057]     A third switch SW 3  is disposed in the vicinity of substantially central portion or backward portion of the lower rail member  20 . When the upper rail member  10  slides backward (returns to the original position), the upper rail member  10  presses the switch SW 3  (operates) to inactivate the unlocking unit  40 , the motor  70  and the clutch  80 . In this embodiment, the third switch SW 3  is not particularly illustrated. Same as the second switch SW 2 , a limit switch is provided on the upper face of one lower rail member  10 . The front/rear position of the switch SW 3  is located below the upper rail member  10  in the seat slide apparatus  100  shown in  FIG. 1 .  
         [0058]     In this embodiment, the above-described motor  70 , the clutch  80 , the first switch SW 1 , the second switch SW 2  and the third switch SW 3  are connected to a control device (not shown) respectively. The control device controls the respective units as illustrated in block diagrams of  FIG. 9  or  FIG. 10 .  
         [0059]     In this embodiment, the rotation dram  60 , the motor  70 , the clutch  80  and the like are disposed on the upper rail member  10 . However, the present invention is not particularly limited to the above-described constitution. The rotation dram  60 , the motor  70 , clutch  80  and the like may be disposed to the vehicle body-side (lower rail member  20 ). When such constitution is employed, a pulley is attached respectively to the end brackets  23  provided to the ends of a lower rail member  20 , the wire end  53  of the inner wires  51  is hooked to the end portions of the upper rail member  10 . The inner wires  51  are connected to the rotation dram  60  disposed at the vehicle body-side (lower rail member  20 ) via the pulley.  
         [0060]     Next, the operation of the seat slide apparatus  100  in accordance with this embodiment will be described using the block diagrams shown in  FIG. 9  and  FIG. 10 .  
         [0061]     First, the case that the seat is slid forward (walk-in operation) using the driving force of the motor  70  will be described. When the first switch SW 1  is turned ON and the unlocking unit  40  is activated by an operation of a passenger, the locking with the locking unit  30  is released. Almost simultaneously, the clutch  80  is connect with the motor  70 , and the motor  70  is driven forward; thus, the upper rail member  10  is slid forward. Then, when the upper rail member  10  comes into contact with the second switch SW 2 , the second switch SW 2  is turned ON. The unlocking unit  40  is inactivated and the locking unit  30  is pressed down onto the lower face of the lower rail member  20 . Almost simultaneously when the unlocking unit  40  is inactivated, the clutch  80  is disconnected from the motor  70 , and the drive of the motor  70  is stopped. While the upper rail member  10  slides through inertia, the locking unit  30  enters into a closest rocking hole  21  and the upper rail member  10  is prevented from sliding.  
         [0062]     Next, the case that the seat is slid backward using the driving force of the motor  70  (return to the original position after the walk-in operation) will be described. First, when a passenger operates the first switch SW 1  to turn ON, the unlocking unit  40  is activated and the locking with the locking unit  30  is released. Almost simultaneously, the motor  70  is connected with the clutch  80  and driven in the reverse direction to slide the upper rail member  10  backward. After that, when the upper rail member  10  comes into contact with the third switch SW 3 , the third switch SW 3  is turned ON. The unlocking unit  40  is inactivated and the locking unit  30  is pressed down onto the lower face of the lower rail member  20 . Almost simultaneously when the unlocking unit  40  stops, the clutch  80  is disconnected and the motor  70  is stopped from driving. While the upper rail member  10  slides through inertia, the locking unit  30  enters into a closest rocking hole  21  and the sliding is prevented. The present invention is not particularly limited to this arrangement. The following arrangement may be employed. That is, the “return to the original position” may be arranged so that, after walk-in operation, a passenger sitting on the third row seat pull the seat back of the second row seat manually to return the second row seat to the position; or, a passenger sitting on the second row seat manually pushes the seat back of the second row seat backward to return the second row seat to the original position.  
         [0063]     Next, the case that the seat is slid forward (forward fine adjustment) manually (manual operation) by a passenger will be described. First, when the handle lever  90  is pushed down, the locking unit  30  (lock lever  31 ) is pulled out from the rocking hole  21  to release the locking by the locking unit  30 . Then a forward force is given to the upper rail member  10  to make a slide forward. Then, before the rocking hole  21  for locking the slide, the handle lever  90  is returned (released). The projection of the locking unit  30  proceeds while sliding on the lower inside surface of the lower rail member  20 ; thus, enters into the rocking hole  21  and the sliding is locked. Here, the clutch  80  is in a disconnected state, a light operation touch is obtained without receiving any resistance from the motor  70  and the traction member  50 .  
         [0064]     Next, the case that the seat is slid backward (backward fine adjustment) manually (manual operation) by a passenger will be described. First, when the handle lever  90  is pushed down, the locking unit  30  (lock lever  31 ) is pulled out from the rocking hole  21  to release the locking by the locking unit  30 . Then a backward force is given to the upper rail member  10  to make a slide backward. Then, before the rocking hole  21  for locking the slide, the handle lever  90  is returned (released). The projection of the locking unit  30  proceeds while sliding on the lower inside surface of the lower rail member  20  and enters into the rocking hole  21 , thus, the sliding is locked. Here, the clutch  80  is in a disconnected state, a light operation touch is obtained without receiving any resistance from the motor  70  and the traction member  50 .  
         [0065]     While the preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the appended claims.