Abstract:
The present invention provides a sliding door opening/closing device for a vehicle that applies a sufficient opening/closing drive force to the left and right sliding doors and reduces a force necessary to lock and unlock the latch, despite a simple configuration of the device, and that facilitates the manufacturing process, improves operability and safety, and reduces noise. A lock device, against both sides of which locking portions abut, rotates a columnar permanent magnet so as to form magnetic locking circuits and fixes the locking portions by magnetic forces of the locking magnetic circuits. The rotational operation of the columnar permanent magnet is converted into the downward operation of a latch, and the lowered latch restrains the locking portions with respect to the lock device.

Description:
This application claim priority to Japanese Patent Application 2009-014995, filed Jan. 27, 2009, the entirety of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sliding door opening/closing device for a vehicle that serves to open and close a sliding door of a vehicle. 
     2. Description of the Related Art 
     The related art of sliding door opening/closing devices for vehicles is disclosed, for example, in Japanese Patent Application Laid-open No. 2000-142392 (JP-A-2000-142392), the invention being titled “Sliding Door Opening/Closing Device for Vehicle”. The sliding door opening/closing device for a vehicle disclosed in JP-A-2000-142392 is provided with a door lock device that locks and unlocks the sliding door in response to opening and closing of the sliding door. This door lock device locks the door so that it cannot be opened or closed, by dropping a latch into a lock hole. This door lock device is configured to lift the latch with a wire device and makes it possible to unlock the door by manually operating a handle device. 
     In the conventional sliding door opening/closing device for a vehicle, the latch has to be lowered after the latch has been correctly positioned above the lock hole, but this positioning is not easy to perform, as described hereinbelow. 
     A door edge rubber is provided at the left and right sliding doors as a measure against door clamping, and when the door is closed, the door edge rubber is compressed and deformed, thereby eliminating a gap between the sliding doors. However, a problem arising in a case where the crushing amount of the door edge rubber is large when the door is closed is that a resistance force applied to the sliding door increases, the latch shifts from a position above the lock hole, and locking with the latch is impossible. 
     Vibration preventing parts that have soundproofing, wind-stopping, and vibration damping functions are provided to abut against the sliding door when the vehicle is travelling (that is, when the door is closed), and a problem arising when these vibration preventing parts apply a force that exceeds a supposed value when the door is closed is that a resistance force applied to the sliding door increases, the latch shifts from a position above the lock hole, and locking with the latch is impossible. 
     Conversely, where the crushing amount of the door edge rubber is small, a resistance force applied to the sliding door is small. Furthermore, when the vibration preventing parts apply a force that is less than a supposed value when the door is closed, a resistance force applied to the sliding door is also small. The problem arising in these cases is that the resistance force falls within the specified range and the latch is closed even when a specified obstacle is squeezed by the sliding doors, and the sliding door does not comply with a door clamping test. 
     Because problems arise both in the case where the resistance force applied to the door is small and in the case where the force is large, as described above, this force has to be adjusted to fall in a predetermined range. The problem is, however, that the resistance force is not easy to adjust from both sides of the range, while correctly positioning the latch above the lock hole. 
     A structure can be used in which a gap is provided between the door edge rubbers at the left and right sides to facilitate the adjustment operation in order to satisfy the requirements placed on both the locking operation and the specified accuracy of door clamping detection, but with the door edge rubber of a shape protruding to the left and right, water and wind penetrate from the gap and noise is generated, thereby making it difficult to follow this approach. 
     Because the conventional door lock device uses a system such that the latch is lowered by spring pressure and the door lock device is locked by using an insertion force created by the inertia force of the doors that are shut at a certain door closing speed, the sound of the dropping part and the sound of collision are loud. 
     Because a force exceeding a large door counterforce that is applied to the latch in addition to the spring pressure pulling the latch has to be applied when the conventional door lock device is locked, a metal noise sound is loud. 
     A counterforce from the door edge rubber that is compressed when the door is closed is applied to the sliding door, a large door counterforce is applied to the latch in the lock device during locking, and the latch is difficult to move. The resultant problem is that where the handle is operated in a case of emergency in a state with such a large door counterforce, the outer wire is sometimes contracted, the inner wire is not drawn relative thereto, and emergency unlocking cannot be performed. 
     SUMMARY OF THE INVENTION 
     With the foregoing in view, in one aspect of the present invention a sliding door opening/closing device for a vehicle is configured to apply a sufficient opening/closing drive force to the left and right sliding doors and to reduce a force necessary to lock and unlock the latch, despite a simple configuration of the device, and that facilitates the manufacturing process, improves operability and safety, and reduces noise. 
     The sliding door opening/closing device for a vehicle in accordance with the present invention is described below. 
     The sliding door opening/closing device for a vehicle is provided with a magnetic lock device in which a columnar permanent magnet is rotatably supported and also provided with a latch lifting lock device comprising a latch and a conversion unit that converts a rotation operation of the columnar permanent magnet of the magnetic lock device into a lifting operation of the latch and vice versa. In such a sliding door opening/closing device for a vehicle, in an unlocked state in which the two sliding doors are opened and the two locking portions are separated from both sides of the magnetic lock device, the magnetic lock device rotates and fixes the columnar permanent magnet so as to form therein a magnetic circuit for unlocking, and the latch lifting lock device fixes the latch in a lifted position in response to the fixing of the columnar permanent magnet. Further, in a locked state in which the two sliding doors are closed and the two locking portions abut against both sides of the magnetic lock device, the magnetic lock device attracts and fixes the two locking portions by a magnetic force, while rotating and fixing the columnar permanent magnet, so as to form therein a magnetic circuit for locking together with the two locking portions that abut against both sides, and the latch lifting lock device, while fixing the latch in a lowered position in response to the fixing of the columnar permanent magnet, restrains the two locking portions to prevent them from separating from the magnetic lock device, using the lowered latch. 
     The locking portions are strongly attracted and fixed by magnetic forces. Further, the locking portions are reliably restrained to prevent them from being moved by the latch. 
     Further, in an unlocked state in which the two sliding doors are opened and the two locking portions are separated from both sides of the magnetic lock device, the columnar permanent magnet of the magnetic lock device is applied with an initial rotation force that causes rotation in one direction, which is obtained by converting a lowering force created by the own weight of the lifted latch by the conversion unit. As a result, the columnar permanent magnet provides a force that causes rotation in the direction of lowering the latch. 
     Further, the columnar permanent magnet of the magnetic lock device is fixed by a fixing force that exceeds the initial rotation force and is applied by the magnetic circuit for unlocking formed inside the columnar permanent magnet. As a result, the latch lifting lock device maintains the lifted position of the latch. Therefore, in the unlocked state, the latch is fixed so as to maintain the lifted position, regardless of the initial rotation force. 
     Further, when a transition is made from an unlocked state to a locked state in which the two sliding doors are closed and the two locking portions abut against both sides of the magnetic lock device, the magnetic lock device rotates the columnar permanent magnet while applying a rotation force thereto so as to form therein a magnetic circuit for locking together with the two locking portions that abut against both sides, and attracts and fixes the two locking portions by a magnetic force at the same time of the formation of the magnetic circuit for locking, and the latch lifting lock device converts the rotation force of the columnar permanent magnet into the lowering force of the latch, and restrains the two locking portions and the magnetic lock device by the lowered latch. Therefore, during locking, the rotation of the columnar permanent magnet applies the magnetic forces and lowers the latch. 
     In the latch lifting lock device, an actuator lifts the latch and cancels the restraint created by the latch, the lifting operation of the latch is converted into a rotation operation of the columnar permanent magnet, the magnetic circuit for locking is opened, and the restraint of the two locking portions created by the magnetic attraction is canceled. Because the latch does not apply a strong force, the latch can be lifted even by a small force of a small actuator. 
     Further, the latch lifting lock device includes a wire device that performs an operation of lifting the latch, and the wire device lifts the latch and cancels the restraint created by the latch, the lifting operation of the latch is converted into a rotation operation of the columnar permanent magnet, the magnetic circuit for locking is opened, and the restraint of the two locking portions created by the magnetic attraction is canceled. Because the latch does not apply a strong force, the latch can be lifted even by a small force of a small actuator. 
     The wire device of the latch lifting lock device further includes a handle device that moves the inner wire of the wire device, and the inner wire is moved by a handle operation of the handle device. In case of emergency, the latch can be released easily and reliably by manual operation. Further, because a small force is sufficient, the outer wire or inner wire is not deformed. 
     Where the inner wire is fixed by a stopper so as to prevent the inner wire from moving, the lowering of the latch by the latch lifting lock device and the rotation of the columnar permanent magnet of the magnetic lock device that accompanies this lowering are prevented. As a result, the formation of a magnetic circuit for locking is prevented. Therefore, as long as fixing is performed with the stopper in the lifted position of the latch, the two sliding doors can be opened and closed manually. 
     When the restraint of the latch is canceled by operating the handle device, the lifted position of the latch is held by the magnetic circuit for unlocking, and upon closing the two sliding doors manually, a magnetic circuit for locking is formed and locking is performed. 
     The conversion unit of the latch lifting lock device includes a pinion attached so as to be coaxial with a rotation shaft of the columnar permanent magnet and a rack attached so as to mesh with the pinion and extend along the lifting direction of the latch. The conversion unit therefore has a simple structure. 
     In the magnetic lock device, when the two locking portions are withdrawn from the magnetic circuit mechanism, a magnetic circuit for unlocking is formed by the columnar permanent magnet and the upper iron yoke, and a magnetic circuit for unlocking is formed by the columnar permanent magnet and the lower iron yoke, to stop the rotation of the columnar permanent magnet and fix the latch. 
     When the two locking portions abut against the magnetic circuit mechanism, the columnar permanent magnet is rotated, magnetic circuits for locking are formed by the columnar permanent magnet, the upper and lower iron yokes, and the two locking portions, and the two locking portions are attracted and fixed by a magnetic force. 
     With such a magnetic lock device, it is possible to form a magnetic circuit for unlocking and magnetic circuit for locking that have a simple configuration. 
     The opening/closing drive device may have a configuration in which the linear motor supplies an opening/closing drive force to one of the sliding door drive racks, supplies the opening/closing drive to one sliding door, and rotates the sliding door drive pinion, and the other sliding door drive rack supplies an opening/closing drive to the other sliding door via the sliding door drive pinion. 
     The opening/closing drive device may have a configuration in which the sliding door drive motor rotationally drives the pinion, an opening/closing drive force is supplied to one sliding door drive rack and the opening/closing drive force is supplied to one sliding door, and the other sliding door drive rack supplies an opening/closing drive force to the other sliding door. 
     Summarizing, the present invention can provide a sliding door opening/closing device for a vehicle that is configured to apply a sufficient opening/closing drive force to the left and right sliding doors and reduce a force necessary to lock and unlock the latch, despite a simple configuration of the device, and that facilitates the manufacturing process, improves operability and safety, and reduces noise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural diagram illustrating the configuration of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 2  is a structural diagram of an opening/closing drive device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 3  is an explanatory drawing illustrating a state of the sliding door opening/closing device for a vehicle of an embodiment of the present invention in which the sliding doors are opened; 
         FIG. 4  is a structural diagram of another opening/closing drive device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 5  is a front view of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 6  is a plan view of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 7  is a sectional view along section A-A of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 8  is a sectional view along section B-B of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 9  is partially cut-out sectional view of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 10  is a sectional view along section C-C of the lock device of the sliding door opening/closing device for a vehicle of an embodiment of the present invention; 
         FIG. 11  shows an internal structure of the lock device in the unlocked state; 
         FIG. 12  is an explanatory drawing of a magnetic circuit for unlocking that is formed in the unlocked state of the lock device; 
         FIG. 13  shows an internal structure of the lock device during locking when the locking portions are in contact; 
         FIG. 14  is an explanatory drawing of a magnetic circuit formed when the lock device is locked and the locking portions are in contact; 
         FIG. 15  shows an internal structure of the lock device in the locked state; 
         FIG. 16  is an explanatory drawing of a magnetic circuit for locking that is formed in the locked state of the lock device; 
         FIG. 17  is an explanatory drawing illustrating the operation of unlocking the lock device that is performed by the actuator; 
         FIG. 18  is an explanatory drawing illustrating the operation of opening the sliding door in the lock device; 
         FIG. 19  is an explanatory drawing illustrating the operation of unlocking the lock device by the wire device; and 
         FIG. 20  is an explanatory drawing illustrating the operation of opening the sliding door in the lock device. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments of the present invention will be described below with reference to the appended drawings. The entire structure of the sliding door opening/closing device  1  for a vehicle will be in initially explained with reference to  FIGS. 1 ,  2 ,  3 , and  4 . As shown in  FIG. 1 , the sliding door opening/closing device  1  for a vehicle is provided at least with a lock device  100 , a pair of left and right sliding doors  200 ,  300 , a rail moving bodies  400 ,  500 , a sliding door rail  600 , and an opening/closing drive device  700 . 
     The lock device  100  has a function of locking so as to prevent the pair of left and right sliding doors  200 ,  300  from opening when the pair of left and right sliding doors  200 ,  300  have been closed. The lock device  100  is generally composed of a magnetic lock device and a latch lifting lock device that will be described below in greater detail. 
     The sliding doors  200 ,  300  open and close the entrance/exit port of a railroad train by moving in the mutually opposite direction. 
     The sliding door  200  is suspended from the rail moving body  400 . The sliding door  300  is suspended from the rail moving body  500 . Door edge rubber  201 ,  301  is provided at the sliding doors  200 ,  300 , respectively (see  FIG. 3 ), and is compressed when the doors are closed, thereby eliminating the gap between the doors. 
     The rail moving bodies  400 ,  500  have door wheels, rollers, or slide rails and are configured to enable smooth movement of the doors along the sliding door rail  600  provided at the vehicle body. The sliding doors  200 ,  300  also smoothly move along the sliding door rail  600 . The lock device  100  is positioned between the rail moving bodies  400 ,  500 . These rail moving body  400 , lock device  100 , and rail moving body  500  are disposed side by side along the longitudinal direction of the sliding door rail  600 . 
     The opening/closing drive device  700  opens and closes the rail moving bodies  400 ,  500  synchronously to the left and right. The opening/closing drive device  700  may be of various kinds. For example, an opening/closing drive device  700  of a linear motor type, such as shown in  FIG. 2 , can be used. The opening/closing drive device  700  is provided with a linear motor  701 , a moving member  702  that moves horizontally with respect to the linear motor  701 , a link body  703  that is linked to the moving member  702 , a first sliding door drive rack  704  that is linked to the link body  703  and supported to be movable in the horizontal direction, a sliding door drive pinion  705  that is meshed with the first sliding door drive rack  704 , a second sliding door drive rack  706  that is meshed with the sliding door drive pinion  705  and supported to be movable in the horizontal direction, a link body  707  that is linked to the second sliding door drive rack  706 , and a body  708  that accommodates the aforementioned components. The first sliding door drive rack  704  and second sliding door drive rack  706  are mounted so that they can move parallel each other, while the teeth thereof face each other, at two substantially parallel planes inside the body  708 . The link body  703  is fixed to the rail moving body  400 , and the link body  707  is fixed to the rail moving body  500 . The link body  707  is configured so as to avoid contact thereof with the first sliding door drive rack  704 . The body  708  of the opening/closing drive device  700  is fixed to a vehicle body (not shown in the figure). 
     The link body  703  is fixed to the rail moving body  400 . The moving member  702  of the linear motor  701  and the sliding door drive first rack  704  are fixed to the link body  703 . The moving member  702  moves in the horizontal direction in response to a magnetic force supplied by a stator (not shown in the figure) of the linear motor  701 . 
     The first sliding door drive rack  704  attached to the link body  703  is configured so as to move parallel to the sliding door rail  600  and is meshed with the sliding door drive pinion  705 . The pinion sliding door drive  705  meshes with the second sliding door drive rack  706 . The pinion sliding door drive  705  drives the second sliding door drive rack  706  in the direction opposite the advance direction of the first sliding door drive rack  704 . The second sliding door drive rack  706  is configured to move substantially parallel to the sliding door rail  600  and has the link body  707  attached thereto. The link body  707  is fixed to the rail moving body  500 . 
     Thus, the opening/closing drive force supplied from the moving member  702  of the linear motor  701  is transmitted to the sliding door  200  via the link body  703  and rail moving body  400  and also transmitted to the sliding door  300  via the link body  703 , first sliding door drive rack  704 , sliding door drive pinion  705 , second sliding door drive rack  706 , link body  707 , and rail moving body  500 . 
     The operation of opening and closing the sliding doors that is performed by the sliding door opening/closing device  1  for a vehicle of the present embodiment will be described below. Where the moving member  702  of the linear motor  701  moves the link body  703 , which is fixed to the moving member  702 , in the direction of arrow (a) (to the left), as shown in  FIG. 2 , in a state in which the sliding doors are closed as shown in  FIG. 1 , the sliding door  200  also moves in the direction of arrow (a). 
     At the same time as the link body  703  moves in the direction of arrow (a) (to the left), the first sliding door drive rack  704  also moves in the direction of arrow (a) (to the left). The first sliding door drive rack  704  rotationally drives the sliding door drive pinion  705 , and the pinion sliding door drive  705  drives the second sliding door drive rack  706  in the direction of arrow (b) (to the right). The second sliding door drive rack  706  drives the link body  707 , which is fixed to the second sliding door drive rack  706 , in the direction of arrow (b) (to the right), and the sliding door  300  is driven in the direction of arrow (b) (to the right). The operations of opening the sliding doors  200  and  300  are performed simultaneously. The sliding doors  200 ,  300  thus assume an open state such as shown in  FIG. 3 . 
     An opening/closing drive device  700  of a rotary motor type such as shown in  FIG. 4  may be used as another opening/closing drive device. This opening/closing drive device  700  is provided, for example, as shown in  FIG. 4 , with a link body  709 , a first sliding door drive rack  710  that is linked to the link body  709  and supported to be movable in the horizontal direction, a sliding door drive pinion  711  that is meshed with the first sliding door drive rack  710 , a second sliding door drive rack  712  that is meshed with the sliding door drive pinion  711  and supported to be movable in the horizontal direction, a link body  713  that is linked to the second sliding door drive rack  712 , a sliding door drive motor  714  that rotationally drives the sliding door drive pinion  711 , and a body  715  that accommodates the aforementioned components. The drive axis of the sliding door drive motor  714  extend in the direction perpendicular to the paper sheet in  FIG. 4 , and the body is shown in the figure only in mutual arrangement by a dot line. The first sliding door drive rack  710  and second sliding door drive rack  712  are mounted so that they can move parallel to each other, while the teeth thereof face each other, at two substantially parallel planes inside the body  715 . The link body  709  is fixed to the rail moving body  400 , and the link body  713  is fixed to the rail moving body  500 . The link body  713  is configured so as to avoid contact thereof with the first sliding door drive rack  710 . The body  715  of the opening/closing drive device  700  is fixed to a vehicle body (not shown in the figure). 
     The sliding door drive motor  714  rotationally drives the sliding door drive pinion  711 . The sliding door drive pinion  711  meshes with the first sliding door drive rack  710  and second sliding door drive rack  712 . When the sliding door drive pinion  711  rotates, the first sliding door drive rack  710  and second sliding door drive rack  712  are driven to move in opposite directions. 
     The operation of opening and closing the sliding doors with the sliding door opening/closing device for a vehicle of the present embodiment will be described below. In the state in which the sliding door is closed as shown in  FIG. 1 , when the sliding door drive motor  714  rotationally drives the sliding door drive pinion  711  as shown in  FIG. 4 , the first sliding door drive rack  710  and the link body  709 , which is fixed to the first sliding door drive rack  710 , move in the direction of arrow (c) (to the left), and the sliding door  200  also moves in the direction of arrow (c). Further, the second sliding door drive rack  712  and the link body  713 , which is fixed to the second sliding door drive rack  712 , move in the direction of arrow (d) (to the right), and the sliding door  300  also moves in the direction of arrow (d) (to the right). The sliding doors  200 ,  300  thus assume an open state such as shown in  FIG. 3 . 
     A device using a belt drive or a device using a feed screw drive may be also used as another opening/closing drive device  700 . The entire structure of the sliding door opening/closing device  1  for a vehicle is described above. 
     The lock device  100  will be described below in greater detail with reference to the appended drawings. The configuration of the lock device  100  will be described with reference to  FIGS. 5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 , and  12 . The explanation below is conducted under an assumption that the arrow X direction is the left-right direction, and the arrow Y direction is the up-down direction, as shown in  FIG. 5 . Further,  FIG. 7  shows a side view of the lock device in which a locking part  402  is omitted. 
     The lock device  100  is provided with a rear surface base  101 , a lower base  102 , an upper base  103 , a front surface base  104 , an iron yoke  105 , an iron yoke  106 , a nonmagnetic body  107 , a columnar permanent magnet  108 , a pinion  109 , a rack  110 , a lifting base  111 , a slide rail  112 , a latch  113 , a support column  114 , a locking plate  115 , an actuator  116 , a shaft fixing portion  117 , an elastic body  118 , an inner wire  119 , an outer wire  120 , a handle device  121 , a hole  122 , a hole  123 , a gap  124 , and a gap  125 . 
     As shown in  FIG. 6 , a locking portion  402  is attached to the rail moving body  400 , with an iron arm portion  401  being interposed therebetween. A door wheel  403  can move on a door wheel rail  600 . Further, a locking portion  502  is attached to the rail moving body  500 , with an iron arm portion  501  being interposed therebetween. A door wheel  503  can move on the door wheel rail  600 . The locking portion  402 , lock device  100 , and locking portion  502  are disposed side by side along the sliding door rail  600 . These locking portions  402 ,  502  are both formed by magnetic bodies. In particular, as shown in  FIG. 11 , these locking portions are formed to have protruding portions  402   a ,  502   a  that protrude upward. The lock device  100  has a locking function of maintaining the closed state of the sliding doors  200 ,  300  by fixing when the device comes by the side surfaces thereof into contact with the locking portions  402 ,  502  that come close thereto as the sliding doors  200 ,  300  are closed. 
     The configuration of each component will be described below. 
     The rear surface base  101  is made from iron and is a plate body as shown in  FIGS. 7 and 8 . The rear surface base  101  is fixed to a pedestal portion  800  provided at the vehicle body, thereby fixing the lock device  100 . A lower base  102  made of iron and having a Π-like shape in the side view and an upper base  103  made from iron and having an L-like shape in the side view are fixed to the rear surface base  101 . As shown in  FIG. 12 , the iron yoke  105  formed from a magnetic body is also fixed to the lower base  102 . The iron yoke  106  formed from a magnetic body is fixed to the upper base  103 . Two plate-shaped nonmagnetic bodies  107  are disposed between the iron yoke  105  and iron yoke  106 . These iron yoke  105 , non-magnetic bodies  107 , and iron yoke  106  form a magnetic circuit mechanism. 
     A hole  122  passing through the iron yoke  105 , iron yoke  106 , and nonmagnetic body  107  is formed in the center of the magnetic circuit mechanism, and the columnar permanent magnet  108  is rotatably supported in the hole  122 . The front surface base  104  is fixed to the lower base  102 , iron yoke  105 , nonmagnetic body  107 , iron yoke  106 , and upper base  103  so as to cover the iron yoke  105 , iron yoke  106 , and nonmagnetic body  107 . These rear surface base  101 , lower base  102 , upper base  103 , front surface base  104 , iron yoke  105 , iron yoke  106 , nonmagnetic body  107 , and columnar permanent magnet  108  constitute the magnetic lock device in accordance with the present invention. 
     A hole  123  is also formed, as shown in  FIGS. 8 and 10 , in the front surface base  104 , and the pinion  109  can be coupled and fixed to the columnar permanent magnet  108  through the hole  123 . The columnar permanent magnet  108  and pinion  109  are constituted so as to be disposed coaxially and rotate together without eccentricity. 
     As shown in  FIGS. 9 and 10 , a rail portion of the slide rail  112  is fixed at the front surface side of the front surface base  104 , and the lifting base  111  is further fixed to the moving portion of the slide rail  112 . Further, the pinion  109  is disposed at the front surface side of the front surface base  104 , and the rack  110  is disposed and fixed at the rear surface side of the lifting base  111 . The pinion  109  and rack  110  are disposed to mesh with each other. 
     In other words, due to the presence of the slide rail  112 , the lifting base  111  can easily move in the vertical direction with respect to the front surface base  104 . Further, where the lifting base  111  is driven so as to be lifted with respect to the front surface base  104 , the pinion  109 , which meshes with the rack  110 , rotates and the columnar permanent magnet  108  also rotates. Conversely, where the columnar permanent magnet  108  rotates, the rack  110 , which meshes with the pinion  109 , moves in the vertical direction and the lifting base  111  is lifted or lowered. These pinion  109 , rack  110 , lifting base  111 , and slide rail  112  constitute a conversion unit in accordance with the present invention that converts the rotational movement into the vertical movement and vice versa. 
     As shown in  FIG. 8 , the lifting base  111  is made from iron, has a Γ-like shape in the side view, and can move up and down in the vertical direction with respect to the front surface base. A latch  113  made of iron and having a Π-like shape in the front view is attached to the distal end of the lifting base  111 , as shown in  FIG. 11 . The latch  113  is moved down when the door is closed, positioned on a path of the protruding portion  402   a  of the locking part  402  or the protruding portion  502   a  of the locking part  502  that are attached at both sides of the lock device  100 , and restrained to prevent it from moving. The elastic body  118  is disposed above the upper base  103 , and where the latch  113  abuts against the elastic body  118 , the downward movement of the latch  113  is restrained. In this state, only the left and right protruding portions  113   a ,  113   b  of the latch  113  (see  FIG. 11 ) serve as restraining portions. The elastic body  118  also absorbs impacts during collision. 
     As shown in  FIGS. 6 and 7 , the locking plate  115  is fixed above the lifting base  111 , with two support columns  114  being interposed therebetween. Where a vertical force is applied to the locking plate  115 , the lifting base  111  is also moved in the vertical direction. 
     The actuator  116  is fixed to the front surface of the front surface base  104 , and a lifting shaft is fixed by the shaft fixing portion  117  to the locking plate  115 . The actuator  116  causes the locking plate  115  to move in the vertical direction and moves the lifting base  111  in the vertical direction. 
     This conversion unit (pinion  109 , rack  110 , lifting base  111 , and slide rail  112 ), latch  113 , support columns  114 , and locking plate  115  constitute the latch lifting lock device in accordance with the present invention. 
     As shown in  FIG. 9 , the inner wire  119  is inserted into the outer wire  120  that has a strong tubular structure and can move inside the outer wire  120 . These inner wire  119  and outer wire  120  constitute a wire device. Where the handle device  121  located on the opposite side is operated, the locking plate  115  is pulled and lifted in the direction of arrow (e) via the inner wire  119 , and the entire latch lifting lock device is lifted. In this case, the pulling amount of the inner wire is adjusted so that the columnar permanent magnet  108  is rotated by the pinion  109  through about 90°. The operation using the handle device  121  and wire device is conducted only for unlocking, and the opening/closing operation of the sliding doors  200 ,  300  is performed manually. 
     Locking and unlocking with the lock device  100  will be explained below with reference to  FIGS. 1 ,  3 ,  11 ,  12 ,  13 ,  14 ,  15 , and  16 . In  FIGS. 11 to 16 , some parts are omitted to clarify the internal structure and magnetic circuit formation in the lock device. 
     Initially, an unlocked state is assumed in which the sliding doors  200 ,  300  are opened, as shown in  FIG. 3 . In this case, as shown in  FIG. 11 , the latch  113  is in the lifted state. In the columnar permanent magnet  108 , the N pole and S pole are assumed to be in a horizontal direction (left-right direction), as shown in  FIGS. 11 and 12 . The locking portions  402 ,  502  are positioned at a sufficient distance from the lock device  100  as shown in  FIGS. 11 and 12 . In this case, as shown in  FIG. 12 , a magnetic circuit is formed by the columnar permanent magnet  108  and upper iron yoke  106  and a magnetic circuit is also formed by the columnar permanent magnet  108  and lower iron yoke  105 . These magnetic circuits are internally formed magnetic circuits for unlocking. The magnetic force of the magnetic circuits for unlocking stops the rotation of the columnar permanent magnet  108 , and the latch  113  is fixed in a lifted state. An initial rotation force, obtained by converting the lowering force created by the weight of the latch lifting lock device, is applied to the columnar permanent magnet  108  of the lock device  100  in one direction, but because the magnetic force created by the magnetic circuits for unlocking is stronger than the initial rotation force, the columnar permanent magnet  108  does not rotate and the latch  113  is maintained in the lifted position. Because no magnetic force is formed between the lower iron yoke  105  and upper iron yoke  106 , the attachment forces at both side surfaces of the iron yokes  105 ,  106  are zero. 
     Locking with the lock device  100  (transition from the unlocked state to the locked state) is conducted in the following manner. The opening/closing drive device  700  conducts the door closing drive and closes the sliding doors  200 ,  300  as shown in  FIG. 1 . In this case, as shown in  FIG. 13 , the locking portion  402  of the rail moving body  400  moves in the direction of arrow (f), and the locking portion  502  of the rail moving body  500  simultaneously moves in the direction of arrow (g). The locking portions  402 ,  502  eventually abut against the lock device  100 . 
     In the lock device  100 , the protruding portions  105   a ,  105   b  are formed at the side surface of the iron yoke  105 , as shown in detail in  FIG. 14 . Further, the protruding portions  106   a ,  106   b  are formed at the side surface of the iron yoke  106 . Where the locking portion  402  abuts against the protruding portions  105   a ,  106   a , a gap  124  is formed, and where the locking portion  502  abuts against the protruding portions  105   b ,  106   b , a gap  125  is formed. Because of the gaps  124 ,  125 , the locking portions  402 ,  502  are caused to abut only in the positions that are located above and below the nonmagnetic body  107  and the magnetic circuit is formed reliably. 
     In this case, as shown in  FIG. 14 , a magnetic circuit is formed in which magnetic force lines return from the N pole of the columnar permanent magnet  108  to the N pole through the locking portion  402 , and a magnetic circuit is formed in which magnetic force lines return from the S pole of the columnar permanent magnet  108  to the S pole through the locking portion  502 . However, in this case a repulsive force acts, and therefore the columnar permanent magnet  108  is to be rotated in order to prevent the repulsive force from acting. 
     Concerning the rotation direction, an initial rotation force, which is obtained by converting the lowering force created by the weight of the latch lifting lock device, is applied to the columnar permanent magnet  108  of the magnetic lock device in one direction (in the direction of arrow (h), that is, the clockwise direction). Therefore, the columnar permanent magnet  108  rotates and the latch  113  is lowered mechanically in the direction of arrow (i). The latch  113  then abuts against the elastic body  118 , and the columnar permanent magnet  108  is stopped in a position such that the N pole and S pole are oriented in the vertical direction as shown in  FIGS. 15 and 16 . 
     In this case, as shown in  FIG. 16 , a magnetic circuit is formed in which the magnetic force lines return to the S pole of the columnar permanent magnet  108  via the N pole of the columnar permanent magnet  108 , upper iron yoke  106 , locking portion  402 , and lower iron yoke  105 , a magnetic circuit is formed in which the magnetic force lines return to the S pole of the columnar permanent magnet  108  via the N pole of the columnar permanent magnet  108 , upper iron yoke  106 , locking portion  502 , and lower iron yoke  105 , and the system is stabilized. As a result, the columnar permanent magnet  108  does not move and maintains the position. These magnetic circuits are magnetic circuits for locking. Under the effect of magnetic forces of these magnetic circuits for locking, the locking portions  402 ,  502  are attached and fixed to the lock device  100 . 
     The rotational movement of the pinion  109  that rotates together with the columnar permanent magnet  108  is converted into a descending movement of the rack  110 , the latch  113  moves in the direction of arrow (i) in  FIG. 15  and descends, and the latch  113  abuts against the elastic body  118  and stops. This stop position is adjusted so that the columnar permanent magnet  108  rotates through 90°. In this case, as shown in a circle in  FIG. 15 , a very small gap (d) is formed between the protruding portions  402   a ,  502   a  of the locking portions  402 ,  502  and the protruding portions  113   a ,  113   b  of the latch. Such an alignment is easy because the protruding portions  402   a ,  502   a  of the locking portions  402 ,  502  that are strongly fixed in the same position at all times by the magnetic circuits for locking are taken as a reference. 
     The attachment caused by the formation of the above-described magnetic circuits for locking and the descent of the latch  113  are attained simultaneously with the completion of rotation of the columnar permanent magnet  108 . 
     Because the protruding portions  113   a ,  113   b  of the latch  113  are thus positioned on the movement paths of the locking portions  402 ,  502 , the protruding portions are not separated from the lock device  100 . With such a structure, even if the magnetic circuit for locking is opened in the locking process and unlocking is conducted, or when the attachment is incomplete, the sliding doors  200 ,  300  move through a distance equal to a very small gap (d) and the doors are not opened to more than the gap (d). Because this movement through the gap (d) is also absorbed by the deformation of the door end rubber  201 ,  301 , the gap is formed between the sliding doors  200 ,  300 . In accordance with the present invention, because of the gap (d) of the latch  113 , the latch  113  has no mechanical contact, except that the latch  113  abuts against the elastic body  118 . Therefore, there is practically no mechanical resistance and the lifting operation can be smoothly performed by a small force. 
     Thus, during locking, magnetic locking is performed in the magnetic lock device by which the locking portions  402 ,  502  are strongly attracted and fixed by magnetism. As a result, the sliding doors  200 ,  300  are strongly fixed. In this case, the sliding doors  200 ,  300  are closed by simple adjustment of regulating the attachment position of the arms  401 ,  501  to the locking portions  402 ,  502 , thereby strongly closing the sliding doors  200 ,  300  in a predetermined door closing position. 
     Further, latch locking by the latch  103  is conducted simultaneously with the magnetic locking. Because magnetic locking ensures strong fixing, in the latch locking, the gap (d) is opened, mechanical interference is limited to positioning the protruding portions  103   a ,  103   b , which are parts of the latch  103 , at the path, and the latch  103  that is not in mechanical contact is smoothly lifted or lowered. By using latch locking in addition to magnetic locking it is possible to prevent the sliding doors  200 ,  300  from being unintentionally opened. 
     The usual unlocking with the lock device (transition from the locked state to the unlocked state) is performed in the following manner. It is assumed that in the unlocked state, the locking portions  402 ,  502  abut against the side surfaces of the lock device  100 , as shown in  FIG. 15 . Further, the latch  113  is in a lowered state. For example, where an instruction to open the sliding doors  200 ,  300  is issued, the actuator  116  is actuated and moved through the distance X (mm) in the direction of arrow (j) and lifts the locking portion  115 , as shown in  FIG. 17 . 
     Then, the operation of lifting the rack  110  in the direction of arrow (j) shown in  FIG. 17  that is conducted as the locking portion  115  is lifted is converted into the operation of rotating the columnar permanent magnet  108  and the pinion  109  that rotates in the direction of arrow (k) (counterclockwise). The columnar permanent magnet  108  rotates through 90°. In this case, because the magnetic circuit is eliminated between the lower iron yoke  105  and upper iron yoke  106 , the attachment forces at both side surfaces of the iron yokes  105 ,  106  become zero and the attachment state of the magnetic circuit is canceled. 
     The opening/closing drive device  700  then opens the doors, and the sliding doors  200 ,  300  are opened as shown in  FIG. 3 . In this case, as shown in  FIG. 18 , the locking portion  402  of the rail moving body  400  moves in the direction of arrow (l), and the locking portion  502  of the rail moving body  500  simultaneously moves in the direction of arrow (m). 
     Further, as shown in  FIG. 12 , a magnetic circuit is formed by the columnar permanent magnet  108  and upper iron yoke  106 , and a magnetic circuit is formed by the columnar permanent magnet  108  and lower iron yoke  105 . Because of the magnetic forces of the magnetic circuits for unlocking, the rotation of the columnar permanent magnet  108  is stopped and the latch  113  is fixed in a lifted state. Therefore, the actuator  116  can be actuated only within a very short time from the moment the door is opened to immediately after the locking portions  402 ,  502  are separated. 
     Thus, simultaneously with lifting the latch  113 , the magnetic circuit for locking is opened, strong attraction of the locking portions  402 ,  502  by the lock device  100  is released, and then the locking portions  402 ,  502  can be easily separated. In this case, too, practically no mechanical resistance is applied to the latch  113  due to the gap (d) formed by the protruding portions  113   a ,  113   b  of the latch  113  and the protruding portions  402   a ,  502   a  of the locking portions  402 ,  502 . As a result, the lifting operation can be performed smoothly by a small force. 
     Thus, during unlocking, as the latch  113  is lifted, the locking portions  402 ,  502  are released from being magnetically attracted and fixed by the lock device  100  and, therefore, the opening operation can be performed at a high speed by a small force. 
     Emergency unlocking (transition from the locked state to the unlocked state) with the lock device  100  is performed in the following manner. In emergency unlocking, unlocking is conducted with a handle device (emergency lock)  121  shown in  FIG. 9 . In the unlocked state, the locking portions  402 ,  502  are assumed to abut against the side surfaces of the lock device  100 , as shown in  FIG. 15 . Further, in this state, the latch  113  is lowered. For example, where a handle operation is performed in the handle device  121 , the inner wire  119  is driven in the direction of arrow (n), as shown in  FIG. 19 , and the locking plate  115  is lifted through a distance X (mm). As a result, the latch  113  is also lifted and the unlocked state is assumed. The inner wire  119  is fixed by the stopper of the handle device  121  in this pulled state. 
     The operation of lifting the rack  110  in the direction of arrow (o) shown in  FIG. 19  that is performed as the latch  113  is lifted is converted into the operation of rotating the pinion  109  that rotates the columnar permanent magnet  108  in the direction of arrow (p) (counterclockwise). The columnar permanent magnet  108  rotates through 90° in the direction of arrow (p) (counterclockwise). 
     In this case, a magnetic circuit is formed by columnar permanent magnet  108  and the upper iron yoke  106  and a magnetic circuit is formed by columnar permanent magnet  108  and the lower iron yoke  105  as the magnetic circuits, as shown in  FIG. 12 . These magnetic circuits constitute magnetic circuits for unlocking. Magnetic forces of the magnetic circuits for unlocking stop the rotation of columnar permanent magnet  108 , and the latch  113  is fixed in the lifted state. Further, the inner wire  119  is prevented from moving by the stopper, as described hereinabove, the locking plate  115  is fixed and prevented from lowering, and the columnar permanent magnet  108  does not rotate. 
     The sliding doors  200 ,  300  are then manually opened. Because the magnetic circuits for unlocking are thus provided instead of the magnetic circuits for locking, the locking portions  402 ,  502  are separated from the lock device  100  even by a very small force. Then, as shown in  FIG. 20 , the locking portion  402  of the rail moving body  400  moves in the direction of arrow (q), and the locking portion  502  of the rail moving body  500  moves, in the direction of arrow (r). While the handle operation is performed, the lock is released. Where the handle is fixed with the stopper in the handle device  121 , attachment and locking are not performed with the lock device  100  even if the sliding doors  200 ,  300  are manually closed again in this state. 
     Thus, simultaneously with lifting the latch  113 , the magnetic circuit for locking is opened, strong attraction of the locking portions  402 ,  502  by the lock device  100  is released, and then the locking portions  402 ,  502  can be easily separated. In this case, too, practically no mechanical resistance is applied to the latch  113  due to the gap (d) formed by the protruding portions  113   a ,  113   b  of the latch  113  and the protruding portions  402   a ,  502   a  of the locking portions  402 ,  502 . As a result, the lifting operation can be performed smoothly by a small force. 
     Thus, during unlocking, as the latch  113  is lifted, the locking portions  402 ,  502  are released from being fixed by the lock device  100  and, therefore, the opening operation can be performed at a high speed by a small force. 
     Where the handle of the handle device  121  is returned to the original position, pulling of the inner wire  119  is released, but because the columnar permanent magnet  108  forms the magnetic circuits for unlocking, the latch  113  is held in the lifted position and the unlocked state is assumed. Therefore, the sliding doors  200 ,  300  can be manually closed, but once they are closed, they are locked and attached and the locked state is assumed. 
     The sliding door opening/closing device in accordance with the present invention is described above. The advantages of the sliding door opening/closing, device over the conventional configuration are described below. 
     In the sliding door opening/closing device in accordance with the present invention, where the locking portions of the sliding doors abut against the lock device, the locking portions are attached, locking is simultaneously performed, and the sliding doors are locked. In particular because the magnetic circuit for locking is characterized in that the attachment force greatly increases as the locking portions approach the magnetic lock device, the attachment force is greatly increased over that of the conventional system, the left and right door edge rubber is sufficiently crushed, the door gap is eliminated, and the occurrence of a state in which the latch cannot be lowered is avoided. In addition, locking can be conducted even if the resistance caused by the crushing amount of the door edge rubber and the resistance of the damping part that has a soundproofing function, a wind-stopping function, and a vibration damping function increase. The resistance force also can be regulated by adjusting the attachment position of the moving rail and arms with a screw unit. 
     Further, where an obstacle is clamped between the sliding doors, because the locking portions are prevented from contact with the magnetic lock device, the magnetic circuit for locking is not formed and the columnar permanent magnet does not move. Therefore, the latch cannot be lowered and locking is not performed. Therefore, door clamping detection accuracy is greatly increased. As a result, the problem of tradeoff between the locking and the door clamping detection that is inherent to conventional configurations is resolved. 
     No mechanical restraint is used to prevent movement as in conventional door lock devices, and positioning is performed in a location in which a tiny gap is opened at a path of the magnetically attached locking portions. Therefore, mechanical contact is reduced and locking and unlocking can be performed quietly by a small force, while attaining the object of preventing the sliding doors from opening. In addition, the conventional configuration uses a spring for lifting the latch, but in accordance with the present invention, the latch is lowered by a magnetic force created by the formation of magnetic circuit for locking and the latch is lifted by a magnetic force by the formation of magnetic circuit for unlocking. Therefore, noise can be reduced. Further, when the latch is lowered, it is positioned by contact with the elastic body. Therefore, noise can be further reduced. 
     The load applied to the latch during locking is created only by magnetic forces of the magnetic circuit during locking, and this load does not act as a counterforce for the sliding doors. Therefore, the outer wire is prevented from being deformed even by manual handle operation during emergency, and the situation in which the inner wire is extended above the specified limit, the relative pull-in amount of the inner wire is insufficient, and unlocking can be performed, as in the conventional configuration, can be avoided. 
     Attachment is possible even if the door inertia force created by the door closing speed is zero. Therefore, noise of collision during locking can be reduced. 
     During unlocking, the latch may be lifted by a force exceeding the couple of forces created by the formation of magnetic circuit for locking, and the effect of door repulsive force is eliminated. Therefore, the unlocking force may be small and therefore a small-size actuator serving as a separate installation can be used. As a result, metal contact noise during unlocking can be reduced. 
     The invention can be used for opening and closing sliding doors of vehicles such as trains and streetcars. 
     It will be appreciated by those skilled in the art that variations and modifications are possible, and that the invention may be practiced otherwise than as specifically described herein without departing from the scope of the invention.