Buckle device

In a buckle device, a pressing force, applied from wire ropes to an inside wall face of a wire guide groove of a wire guide, is along an imaginary line passing through a center of a cover plate first hole portion of a cover plate fixing tab of a cover plate and a center of a wire guide hole portion of the wire guide as viewed from the vehicle inside, similarly to a pressing force applied to a first fixing bolt that fixes the cover plate to a support plate, and these pressing forces are both oriented in the same direction. This enables rotation moment to be suppressed from occurring at the cover plate when the wire ropes are pulled toward their length direction leading end side.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2016-010973 filed Jan. 22, 2016, the disclosure of which is incorporated by reference herein.

BACKGROUND

Field of the Invention

The present invention relates to a buckle device that is capable of moving a buckle by driving a drive section.

Related Art

Buckle devices exist in which a length direction intermediate portion of a moving member configured by a wire or the like is bent around an intermediate member, the moving member is moved in the length direction of the moving member by drive force of a drive section, and a buckle provided at a length direction leading end portion of the moving member is moved accordingly (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2015-44460).

In such buckle devices, in a case in which a coupling member is provided between the intermediate member and the vehicle side, and the intermediate member is fixed to the vehicle side via the coupling member, rotation moment sometimes occurs at the coupling portion between the coupling member and the intermediate member when the moving member is pulled toward its length direction leading end side and the intermediate member receives load from the moving member.

SUMMARY

In consideration of the above circumstances, a buckle device capable of suppressing rotation moment from occurring at a coupling portion between a coupling member and an intermediate member when a moving member is pulled toward its length direction leading end side is obtained.

A buckle device of a first aspect includes: a buckle that is configured to engage with a tongue provided at webbing of a seatbelt device; a moving member whose leading end side in a length direction of the movement member is anchored to the buckle; a drive section that, by drive force which the drive section outputs, moves a base end portion in the length direction of the moving member along the length direction of the moving member to move the buckle; an intermediate member at which an intermediate portion in the length direction of the movement member is disposed, and at which the moving member is bent; and a coupling member that includes a first coupling section which is coupled to a vehicle side support section and a second coupling section to which the intermediate member is coupled and retained, wherein a direction of load acting on the first coupling section due to the moving member being pulled toward the leading end side in the length direction is along a direction of load acting on the second coupling section due to the moving member being pulled toward the leading end side in the length direction.

In the buckle device of the first aspect, the first coupling section of the coupling member is coupled to the vehicle side support section, and the intermediate member is coupled to and retained by the second coupling section of the coupling member. Note that the direction of load acting on the first coupling section due to the moving member being pulled toward the leading end side in the length direction is along the direction of load acting on the second coupling section due to the moving member being pulled toward the leading end side in the length direction. This enables rotation moment to be suppressed from occurring at the second coupling section of the coupling member.

A buckle device of a second aspect is the buckle device of the first aspect, wherein: a portion of the first coupling section where load acts and a portion of the second coupling section where load acts, due to the moving member being pulled toward the leading end side in the length direction, are single in the first coupling section and the second coupling section respectively, and the portion of the second coupling section where load acts is disposed in the direction of load acting on the first coupling section with respect to the portion of the first coupling section where load acts.

In the buckle device of the second aspect, the portion of the first coupling section of the coupling member where load acts and the portion of the second coupling section of the coupling member where load acts due to (when) the moving member being pulled toward the length direction leading end side are each single. Note that the portion of the second coupling section of the coupling member where load acts is disposed with respect to the portion of the first coupling section of the coupling member where load acts in the direction of the load acting on the first coupling section of the coupling member. This enables rotation moment to be effectively suppressed from occurring at the second coupling section of the coupling member due to (when) the moving member being pulled toward the length direction leading end side.

A buckle device of a third aspect is the buckle device of the first aspect, wherein at least one of the first coupling section or the second coupling section includes a plurality of portions where load acts due to the moving member being pulled toward the leading end side in the length direction, and a direction of a resultant force of loads at the respective plurality of portions is along a direction of load applied from the moving member to the intermediate member.

In the buckle device of the third aspect, at least one of the first coupling section of the coupling member or the second coupling section of the coupling member has plural portions where load acts when the moving member is pulled toward the length direction leading end side. Note that the direction of the resultant force of loads at the respective plural portions runs along the direction of load applied from the moving member to the intermediate member. This enables rotation moment to be effectively suppressed from occurring at the second coupling section of the coupling member.

As explained above, the buckle device according to the aspects is capable of suppressing rotation moment from occurring at a coupling portion between the coupling member and the intermediate member when the moving member is pulled toward its length direction leading end side.

DETAILED DESCRIPTION

Explanation follows regarding exemplary embodiments, based onFIG. 1toFIG. 6. Note that in each of the drawings, the arrow FR indicates the vehicle front side, the arrow OUT indicates the vehicle width direction outside, and the arrow UP indicates the vehicle upper side of a location where a buckle device10is applied.

Configuration of Present Exemplary Embodiment

As illustrated inFIG. 1, the buckle device10includes a buckle drive device12serving as a drive section. The buckle drive device12is provided at the vehicle width direction inside of a seat14applied with the buckle device10. The buckle drive device12includes a guide rail16serving as a slider guiding mechanism. The guide rail16is fixed to the vehicle body side, such as a floor section of the vehicle body of the vehicle, by a fastener such as a bolt. As illustrated inFIG. 2, the guide rail16includes a pair of guide walls20and22that face each other in the vehicle width direction and serve as slider guiding section. A drive screw26serving as a drive member is provided between the guide walls20and22. The central axial direction of the drive screw26extends along the vehicle front-rear direction, and the drive screw26is capable of rotating about its central axis.

A motor actuator24, serving as a drive force output unit, is provided at the vehicle front side of the guide rail16. A vehicle front side end portion of the drive screw26is coupled to the motor actuator24, and the drive screw26is rotated about the central axis of the drive screw26by drive force output from a motor of the motor actuator24. The motor actuator24is electrically connected to a controller (not illustrated in the drawings) such as a motor driver or an ECU. The controller is electrically connected to a detector, such as a door opening and closing detector such as a courtesy switch that detects opening and closing of a vehicle door corresponding to the seat14applied with the buckle device10, and/or an occupant detector such as a load sensor provided to a seat cushion28of the seat14. The controller is also electrically connected to a buckle switch (also not illustrated in the drawings) that detects when a tongue34provided to webbing32of a seatbelt device30illustrated inFIG. 1has engaged with a buckle36(seeFIG. 2) of the buckle device10, described later. The motor actuator24is controlled based on electrical signals output from the detector, such as the door opening and closing detector, the occupant detector, the buckle switch, and the like.

As illustrated inFIG. 2, a slider38is provided between the guide wall20and the guide wall22of the guide rail16. The slider38is formed in a block shape. As illustrated inFIG. 2, vehicle width direction side faces of the slider38abut the guide walls20and22of the guide rail16. A thread hole which the drive screw26pierces through is formed in the slider38. The slider38is guided by the guide walls20and22so as to slide along the vehicle front-rear direction due to the drive screw26rotating.

As illustrated inFIG. 2, the buckle device10includes two wire ropes40serving as moving member configuring a movement section (one of the wire ropes40corresponds to the movement section at one side, and another of the wire ropes40corresponds to the movement section at another side). The wire ropes40are each formed in an elongated shape, and, as illustrated inFIG. 5, are provided side by side in the vehicle width direction (the width direction of the seat14). As illustrated inFIG. 2, at the side of the wire ropes40that is further toward respective base ends than length direction intermediate portions thereof, the length direction of the wire ropes40runs along the vehicle front-rear direction, and respective length direction base end portions of the wire ropes40are coupled to the slider38at a location further toward the vehicle lower side than the drive screw26. Thus, the wire ropes40are moved along their length direction when the slider38slides along the vehicle front-rear direction.

A wire guide42serving as an intermediate member is provided at the vehicle rear side of the guide rail16. A wire guide groove44serving as a groove portion (abut portion) is formed in the wire guide42. The wire guide groove44is open at an inside face in the vehicle width direction of the wire guide42. One end of the wire guide groove44in a length direction thereof is open at a vehicle front side face of the wire guide42, an intermediate portion of the wire guide groove44in the length direction thereof is curved about an axis, an axial direction thereof being along the vehicle width direction, and another end of the wire guide groove44in the length direction thereof is open at a vehicle upper side face of the wire guide42. The wire ropes40are passed through the wire guide groove44. The wire ropes (intermediate portions)40are bent (curved) (so, bent portions (curved portions) are formed) around an axis, an axial direction thereof being along the vehicle width direction (the width direction of the seat14), so as to follow the wire guide groove44of the wire guide42. The wire ropes40, that are further toward the respective leading ends than the opening at the vehicle upper side face of the wire guide42, extend diagonally toward the vehicle upper front side (see the arrow A direction inFIG. 2).

The buckle device10includes a buckle cover50. The buckle cover50has a tube shape with its length direction in directions (the arrow A direction and the arrow B direction inFIG. 2) sloping in the vehicle front-rear direction with respect to the vehicle up-down direction. The buckle36is provided in a vehicle upper side portion inside the buckle cover50. The buckle36includes a buckle body52. The buckle body52is formed with a U-shaped cross-section profile open toward the vehicle width direction outside. Configuration components (not illustrated in the drawings) of the buckle36, such as a latch, are provided inside the buckle body52. When the tongue34provided at the webbing32of the seatbelt device30illustrated inFIG. 1is inserted diagonally into the buckle body52from the vehicle upper front side of the buckle body52, the latch provided at the buckle body52enters a hole portion formed in the tongue34, and the tongue34engages with the buckle36accordingly.

As illustrated inFIG. 2, the buckle device10includes a buckle guide54. The buckle guide54is formed using a synthetic resin material that is softer than the buckle cover50. The buckle guide54has a long tube shape running along the length direction of the buckle cover50(the arrow A direction and the arrow B direction inFIG. 2). A portion of the of the buckle guide54that is diagonally at the vehicle lower rear side is coupled to the guide rail16. The buckle guide54is inserted into the buckle cover50from an end portion of the buckle cover50that is diagonally at the vehicle lower rear side. The buckle cover50is thereby capable of moving diagonally toward the vehicle upper front side (the arrow A direction inFIG. 2) and diagonally toward the vehicle lower rear side (the arrow B direction inFIG. 2) guided by the buckle guide54.

The wire ropes40are passed through inside the buckle guide54. The leading end side in the length direction of the wire ropes40extends from an end portion that is diagonally at the vehicle upper front side of the buckle guide54toward the outside of the buckle guide54, and is coupled to the buckle body52provided to the buckle cover50. Thus, when the leading end portions in the length direction of the wire ropes40are moved diagonally toward the vehicle upper front side (the arrow A direction inFIG. 2) due to the wire ropes40being moved toward their length direction leading end side, the buckle36is moved diagonally toward the vehicle upper front side accompanying the buckle cover50. In contrast thereto, when the leading end portions in the length direction of the wire ropes40are moved diagonally toward the vehicle lower rear side (the arrow B direction inFIG. 2) due to the wire ropes40being moved toward their length direction base end side, the buckle36is moved diagonally toward the vehicle lower rear side accompanying the buckle cover50.

As illustrated inFIG. 5, an extension tab56extending out from a vehicle rear side end portion of the guide wall20of the guide rail16is disposed at the vehicle width direction outside of the above-described wire guide42. The extension tab56is bent toward the vehicle width direction inside at the vehicle rear side of the wire guide42. A guide rail fixing tab58illustrated inFIG. 5extends out diagonally toward the vehicle lower rear side from a vehicle width direction inside end portion of a part of the extension tab56, which part is bent toward the vehicle width direction inside.

As illustrated inFIG. 1andFIG. 3, a cover plate60serving as a coupling member is provided at the vehicle width direction inside of the wire guide42. The cover plate60is provided with a cover plate main body61serving as a second coupling section. The wire guide groove44of the wire guide42is closed off from the vehicle width direction inside by the cover plate main body61of the cover plate60. As illustrated inFIG. 3, the cover plate60is provided with a cover plate fixing tab62serving as a first coupling section. The cover plate fixing tab62extends out diagonally toward the vehicle lower rear side from the cover plate main body61of the cover plate60. The cover plate fixing tab62of the cover plate60faces the guide rail fixing tab58at the vehicle width direction inside of the guide rail fixing tab58of the guide rail16. As illustrated inFIG. 5, a support plate64, which is provided at the floor section of the vehicle body of the vehicle, is disposed at the vehicle width direction outside of the guide rail fixing tab58of the guide rail16.

A cover plate first hole portion66is formed in the cover plate fixing tab62of the cover plate60, a guide rail fixing tab hole portion68is formed in the guide rail fixing tab58of the guide rail16, and a support plate hole portion70is formed in the support plate64of the floor section of the vehicle body of the vehicle. The cover plate first hole portion66, the guide rail fixing tab hole portion68, and the support plate hole portion70all face in the vehicle width direction. A first fixing member (bolt)72is disposed piercing through the cover plate first hole portion66, the guide rail fixing tab hole portion68, and the support plate hole portion70. A first nut74is screwed onto a leading end portion of the first fixing bolt72. The cover plate fixing tab62of the cover plate60and the guide rail fixing tab58of the guide rail16are thereby fixed to the support plate64of the floor section of the vehicle body of the vehicle.

As illustrated inFIG. 4, a wire guide hole portion76is formed in a portion of the wire guide42, the portion is at further toward the inside in the direction of the radius of curvature of the wire guide groove44than the wire guide groove44. As illustrated inFIG. 5, the wire guide hole portion76of the wire guide42pierces through in the vehicle width direction. The above-described extension tab56of the guide rail16is disposed at the vehicle width direction outside of the wire guide hole portion76of the wire guide42. An extension tab hole portion78is formed in the extension tab56. The extension tab hole portion78of the extension tab56faces the wire guide hole portion76of the wire guide42in the vehicle width direction. A cover plate second hole portion80, formed in the cover plate main body61of the cover plate60, faces the wire guide hole portion76at the vehicle width direction inside of the wire guide hole portion76of the wire guide42.

As illustrated inFIG. 5, a second fixing member (bolt)82is disposed piercing through the wire guide hole portion76of the wire guide42, the extension tab hole portion78of the extension tab56of the guide rail16, and the cover plate second hole portion80of the cover plate60. A second nut84is screwed onto a leading end portion of the second fixing bolt82. Thus, the wire guide42is fixed to the cover plate60and the extension tab56of the guide rail16, and further the wire guide42is fixed, via the cover plate60and the extension tab56of the guide rail16, to the support plate64provided at the floor section of the vehicle body of the vehicle.

Note that in the present exemplary embodiment, an angle formed by an imaginary line L1passing through the center of the wire guide hole portion76of the wire guide42and the center of the cover plate first hole portion66of the cover plate60, with respect to the length direction of the wire ropes40(the arrow FR direction and the opposite direction thereto inFIG. 3) at the side of the wire ropes40further toward their length direction base end side than the wire guide42, is substantially ½ of an angle formed by the length direction of the wire ropes40(the arrow A direction and the arrow B direction inFIG. 3) at the side of the wire ropes40further toward their length direction leading end side than the wire guide42, with respect to the length direction of the wire ropes40(the arrow FR direction and the opposite direction thereto inFIG. 3) at the side of the wire ropes40further toward their length direction base end side than the wire guide42. In a case in which the wire ropes40are pulled toward their length direction leading end side, the imaginary line L1is (runs) along the direction of a pressing force F1which is received from the wire ropes40by an inside wall face44A, this inside wall face44A being a wall face disposed at the inner side of bent portions of the wire ropes40(at the inner side of bend-curve of the wire ropes40inFIG. 2) (namely, the inside wall face44A is located at a side of center-of-curvature of bending of the bent portions of the wire ropes40with respect to the wire ropes40).

Operation and Advantageous Effects of First Exemplary Embodiment

In the buckle device10, when the vehicle door corresponding to the seat14applied to the buckle device10is changed from a closed state to an open state, for example, this change in the open and closed states of the door is detected by a detector such as a door opening and closing detector such as a courtesy switch. When an occupant86then sits on the seat14, for example, this seating of the occupant86on the seat14is detected by a detector such as an occupant detector such as a load sensor provided at the seat cushion28of the seat14or the like. The level of electrical signal(s) output from the detector(s) to the controller is changed by the change in the state of the door and/or the seat14accompanying the occupant boarding the vehicle in this manner. When the motor actuator24is accordingly driven to rotate the drive screw26, the slider38is guided by the guide walls20and22of the guide rail16and slides toward the vehicle rear side. When the wire ropes40are accordingly moved toward their length direction leading end side, the buckle body52is pressed diagonally toward the vehicle upper front side by the wire ropes40.

When pressing force from the wire ropes40is transmitted to the buckle cover50through the buckle body52, then, as illustrated inFIG. 2, the buckle cover50is guided by the buckle guide54and moved diagonally toward the vehicle upper front side (the arrow A direction side inFIG. 2). Due to the buckle cover50being moved in this manner, the occupant86can easily engage the tongue34with the buckle36, and can easily put on the webbing32.

When the tongue34engages with the buckle36, the level of electrical signal output from the buckle switch of the buckle36to the controller changes. When the motor actuator24is accordingly driven to rotate the drive screw26, the slider38is guided by the guide walls20and22of the guide rail16and slides toward the vehicle front side. When the wire ropes40are moved toward their length direction base end side accordingly, the buckle cover50is pulled through the buckle body52by the wire ropes40. Thus, the buckle cover50is guided by the buckle guide54, and, as illustrated inFIG. 1, the buckle cover50is moved diagonally toward the vehicle lower rear side (the arrow B direction inFIG. 3).

When the vehicle suddenly decelerates during a vehicle collision or the like, the webbing32that is worn on the body of the occupant86seated in the seat14is pulled by the body of the occupant86. When the buckle36of the buckle device10is accordingly pulled diagonally toward the vehicle upper front side by the tongue34provided at the webbing32, the length direction leading end side of the wire ropes40coupled to the buckle36of the buckle device10are also pulled diagonally toward the vehicle upper front side.

When the length direction leading end side of the wire ropes40is pulled diagonally toward the vehicle upper front side in this manner, the side of the wire ropes40, that is further toward the length direction base end than the wire guide42, is pulled toward the vehicle rear side. However, the length direction base end portions of the wire ropes40are retained by the slider38, and so movement of the length direction base end portions of the wire ropes40toward the vehicle rear side is prevented. Thus, reaction force against the pulling force applied to the length direction leading end side of the wire ropes40acts on the length direction base end portions of the wire ropes40. In this state, the inside wall face44A of the wire guide groove44of the wire guide42is pressed by the wire ropes40.

Thus, when the inside wall face44A of the wire guide groove44of the wire guide42receives a pressing force F1(seeFIG. 4) from the wire ropes40in this manner, a shaft portion (thread portion) of the second fixing bolt82disposed piercing through the wire guide hole portion76of the wire guide42is pressed by an inner peripheral portion of the wire guide hole portion76of the wire guide42, and the cover plate second hole portion80of the cover plate main body61of the cover plate60is pressed by the shaft portion (thread portion) of the second fixing bolt82. Due thereto, the first fixing bolt72disposed piercing through the cover plate first hole portion66of the cover plate fixing tab62of the cover plate60receives a pressing force F2(seeFIG. 3) from an inner peripheral portion of the cover plate first hole portion66of the cover plate fixing tab62of the cover plate60.

However, the first fixing bolt72is fixed to the support plate64provided at the floor section of the vehicle body of the vehicle, and the wire guide42is accordingly fixed to the floor section of the vehicle body via the cover plate60. This enables movement of the wire guide42to be suppressed when the wire ropes40are pulled toward their length direction leading end side.

As viewed from the vehicle width direction inside, the pressing force F1applied from the wire ropes40to the inside wall face44A of the wire guide groove44of the wire guide42is (runs) along the imaginary line L1passing through the center of the wire guide hole portion76of the wire guide42(the center of the cover plate second hole portion80) and the center of the cover plate first hole portion66of the cover plate fixing tab62of the cover plate60. In other words, the direction of load acting on the cover plate second hole portion80of the cover plate main body61(the second coupling section) of the cover plate60is along the imaginary line L1(on the imaginary line L1).

As also viewed from the vehicle width direction inside, the pressing force F2(as mentioned above, the first fixing bolt72receives the pressing force F2from the inner peripheral portion of the cover plate first hole portion66of the cover plate fixing tab62of the cover plate60) applied, from the support plate64, which fixes thereto the cover plate60, on the floor section of the vehicle body of the vehicle, to the first fixing bolt72that fixes the cover plate60to the support plate64, also is (runs) along the imaginary line L1. In other words, the direction of load acting on the cover plate first hole portion66of the cover plate fixing tab62(the first coupling section) of the cover plate60is along the imaginary line L1(on the imaginary line L1).

Thus, the direction of the pressing force F2and the direction of the pressing force F1are the same directions.

Thus, even when the wire ropes40are pulled toward their length direction leading end side and the pressing force F2acts on the cover plate60, generation of rotation moment (torque) (such as rotation moment about the central axis of the first fixing bolt72that fixes the cover plate60to the support plate64) at the cover plate60can be suppressed. This enables rotation force based on this rotation moment to be suppressed from acting on the second fixing bolt82that couples the wire guide42to the cover plate60, and enables a substantially stable load to be input to the second fixing bolt82when the wire ropes40are pulled toward their length direction leading end side. This facilitates selection of the mechanical strength of the second fixing bolt82, for example.

Thus, there is no need to especially increase the mechanical strength of the second fixing bolt82or the like, or to provide a separate member to the second fixing bolt82in order to couple the wire guide42to the cover plate60. This enables an increase in the number of components, such as bolts, to be suppressed, enables the buckle device10to be made more compact, and enables the ease of installation of the buckle device10in the vehicle to be improved, enabling the buckle device10to be assembled to a frame member of the seat14, for example.

Second Exemplary Embodiment

Explanation follows regarding a second exemplary embodiment. Note that when explaining the second exemplary embodiment, locations that are basically the same as those in the first exemplary embodiment are appended with the same reference numerals, and detailed explanation thereof is omitted.

As illustrated inFIG. 6, in the present exemplary embodiment, plural cover plate second hole portions80are provided in the cover plate60. Although not illustrated inFIG. 6, plural wire guide hole portions76are formed in the wire guide42and plural extension tab hole portions78are formed in the extension tab56of the guide rail16, corresponding to the respective cover plate second hole portions80of the cover plate60. Although not illustrated inFIG. 6, second fixing bolts82are disposed piercing through the respective cover plate second hole portions80of the cover plate60.

Note that as viewed from the vehicle width direction inside, an angle formed by a single-dotted dashed line L2that passes through the center of one of the cover plate second hole portions80of the cover plate60and that intersects the imaginary line L1, and by the imaginary line L1, is set at the same size as an angle formed by a single-dotted dashed line L3that passes through the center of another of the cover plate second hole portions80of the cover plate60and passes through a portion where the imaginary line L1and the single-dotted dashed line L2intersect, and by the imaginary line L1. Thus, when the wire ropes40are pulled toward their length direction leading end side, the resultant force of loads applied, from the inner peripheral portions of the respective cover plate second hole portions80of the cover plate60, to the respective second fixing bolts82disposed piercing through the respective cover plate second hole portions80, is (runs) along the imaginary line L1, and is in the same direction as the pressing force F2applied, from the support plate64to the first fixing bolt72that fixes the cover plate60to the support plate64.

Thus, in the present exemplary embodiment also, even when the wire ropes40are pulled toward their length direction leading end side and the pressing force F2is applied to the cover plate60, rotation moment (such as rotation moment about the central axis of the first fixing bolt72that fixes the cover plate60to the support plate64) at the cover plate60can be suppressed from occurring. This enables rotation force based on this rotation moment to be suppressed from acting on the second fixing bolts82that couple the wire guide42to the cover plate60, and enables substantially stable load to be input to the second fixing bolts82when the wire ropes40are pulled toward their length direction leading end side. This facilitates selection of the mechanical strength of the second fixing bolts82, for example.

Thus, there is no need to especially increase the mechanical strength of the second fixing bolts82or the like, or to provide a separate member to the second fixing bolts82in order to couple the wire guide42to the cover plate60. This enables an increase in the number of components, such as bolts, to be suppressed, enables the buckle device10to be made more compact, and enables the ease of installation of the buckle device10in the vehicle to be improved, enabling the buckle device10to be assembled to a frame member of the seat14, for example.

Note that the present exemplary embodiment is configured such that plural cover plate second hole portions80are formed in the cover plate60; however, configuration may be such that plural cover plate fixing tabs62are provided at the cover plate60, and cover plate first hole portions66are provided in each of the cover plate fixing tabs62, such that the resultant force of loads applied, from inner peripheral portions of the respective cover plate first hole portions66, to the respective first fixing bolts72disposed piercing through the respective cover plate first hole portions66is positioned on the imaginary line L1.