JP3057309B2 - Center hinge of interlocking folding door - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center hinge in an interlocking folding door used for opening and closing a front opening of a storage space in furniture such as a clothes wardrobe and a closet.

[0002]

2. Description of the Related Art Conventionally, interlocking folding doors used for furniture and the like are provided with a plurality of door pairs a, b, and c as shown in schematic views of FIGS. 7 and 8A and 8B. Pairs a, b, c
Is connected by a hinge e so that the pair of doors d and d 'can be folded with their back surfaces facing each other, and the opposing ends of two adjacent door pairs a and b and b and c are
A common traveling body f such that the surfaces of the doors d 'and d face each other.
Are connected to each other by a center hinge (not shown). Further, the outer doors d and d 'of the two door pairs a and c at the left and right ends are connected to the traveling body g so as to be freely opened and closed by hinges. An upper guide rail i provided side by side along both upper and lower opening edges of the door mounting body h and a lower guide rail j are engaged with each other via rollers (not shown) so as to be able to run laterally. is there.

In this type of interlocking folding door, when the door is opened, a torque in the opening direction can be applied via the handle k attached to the first door pair a at the end, but the subsequent second door can be applied. It is impossible to directly apply such a torque to the third pair of doors b and c. Therefore, first, the first
By pulling forward through the handle k while pulling the outer door d in the door pair a in the lateral direction, the first door pair a
Is folded and slid laterally along the guide rails i, j, whereby the subsequent pair of second and third doors b, c are folded together to open.

[0004] However, each door pair a, b, c has a door d,
A force acting as a stop (close) catch and a force acting as an open catch for holding d ′ ‥‥‥ closed in a plane are given, and the forces increase in proportion to the number of door pairs. Therefore, it is extremely difficult to open or close a plurality of door pairs a, b, and c at once against such a force. As the number of door pairs increases, the opening of the doors increases. And the closing operation becomes almost impossible.

[0005] Therefore, a folding door already provided with a door opening assisting device has been disclosed in Japanese Patent Publication No. 3-500433. This door opening assist device is shown in FIG.
As shown in FIG. 12, hinges m and m ′ are provided on a common holding device 1 guided so as to be able to travel along the guide rail.
Rotatably connected to the two doors to n adjacent and on each door n _1, o ₁ o For mounting the entraining lug p, p folding by, from the holding device l, hinge m, parallel to the axis of the m ' , the rotary shaft q obtained by projecting forward, bifurcated lever r to pivot about the coaxial q, fitted with r, the lever r, one lever r arm r _1, the r ₁ entraining lug p ,
p and the other lever arm r ₂ , r
₂ is each door n ₁ , o in two adjacent door pairs n, o
_This is a configuration that extends within the range of ₁ .

When the door opening assist device is used, when the doors n ₁ and o ₁ provided with the entrainers p and p have a predetermined turning angle or more,
The torque acting in the opening direction is applied to the door n ₁ via the lever r,
It was added to o _1, a plurality of door body n in this, will be sequentially folded and opened state o from one to the other. Further, in the open state, by applying a torque in the closing direction to the other door pair o, a torque acting in the closing direction is applied to the adjacent door body n via the lever r, whereby the plurality of door pairs n, o are sequentially closed in the direction opposite to the opening.

[0007]

However, in the above door opening assist device, the levers r, r are extended long outside the holding device l by the rotating shaft q, and the doors are opened and closed when the door is opened and closed. In order to reliably and smoothly transmit the required torque between n ₁ and o ₁ , it is necessary to protrude the lever arms r ₁ and r ₂ of the levers r and r long, It will inevitably become larger.

Further, the lever r, r is exposed longer to the rear side of the door n _1, o _1, at the time of opening the door, a large gap is formed between the back surface of the lever arm r ₂ and the door n ₁ since, there during door closing, clothes or the like caught in the lever arm r _2, clothes between the lever arm r ₂ and the door rear surface, also resulting sandwich the other storage products.

Further, between adjacent door pairs n and o,
To ensure that the required torque is transmitted accurately,
Since the dimensional accuracy of the shape and the mounting position of the entraining member p and the levers r and r must be increased, there is also a problem that the working and the mounting operation are complicated.

The present invention has been made in view of the above-mentioned problems of the related art, and in the first aspect, an adjacent pair of doors opens and closes following the opening and closing of the pair of doors at an end portion. Enables running along a pair of guide rails,
The following pair of doors can be opened and closed lightly and smoothly by the running force of the door pair, not at once, and at the same time, each component is included in the traveling body, enabling reduction in size and weight, In addition, an object of the present invention is to provide a center hinge of an interlocking folding door which can improve the door mounting workability and can be provided at a low cost.

Further, according to the present invention, the pair of transmission arms and the pair of interlocking gears are separately supported by a common support shaft so as to rotate separately, and the two interlocking gears are engaged with each other. By connecting the transmission arm and the interlocking gear by the engagement of the interlocking pin and the long hole, the transmission of the door opening / closing force between two adjacent door pairs has a delayed timing, thereby providing a more stable and reliable operation. Claim 3 seeks to further simplify a mechanism for transmitting the door opening / closing force to each other at a delayed timing between two adjacent door pairs. Claim 4 describes the same mechanism as the above. In addition, it is trying to provide a simpler, less expensive and inexpensive unnecessary high precision.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a plurality of door pairs in which a pair of doors are foldably connected are provided. A center hinge of an interlocking folding door that connects a pair to a common traveling body so that the pair can be interlockingly opened and closed.
A pair of attachment bodies respectively attached to opposing ends of the two door pairs, and a traveling body which is pivotally connected to the inner ends of the traveling bodies so that the outer ends are symmetrical outer ends of the respective attachments. A pair of power arms rotatably connected via a link and a pair of power arms each having a distal end rotatably connected to the opposite end of each of the mounting bodies, and a substantially intermediate portion in the longitudinal direction. A pair of interlocking arms whose parts are pivotally connected to the power arms, and a substantially intermediate portion in the longitudinal direction is in a common traveling body, and is supported inside the pair of interlocking arms. A pair of transmission arms rotatably pivotally connected to a rear end of each of the interlocking arms, each of which is pivotally supported so as to be rotatable via a shaft, and Pins with large diameters are attached to both ends of the transmission arms, which are vertically overlapped with each other. The through hole is penetrated to correspond, whereas,
A slide hole is formed in the middle part of the traveling body so as to be long in the front-rear direction, and an interlocking pin slidably inserted in the front-rear direction is loosely fitted in the pin insertion hole and connected to a pair of transmission arms. It is intended to provide a center hinge for an interlocking folding door.

According to a second aspect of the present invention, as compared with the first aspect, a rear end portion is pivotally connected to a rear end portion of each of the interlocking arms, and a front end portion is provided on the left and right inside the traveling body. A pair of transmission arms rotatably supported by a support shaft, and a common support shaft which is vertically overlapped with the transmission arm so as to be rotatable together with the transmission arm and individually. A pair of interlocking gears that are pivotally supported by each other, and each of the transmission arms and the base end of each of the interlocking gears is formed in an elongated hole penetrating one of them, and an interlocking pin protruding from the other. Are different in that they are slidably engaged and connected.

Further, the third embodiment is different from the first embodiment in that a tooth portion is engraved on the peripheral surface of the distal end, and a substantially middle portion in the longitudinal direction is provided inside the traveling body. A pair of interlocks, which are located inside the interlocking arm and are rotatably supported by the support shaft so as to be rotatable and have a base end pivotally connected to the rear end of each of the interlocking arms. A gear is provided, and the both interlocking gears are meshed with a play provided between the respective tooth portions by forming a tooth groove width larger than a tooth thickness by a required dimension.

Further, a different point from the first aspect of the present invention resides in that an opposing shaft is provided such that a substantially middle portion in the longitudinal direction is rotatable by a support shaft at a position inside the two power arms inside the traveling body. A pair of transmission arms are supported, and the inner ends of both transmission arms are provided with an interlocking pin protruding from one side thereof and a wide slide groove formed on the other side to allow play in the groove width direction. It is at a point where they are engaged.

[0016]

When the doors are to be opened, the first pair of doors located at the end of each of the two adjacent pairs of doors is pulled from the closed position along the guide rail while being pulled forward by the handle. This causes the door pair to be opened while being folded.
With the opening of the first door pair, one of the interlocking arms is pivoted outward about the pivot point at the distal end thereof via the link and the power arm.

According to the first aspect of the present invention, the rotation of the interlocking arm causes one of the transmission arms to rotate in a predetermined direction, and the pin insertion hole at the tip end thereof is displaced toward the back side of the traveling body, so that the pin insertion can be performed. The lower opening edge of the hole abuts on the interlocking pin, and the interlocking pin is vertically held by the lower opening edge and the upper opening edge of the pin insertion hole in the other transmission arm. The pair of transmission arms are connected to be able to interlock with each other, whereby the interlocking start state of the two adjacent door pairs is established.

Further, when the first door pair is opened, the interlocking pin is pressed toward the back side of the traveling body by the transmission arm, so that it slides along the slide hole of the traveling body, and the interlocking pin is moved. Is transmitted to the other transmitting arm via the link, where a torque is applied to the second door pair via the interlocking arm, the power arm, and the link, whereby the second door pair is folded. It becomes open.

That is, the opening force of the first door pair is
Since the second door pair is transmitted to the second door pair with a delay timing, the rotation of the second door pair is started when the first door pair is opened at a predetermined angle or more. By following the opening of the first pair of doors and opening the second pair of doors to a certain extent in this way, the second pair of doors together with the first pair of doors can be moved in the lateral direction along the guide rail. Traveling is possible. Therefore, after the second door pair is opened to some extent, the second door pair is opened while being folded by the running force, and by the opening of the door pair, the subsequent third door pair is also opened as described above. Are opened while being folded sequentially from the first door pair at the end.

When the door is to be closed, the first pair of doors is driven along the guide rail from the closed position.
The door pair and the subsequent door pair are run in a folded state, and this running force is applied to the terminal door pair. Thereby, the door pair of the terminal is closed, further, the door pair adjacent thereto is also closed, and thereafter, as in the case of the above-described opening, a plurality of door pairs are sequentially closed, Finally, the first door pair is closed, and the closing of the door is completed.

According to the second aspect, the rotational force of the transmission arm is transmitted to the interlocking gear with a delay within the effective length of the elongated hole. Both interlocking gears are interlocked with a delay of play. Further, according to the fourth aspect, between the pair of transmission arms, the rotational force is transmitted to each other with a delay corresponding to the play between the interlocking pin and the slide groove.

[0022]

1 and 2 show the first embodiment of the present invention.
According to the embodiment of the present invention, the center hinge is located at two adjacent door pairs 1 and 2, and two pairs of doors 1a, 2a are provided respectively.
a are pivotally mounted so that they can be folded freely with their back surfaces facing each other.

This center hinge has a common traveling body 3 (in this embodiment, an upper traveling body) common to the two adjacent door pairs 1 and 2, which has a hollow front surface with an opening 3a. A pair of vertical rollers 4, 4 for preventing horizontal runout and a pair of horizontal rollers 5, 5 for running are respectively supported on a top plate (not shown) of the body, and are shown by furniture or the like. The vertical and horizontal rollers 4, 4, 5, and 5 are rollably engaged with the upper guide rail 6, which is horizontally disposed along the upper opening edge of the door mounting body not to be driven. It is arranged freely.

A pair of plate-like mounting members 7 and 8 are fixed to the back surfaces of the opposing ends of two opposing door pairs 1 and 2 by screws 9 ‥‥‥. Have been.

The pair of left and right power arms 10 and 11 housed in the traveling body 3 are formed in a substantially L-shape in a plane, and the inner ends 10a and 11a of the power arms 10 and 11a 12 are pivotally connected to each other. The power arms 10 and 11 have inner ends 10a and 11a, respectively.
And the outer ends 10b, 11b face forward, and the outer ends 10b, 11b are attached to brackets 7a, 8a protruding from the outer ends that are symmetrical ends of the upper and lower mounting bodies 7, 8.
It is pivotally connected via short links 13 and 14 so as to be rotatable.

The pair of left and right interlocking arms 15 and 16 are formed to be long in the front-rear direction, and have respective front ends 15a and 16a.
Are pivotally attached to brackets 7b, 8b protruding from the opposite ends of the mounting members 7, 8 by pins 17 so as to be rotatable in the left-right direction. , 11 are pivotally connected by pins 18 respectively.

The pair of left and right transmission arms 19 and 20 include:
Large-diameter pin insertion holes 21 and 22 are respectively provided at the distal ends in the up-down direction, and substantially middle portions in the length direction are located on the left and right sides in the traveling body 3, and the top plate and the bottom plate 3a are provided. , Which are rotatable by the support shafts 23 provided on the inner side of the pair of interlocking arms 15, 16, and whose base ends are behind the interlocking arms 15, 16. The pins 15 are pivotally attached to the ends 15b and 16b by pins 24, and the respective tips are vertically overlapped.

The top plate (not shown) of the traveling body 3 and the bottom plate 3
a, the support shafts 23, 23 in the intermediate portion in the left-right direction and in the pair of transmission arms 19, 20.
A slide hole 25 is formed in the middle of the slide hole 25 in the front-rear direction.
It is slidably inserted in the direction perpendicular to the axis in the front-rear direction. This link pin 26 is not shown,
It is supported by the traveling body 3 in a state where it is prevented from dropping out of the slide hole 25 by a washer locked at its upper and lower parts, a nut to be hinged, and the like. The interlocking pin 26 is connected to the pair of transmission arms 19, 2
0 through the pin insertion holes 21 and 22.

Here, the two pin insertion holes 21 and 22 are
By forming the diameter of the interlocking pin 26 larger than the diameter of the interlocking pin 26 by an appropriate dimension, an appropriate play is provided between the two, so that the transmission arms 19, 20 are opened and closed by opening and closing the door pairs 1, 2. When rotated, the rotational forces are transmitted with a time delay to each other.

Therefore, when the door is opened, when one door pair 2 is opened from the closed position by a predetermined angle in the direction of arrow A as shown in FIG.
That is, the transmission arm 20 is rotated in the direction shown by arrow B, whereby one of the transmission arms 20 is rotated clockwise about the support shaft 23, and the lower opening edge of the pin insertion hole 22 and
The interlocking pin 26 is sandwiched by the upper opening edge of the pin insertion hole 21 of the other transmission arm 19, and the two transmission arms 19, 20 are interposed via the interlocking pin 26.
Is directly connected with no play during that time. Therefore, when the door 2a is opened at the predetermined angle or more, the torque in the opening direction is applied to the adjacent door pair 1 via the interlocking arm 15 and the power arm 10 and the link 13 via the transmission arms 19 and 20. Will be given.

In the center hinge according to the second aspect, as shown in FIGS. 3 and 4, a pair of transmission arms 19 and 20 are formed in a short length, and the tip end thereof and a pair of interlocking gears 27 and
28 in the vertical direction, and a common support shaft 2
3 is provided inside the running body 3 so as to be rotatable and rotatable separately. The two interlocking gears 27 and 28 are meshed with each other. Further, at a substantially intermediate portion in the length direction of each of the transmission arms 19 and 20, and at the base end of each of the interlocking gears 27 and 28 opposed thereto,
Interlocking pins 29 and 30 protrude from either one of them,
On the other side, arc-shaped long holes 31 and 32 are formed along a circumferential line centered on the support shaft 23, and the interlocking pins 29 and 30 are slidably engaged with the long holes 31 and 32, respectively. .

When one door pair 2 is opened in the direction of arrow A as shown in FIG. 4, the transmission arm 20 is rotated by the rotation of the interlocking arm 16 in the direction of arrow B. The interlocking pin 30 is in contact with one end of the long hole 32. When the door pair 2 is further opened, the interlocking gear 28 is rotated in the direction of the arrow shown in FIG.
7 is rotated in the direction of the arrow shown in the figure, whereby the linking pin 29 and the end of the elongated hole 31 come into contact with each other, and the linking is started. Therefore, when the door pair 2 is opened by a predetermined angle or more, the adjacent door pair 1 is opened in conjunction with the opening.

The center hinge shown in FIG. 5 according to claim 3 has a pair of interlocking gears 27a and 28a having a substantially middle portion and a base end in the length direction, which are described above with reference to FIGS. And the teeth 27b and 28b are meshed with each other in the same manner as the transmission arms 19 and 20 of FIG. Here, the tooth groove width A of each of the interlocking gears 27a and 28a is formed to be larger than the tooth thickness B by an appropriate dimension, so that both the interlocking gears 27a and 28a
It is engaged with play between b.

Therefore, between the two adjacent door pairs 1 and 2, the rotational force of one interlocking gear due to the opening of one door pair is not immediately transmitted to the other interlocking gear. When the door pair is opened at a predetermined angle or more, the rotational force is transmitted to the other transmission gear. That is, with respect to the opening of one door pair, the other door pair is opened interlocked with a slight delay.

In the center hinge shown in FIG. 6 according to the fourth aspect, the pair of transmission arms 19a and 20a are connected to the first hinge.
As in the case of the embodiment, it is pivotally attached to the traveling body 3 and the interlocking arms 15 and 16, but the transmission arms 19a,
20a itself is different from that according to the first embodiment as follows. That is, the pair of transmission arms 19a, 20
a is located at the tip end, and the link pin 3
3, a slide groove 34 is formed in the other end in an open state, and the interlocking pin 33 is engaged with the slide groove 34.

Here, the width of the slide groove 34 is formed to be wider than the diameter of the interlocking pin 33 by an appropriate dimension, and when both are engaged, an appropriate play is provided in the groove width direction. In this case, the opening force of the pair of doors is transmitted as the opening force to the other door pair with a slight delay in time.

Although the above description has been made with reference to the upper center hinge, the lower center hinge can be configured in the same manner as the upper center hinge.

[0038]

According to the present invention, as described above, according to the first aspect, in an interlocking folding door having a plurality of door pairs, each of two adjacent door pairs has one of them. By being opened at a predetermined angle or more, the other is folded and opened to some extent, whereby it is possible to run along the guide rail, and with the running force, the subsequent door pair can be opened smoothly sequentially. In addition, since each component is included in the traveling body, it is possible to reduce the size and weight, and it is not necessary to have high precision in dimensions between each component and mounting of the door, so that it can be manufactured at low cost. hand,
In addition, the door can be efficiently attached with good workability.

According to the second aspect, the action of transmitting the door opening / closing force between the two adjacent pairs of doors with a time delay by the pair of interlocking gears becomes more stable and reliable. According to the third aspect of the present invention, the transmission with a delay of the door opening / closing force between two adjacent door pairs can be achieved by a simpler structure by the pair of transmission gears. In some cases, the above-described door opening / closing force transmission mechanism between two adjacent door pairs is
It can be configured more simply, which makes it possible to provide such a hinge at a lower cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view showing a center hinge of an interlocking folding door according to a first embodiment of the present invention in a door-closed state according to one embodiment.

FIG. 2 is a cross-sectional plan view showing a door opening interlocking start state of the embodiment.

FIG. 3 is a cross-sectional plan view showing a center hinge according to an embodiment of the present invention in a door closed state.

FIG. 4 is a cross-sectional plan view showing the door opening and interlocking start state of the embodiment.

FIG. 5 is a cross-sectional plan view showing one embodiment of the center hinge according to claim 3;

FIG. 6 is a cross-sectional plan view showing one embodiment of the center hinge according to claim 4;

FIG. 7 is a schematic front view of an interlocking folding door.

8A and 8B are schematic plan views of the interlocking folding door, wherein FIG. 8A is a schematic plan view of a door closed state, and FIG. 8B is a schematic plan view of a door opened state.

FIG. 9 is a rear view showing a door opening assist device in a conventional interlocking folding door.

FIG. 10 is a plan view showing a state in which the door is closed, showing the device.

FIG. 11 is a plan view showing a door opening interlocking start state showing the same device.

FIG. 12 is a plan view showing a door closing interlocking start state showing the same device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 door pair 2 door pair 1a door 2a door 3 traveling body 7 mounting body 8 mounting body 10 power arm 11 power arm 13 link 14 link 15 interlocking arm 16 interlocking arm 19 transmission arm 20 transmission arm 19a transmission arm 20a transmission Arm 21 Pin insertion hole 22 Pin insertion hole 25 Slide hole 26 Interlocking pin 29 Interlocking pin 30 Interlocking pin 27 Interlocking gear 27a Interlocking gear 28 Interlocking gear 28a Interlocking gear 27b Tooth 28b Tooth 31 Long hole 32 Long hole A tooth Groove width B Tooth thickness

Claims (4)

(57) [Claims] 1. An interlocking folding door having a plurality of door pairs in which a pair of doors are foldably connected, and connecting two adjacent door pairs to a common traveling body so as to be able to integrally open and close in an interlocking manner. A center hinge, a pair of attachment bodies respectively attached to opposing ends of two adjacent door pairs, and a traveling body, which is rotatably pivoted at an inner end to each other, and each outer end is A pair of power arms connected rotatably via a link and a symmetrical outer end of each of the mounting bodies,
A pair of opposed ends, each of which has a distal end pivotally attached to the opposite end of each of the mounting bodies so as to be rotatable, and a substantially intermediate portion in the length direction pivotally attached to each of the power arms. An interlocking arm and a substantially intermediate portion in the longitudinal direction are in a common traveling body, and are each pivotally supported inside a pair of the interlocking arms via a support shaft, and each base end portion. Has a pair of transmission arms rotatably pivotally connected to the rear end of each of the interlocking arms, and the two transmission arms have two end portions that are vertically overlapped with each other, A large-diameter pin insertion hole is correspondingly penetrated, while a slide hole is formed long in the front-rear direction in an intermediate portion of the traveling body, and an interlocking pin slidably inserted in the front-rear direction is provided in the pin insertion hole. Characterized by being loosely fitted to and connected to a pair of transmission arms. Folding door of the center hinge. 2. An interlocking folding door having a plurality of door pairs in which a pair of doors are foldably connected, and connecting to a common traveling body so that two adjacent door pairs can be opened and closed in an integrated manner. A pair of attachment bodies respectively attached to opposing ends of two adjacent door pairs,
A pair of powers which are rotatably connected to each other at the inner ends of the traveling body and whose outer ends are rotatably connected to the symmetrical outer ends of the mounting bodies via links. The arm and the distal ends are rotatably pivotally attached to the opposite ends of the mounting bodies, respectively, and a substantially middle portion in the length direction is pivotally pivotally attached to each of the power arms. A pair of interlocking arms and a rear end are rotatably pivotally connected to a rear end of each of the interlocking arms, and a front end is rotatably supported by left and right support shafts inside the traveling body. A pair of transmission arms, and a pair of interlocks that are vertically overlapped with the transmission arm and supported by a common support shaft so as to be rotatable together with the transmission arm and individually. A gear, and each of the transmission arms and a base end of each of the interlocking gears, Interlocking folding door of the center hinge long hole which is formed through the one, characterized in that the concatenation of the interlocking pin which projects from the other slidably in Kakarihama to. 3. An interlocking fold comprising a plurality of door pairs in which a pair of doors are pivotally mounted so as to be freely foldable, and two adjacent door pairs are connected to a common traveling body so as to be able to open and close integrally with each other. A center hinge of the door, and a pair of attachment bodies respectively attached to opposed ends of two adjacent door pairs; A pair of power arms that are rotatably connected via a link and a symmetrical outer end of each of the mounting bodies,
A pair of opposed ends, each of which has a distal end pivotally attached to the opposite end of each of the mounting bodies so as to be rotatable, and a substantially intermediate portion in the length direction pivotally attached to each of the power arms. An interlocking arm and a tooth portion are engraved on the distal end peripheral surface, and a substantially middle portion in the length direction is opposed to the inside of the traveling body such that the interlocking arm is rotatable by a support shaft located inside the pair of interlocking arms. And a pair of interlocking gears whose base ends are rotatably pivotally connected to the rear ends of the interlocking arms. The center hinge of the interlocking folding door, characterized in that the center hinge of the interlocking folding door is formed so as to have a play between the respective tooth portions by being formed by a required dimension. 4. An interlocking folding door having a plurality of door pairs in which a pair of doors are foldably connected, and connecting two adjacent door pairs to a common traveling body so as to be able to open and close integrally with each other. A center hinge, a pair of attachment bodies respectively attached to opposing ends of two adjacent door pairs, and a traveling body, which is rotatably pivoted at an inner end to each other, and each outer end is A pair of power arms connected rotatably via a link and a symmetrical outer end of each of the mounting bodies,
A pair of opposed ends, each of which has a distal end pivotally attached to the opposite end of each of the mounting bodies so as to be rotatable, and a substantially intermediate portion in the length direction pivotally attached to each of the power arms. An interlocking arm, and a pair of transmission arms, each of which has a substantially middle portion in the longitudinal direction and is rotatably supported by a support shaft at a position inside the power arms inside the traveling body so as to be rotatable by a support shaft; An interlocking fold wherein an interlocking pin protruding from one side of an inner end of a transmission arm and a wide sliding groove formed on the other side are engaged with play in a groove width direction. Door center hinge.