Patent Description:
For example, a hinge device is used to rotatably attach a door (rotating object) to a housing (stationary object). A hinge device disclosed in Patent Document <NUM> (<CIT>) has a first hinge body attached to an inner surface of an opening side edge portion of a housing, a second hinge body fixed to a housing side surface of a side edge portion of a door and a link mechanism interposed between the first and second hinge bodies.

The above link mechanism will be briefly described. A moving link is movably connected to the first hinge body in a front-rear direction via a front and rear connecting links. That is, a proximal end of the rear connecting link is rotatably connected to a rear end of the first hinge body (an end farther from the second hinge body), and a proximal end of the front connecting link is rotatably connected to a front end of the first hinge body (an end closer to the second hinge body). A rear end of the moving link is rotatably connected to a distal end of the rear connecting link and an intermediate portion of the moving link is connected to an intermediate portion of the front connecting link so that the moving link moves in a front-rear direction as the front and rear connecting links rotate.

A front end of the moving link is rotatably connected to the second hinge body. One end of a supporting link is rotatably connected to a distal end of the front connecting link and the other end of the supporting link is rotatably connected to the second hinge body.

When the hinge device disclosed in Patent Document <NUM> is used, the door rotates from a closed state so as to cover an opening side end face of the housing while a side edge portion of the door on the hinge device side moves away from the housing. Therefore, the door can be opened at a relatively large opening angle without interfering with the housing.

Generally, the first and second hinge bodies and the four links are made of metal, and in order to prevent the metals of these constituent members from rubbing against each other, resin spacers are interposed between the constituent members that are rotatably connected to each other. These spacers are supported by shaft members that penetrate the constituent members. Patent Document <NUM> also shows a resin spacer interposed between the moving link and the front connecting link.

In the hinge device described above, the first hinge body has a pair of side walls, and the moving link has side walls of which a distance is wider than a distance between the pair of side walls of the first hinge body. Even when the moving link and the first hinge body overlap in the direction of the rotation axis, a gap is formed between the side wall of the first hinge body and the side wall of the moving link so that the metals do not rub against each other.

However, if the weight of the door to be supported becomes large, the constituent members of the hinge device are likely to be distorted and the door cannot be stably supported because there is a gap between the side wall of the first hinge body which is a main bearer of a load and the side wall of the moving link.

In order to solve the above problem, the present invention is a hinge device including a first hinge body having a pair of side walls, a second hinge body provided on a front side of the first hinge body and a link mechanism interposed between the first hinge body and the second hinge body, wherein the link mechanism including a moving link supported by the first hinge body so as to be movable in a front-rear direction, the moving link having a pair of side walls and a front end portion rotatably connected to the second hinge body, a front connecting link having a proximal end portion rotatably connected to a front end portion of the first hinge body and an intermediate portion rotatably connected to an intermediate portion of the moving link, and a supporting link having one end rotatably connected to a distal end of the front connecting link and the other end rotatably connected to the second hinge body, wherein the hinge device is configured such that the pair of side walls of the moving link overlap an outside of the pair of side walls of the first hinge body, and wherein the front connecting link has a main part connected to the first hinge body, the moving link and the supporting link and a pair of spacers made of resin interposed between the pair of side walls of the first hinge body and the pair of side walls of the moving link.

According to the above configuration, since the resin spacers are interposed between the side wall of the first hinge body which is a main bearer of a load but are not in a direct rotational connection relationship and the side wall of the moving link, the first hinge body attached to a stationary object can receive the load of a rotating object via the second hinge body and the moving link, and further via the spacer so that it is possible to suppress distortion of the constituent members of the hinge device due to a gap between the side wall of the first hinge body and the side wall of the moving link. As a result, the rotating object can be stably supported even if the weight of the rotating object is large.

Further, since the spacer is made of resin, even if the first hinge body and the moving link are made of metal, it is possible to avoid rubbing between the metals.

It is preferred that the main part of the front connecting link has a proximal end side connecting portion that enters between the pair of side walls of the first hinge body and is rotatably connected to the front end portion of the first hinge body and an intermediate connecting portion that enters between the pair of side walls of the moving link and is rotatably connected to the intermediate portion of the moving link, and at least both sides of the proximal end side connecting portion and the intermediate connecting portion are made of resin.

According to the above configuration, the first hinge body can firmly receive the load from the moving link while avoiding the rubbing between the metals even through the main part of the front connecting link so that the rotating object can be supported more stably.

It is preferred that both side surfaces of the intermediate connecting portion and outer surfaces of the pair of spacers are flush with each other.

According to the above configuration, since the front connecting link supports the moving link over a wide area, it is possible to support the rotating target more stably.

It is preferred that the pair of spacers extends between the intermediate connecting portion of the main part and the proximal end side connecting portion, a pair of slits are formed between both side surfaces of the main part and an inner surface of the pair of spacers and the pair of side walls of the first hinge body enters the pair of slits.

According to the above configuration, the side wall of the first hinge body, the side wall of the moving link, the main part of the front connecting link and the spacer overlap each other so that the load can be borne even more firmly.

It is preferred that the main part of the front connecting link has a distal end side connecting portion that enters between a pair of side walls of the supporting link and is rotatably connected to the one end of the supporting link, and at least both sides of the distal end side connecting portion are made of resin.

According to the above configuration, the first hinge body can firmly bear the load while avoiding rubbing between the metals even through the main part of the front connecting link from the supporting link. Further, even if the supporting link is made of metal, the metal does not rub against each other between the front connecting link and the supporting link.

It is preferred that the entire front connecting link is made of resin and the main part and the pair of spacers are integrated.

According to the above configuration, the front connecting link can be easily manufactured.

It is preferred that the front connecting link includes a pair of halved members that are assembled together, an storage hole is formed between the pair of halved members, a linear damper is stored in the storage hole and a contact member provided at a distal end of the linear damper is in contact with the front end portion of the first hinge body.

According to the above configuration, the storage hole for storing the linear damper can be easily formed.

The hinge device further includes a rear connecting link made of resin and the rear connecting link integrally includes a proximal end side connecting portion that enters between the pair of side walls of the first hinge body and is rotatably connected to a rear end portion of the first hinge body, a distal end side connecting portion that enters between the pair of side walls of the moving link and is rotatably connected to a rear end of the moving link, and a pair of spacers interposed between the pair of side walls of the first hinge body and the pair of side walls of the moving link.

According to the above configuration, the load can be borne by the spacer of the rear connecting link being interposed between the first hinge body and the moving link so that the rotating object can be supported more stably.

According to the present invention, the rotating object can be stably supported even when the weight of the rotating object is large.

As shown in <FIG>, a hinge device <NUM> rotatably connects one side edge (right edge) of a door <NUM> (rotating object) to one side edge (in this embodiment, a side edge located on a right side when a housing <NUM> is viewed from an opening side thereof) of the opening of the housing <NUM> (stationary object) and are installed at two locations (plural locations) separated in the vertical direction (direction orthogonal to the paper surface in <FIG>). Hereinafter, the opening side of the housing <NUM> will be referred to as a front side, and a back side of the housing <NUM> will be referred to as a rear side.

The door <NUM> can be opened up to <NUM> degrees as shown in <FIG> from a state in which the opening of the housing <NUM> is closed as shown in <FIG> via a state in which the door <NUM> is opened by <NUM> degrees.

As shown in <FIG>, the hinge device <NUM> includes a washer <NUM>, a first hinge body <NUM>, a second hinge body <NUM>, and a link mechanism <NUM> interposed between the first and second hinge bodies <NUM>, <NUM>.

The washer <NUM> is fixed to an inner surface of a side wall of the housing <NUM> with screws. The first hinge body <NUM> is detachably attached to the washer <NUM>. Since this attaching structure is known, detailed description thereof will be omitted. The washer <NUM> and the first hinge body <NUM> are made of metal.

The first hinge main body <NUM> extends in a front-rear direction and has a pair of side walls <NUM> that are parallel to each other and face each other in the vertical direction.

The second hinge body <NUM> is made of hard resin and has a socket portion <NUM> and a pair of flange portions <NUM> protruding in the vertical direction from the socket portion <NUM>. As shown in <FIG>, a recess 2a is formed on a surface of the right edge of the door <NUM> on a side of the housing <NUM>, the socket portion <NUM> is fitted into the recess 2a, and the flange portions <NUM> are fixed to the door <NUM> with screws, so that the second hinge body <NUM> is attached to the door <NUM>.

The link mechanism <NUM> includes a moving link <NUM> made of metal, a rear connecting link <NUM> made of hard resin, a front connecting link <NUM> made of hard resin and a supporting link <NUM> made of metal.

The moving link <NUM> is formed into an elongated shape in a longitudinal direction of the first hinge body <NUM>, and has a pair of side walls <NUM> that are parallel to each other and face each other in the vertical direction and a connecting wall <NUM> that connects rear portions of the side walls <NUM> to be formed to have a substantially U-shaped cross section. The supporting link <NUM> also has a pair of side walls <NUM> that are parallel to each other and face each other vertically and a connecting wall <NUM> that connects the side walls <NUM> to be formed to have a substantially U-shaped cross section.

The moving link <NUM> is movably connected to the first hinge body <NUM> in the front-rear direction via the rear connecting link <NUM> and the front connecting link <NUM>. Briefly, a proximal end portion of the rear connecting link <NUM> is rotatably connected to a rear end portions of the pair of side walls <NUM> of the first hinge body <NUM> by a first shaft member <NUM>. The proximal end portion of the front connecting link <NUM> is rotatably connected to a front end portions of the pair of side walls <NUM> of the first hinge body <NUM> by a second shaft member <NUM>.

A rear end portion of the moving link <NUM> is rotatably connected to a distal end of the rear connecting link <NUM> by a third shaft member <NUM> and an intermediate portion of the moving link <NUM> is rotatably connected to an intermediate portion of the front connecting link <NUM> by a fourth shaft member <NUM>. With this configuration, the moving link <NUM> can move in the front-rear direction (longitudinal direction of the first hinge body <NUM> and the moving link <NUM>) as the rear connecting link <NUM> and the front connecting link <NUM> rotate.

A front end portion of the side wall <NUM> of the moving link <NUM> enters the socket portion <NUM> of the second hinge body <NUM> and is rotatably connected to the socket portion <NUM> by a fifth shaft member <NUM>.

One end of the side wall <NUM> of the supporting link <NUM> is rotatably connected to a distal end of the front connecting link <NUM> by a sixth shaft member <NUM>. The other end of the side wall <NUM> of the supporting link <NUM> enters the socket portion <NUM> of the second hinge body <NUM> and is rotatably connected to the socket portion <NUM> by a seventh shaft member <NUM>.

The shaft members <NUM> to <NUM> extend in the vertical direction and are parallel to each other. The fifth shaft member <NUM> and the seventh shaft member <NUM> are separated from each other at the socket portion <NUM> of the second hinge body <NUM>.

The moving link <NUM> is wider than the first hinge body <NUM>, the front and rear connecting links <NUM> and <NUM> and the supporting link <NUM>, and these components can be stored between the pair of side walls <NUM>.

Since a distance between inner surfaces of the pair of side walls <NUM> of the moving link <NUM> is wider than a distance between outer surfaces of the pair of side walls <NUM> of the first hinge body <NUM> and a distance between outer surfaces of the pair of side walls <NUM> of the supporting link <NUM>, the side wall <NUM> and the side walls <NUM> and <NUM> are separated from each other, so that the metals do not rub directly against each other even when the side wall <NUM> of the moving link <NUM> and the side wall <NUM> of the first hinge body <NUM> and the side wall <NUM> of the supporting link <NUM> overlap in the direction of the rotation axis.

Next, the configuration of the front connecting link <NUM> made of resin will be described in detail. As shown in <FIG>, the front connecting link <NUM> is configured by assembling two halved members 50a and 50b made of the resin. As shown in <FIG>, a main part 50x of the front connecting link <NUM> includes a proximal end side connecting portion <NUM> rotatably connected to a front end portion of the first hinge body <NUM>, an intermediate connecting portion <NUM> rotatably connected to an intermediate portion of the moving link <NUM>, a distal end side connecting portion <NUM> rotatably connected to one end of the supporting link <NUM>, a cam portion <NUM> and a cover attaching portion <NUM>. Further, the main part 50x has a linearly extending storage hole <NUM> (see, <FIG>) formed between the two halved members 50a and 50b.

Through holes 51a, 52a and 53a are formed in each connecting portion <NUM>, <NUM> and <NUM> for passing the second shaft member <NUM>, the fourth shaft member <NUM> and the sixth shaft member <NUM>, respectively.

The front connecting link <NUM> further has a pair of thin plate-shaped spacers <NUM> formed integrally with the main part 50x on both sides of the main part 50x. These spacers <NUM> are arranged so as to extend between the distal end side connecting portion <NUM> and the intermediate connecting portion <NUM> of the main part 50x and reach the cam portion <NUM>. A slit <NUM> is formed between the pair of spacers <NUM> and both side surfaces of a portion of the main part 50x facing the spacer <NUM>.

As shown in <FIG>, the side wall <NUM> of the first hinge body <NUM> is inserted into the slit <NUM> of the front connecting link <NUM> without a gap. In the main part 51x of the front connecting link <NUM>, both side surfaces of a portion including the proximal end side connecting portion <NUM> and the cam portion <NUM> are provided as continuous flush surfaces 59a in contact with an inner surface of the side wall <NUM>. An inner surface of the spacer <NUM> is provided as a sliding surface 59b in contact with an outer surface of the side wall <NUM>.

A portion including the pair of spacers <NUM> of the front connecting link <NUM>, the intermediate connecting portion <NUM> of the main part 51x and the cover attaching portion <NUM> is inserted between the pair of side walls <NUM> of the moving link <NUM> without a gap and an outer surfaces of the pair of spacers <NUM> and both side surfaces of the main part 51x are provided as continuous flush surfaces 59c in contact with an inner surface of the side wall <NUM>.

As shown in <FIG>, the distal end side connecting portion <NUM> is inserted between the pair of side walls <NUM> of the supporting link <NUM> without a gap and both side surfaces thereof are provided as sliding surfaces 59d in contact with the side wall <NUM>.

Since the distance between the pair of side walls <NUM> of the moving link <NUM> is wider than the distance between the pair of side walls <NUM> of the first hinge body <NUM> and the pair of side walls <NUM> of the supporting link <NUM>, the sliding surface 59c projects outward in the width direction from the sliding surfaces 59a and 59d.

Next, the rear connecting link <NUM> made of resin will be described in detail with reference to <FIG>. The rear connecting link <NUM> integrally has a main part 40x and a pair of spacers <NUM> arranged on both sides of the main part 40x.

The main part 40x of the rear connecting link <NUM> has a proximal end side connecting portion <NUM> and a distal end side connecting portion <NUM>. Through holes 41a and 42a for passing the first shaft member <NUM> and the third shaft member <NUM> are formed in the connecting portions <NUM> and <NUM>. The proximal end side connecting portion <NUM> is inserted between the pair of side walls <NUM> of the first hinge body <NUM> without a gap and is rotatably connected to a rear end portion of the first hinge body <NUM>, and the distal end side connecting portion <NUM> is inserted between the pair of side walls <NUM> of the moving link <NUM> without a gap and is rotatably connected to a rear end portion of the moving link <NUM>.

The side wall <NUM> of the first hinge body <NUM> is inserted into a slit <NUM> formed between the main part 40x and a spacer <NUM> without a gap and the spacer <NUM> is inserted between the side wall <NUM> of the first hinge body <NUM> and the side wall <NUM> of the moving link <NUM> without a gap.

Next, the configuration associated with the hinge device <NUM> will be briefly described. As shown in <FIG> and <FIG>, the hinge device <NUM> includes an energizing mechanism <NUM>. The energizing mechanism <NUM> has a spring holder <NUM> supported by the shaft member <NUM> that connects the rear connecting link <NUM> and the moving link <NUM>, a slider <NUM> that can slide along the connecting wall <NUM> of the moving link <NUM>, a compression coil spring <NUM> arranged between the spring holder <NUM> and the slider <NUM> and a pressing roller <NUM> provided at a distal end of the slider <NUM>. The pressing roller <NUM> is pressed against a peripheral surface of the cam portion <NUM> of the front connecting link <NUM> by the force of the compression coil spring <NUM> and the door <NUM> is energized in a closing direction in a state of less than a predetermined opening angle by the cam action of the cam portion <NUM>.

A linear damper <NUM> is stored in the storage hole <NUM> of the front connecting link <NUM>. A contact member <NUM> is provided at a distal end of a rod of the linear damper <NUM> and the contact member <NUM> is in contact with a front end portion of the first hinge body <NUM>. The linear damper <NUM> cushions a impact when the door <NUM> is closed.

A cover <NUM> is attached to the front connecting link <NUM> by a pin <NUM>. The cover <NUM> is energized toward the front connecting link <NUM> by a spring <NUM> wound around the pin <NUM>. The cover <NUM> can cover the cam portion <NUM> when the door <NUM> is in the open state.

An operation of the hinge device <NUM> having the above configuration will be described. As shown in <FIG>, when the door <NUM> closes the opening of the housing <NUM>, the second hinge body <NUM> is located at a position close to the first hinge body <NUM> at a substantially right angle to the first hinge body <NUM> and the door <NUM> covers an end surface 1a on the opening side of the housing <NUM>.

As shown in <FIG>, in the closed state of the door <NUM>, the pair of side walls <NUM> of the moving link <NUM> overlap the pair of side walls <NUM> of the first hinge body <NUM> over a wide range and the pair of spacers <NUM> of the front connecting link <NUM> are interposed between the side wall <NUM> of the hinge body <NUM> and the side wall <NUM> of the moving link <NUM> over a relatively wide area A0 (shown by hatching) in this overlapping region. As a result, the load of the door <NUM> is received by the first hinge body <NUM> from the moving link <NUM> via the spacer <NUM>. In particular, in this embodiment, the load is transmitted in a state where the main portion 50x of the front connecting link <NUM>, the side wall <NUM> of the first hinge body <NUM>, the spacer <NUM> and the side wall <NUM> of the moving link <NUM> are overlapped, so that the load can be received even more effectively.

Further, in a region other than the region A0, the load is transmitted from the side wall <NUM> of the moving link <NUM> to the main part 50x of the front connecting link <NUM> via the sliding surface 59c, and is transmitted from the side wall <NUM> of the supporting link <NUM> to the main part 50x via the sliding surface 59d, and is further transmitted from the main part 50x to the side wall <NUM> of the first hinge body <NUM> via the sliding surface 59a, so that the load of the door <NUM> can be received even through this path.

Further, also in the rear connecting link <NUM>, the pair of spacers <NUM> are interposed between the side wall <NUM> of the hinge body <NUM> and the side wall <NUM> of the moving link <NUM> in the region B0 (shown by hatching), so that the load of the door <NUM> can be received.

Since the load of the door <NUM> is received as described above, the door <NUM> can be stably supported without distorting the constituent members of the hinge device <NUM> even if the weight of the door <NUM> is large.

When the door <NUM> is opened against the energizing force in the closing direction, as the moving link <NUM> moves forward due to the rotation of the front and rear connecting links <NUM> and <NUM>, the door <NUM> is rotated in the opening direction while the side edge portion of the door <NUM> moves away from the housing <NUM>. In the rotation range in which the door <NUM> reaches an opening angle of <NUM> degrees, the spacer <NUM> is temporarily disengaged from the overlapping region of the side wall <NUM> of the first hinge body <NUM> and the side wall <NUM> of the moving link <NUM> in a partial angle range, but similar to the closed state described above, the load of the door <NUM> is received by the first hinge body <NUM> from the moving link <NUM> and the supporting link <NUM> via the main part 50x of the front connecting link <NUM>. The same applies to the rear connecting link <NUM>.

As shown in <FIG>, when the door <NUM> is in an intermediate opening position, for example, the opening position of <NUM> degrees, an overlapping region between the pair of side walls <NUM> of the moving link <NUM> and the pair of side walls <NUM> of the first hinge body <NUM> becomes narrower, but the pair of spacers <NUM> of the front connecting link <NUM> are interposed between the side wall <NUM> of the first hinge body <NUM> and the side wall <NUM> of the moving link <NUM> in a partial area A1 (indicated by hatching) of this overlapping region. Further, the sliding surface 59c is in contact with the inner surface of the side wall <NUM> of the moving link <NUM> in a wide range, and the sliding surface 59d is in contact with the inner surface of the side wall <NUM> of the supporting link <NUM>, and the sliding surface 59a of the main part 50x is in contact with the inner surface of the side wall <NUM> of the first hinge body <NUM>, so that the load transmission via the main part 50x is also maintained. In the rear connecting link <NUM>, the load is transmitted only through the main part 40x.

As shown in <FIG>, the door <NUM> can be further opened up to a set angle (<NUM> degrees in this embodiment). In a partial area A2 (indicated by hatching) in the overlapping region of the pair of side walls <NUM> of the moving link <NUM> and the pair of side walls <NUM> of the first hinge body <NUM>, the pair of spacers <NUM> of the front connecting link <NUM> are interposed between the side wall <NUM> of the first hinge body <NUM> and the side wall <NUM> of the moving link <NUM>. Further, the sliding surface 59c of the main part 50x is in contact with the inner surface of the side wall <NUM> of the moving link <NUM> in a wide area, and the sliding surface 59d is in contact with the side wall <NUM> of the supporting link <NUM>, and the sliding surface 59a of the main part 50x is in contact with the inner surface of the side wall <NUM> of the first hinge main body <NUM>, so that the load transmission via the main part 50x is also maintained. In the rear connecting link <NUM>, the load is transmitted only through the main part 40x.

As described above, since the load of the door <NUM> in the open position can be received, the door <NUM> can be stably supported and opened/closed. When opening and closing the door <NUM>, since the front and rear connecting links <NUM> and <NUM> are made of resin, it is possible to avoid rubbing between the metals.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention as defined by the appended claims.

The side wall of the first hinge body and the side wall of the moving link may overlap in the entire rotation range from the closed position of the door to the fully open position, or may overlap in a partial angle range.

The spacer of the front connecting link may be interposed between the side wall of the first hinge body and the side wall of the moving link over the entire angle range where the side wall of the first hinge body and the side wall of the moving link overlap, or the spacer may be interposed only in a part of the above angle range.

The front connecting link may be composed of a single resin molded product instead of assembling the two halved members.

The spacer may be separated from the main part of the front connecting link and fixed to this main part.

The front connecting link may be made of metal in the middle and resin on both sides thereof.

In the above embodiment, the rear end portion of the moving link <NUM> is connected to the first hinge body <NUM> via the rear connecting link <NUM> so as to be movable in the front-rear direction. Instead of using the rear connecting link <NUM>, by providing a slide pin at the rear end of the moving link and slidably inserting the slide pin into the slit formed in the first hinge body, the rear end of the movement link may be connected to the first hinge body so as to be movable in the front-rear direction.

The stationary object may be a door frame instead of the housing.

Claim 1:
A hinge device comprising:
a first hinge body (<NUM>) having a pair of side walls (<NUM>),
a second hinge body (<NUM>) provided on a front side of the first hinge body (<NUM>) and
a link mechanism (<NUM>) interposed between the first hinge body (<NUM>) and the second hinge body (<NUM>),
the link mechanism (<NUM>) comprising:
a moving link (<NUM>) supported by the first hinge body (<NUM>) so as to be movable in a front-rear direction, the moving link (<NUM>) having a pair of side walls (<NUM>) and a front end portion rotatably connected to the second hinge body (<NUM>),
a rear connecting link (<NUM>), having a proximal end portion (<NUM>) rotatably connected to a rear end portion of the first hinge body (<NUM>), and a distal end portion (<NUM>) rotatably connected to a rear end portion of the moving link (<NUM>),
a front connecting link (<NUM>) having a proximal end portion rotatably connected to a front end portion of the first hinge body (<NUM>) and an intermediate portion rotatably connected to an intermediate portion of the moving link (<NUM>), and
a supporting link (<NUM>) having one end rotatably connected to a distal end of the front connecting link (<NUM>) and the other end rotatably connected to the second hinge body (<NUM>),
wherein the hinge device is configured such that the pair of side walls (<NUM>) of the moving link (<NUM>) overlap an outside of the pair of side walls (<NUM>) of the first hinge body (<NUM>),
characterized in that the front connecting link (<NUM>) has a main part (50x) connected to the first hinge body (<NUM>), the moving link (<NUM>) and the supporting link (<NUM>) and a pair of spacers (<NUM>) made of resin interposed between the pair of side walls (<NUM>) of the first hinge body (<NUM>) and the pair of side walls (<NUM>) of the moving link (<NUM>),
and in that the main part (50x) of the front connecting link (<NUM>) has a proximal end side connecting portion (<NUM>) that enters between the pair of side walls (<NUM>) of the first hinge body (<NUM>) and is rotatably connected to the front end portion of the first hinge body (<NUM>) and an intermediate connecting portion (<NUM>) that enters between the pair of side walls (<NUM>) of the moving link (<NUM>) and is rotatably connected to the intermediate portion of the moving link (<NUM>), and at least both sides of the proximal end side connecting portion (<NUM>) and the intermediate connecting portion (<NUM>) are made of resin.