LOAD-TYPE DOOR OPENING AND CLOSING DEVICE

Abstract

A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.

Claims

1. A load-type door opening and closing device provided with an opening and closing mechanism that uses a body weight of a person to open and close a door, the device comprising: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; and a footboard that is coupled with a sliding member through a coupling member and moves the door in the opening direction with use of stepping force, the sliding member being configured to slide on the door opening rail, wherein the sliding member is located at an upper end side of the door opening rail in a state in which the door is closed, and stepping force applied to the footboard during opening operation depresses the sliding member against the door opening rail to displace the door in the opening direction.

2. The load-type door opening and closing device according to claim 1, wherein the coupling member is of a type selected from: a pantograph type that includes a first coupling body and a second coupling body, the first coupling body being coupled with the footboard and operating in a vertical direction, the second coupling body having one end coupled with the sliding member and an other end in contact with a ground, and being rotatably fitted to the first coupling body between the one end and the other end; a gear type that includes a first arm, a second arm, and a gear part, the first arm having an end coupled with the footboard, the second arm having an end coupled with the sliding member, and the gear part journaling the first arm and the second arm independently and operating the first arm and the second arm in opposite directions from each other; a cam type that includes a first arm, a second arm, and a cam mechanism, the first arm having an end coupled with the footboard, the second arm having an end coupled with the sliding member, and the cam mechanism being provided between the first arm and the second arm that are journaled to a common rotational shaft and operating the first arm and the second arm in opposite directions from each other; and a direct depressing type in which a coupling rod that extends in a perpendicular direction from the footboard and has an end coupled with the footboard and the other end provided with the sliding member.

3. The load-type door opening and closing device according to claim 1, wherein the door opening rail has an upward inclination angle in the opening direction of the door that is large at an upper end side of the door opening rail and is small at a lower end side of the door opening rail.

4. The load-type door opening and closing device according to claim 1, further comprising a winding device that biases the door in a closing direction by winding force of a wire coupled with the door.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0068] FIG. 1A and FIG. 1B are entire configuration diagrams of a load-type door opening and closing device according to an embodiment.

[0069] FIG. 2 is a plan view of the toad-type door opening and closing device of FIG. 1.

[0070] FIG. 3 is a detailed explanatory diagram of the load-type door opening and closing device of FIG. 1.

[0071] FIG. 4A and FIG. 4B are detailed explanatory diagrams of a modification of the load-type door opening and closing device of FIG. 1.

[0072] FIG. 5A and FIG. 5B are diagrams in which FIG. 5A is a detailed explanatory diagram illustrating another modification of the load-type door opening and closing device of FIG. 1, and FIG. 5B is a plan view of the load-type door opening and closing device of FIG. 5A.

[0073] FIG. 6 is a detailed explanatory diagram illustrating still another modification of the load-type door opening and closing device of FIG. 1.

[0074] FIG. 7 is an explanatory diagram of Example 1 that illustrates an installation example of the load-type door opening and closing device of the present embodiment.

[0075] FIG. 8 is an explanatory diagram of Example 2 that illustrates another installation example of the load-type door opening and closing device of the present embodiment.

DESCRIPTION OF EMBODIMENTS

First Embodiment

[0076] A load-type door opening and closing device as an embodiment of the present invention is described with reference to FIGS. 1 to 3.

[0077] As illustrated in FIG. 1, the load-type door opening and closing device comprises an opening and closing mechanism that opens and closes a door 1. The load-type door opening and closing device comprises: a sliding support rail 2 that slidably supports the door 1 so as to open and close the door 1; a door opening rail 3 that is provided in the door 1; a sliding member 4 that is slidably attached to the door opening rail 3; a footboard 5; and a coupling member 6 that couples the sliding member 4 with the footboard 5,

[0078] Note that FIG. 1(a) illustrates a state before operation a state in which the door 1 is closed) and FIG. 1(b) illustrates a state after operation (a state in which the door 1 is open).

[0079] The door 1 is one sliding door (a single sliding door), and suspension hooks 11 and 11 are extended at both ends of an upper side of the door 1. Rollers 12 and 12 that are rotatably supported by the sliding support rail 2 are rotatably fitted respectively to the suspension hooks 11 and 11.

[0080] The sliding support rail 2 is a rail supported by a sash frame F or a building (not illustrated) in a horizontal direction, and the door 1 is slidably supported by the sliding support rail through the rollers 12 and 12.

[0081] Note that the suspension hooks 11 and 11 are respectively provided with auxiliary rollers 13 and 13 in addition to the rollers 12 and 12, and the auxiliary rollers 13 and 13 function to stabilize operation speed in auxiliary rails 14 and 14 that are provided at both ends of the sliding support rail 2.

[0082] Also, in the present embodiment, the sliding support rail 2 is installed horizontally, and the suspension hook 11 is biased (biased while winding force of a wire 16 is set to 2 to 10N with respect to 20 kg to 100 kg of the weight of the door 1) in a closing direction of the door 1 with use of a. constant force spring 15 (corresponding to a winding device of the present invention) through the wire 16. In addition thereto or in place thereof, the sliding support rail 2 may be slightly inclined upward in the opening direction (slightly inclined downward in the closing direction) of the door 1. In any case, the sliding support rail 2 assists the closing operation of the door 1 to smooth the closing operation.

[0083] The door opening rail 3 is a rail inclined upward in the opening direction at a lower part of the door 1, and is configured to be slidable while being in a state fitted with the sliding member 4.

[0084] An upward inclination angle of the door opening rail 3 varies, in a stepwise manner, such that the inclination angle becomes larger at an upper end side of the door opening rail and becomes smaller at lower end side of the door opening rail. Note that, in the present embodiment, the upward inclination angle is set in three stages, namely, the gradient is set to 15 to 16 degrees in an initial stage, 6 to 4 degrees in next stage, and 4 to 2 degrees in a final stage. Thus, the width in the initial stage is set within of the length of the rail. However, it is not limited as such, and alternatively, the upward inclination angle may be set in two or four or more stages, or may be continuously varied as long as the upward inclination angle is large at the upper end side corresponding to the initial stage and is small at the lower end side corresponding to the final stage.

[0085] Note that the door opening rail 3 is incorporated in the lower part of the door 1, and an outer side thereof is covered by a cover (a decorative cover covering the lower end side of the door), which makes the door opening rail 3 invisible from a user in a normal usage state.

[0086] The sliding member 4 is a roller sliding while being fitted with the door opening rail 3, and is rotatably fitted to an end of the coupling member 6. Note that relationship between the sliding member 4 and the coupling member 6 is described in detail later.

[0087] As illustrated in a plan view of FIG. 2 (the door 1 and the sliding support rail 2 are omitted from illustration), the footboard 5 is a flat plate over the inside and the outside separated by the door 1, and is settled according to a stepping amount of a person.

[0088] Note that the footboard 5 is floated by a returning sliding member 40 that is in contact with a lower surface of the footboard 5 (a lower surface outside the footboard 5 in the figure) in a state in which no person steps on the footboard 5, More specifically, an arm 42 is rotatably fitted to the ground by a shaft part 43. The arm 42 has an end rotatably fitted with the returning sliding member 40, and the other end provided with a weight 41. Accordingly, in a state in which no person steps on the footboard 5, the returning sliding member 40 pushes up the lower surface of the footboard 5 by the weight 41 through the principle of the leverage with the shaft part 43 as a fulcrum. This causes the arm 42 to perform closing operation opposite to the opening operation of the sliding member 4. Note that, in addition thereto or in place thereof, a biasing unit or the like that biases the footboard 5 in an up direction may be provided.

[0089] The coupling member 6 is rotatably fitted to the lower surface of the footboard 5, and is configured of a first coupling body 61 and a second coupling body 62. The first coupling body 61 operates in a vertical direction in association with vertical operation of the footboard 5. The second coupling body 62 has an end that journals the sliding member 4, and the other end that is in contact with ground GL under the footboard 5.

[0090] Note that the first coupling body 61 may be extended from the lower surface of the footboard in the horizontal direction and operate in the vertical direction integrally with the footboard 5.

[0091] As illustrated in FIG. 2, the first coupling body 61 has an end that is coupled with (in the present embodiment, rotatably fitted to) the footboard 5, and the other end that journals the second coupling body 62.

[0092] As illustrated in FIG. 3, the second coupling body 62 is rotatably fitted, at a center part (a position of a predetermined ratio between the one end and the other end that regulates the vertical movement), to the first coupling body 61., and the other end (a grounding point with the ground GL) of the second coupling body 62 is rotatably fitted to a grounding roller 63, and operates with the grounding roller 63 as a fulcrum.

[0093] The sliding member 4 is connected with the second coupling body 62 through a coupling rod 60. The coupling rod 60 is adjustable in length based on the connection position with the second coupling body 62, which allows positioning of the sliding member 4 to be fitted to the door opening rail 3.

[0094] According to the load-type door opening and Closing device having the above-described configuration, when no person steps on the footboard 5, the footboard 5 is floated, and the sliding member 4 is accordingly fined with the door opening rail 3 at the highest position (at an upper end position of the door opening rail 3) in the perpendicular direction.

[0095] When a person steps on the footboard 5 in this state, stepping force generated on the footboard 5 becomes component force in a down direction of the second coupling body 62 through the first coupling body 61 that is integrated with the footboard 5. This pushes down the coupling rod 60 side of the second coupling body 62 with the grounding roller 63 as a fulcrum, and the sliding member 4 that is journaled to the coupling rod 60 so acts as to press down the lower surface of the door opening rail 3.

[0096] This displaces the door 1 in the opening direction along the inclination direction of the door opening rail 3 so as to release the component force applied through the sliding member 4. At this time, the weight of the door 1 is not applied to the sliding member 4, which makes it possible to reduce the load of the sliding member 4 to improve durability thereof.

[0097] Further, to move the door 1 in the opening direction, it is sufficient to move the sliding member 4 from the upper end side of the door opening rail 3 in the down direction along the downward inclination direction of the door opening rail 3. This makes it possible to improve operation speed of the door.

[0098] Further, since the upward inclination angle on the upper end side of the door opening rail 3 is large, it is possible to increase the component force in the door opening rail direction of downward acting force of the sliding member 4 that acts on the door opening rail 3. This makes it possible to rapidly start the opening operation of the door 1.

[0099] As mentioned above, according to the load-type door opening and closing device of the present embodiment, it is possible to reduce the load of the sliding member 4 to improve durability, and also to achieve quick operation of the door 1.

Second Embodiment

[0100] Next, as another load-type door opening and closing device of the present embodiment, a configuration that uses a gear section 70 serving as the coupling member 6 is described with reference to FIG. 4. Note that the components same as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

[0101] In this case, the coupling member 6 is configured of a first arm 71, a second arm 72, and the gear section 70. The first arm 71 has an end coupled with the footboard 5. The second arm 72 has the other end coupled with the sliding member 4. The gear section 70 is disposed between the first arm 71 and the second arm 72, and operates these arms in opposite directions from each other.

[0102] The gear section 70 includes a first gear 70a and a second gear 70b. The first gear 70a rotates integrally with the first arm 71 by a first coupling shaft 71a. The second gear 70b rotates integrally with the second arm 72 by a second coupling shaft 72a.

[0103] The first gear 70a and the second gear 70b are so engaged with each other as to respectively rotate the first arm 71 and the second arm 72 in opposite directions from each other, and a diameter ratio of the first gear 70a and the second gear 70b is a value exceeding 1 time in order to double the operation of the first arm 71 (Tor example, 2 to 3 times).

[0104] Note that the gear section 70 is incorporated in a space under the footboard 5, and is fixed to an unillustrated base.

[0105] The first arm 71 is brought into contact with and coupled with the footboard 5 through a footboard-side roller 50 that is rotatably fitted to the end of the first arm 71. In addition, the extending other end of the first arm 71 is provided with a weight 71c. Also, the first arm 71 is rotatably fitted at a center part to the first coupling shaft 71a.

[0106] The second arm 72 has an end that is rotatably fitted to the second coupling shaft 72a, and the other end that is coupled with the sliding member 4. Note that a mechanism with which the sliding member 4 is coupled is configured of the coupling rod 60 as with the above-described embodiment.

[0107] According to the load-type door opening and closing device having the above-described configuration, when a person steps on the footboard 5 from a state where no person steps on the footboard 5, stepping force generated on the footboard 5 acts on the end of the first arm 71 through the footboard-side roller 50, thereby moving the first arm 71 around the first coupling shaft 71a in a clockwise direction in the figure.

[0108] This causes the second gear 70b to rotate in the opposite direction through the first gear 70a on the common first coupling shaft 71a, and accordingly the second arm 72 on the second coupling shaft 72a moves in a counterclockwise direction in the figure.

[0109] When the second arm moves around in the counterclockwise direction, the coupling rod 60 side of the second arm 72 is depressed, and the sliding member 4 journaled to the coupling rod 60 so acts as to depress the lower surface of the door opening rail 3.

[0110] As with the above-described embodiment, the door 1 is displaced in the opening direction along the inclination direction of the door opening rail 3 so as to release the component force applied through the sliding member 4. At this time, the weight of the door 1 is not applied to the sliding member 4, which makes it possible to reduce the load of the sliding member 4 to improve durability thereof.

[0111] Further, to move the door 1 in the opening direction, it is sufficient to move the sliding member 4 from the upper end side of the door opening rail 3 in the down direction along the downward inclination direction of the door opening rail 3. This makes it possible to improve operation speed of the door.

[0112] As mentioned above, according to the load-type door opening and closing device of the present embodiment, it is possible to reduce the load of the sliding member 4 to improve durability, and to achieve quick operation of the door 1.

[0113] Note that, in the present embodiment, when no person steps on the footboard 5, the first arm 71 moves around in the counterclockwise direction in the figure by the weight 71c of the first arm 71, and the footboard 5 returns to the floating state through the footboard-side roller 50.

Third Embodiment

[0114] Next, another load-type door opening and closing device according to the present embodiment is described with reference to FIG. 5. Note that the components same as those of any of the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

[0115] In this case, the coupling member 6 is configured of a first arm 81, a second arm 82, and a cam mechanism 83. The first arm 81 has an end coupled with the footboard 5. The second arm 82 has the other end coupled with a sliding member 4 (the sliding member is distinguished from the above-described sliding member 4 because one sliding member is half-supported in the present embodiment; the same shall apply hereinafter). The cam mechanism 83 is provided between the first arm 81 and the second arm 82, and respectively rotates the first arm 81 and the second arm 82 in opposite directions from each other.

[0116] The first arm 81 and the second arm 82 are rotatably journaled to a shaft body 80 at respective predetermined positions.

[0117] The first arm 81 is brought into contact with and coupled with the footboard 5 through the footboard-side roller 50 that is rotatably fitted to the end of the first arm 81. In addition, the extending other end of the first arm 81 is provided with a weight 81c.

[0118] The second arm 82 is coupled with and supports the sliding member 4 at the other end through the coupling rod 60, as with the above-described embodiments.

[0119] The pcam mechanism 83 includes an elliptical first cam 83a and an elliptical second cam 83b that are disposed on both sides of the shaft body 80. Arms 81a and 82a project from the cam 83a respectively toward the first arm 81 and the second arm 82, and arms 81b and 82b project from the cam 83b respectively toward the first arm 81 and the second arm 82. Note that the first cam 83a and the second cam 83b are attached to a shaft body that is supported by a frame provided on an unillustrated base, and are movable around the shaft body.

[0120] More specifically, the first cam 83a includes the arm 81a and the arm 82a. The arm 81a projects from the first cam 83a as to be in contact with a lower side surface of the first arm 81. The aim 82a projects from the first cam 83a as to be in contact with a lower side surface of the second arm 82.

[0121] The second cam 83b includes the arm 81b and the arm 82b. The arm 81b projects from the second cam 83b as to be in contact with the lower side surface of the first arm 81. The arm 82b projects from the second cam 83b as to be in contact with the lower side surface of the second arm 82.

[0122] According to the load-type door opening and closing device having the above-described configuration, when a person steps on the footboard 5 from a state where no person steps on the footboard 5, stepping force generated on the footboard 5 acts on one end of the first arm 81 through the footboard-side roller 50, thereby moving the first arm 81 around the shaft body 80 in the clockwise direction.

[0123] At this time, the arm 81b of the second cam 83b is depressed and also the arm 82b is raised. This causes the second arm 82 to move around in the counterclockwise direction.

[0124] Note that the positions of the anus 81a, 82a, 81b, and 82b after the moving operation are respectively denoted by arms 81a, 82a, 81b, and 82b.

[0125] When the second arm 82 moves around in the counterclockwise direction, the coupling rod 60 side of the second arm 82 is depressed, and the sliding member 4 journaled to the coupling rod 60 acts as to depress the lower surface of the door opening rail 3.

[0126] As with the above-described embodiments, the door 1 is displaced in the opening direction along the inclination direction of the door opening rail 3 so as to release the component force applied through the sliding member 4. At this time, the weight of the door 1 is not applied to the sliding member 4, which makes it possible to reduce the load of the sliding member 4 to improve durability thereof.

[0127] Further, to move the door 1 in the opening direction, it is sufficient to move the sliding member 4 from the upper end side of the door opening rail 3 in the down direction along the downward inclination direction of the door opening rail 3. This makes it possible to improve operation speed of the door.

[0128] As mentioned above, according to the load-type door opening and closing device of the present embodiment, it is possible to reduce the load of the sliding member 4 to improve durability, and also to achieve quick operation of the door 1.

[0129] Note that, in the present embodiment, when no person steps on the footboard 5, the first arm 81 moves around in the counterclockwise direction by the weight 81c of the first arm 81. At this time, the arm 81a of the first cam 83a is depressed and also the arm 82a is raised. This causes the second arm 82 to move around in the clockwise direction. Thus, the first arm 81 moves around in the counterclockwise direction to return the footboard 5 to the flowing state, and also the second arm 82 returns to the initial position (the upper end of the door opening rail 3) of the sliding member 4.

Fourth Embodiment

[0130] Next, another load-type door opening and closing device according to the present embodiment is described with reference to FIG. 6. Note that the components same as those of any of the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted. In addition, description of the configurations of the returning sliding member 40 to return the footboard 5, the weight 41, the arm 42, and the shaft part 43 (respectively having the same configuration as components 40 to 43 in the first embodiment) that are configured is also omitted.

[0131] In the opening and closing device of FIG. 6, the coupling rod 60 is directly coupled with the footboard 5. In other words, the coupling member 6 is configured only of the coupling rod 60. The coupling rod 60 is extended in the perpendicular direction from the footboard 5, and has an end coupled with the footboard and the other end provided with the sliding member 4.

[0132] Accordingly, the stepping force of the footboard 5 is directly transferred to the sliding member T through the coupling rod 60 that is integrated with the footboard 5, and the sliding member T accordingly acts as to depress the lower surface of the door opening rail 3.

[0133] As with the above-described embodiments, the door I is displaced in the opening direction along the inclination direction of the door opening rail 3 so as to release the component force applied through the sliding member 4. At this time, the weight of the door 1 is not applied to the sliding member 4, which makes it possible to reduce the load of the sliding member 4 to improve durability thereof.

[0134] Further, to move the door 1 in the opening direction, it is sufficient to move the sliding member 4 from the upper end side of the door opening rail 3 in the down direction along the downward inclination direction of the door opening rail 3. This makes it possible to improve operation speed of the door.

[0135] As mentioned above, according to the load-type door opening and closing device of the present embodiment, it is possible to reduce the load of the sliding member 4 to improve durability, and to achieve quick operation of the door 1.

[0136] In the following, installation examples of the load-type door opening and closing device according to any of the present embodiments are described as Examples for reference.

EXAMPLE 1

[0137] An aluminum alloy door illustrated in II of FIG. 7 was fabricated with use of A6063S-T5 aluminum alloy extraction mold prescribed in JIS H 4100, The aluminum alloy door was a single sliding door that had an effective opening of 800 mm width and 2000 mm height and an outer frame size of 1600 mm width and 2200 mm height. Also, a footboard mechanism unit having a top panel, illustrated in III of FIG. 7 was fabricated. The top panel was freely movable in the vertical direction, and a bottom surface of the top panel had 556 mm width, 956 mm length, and 70 mm height. These were disposed at predetermined positions of a wall opening and a floor dug part of the building, illustrated in I of FIG. 7.

[0138] At this time, a level was accurately adjusted in each of the perpendicular direction and the horizontal direction with use of a laser, followed by fixing. A coupling metal fitting that transferred stepping force of the above-described footboard mechanism unit was installed and fixed at a connection part of the footboard mechanism unit and a meeting mullion of the above-described aluminum alloy door with accuracy at which errors of a distance from the meeting mullion and the height from the bottom surface of the footboard mechanism unit were 0.5 mm. A returning hardware was installed and fixed side by side with the coupling metal fitting. The returning hardware was configured to return atop plate of the footboard to an original position with use of a weight by the principle of leverage.

[0139] After it was confirmed that the top plate of the footboard was vertically moved by 20 mm to 30 mm, the aluminum alloy door was suspended to the supporting rail, and then fixed to a front end of the coupling fitting while the height of a depression runner roller serving as a sliding member was adjusted with respect to the door opening rail. The door opening rail was attached to a lower end skirt part of the door and had gradient of 1 to 3 stages. Then, transferring condition of the stepping force, a size of an opening of the door, and the opening and closing speed of the door were adjusted, and the exerted desired property was confirmed. The installation was thus completed. The door and the footboard mechanism unit operated with favorable response without jumping of the door caused by the impact force by a plurality of concurrent users, and no failure was observed.

EXAMPLE 2

[0140] A development diagram of a frame and a door of a single sliding steel lightweight door was created. The door was to be formed with use of HS G 3302 hot dip galvanized steel sheet that had a thickness of 0.8 min, 1.6 mm, and 2.3 mm, and had a rectangular inner size of 0.95 m0.2 m in an assembled state. Further, the lightweight door was manufactured through cutting process, pressing process, bending process, door assembling process, frame assembling process, painting of rust inhibitor and finish coating, temporal assembling inspection, appearance and dimension inspection. In addition, a footboard mechanism unit including a top plate that had a bottom surface of 556 mm width, 956 mm length, and 70 mm height and was freely movable in the vertical direction was manufactured. The products were packaged and shipped together with fittings and a shipping item list.

[0141] In construction site, the sizes of the wall opening and the floor dug part were confirmed before the installation construction according to the entire configuration diagram of FIG. 8. The steel lightweight door and the footboard mechanism unit were respectively installed in the wall opening and the floor dug part, levels in the perpendicular direction and the horizontal direction were accurately adjusted with use of a laser, followed by fixing.

[0142] A coupling metal fitting that transferred stepping force of the above-described footboard mechanism unit was installed and fixed at a connection part of the footboard mechanism unit and a meeting mullion of the above-described steel lightweight door with accuracy at which errors of a distance from the meeting mullion and the height from the bottom surface of the footboard mechanism unit were 0.5 mm. A returning hardware was installed and fixed side by side with the coupling metal fitting. The returning hardware was configured to return a top plate of the footboard to an original position with use of a weight included therein by the principle of leverage.

[0143] After it was confirmed that the top plate of the footboard was vertically moved by 20 mm to 30 mm, the steel lightweight door was suspended to the supporting rail, and then fixed to a front end of the coupling fitting while the height of a depression pin was adjusted with respect to the door opening rail that was attached to a lower reinforced part of the steel lightweight door. Then, transferring condition of the stepping force, a size of an opening of the door, and the opening and closing speed of the door were adjusted, and the exerted desired property was confirmed. The installation was thus completed. The door and the footboard mechanism unit operated with favorable response without jumping of the door caused by the impact force by a plurality of concurrent users, and no failure was observed.

[0144] As with Examples mentioned above, since the present invention is configured such that the stepping force acts on the door opening rail in the vertical downward direction, it is possible to rapidly response to the stepping operation of the footboard to quickly move the sliding door in the opening direction. Also, the sliding door is moved in the closing direction with use of the winding device, and the moving biasing force is applied to the sliding door by a depressing device in an accelerated manner. Thus, rapid opening and closing operation is possible. Further, it is easy to secure large front width.

[0145] The coupling fitting with a depressing rod that has an end coupled with the footboard mechanism unit and the other end attached with a runner roller serving as the sliding member may be easily changed in setting of biasing force, which allows for automatic opening and closing of the door even with application of light body weight of a child. In addition, this moves the door in the closing direction manually to lock without effort. The sliding door opening and closing device having such remarkable effects is of a type that opens the door with use of a weight applied to the footboard when a person steps. Thus, the device can be easily installed at a place where securement of electricity for an electric motor is difficult, for example, outdoor simple buildings such as a greenhouse. The automatic door opening and closing device for a heavy door may be operated by a user with light body weight, because of high energy efficiency.

[0146] Also, in a steel lightweight door, the size of the skirt part is freely determined. Thus, it is possible to fabricate the steel lightweight door with appropriately set inclined angle and rail width of the door opening rail. Further, a diameter of a runner roller may be set within a range from 50 mm to 60 mm to easily change setting of the biasing force. This makes it possible to improve response, and to improve reliability with less failure, even in a heavy door.

REFERENCE SIGNS LIST

[0147] 1 door

[0148] 2 sliding support rail

[0149] 3 door opening rail

[0150] 4, 4 sliding member

[0151] 5 footboard

[0152] 6 coupling member

[0153] 11 suspension hook

[0154] 12 roller

[0155] 15 constant force spring (winding device

[0156] 40 returning sliding member

[0157] 50 footboard-side roller

[0158] 60 coupling rod

[0159] 61 first coupling body

[0160] 62 second coupling body

[0161] 63 grounding roller

[0162] 70 gear section

[0163] 70a first gear

[0164] 70b second gear

[0165] 71,81 first arm

[0166] 72, 82 second arm

[0167] 41, 71c, 81c weight

[0168] 83 cam mechanism

[0169] 83a, 86 first cam

[0170] 83b, 87 second cam.