JP6109866B2 - Fall prevention device - Google Patents

Description

  The present invention relates to a fall prevention device that is installed on a platform of a station in a railway and blocks a gap between a train and the platform.

  In recent years, an increasing number of stations have fall prevention devices installed on platforms. The platform fall prevention device is a device that projects a fall prevention plate from the platform when getting on and off the train and closes the gap between the train and the platform. The fall prevention device for platforms accommodates the fall prevention plate on the platform side except when getting on and off, while projecting it onto the track side when getting on and off the train, narrowing the gap between the platform and the train to prevent the fall (For example, refer to Patent Document 1).

JP-A-2005-14805

The conventional fall prevention device for a platform is used to prevent the fall prevention plate from moving due to a reaction force when a passenger steps on the fall prevention plate with the fall prevention plate protruding from the platform when getting on and off the train. A brake mechanism and a lock mechanism are provided.
Since the lock mechanism operates using electromagnetic force as described in Patent Document 1, electric power is required to shift the lock state. Further, if the power supply is cut off in a state where the fall prevention plate does not complete the protrusion or the storage, the brake of the electric drive mechanism is activated and the manual drive cannot be performed. Since the train cannot be operated while the fall prevention plate is protruding or in the middle of storage, the operation of the train cannot be resumed until the power is restored. In order to avoid such a situation, a backup power source that enables a release operation so that a command to release the brake can be issued even when a failure or a power failure occurs is necessary.

  Furthermore, the platform may be provided not only in the straight section of the track but also in the curve section. When the fall prevention device is installed on the platform provided in the curve section, the distance between the vehicle and the platform varies depending on the position of the door, and therefore it is necessary to determine the protrusion amount of the fall prevention plate for each installation position. Therefore, when manufacturing the fall prevention device, it is necessary to design and manufacture a fall prevention device that matches the installation position. In this case, the number of unique parts and devices increases, leading to an increase in price. Moreover, it becomes a factor of an incorrect ordering and an assembly mistake on site. In Patent Document 1, in order to avoid this, the brake is applied at the projecting completion position, and the fall prevention plate is fixed by the braking force. However, in this case, there is a problem that the brake needs to be inspected because the fixing cannot be performed when the braking force is reduced due to wear of the brake.

  The present invention has been devised based on such a background, and includes a lock mechanism that is simpler and cheaper and does not require power with excellent durability, and can change the protrusion amount of the fall prevention plate. An object of the present invention is to provide a fall prevention device having a structure that can be used.

  A first invention for solving the above problem is a fall prevention device for preventing a fall from a platform by projecting a fall prevention plate to the track side, wherein the swinging mechanism is operated by driving the drive mechanism section. A link mechanism that converts the swing motion that works into a linear motion of a driven slider that moves the fall prevention plate in the forward and backward direction, and changes the conversion rate from the swing motion to the linear motion by the link mechanism portion. And when the falling prevention plate is in the projecting completion state and the housing completion state, the engagement relationship between the rocking body and the link mechanism portion is the order from the rocking body to the link mechanism portion. This is a fall prevention device that constitutes a reverse motion prevention structure that is effective only in the direction of motion transmission.

  According to a second aspect of the present invention, the rocking body has a driving end connected to and connected to a driving slider linearly driven by the driving mechanism section, and a driven end that rocks on the opposite side across the rocking shaft. A first link lever portion, wherein the link mechanism portion has an input end portion having a contact surface in contact with the driven end of the first link lever portion, and a roller that rolls in a groove provided in the driven slider. And a second link lever portion pivotally supporting the roller portion so that the pivot position can be changed, and the conversion rate is changed by changing the pivot position of the roller portion. It is a fall prevention device of the 1st invention constituted so that it is possible.

  A third invention is the fall prevention device of the second invention, wherein the output end portion is provided with a plurality of bolt holes that are screwed into through-bolts inserted through the rotation shaft of the roller portion.

  According to a fourth aspect of the present invention, there is a long hole through which the through bolt is inserted through the roller portion and the roller pedestal at the output end, and a fitting unevenness that is fitted to the roller pedestal provided around the long hole. A fall prevention device according to the second aspect of the present invention.

  A fifth invention is the fall prevention device according to any one of the first to fourth inventions, further comprising a movement restricting portion for restricting a range in which the fall prevention plate can advance and retract.

  According to any one of the first to fourth inventions, when the fall prevention plate is in the projecting completion state and the housing completion state, the swinging motion is performed only by the forward power transmission from the drive mechanism unit to the link mechanism unit. It is possible to realize a fall prevention device that can convert into a linear motion and project / store the fall prevention plate. That is, even if a brake that requires a power supply is not provided, the fall prevention plate is locked even if it is forcibly stored from the protruding completion state or forcibly protruding from the storage completed state. Since no electrical / electronic parts or electronic control is used, the lock mechanism can be made simpler and cheaper, and the durability is excellent. In addition, since the conversion rate from the swing motion to the linear motion can be changed for the link mechanism, the amount of protrusion of the fall prevention plate can be changed. Therefore, it is possible to provide a fall-preventing device that includes a lock mechanism that is less expensive than conventional and does not require electric power that is excellent in durability, and that can easily change the protruding amount of the fall-preventing plate.

  According to the fifth aspect of the present invention, it is possible to limit the movable range of the fall prevention plate and further improve the safety.

The top view and (2) side view which show the structural example of the fall prevention apparatus for platforms in the installation state. It is a figure which shows the example of an internal structure of the fall prevention apparatus for platforms in a protrusion completion state, Comprising: (1) Top view and (2) Partial enlarged view. AA sectional drawing of FIG. It is a figure which shows the structural example of a 2nd link lever part, Comprising: (1) Top view, (2) Side view exploded view seen from roller contact surface side. It is an enlarged view of a principle mechanism, (1) Projection completion state, (2) Intermediate state between projection completion state and storage completion state, and (3) Storage completion state, respectively. The figure for demonstrating manual operation of a drive mechanism part. The figure which shows the modification of the adjustment structure of the attachment position of an output end roller. The figure which shows the modification of the movement restriction | limiting structure which restrict | limits the advancing / retreating movement range of a fall prevention board. The figure which shows the modification of the movement restriction | limiting structure which restrict | limits the advancing / retreating movement range of a fall prevention board.

[First Embodiment]
An outline of a platform fall prevention device to which the present invention is applied will be described.
FIG. 1 is a (1) top view and (2) side view showing a configuration example of a platform fall prevention device 10 in an installed state. The platform fall-preventing device 10 is fixed to an installation space recessed in the upper side edge of the platform 2 of the station.

  The platform fall prevention device 10 includes a main frame 14 fixed in the installation space and a top plate 12 that contacts the lid. The platform fall prevention device 10 defines a thin rectangular internal space that opens to the track side, and falls into the internal space. The prevention plate 16 is supported by a ball bearing type slide rail 18 so as to be slidable substantially horizontally. The fall prevention plate 16 can be moved back and forth by the drive mechanism 20 toward the track side / home side.

  Except when getting on and off the train 4, the fall prevention plate 16 is maintained in a movement restrained state in a position where the entire plate is accommodated in the internal space so that the end of the track side does not protrude toward the track side. This state is called “accommodation complete state”.

  When getting on and off the train 4, the fall prevention plate 16 automatically shifts to a movable state as the drive mechanism unit 20 operates, and the fall prevention plate 16 is projected to the track side so that the platform and the train 4 The gap D is narrowed to prevent the passenger from falling between the platform and the train. This state is called a “projection completion state”. FIG. 1 (1) and FIG. 1 (2) both show this “projection completion state”.

  When the protrusion completion state is reached, the fall prevention plate 16 is automatically switched from the movable state to the movement restrained state, and an input from the fall prevention plate 16 side (for example, when a passenger gets into the fall prevention plate 16 and tries to get in) The fall prevention plate 16 maintains its current position against the generated reaction force and the like. That is, it becomes a locked state.

  And when boarding / alighting is complete | finished, the drive mechanism part 20 reverse | inverts. Even if the fall prevention plate 16 is in the movement-inhibited state, when the transmission of the driving force starting from the operation of the drive mechanism unit 20 in the forward direction starts, the fall prevention plate 16 is automatically switched to the movable state. Then, the fall prevention plate 16 is moved to the home side by the transmitted power and returned to the “accommodation complete state”, and the fall prevention plate 16 automatically enters the movement restrained state.

Next, the internal structure of the platform fall prevention device 10 will be described in detail.
2 and 3 are views showing an internal structure according to the present invention housed in the internal space of the platform fall prevention device 10 and showing a projecting completion state. In FIG. 2, the top plate 12, the main frame 14, and the fall prevention plate 16 are seen through, and FIG. 2 (1) is a top view and FIG. 2 (2) is a partially enlarged view thereof. 3 is a cross-sectional view taken along the line AA in FIG.

  The drive mechanism unit 20 includes an electric motor 21 that is electrically controlled by a control device (not shown), a speed reduction mechanism 22 that appropriately decelerates the rotation of the output shaft of the electric motor 21, and a ball screw unit that is coupled to the output shaft of the speed reduction mechanism 22. 23, a drive slider 24 that is slid by the rotation of the ball screw portion 23, and a bearing 25 that pivotally supports the tip of the ball screw portion 23. That is, the electric motor 21 and the speed reduction mechanism 22 function as a drive unit that rotationally drives the ball screw unit 23. The ball screw portion 23 and the drive slider 24 function as a linear motion mechanism. The drive slider 24 is also a function unit of the first link mechanism unit 40.

  In relation to the drive mechanism unit 20, a detection sensor for detecting the position of the drive slider 24 along the ball screw unit 23 is appropriately provided in the main frame 14. In the present embodiment, the protrusion completion detection sensor 30 for detecting the position of the drive slider 24 when the fall prevention plate 16 is in the protrusion completion state and the position of the drive slider 24 when it is in the housing completion state are detected. And a housing completion detection sensor 32 are provided. The protrusion completion detection sensor 30 and the housing completion detection sensor 32 are realized by, for example, a swing switch, and output a detection signal to a control device (not shown) of the electric motor 21 to be used for rotation control of the electric motor 21.

  The drive mechanism unit 20 and the fall prevention plate 16 are linked via the first link mechanism unit 40 and the second link mechanism unit 60.

  The first link mechanism unit 40 is a mechanism unit that converts a linear motion of the drive slider 24 driven by the drive mechanism unit 20 into a swing motion, and includes a roller guide 42 provided on the drive slider 24 and a swing guide. It has the 1st link lever part 43 which is a moving body. The first link lever portion 43, which is a rocking body, operates by driving the drive mechanism portion 20, thereby causing a rocking motion.

  The first link lever portion 43 has a linear shape when viewed from above, and is pivotally supported by a swing shaft 44 that protrudes from the main frame 14 substantially vertically. Then, one end (primary end) on the side of the drive mechanism portion 20 has a prime end roller 45 that rolls and connects in the guide groove of the roller guide 42, and the other end on the opposite side across the swing shaft 44. A swing end roller 46 is provided at the (driven end).

  The second link mechanism unit 60 converts the swinging motion that is caused by the operation of the first link mechanism unit 40 by driving the drive mechanism unit 20 into the linear motion of the driven slider 62 that moves the fall prevention plate 16 in the forward / backward direction. And a second link lever portion 61 and a driven slider 62.

  The second link lever portion 61 forms a substantially L-shaped crank when viewed from above, and is pivotally supported by a swing shaft 63 protruding substantially vertically from the main frame 14. And the roller for the rolling end roller 46 of the 1st link mechanism part 40 to contact and rolls to the one end part (end near the 1st link lever part 43: input end part) by the side of the drive mechanism part 20 It has a contact surface 64, and has an output end roller 67 that rolls in a guide groove of a roller guide 66 provided on the lower surface of the driven slider 62 at the other end (output end), and changes the mounting position It is possible.

  The driven slider 62 is fixed to the back surface of the fall prevention plate 16 with a bolt or the like, and the roller guide 66 forms a guide groove that intersects the advancing and retreating direction of the fall prevention plate 16.

  As shown in the enlarged view of FIG. 2 (2), the roller contact surface 64 of the second link lever portion 61 includes a substantially U-shaped conversion surface 64a in the top view and rotation directions of the lever from both ends of the conversion surface. And a protruding completion state locking surface 64b and an accommodation completion state locking surface 64c.

  The protruding lock surface 64b has a curved surface centered on the swing shaft 44 of the first link lever portion 43 in the positional relationship between the first link lever portion 43 and the second link lever portion 61 in the protruding completed state. ing. And it is designed so that the geometric condition of the predetermined even-numbered relationship in the protrusion completion state of the 1st link mechanism part 40 and the 2nd link mechanism part 60 may be satisfy | filled, and the rocking | fluctuation end roller in the protrusion completion state locking surface 64b The contact position of 46 is on a straight line (or substantially on a straight line) connecting the swing end roller 46 and the swing shaft 44.

  As a result, the fall prevention plate 16 can be placed in the movement restrained state when in the protruding completion state. Specifically, when an acting force F1 (thick white arrow in the figure) that tries to move the fall prevention plate 16 in the accommodation direction is generated, the driven slider 62 pushes the output end roller 67 in the accommodation direction (home direction). A counterclockwise torque is generated in the second link lever portion 61, and the roller contact surface 64 pushes the swing end roller 46 of the first link lever portion 43 with an acting force F2 (a black arrow in the drawing). However, the direction of the acting force F <b> 2 is a linear direction connecting the swing end roller 46 and the swing shaft 44 due to the geometric relationship described above. Therefore, the acting force F <b> 2 is supported by the swing shaft 44 and does not rotate the first link lever portion 43. That is, the locked state is established.

  Similarly, the lock state 64c in the accommodated state is a curved surface centered on the swing shaft 44 of the first link lever portion 43 in the positional relationship between the first link lever portion 43 and the second link lever portion 61 in the accommodated state. have. And it is designed so that the geometric condition of the predetermined even number relationship in the accommodation completion state of the 1st link mechanism part 40 and the 2nd link mechanism part 60 may be satisfy | filled, and the rocking | fluctuation end roller in the accommodation completion state locking surface 64c The contact position with 46 is configured to be on a straight line (or substantially on a straight line) connecting the rocking end roller 46 and the rocking shaft 44. That is, the fall prevention plate 16 can be maintained in the movement restrained state in the housing completion state.

FIGS. 4A and 4B are diagrams showing a configuration example of the second link lever portion 61 in the present embodiment, and are (1) a top view and (2) a side view exploded from the roller contact surface 64 side.
A plurality of bolt holes 612 having different distances from the insertion hole 611 of the swing shaft 63 are provided at the output end of the second link lever portion 61. In the present embodiment, there are three bolt holes 612, but any number of bolt holes 612 may be used as long as it is plural. The output end roller 67 is attached to any one of the plurality of bolt holes 612.

  The output end roller 67 is, for example, inserted through a roller body 671 in which a resin ring is fitted on the outer periphery of the bearing and a roller base 672 for height adjustment through a coaxial bolt 673 and screwed into the bolt hole 612. It is formed. Depending on which bolt hole 612 the output end roller 67 is fixed to, the lever ratio (that is, the conversion rate from the swinging motion to the linear motion) by the second link mechanism 60 is changed, and the protrusion amount of the fall prevention plate 16 is changed. can do.

  In response to the fact that the amount of protrusion of the fall prevention plate 16 can be adjusted by changing the lever ratio of the second link mechanism portion 60, in this embodiment, a movement restriction unit that restricts the range in which the fall prevention plate 16 can be moved back and forth. Is also configured to be adjustable.

  Specifically, as shown in FIGS. 2 and 3, as a movement restricting portion, on the lower surface of the top plate 12, the track side stopper 72k and the home side are arranged along the moving direction (advancing / retracting operation direction) of the fall prevention plate 16. A stopper 72h is projected. Further, on the upper surface of the fall prevention plate 16 (specifically, the upper surface of the portion located in the main frame 14 even when the protrusion is completed), as shown in the enlarged display portion circled in FIG. A bolt hole group in which bolt holes 161 are provided at different positions along the forward / backward movement method of the fall prevention plate 16 is provided on each of the home sides. The number and relative positional relationship of the bolt holes 161 in the bolt hole group can be set as appropriate. A track-side engagement protrusion 76k that engages with the track-side stopper 72k is fastened and fixed to the bolt side 161 of the bolt-hole group on the track-side (left side in FIG. 3) with a bolt 77, so that the home side (FIG. 3, a home side engaging projection 76 h that engages with the home side stopper 72 h is fastened and fixed by a bolt 77.

  The fixed positions of the track-side engagement protrusion 76k and the home-side engagement protrusion 76h are adjusted according to the lever ratio setting of the second link mechanism 60. That is, the track-side engaging projection 76k contacts (or comes close to) the track-side stopper 72k from the home side when the protrusion is completed, and the home-side engagement projection 76h contacts the track-side stopper 72h on the track side when the storage is completed. An appropriate position is selected so as to abut (or approach).

Next, the operation of the platform fall prevention device 10 will be described.
FIG. 5 is an enlarged view of the principle mechanism for moving the fall prevention plate 16, and shows (1) a projection completion state, (2) an intermediate state between the projection completion state and the storage completion state, and (3) a storage completion state, respectively. ing.

As shown in FIG. 5 (1), in the platform fall prevention device 10 in the projecting completed state, the swing end roller 46 of the first link lever portion 43 is in the projecting completed state locking surface 64b of the roller contact surface 64. It is in contact. As described above, in this state, the link mechanism is not operated by the reverse power transmission from the second link lever portion 61 to the first link lever portion 43.
When the electric motor 21 is rotationally driven in a predetermined direction to accommodate the fall prevention plate 16, the driving slider 24 is moved (downward as referred to in FIG. 5) and is a driving end roller engaged by the roller guide 42. 45 is moved. Thereby, the 1st link lever part 43 rotates clockwise, and the rocking | fluctuation end roller 46 moves to the conversion surface 64a from the protrusion completion state locked surface 64b. That is, the locked state of the link mechanism in the protruding completion state is automatically and smoothly released, and the state transitions to the state shown in FIG.

  When the oscillating end roller 46 moves to the conversion surface 64a, the oscillating end roller 46 is accommodated inside the substantially U-shaped top view formed by the conversion surface 64a, and the rotational movement of the first link lever portion 43 causes the second link lever portion 43 to rotate. Rotate 61 counterclockwise. When the second link lever portion 61 rotates counterclockwise, the output end roller 67 relatively moves toward the home side, and moves the driven slider 62 and the fall prevention plate 16 toward the home side.

  When the rotation of the electric motor 21 is continued, the swing end roller 46 eventually comes off the conversion surface 64a and moves to the housed lock state 64c, and the drive slider 24 moves to a predetermined housed position. The electric motor 21 is stopped, and the state shown in FIG.

  When in the accommodated state, the fall prevention plate 16 is in a movement restrained state. Specifically, when an acting force F3 is generated to move the fall prevention plate 16 in the protruding direction (orbit direction: left side in FIG. 5), the driven slider 62 pushes the output end roller 67 in the protruding direction. Then, a torque is generated to rotate the second link lever portion 61 in the clockwise direction, and the housed lock state 64c pushes the swing end roller 46 of the first link lever portion 43 with the acting force F4. However, due to the geometric relationship, the direction of the acting force F4 is on a straight line connecting the swing end roller 46 and the swing shaft 44. As a result, the acting force F4 is supported by the swing shaft 44 and does not rotate the first link lever portion 43. That is, the locked state is established.

  When the electric motor 21 is driven to rotate in the direction opposite to the above in order to make the fall prevention plate 16 protrude, the drive slider 24 is moved (upward in the direction of FIG. 5) and engaged with the roller guide 42. The driving end roller 45 is moved. As a result, the first link lever portion 43 rotates counterclockwise, and the swing end roller 46 moves from the housed lock state 64c to the conversion surface 64a. Thereby, the locked state of the link mechanism in the housing completion state is automatically and smoothly released, and the state transitions to the state of FIG. 5 (2), and eventually returns to the protrusion completion state of FIG.

  In the platform fall prevention device 10 of the present embodiment, as shown in FIG. 6, the gear mechanism 92 can be manually rotated by attaching the handwheel 90 to the speed reduction mechanism 22. Specifically, when the power supply to the platform fall prevention device 10 is cut off, the ball screw portion 23 can be rotated without electric power by inserting the handwheel handle 90 into the connection hole 94 of the gear mechanism 92 and connecting it. it can. It is more preferable to provide a small door on the top plate 12 (FIG. 1) that can access the connection hole 94 without removing the entire top plate 12.

  As described above, according to the present embodiment, the movement preventing state (locked operation state) and the movable state (unlocked state) of the fall prevention plate 16 are mechanically realized. This eliminates the need for electric power for transitioning the lock state without using an electromagnetic brake or the like. Further, since the lock operation / release is mechanically realized, the degree of deterioration of the components can be identified at a glance, so that the maintenance man-hours can be reduced and the durability of the platform fall prevention device 10 can be improved.

  In addition, the position of the output end roller 67 at the output end of the second link lever portion 61 can be changed, and the fixed positions of the track side engaging protrusion 76k and the home side engaging protrusion 76h can also be changed. Even with the fall prevention device 10, the amount of protrusion of the fall prevention plate 16 can be individually adjusted. When the platform 2 is installed in the curve section of the track, the gap with the train 4 varies depending on the installation location. By providing such an adjustment, it is possible to deal with a configuration having a different amount of protrusion at the site, which can greatly contribute to a reduction in manufacturing cost of the platform fall prevention device 10.

[Modification]
In addition, the form of this invention is not restricted to this embodiment, A component can be added, abbreviate | omitted, and changed suitably.

[Part 1]
For example, the linear motion mechanism composed of the ball screw portion 23 and the drive slider 24 in the above embodiment can be replaced with a linear motion mechanism based on a rack and pinion or a linear motion mechanism based on a belt drive.

[Part 2]
Further, the adjustment structure of the attachment position of the output end roller 67 is not limited to the method based on the number and position of the bolt holes 612. For example, as shown in FIG. 7, a long hole 613 into which the through bolt 673 can be inserted along the attachment range of the output end roller 67 is provided, and a fitting uneven part 614 is provided around the hole 613. The through bolt 673 is inserted into the long hole 613 through the roller body 671 and the roller base 672. The roller pedestal 672 may also be provided with a projection 674 that fits with the projections and depressions, and may be adjusted at the fitting position between the fitting projections and depressions 614 and the projections 674. In this case, the position of the output end roller 67 can be finely adjusted as compared with the above-described embodiment according to the unevenness interval of the fitting unevenness portion 614.

In accordance with this, it is preferable that the positions of the track-side engagement projection 76k and the home-side engagement projection 76h can be finely adjusted with screws.
Specifically, as shown in FIG. 8, the track-side engagement protrusion 76k and the home-side engagement protrusion 76h have a base 761, a spacer 762, and an engagement body 763.

  The base portion 761 is fixed to the upper surface of the fall prevention plate 16, and a plurality of base portions 761 are prepared in advance according to the adjustment amount of the spacer 762, and one of them is selected. The engaging body 763 is a main body that comes into contact with and engages with the track-side stopper 72k or the home-side stopper 72h, and is integrally provided with a bolt 763a. The base 761 and the spacer 762 are provided with insertion holes for bolts 763a. Then, the spacer 762 is sandwiched between the base portion 761 and fixed integrally with a bolt 763 a and a nut 765. Alternatively, as shown in FIG. 9, the spacer 762 may be omitted from the configuration of FIG. 8, and the engaging body 763 may be fixed to the base with two nuts 765.

DESCRIPTION OF SYMBOLS 2 ... Platform 10 ... Platform fall prevention device 12 ... Top plate 14 ... Main frame 16 ... Fall prevention plate 18 ... Slide rail 20 ... Drive mechanism part 21 ... Electric motor 22 ... Deceleration mechanism 23 ... Ball screw part 24 ... Drive slider 25 ... Bearing 40 ... 1st link mechanism part 42 ... Roller guide 43 ... 1st link lever part 44 ... Oscillating shaft 45 ... Driving end roller 46 ... Oscillating end roller 60 ... 2nd link mechanism part 61 ... 2nd link lever part 611 ... Insertion hole 612 ... Bolt hole 613 ... Long hole 614 ... Fitting uneven part 62 ... Driven slider 63 ... Oscillating shaft 64 ... Roller contact surface 64a ... Conversion surface 64b ... Projection completion state locking surface 64c ... Housing completion state locking Surface 66 ... Roller guide 67 ... Output end roller 671 ... Roller body 672 ... Roller base 673 ... Through bolt 90 ... Manual rotation Handle 92 ... gear mechanism 94 ... connecting hole

Claims (5)

A fall prevention device for preventing fall from the platform by protruding the fall prevention plate to the track side,
A first link lever portion that is a swinging body in which the driven end on the opposite side swings across the swinging shaft by moving the driving end linearly by driving the drive mechanism;
A link mechanism that converts a swinging motion that is caused by the operation of the first link lever portion into a linear motion of a driven slider that moves the fall prevention plate in the advancing and retracting direction;
In addition,
The link mechanism portion includes an input end portion having a contact surface that contacts the driven end of the first link lever portion, and an output end portion that pivotally supports a roller portion that rolls in a groove provided in the driven slider. A second link lever portion having
Having a structure capable of changing the conversion rate from the swing motion to the linear motion by the link mechanism,
When the engagement relationship between the first link lever portion and the second link lever portion is such that the fall prevention plate is in the protruding completion state and the housing completion state, the first link lever portion to the second link lever portion. Construct a reverse motion prevention structure that is effective only in forward motion transmission to
Fall prevention device. The output end of the link mechanism is pivotally changeable to the roller portion of the pivot position,
The fall prevention device according to claim 1, wherein the conversion rate can be changed by changing the pivot position of the roller portion. The output end portion is provided with a plurality of bolt holes that are screwed into through bolts inserted through the rotation shaft of the roller portion.
The fall prevention device according to claim 2. The output end portion has a long hole through which a through bolt is inserted through the roller portion and the roller pedestal, and a fitting concavo-convex portion fitted to the roller pedestal provided around the long hole.
The fall prevention device according to claim 2. A movement restricting portion for restricting a range in which the fall prevention plate can advance and retreat;
The fall prevention device according to any one of claims 1 to 4, further comprising:

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