Mat attachment structure of seatback and vehicle seat

A mat attachment structure of a seatback includes: a guide wire attached to the mat and provided, at the distal end part, with a straight portion extending in a longitudinal direction of the seatback frame on a tip side of the seatback frame or its root side; and a through-hole formed in the seatback frame and through which the straight portion is insertable. The through-hole is provided with a protruding part which includes a high protruding portion and a low protruding portion formed adjacent to the high protruding portion. In a first movement of the mat, the straight portion moves in a de-insertion direction while coming into contact with the high protruding portion. As the amount of movement of the mat gets larger than the amount of movement of the first movement, a contact position between the straight portion and the protruding part moves toward the low protruding portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on Japanese Patent Application No. 2018-029563, filed on Feb. 22, 2018, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present application relates to a mat attachment structure of a seatback and a vehicle seat.

BACKGROUND

As for an interior structure of a seatback in a vehicle seat, a structure for attaching a mat for supporting a seating occupant's back to a seatback frame through a guide wire is described in JP 2015-067172 A.

In detail, the guide wire includes a pair of vertical wire parts extending substantially vertically and juxtaposed left and right and a horizontal wire part which connects respective lower parts of the pair of vertical wire parts in the horizontal direction.

Then, the horizontal wire part is pivotally supported to a lower frame, while the pair of vertical wire parts are inserted, with their upper straight portions in the form of straights rods, into insertion holes formed in an upper frame of the seatback frame so as to be movable vertically.

SUMMARY

The conventional seatback for vehicle seat is constructed so that a mat is moved from a natural position rearward by a force applied from a seating occupant's back and the mat is returned to the natural position by an occupant's unseating action. With this forward-and-rearward movement of the mat, the straight portions of the vertical wire parts of the guide wire are adapted so as to slide in the insertion holes of the seatback frame vertically.

The guide wire is provided, on its surface, with a lubricant layer. If there is a pointed tip part, such as a burr, on an edge of the insertion hole, the lubricant layer may be gradually shaved due to a friction between the straight portion and the pointed tip part of the insertion hole, thereby causing the vertical wire part to be vertically moved with difficulty. If the vertical movement of the straight portion becomes dull, then there is a fear of degradation in the quality of feeling of an occupant's back against the seatback at the time of seating since the forward-and-rearward movement of the mat becomes unsmooth.

Additionally, if the seatback is strongly pressed rearward by an occupant's back due to a vehicle collision or the like, the mat might move greatly rearward against the seatback frame, thereby causing a possibility that the straight portions fall out of the insertion holes downward, so that a seating occupant's body cannot be supported by the mat.

In consideration of the above problems, an object of the present application is to provide a mat attachment structure of a seatback and a vehicle seat, both of which ensure that the straight portion of the guide wire moves up and down in the insertion hole of the seatback frame smoothly in the normal forward-and-rearward movement of the mat, and which could prevent the straight portion from coming out of the insertion hole even if the rearward displacement of the mat gets large.

According to an embodiment, there is provided a mat attachment structure of a seatback for attaching a mat to a seatback frame, the mat configured to receive a force from a back of an occupant leaning against the seatback, the attachment structure including: a guide wire attached to the mat, the guide wire provided, at a distal end part thereof, with a straight portion which extends in a longitudinal direction of the seatback frame on a tip side of the seatback frame or a root side thereof; and a through-hole which is formed in the seatback frame and through which the straight portion is insertable in the longitudinal direction. The through-hole is provided, at a periphery thereof, with a protruding part which includes a high protruding portion protruding in a burring shape on an insertion outlet side of the straight portion and a low protruding portion formed adjacent to the high protruding portion with a protruding height smaller than that of the high protruding portion. In a first movement of the mat associated with an occupant's seating action, the straight portion moves in a de-insertion direction while coming into contact with the high protruding portion, and a contact position between the straight portion and the protruding part moves toward the low protruding portion as the amount of movement of the mat gets larger than the amount of movement of the first movement.

In the embodiment, the mat attachment structure may be configured so that when the straight portion moves in the de-insertion direction while coming into contact with the low protruding portion, the low protruding portion bites into the straight portion of the guide wire, whereby the movement of the straight portion in the de-insertion direction is restricted.

According to an embodiment, there is provided a vehicle seat including: a seat cushion; a seatback pivotally connected to the seat cushion; a seatback frame arranged inside the seatback; and a mat configured to receive a force from a back of an occupant leaning against the seatback. The mat is attached to the seatback frame by a mat attachment structure including: a guide wire attached to the mat, the guide wire provided, at a distal end part thereof, with a straight portion which extends in a longitudinal direction of the seatback frame on a tip side of the seatback frame or a root side thereof; and a through-hole which is formed in the seatback frame and through which the straight portion is insertable in the longitudinal direction. The through-hole is provided, at a periphery thereof, with a protruding part which includes a high protruding portion protruding in a burring shape on an insertion outlet side of the straight portion and a low protruding portion formed adjacent to the high protruding portion with a protruding height smaller than that of the high protruding portion. The mat attachment structure is configured so that: a first movement of the mat associated with an occupant's seating action allows the straight portion to be moved in a de-insertion direction while coming into contact with the high protruding portion; and a contact position between the straight portion and the protruding part moves toward the low protruding portion as the amount of movement of the mat gets larger than the amount of movement of the first movement.

In the vehicle seat according to the embodiment, the mat attachment structure may be configured so that when the straight portion moves in the de-insertion direction while coming into contact with the low protruding portion, the low protruding portion bites into the straight portion of the guide wire, whereby the movement of the straight portion in the de-insertion direction is restricted.

With the mat attachment structure of the seatback and the vehicle seat related to the embodiment, the straight portion of the guide wire moves up and down in the insertion hole of the seatback frame smoothly in the normal forward-and-rearward movement of the mat. Further, even if the rearward displacement of the mat gets large, it is possible to prevent the straight portion from coming out of the insertion hole.

DETAILED DESCRIPTION

A frame structure of a vehicle seat ST provided with a mat attachment structure TK of a seatback according to an embodiment will be described with reference toFIG. 1.

FIG. 1is a perspective view for explaining a frame structure of a vehicle seat ST (it may be simply referred to as “seat ST” hereinafter). In the following description, respective directions of forward, rear, left, right, up, and down directions are defined by arrows illustrated inFIG. 1, based on a state where the seat ST is mounted on a vehicle. The left-and-right direction may be also referred to as “width direction”.

As illustrated inFIG. 1, the seat ST includes a seat cushion ST1where a seat cushion frame FR1is covered with a cushion member, and a seatback ST2where a seatback frame FR2is covered with a cushion member.

A pair of movable rails62are attached to a bottom part of the seat cushion frame FR1. The pair of movable rails62are supported on a pair of fixed rails61as fixed members installed on a vehicle floor C1of the vehicle so as to be movable in the forward-and-rearward direction. Thus, the seat ST is constructed so as to be slidable to the pair of fixed rails61rearward and forward.

At the rear part of the seat cushion frame FR1, the seatback frame FR2disposed inside the seat ST is supported so as to be rotatable around a rotation axis CLa extending left and right.

The seatback frame FR2is a so-called “panel frame” in the form of a frame made from a panel, and a direction connecting a root side of the panel frame and its tip side is defined as a longitudinal direction of the panel frame.

Specifically, the seatback frame FR2includes a lower panel part1that extends in the left-and-right direction at the lower part of the seat frame FR2, a left side panel part2L and a right side panel part2R both of which stand up from the left and right ends of the lower panel part1in the longitudinal direction (i.e. substantially upward-and-downward direction inFIG. 1), and an upper panel part3that connects respective leading end portions of the left side panel part2L and the right side panel part2R in the left-and-right direction (i.e. width direction).

The upper panel part3includes a pair of shoulder portions4which are connected to the left side panel part2L and the right side panel part2R respectively, at a slant. Each of the shoulder portions4is formed with a through-hole4a(see alsoFIG. 2).

In the central space surrounded by a frame of the seatback frame FR2, there are arranged a guide wire6supported by the seatback frame FR2and a mat5in the form of a thin plate, which is attached to the guide wire6.

The guide wire6is held by the seatback frame FR2at two supporting parts SL, SR, which are arranged in an upper part of the seatback frame FR2at left and right positions corresponding to the pair of through-holes4a, and one supporting part SB in the bottom part of the frame FR2.

Next, the mat5and the guide wire6will be described with reference to alsoFIG. 2andFIG. 3.

FIG. 2is a partial perspective view of the upper part of the mat5as viewed from the rear left and slightly above, whileFIG. 3is a partial perspective view of the lower portion of the mat5as viewed from the rear right and slightly above.

The guide wire6is made from a wire-like spring material. On the surface of the guide wire6, there is formed a lubricant layer for improving the sliding performance of the guide wire with the other member.

The guide wire6includes a pair of vertical wire parts6adisposed on the rear surface side of the mat5to extend up and down and also separated from each other, an upper connecting part6bconnecting respective upper portions of the pair of vertical wire parts6a, and a lower connecting part6cconnecting respective lower portions of the vertical wire parts6a.

The guide wire6further includes a pair of arm parts6dextending from connecting parts Pt1where the upper connecting part6band the vertical wire parts6aare connected, obliquely to the upper left and the upper right. Hereinafter, the arm part6don the left side is referred to as “left arm part6dL”, while the arm part6don the right side is referred to as “right arm part6dR”.

The mat5is attached to the pair of vertical wire parts6aand the upper connecting part6bthrough a plurality of fasteners5a,5bin a manner that the pair of vertical wire parts6aand the upper connecting part6bare deformed together by an external force without being separated from each other.

The lower connecting part6cis shaped straightly. The lower connecting part6cis attached to the lower panel part1by a plurality of holders7(three holders in the embodiment) so as to be rotatable around an axis CL6cof the lower connecting part6cextending in the left-and-right direction.

The holders7are made of resin, for example. Each holder7is attached to the lower panel part1by a well-known attachment structure (in the embodiment, a snap fit structure).

The attaching state of the holder7is illustrated in a sectional view ofFIG. 4.

As illustrated inFIG. 4, the holder7includes a base part7bhaving an insertion hole7aand a pair of engagement legs7cprotruding from the base part7b.

The lower connecting part6cis inserted into the insertion hole7aso as to be rotatable around the axis CL6c. The holder7is attached to the lower panel part1by snap fitting where the pair of engagement legs7care inserted in and engaged with an engagement hole1aformed in the lower panel part1, with elastic deformation.

The left arm part6dL and the right arm part6dR are formed symmetric laterally. Hereinafter, the right arm part6dR will be described as a representative, and reference numerals indicating various portions are respectively common in the left and right arm parts.

The right arm part6dR includes an inclined extended portion6d1extending obliquely upward from the connecting part Pt1where the upper connecting part6band the vertical wire part6aare connected, a bent portion bent6d2in the left-and-right direction to improve torsion and bending elasticity of the right arm part6dR, and a straight portion6d3extending straight upward from the bent portion6d2.

The straight portion6d3is inserted into the through-hole4aof the shoulder part4from downward to upward so as to be movable up and down.

Accordingly, in a lower section of the mat5and the guide wire6, the lower connecting part6cof the guide wire6is supported by the lower panel part1through the holders7so as to be rotatable around the axis CL6c. On the other hand, in an upper section of the mat5and the guide wire6, it is supported by the shoulder part4while the straight portions6d3are being inserted into the through-holes4a. In this way, the mat5and the guide wire6are attached to the seatback frame FR2so as to be movable forward and rearward elastically.

Next, the detailed shape of the through-hole4awill be described with reference toFIG. 5.

FIG. 5is an enlarged perspective view of a portion A inFIG. 2, explaining the straight portion6d3of the left arm part6dL of the guide wire6and the through-hole4aof the left shoulder part4through which the straight portion6d3is inserted.

Also,FIG. 5illustrates a condition where an occupant does not put an occupant's back on the seatback ST2, that is, a situation of the straight portion6d3and the through-hole4ain a natural state where no external force is applied to the mat5.

At the periphery of the through-hole4a, as illustrated inFIG. 5, there is formed a protruding part4bprotruding upward by burring work or the like.

The protruding part4bincludes high protruding portions4b1each having a high protruding height and low protruding portions4b2each having a protruding height lower than that of the high protruding portion4b1and also protruding from the surface4hof the shoulder part4slightly.

The high protruding portions4b1are formed in a direction along which the straight portion6d3in the through-hole4ais inclined by the deformation of the mat5and the guide wire6associated with the normal seating and unseating actions of an occupant (in this example, generally in the front-and-rear direction).

In the illustrated example, the periphery of the through-hole4ais divided into generally-eight equal sections, and the protruding part4bare composed of: four high protruding portions4b1(one pair of protruding portions in the front-and-rear direction and one pair of protruding portions in the left-and-right direction); and four low protruding portions4b2existing in respective oblique directions (i.e. left front direction, right front direction, left rear direction and right rear direction)

For convenience of the following description, the high protruding portion4b1on the rear side is defined as a first high protruding portion4b1a, while the high protruding portion4b1on the front side is defined as a second high protruding portion4b1b. Similarly, the low protruding portion4b2on the right-and-rear side is defined as a first low protruding portion4b2a, while the low protruding portion4b2on the left-and-front side is defined as a second low protruding portion4b2b.

The protruding part4bincluding the high protruding portions4b1and the low protruding portions4b2is manufactured by the following processing method, for example.

First, it is performed to form, as a prepared hole, a cross-shaped hole having a circumscribed circle having a smaller diameter than the inner diameter φ4aof the through-hole4a. Then, the burring work is carried out to protrude portions each extending inside a circle having the inner diameter φ4aconcentric with the circumscribed circle.

Of course, it should be noted that the manufacturing method of the protruding part4bis not limited to the above-mentioned method only.

When the natural state illustrated inFIG. 5is changed to a seating state where an occupant is sitting on the seat ST and also putting an occupant's back on the seatback ST2, the mat5moves rearward. As a result, the guide wire6is deformed so that the straight portion6d3moves in the through-hole4adownward.

In a situation where an occupant is leaning the back against the seatback ST2in the normal seating state, the rearward movement of the mat5and the deformation amount of the guide wire6are small. Consequently, the straight portion6d3moves downward in an inclined posture as a result that the lower side (the mat5side) substantially moves rearward.

FIG. 6illustrates such a condition state. InFIG. 6, the through-hole4ais illustrated with a cross section taken along a line S6-S6ofFIG. 5.

With the rearward movement of the mat5associated with the normal seating action, as illustrated inFIG. 6, the straight portion6d3is inclined to the axis CL4aof the through-hole4aat an angle θa so that its tip side (the upper side inFIG. 6) approaches the second high protruding portion4b1band furthermore, the straight portion6d3moves downward while making contact with the second high protruding portion4b1b(in the direction of an arrow DRa).

Meanwhile, each of the high protruding portions4b1is formed with a protruding height sufficient for a burring shape, and the inner surface of the high protruding portion4b1on the tip side is substantially parallel to the axis CL4a.

Therefore, the contact angle between the straight portion6d3and the second high protrusion4b1bbecomes the angle θa substantially. The angle θa is set to be a small angle with a margin so that the lubricant layer formed on the surface of the straight portion6d3wouldn't be scraped away even when the straight portion6d3moves downward while being in contact with the second high protruding portion4b1bat the angle θa.

As the amount of rearward movement of the mat5increases, the straight portion6d3has its root side facing rearward and inward. That is, the contact position between the straight portion6d3and the protruding part4bgradually moves from the second high protruding portion4b1bto the adjacent second low protruding portion4b2b.

Unlike the rearward movement of the mat5associated with the normal seating action, when the seatback ST2is strongly pushed backward by an occupant's back (for example, a case that a vehicle is rear-end collided while an occupant is being seated), in other words, if the amount of the rearward movement of the mat5is sufficiently large, the amount of deformation of the arm part6dof the guide wire6also increases, so that the straight portion6d3moves downward while keeping a posture that its tip side (the upper side inFIG. 6) is inclined greatly and diagonally forward left.

As a result, the straight portion6d3moves downward (in the direction of an arrow DRb) while being in contact with the second low protruding portion4b2bwhich is formed diagonally forward left at the periphery of the through-hole4a.FIG. 7illustrates such a condition state. InFIG. 7, the through-hole4ais illustrated with a cross section taken along a line S7-S7ofFIG. 5.

Here, it is noted that each of the low protruding portions4b2is formed with a protruding height insufficient for the burring shape, and the inner surface of the low protruding portion4b2on the tip side is curved and inclined to the axis CL4aby an angle θc so as to gradually approach the axis CL4atoward the tip side.

Meanwhile, the angle between the axis CL7of the straight portion6d3and the axis CL4aof the through-hole4ais an angle θb larger than the angle θa since the rearward movement amount of the mat5is large.

Therefore, the contact angle of the side surface of the straight portion6d3with respect to the axis CL4aat the contact point Pt3where the straight portion6d3comes into contact with the low protruding portion4b2becomes an angle θd which is substantially the sum of the angle θb and the angle θc (i.e. angle θd=angle θb+angle θc).

Further, since each of the low protruding portions4b2is raised insufficiently, a tip corner part Pt2of the low protruding portions4b2on the inner surface side has a “sharp-pointed projecting” shape having a cross section with a sharp angle.

Therefore, when the straight portion6d3moves downward in the through-hole4ato come into contact with the low protruding portion4d2, the tip corner part Pt2of the low protruding portion4d2easily bites into the straight portion6d3and prevents the downward movement of the straight portion6d3since the contact angle between the straight portion6d3and the low protruding portion4d2is larger than that at the time of normal seating action (that is, the angle θd), and the tip corner part Pt2of the low protruding portion4d2has the “sharp-pointed projecting” shape.

In particular, when a large acceleration occurs due to a traffic accident such as a rear-end collision, the inclination descending speed of the straight portion6d3rapidly increases and therefore, the biting is more likely to occur.

In this way, in the mat attachment structure TK, when the mat5is moved rearward in the normal seating action, the straight portion6d3comes into contact with the high protruding portion4d1at the periphery of the through-hole4aand moves downward smoothly. When the mat5largely moves rearward due to a rear-end collision or the like, the straight portion6d3comes into contact with the low protruding portion4d2to cause a biting, so that the downward movement of the straight portion6d3is restricted.

Therefore, the straight portion6d3is prevented from coming out of the through-hole4a.

Consequently, according to the mat attachment structure TK and the vehicle seat ST including the mat attachment structure TK, even if the normal seating action is repeated, there is no possibility of degrading the quality in the feeling of an occupant's back on the seatback ST2at the time of seating. Further, since the guide wire6does not come out of the upper panel part3even in a rear-end collision or the like, the body of a seating occupant can be supported by the mat5of the seatback ST2firmly.

Without being limited to the embodiment described above, the present invention may be modified variously without departing from the gist of the present invention.

For instance, in the mat attachment structure TK of the embodiment, the upper part of the guide wire6(i.e. the straight portion6d3) is inserted into and supported by the through-hole4a, while the lower part of the guide wire6is formed with the lower connecting part6cand also supported on the frame side through the holders7. However, this structure may be adapted upside down.

That is, the lower part of the guide wire6may be formed with a straight portion and also configured to be inserted into and supported by the through-hole on the frame side, provided that the upper part of the guide wire6is supported on the frame side through the holders7.