GB2255897A

GB2255897A - Seatbelt through-anchor

Info

Publication number: GB2255897A
Application number: GB9210621A
Authority: GB
Inventors: Muneo Makino
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 1991-05-22
Filing date: 1992-05-19
Publication date: 1992-11-25
Anticipated expiration: 2012-05-19
Also published as: GB2255897B; GB9210621D0; JPH04130568U; JP2584867Y2

Abstract

A seatbelt through-anchor 1 comprises a metal plate 2, which is provided at an upper end portion thereof with a through-hole 7 permitting insertion of a bolt (11. Fig. 2), and with a slot 5 for insertion of a webbing (10) therethrough. Outer surfaces on the side of the free end of the metal plate 2 are covered with a resin covering 8 molded integrally with the outer surfaces. The resin covering 8 has a double layer structure which is formed of an inner layer 3 made of a resin having high mechanical strength and a top layer 4 covering the inner layer 3 and made of a resin having low friction resistance and permitting good slidability. <IMAGE>

Description

SEATBELT THROUGH-ANCHOR BACKGROUND OF THE INVENTION 1) Field of the Invention This invention relates to an improvement in a seatbelt through-anchor which defines a slot for changing the direction of a webbing to guide the webbing to a desired position.

2) Description of the Related Art Conventional seatbelt systems for the safe restraint of a vehicle occupant in a seat include the three-point seatbelt system in which a continuous webbing is used.

In a seatbelt system of this type, as shown in FIG. 3, a webbing 10 is secured at an end portion thereof in a retractor 20, extends through a throughanchor 21, and is held at an opposite end portion thereof on an anchor plate 27 pivotally supported by a bolt 23 on a lower end portion of a center pillar 22.

A through-tongue 24 arranged on an intermediate portion of the webbing 10 between the anchor plate 27 and the through-anchor 21 is latched in a buckle 25 disposed upright at a substantially central portion of the vehicle body, whereby the occupant is restrained in a seat 26.

As is illustrated in FIG. 4, for example, the through-anchor 21 comprises a metal plate 14 defining in an upper end portion thereof a through-hole, through which a bolt 11 extends, and on a side of a free end thereof a slot forming a webbing slot 18 through which the webbing 10 extends. Outer surfaces of the metal plate 14 are covered on the side of the free end thereof with a resin covering 15 integrally molded with the outer surfaces. In other words, a sliding surface 17 of a lower edge portion of the webbing slot 18 through which the webbing 10 extends is formed by the resin covering 15 so that smooth sliding of the webbing 10 is ensured to reduce the sliding resistance of the webbing 10 at the through-anchor 21 upon winding it out or in.

The through-anchor 21 is swingably supported by the bolt 11 on the center pillar 22. As the throughanchor 21 must provide secure transmission of tension, which is applied to the webbing 10 in the event of a vehicular emergency, to the vehicle body via the metal plate 14, a high load is applied to the resin covering 15 on the sliding surface 17 of the lower edge portion of the webbing slot 18. The resin covering 15 covers corner edges 16,16 of the metal plate 14, said edges 16,16 corresponding to the lower edge portion of the webbing slot 18, so that the folding angle of the web bing 10 at the folded back portion of the webbing 10 must remain large to prevent the webbing 10 from contacting the corner edges 16,16 of the metal plate 14.

As a synthetic resin employed as such a resin covering, it is necessary to select a type having sufficient mechanical strength so that it is not deformed upon application of a load.

Generally, however, a resin having high mechanical strength lacks slidability while a resin having a low coefficient of friction and permitting good slidability is low in strength. Accordingly, to obtain sufficient strength, the requirement for low friction has had to be sacrificed. As a result, the slidability of the webbing 10 has not been considered good to date, leading to the problems that the ease and smoothness of operation are not good when winding the webbing 10 and the feeling of operation is not good when winding out the webbing 10.

SUMMARY OF THE INVENTION An object of this invention is therefore to overcome the above problems and, hence, to provide a seatbelt through-anchor improved in the ease and smoothness of operation upon winding a webbing and also in the feeling of operation upon winding it out by applying a resin covering which permits good slidability for the webbing and has high mechanical strength.

In one aspect of the present invention, there is thus provided a seatbelt through-anchor defining therethrough a slot for changing the direction of a webbing to guide the webbing to a desired position. The seatbelt through-anchor comprises a resin covering on a webbing-contacting edge portion of the slot. The resin covering is formed of (i) a lower layer made of a resin with high mechanical strength and molded integrally with the webbing-contacting edge portion and (ii) a top layer made of a resin having a low coefficient of friction, molded integrally with the lower layer and covering the lower layer.

In another aspect of the present invention, there is also provided a seatbelt through-anchor, which comprises: a metal plate swingably fixable on a vehicle body; a through-hole defined in an upper end portion of the plate, through which a bolt can extend; a slot defined in a free end portion of the plate, through which a webbing can extend; and a resin covering on a webbing-contacting edge portion of the slot, said resin covering being formed of (i) a lower layer made of a resin with high mechanical strength and molded integrally with the webbingcontacting edge portion and (ii) a top layer made of a resin having a low coefficient of friction, molded integrally with the lower layer and covering the lower layer.

When a load is exerted on the webbing-contacting edge portion of the slot as a result of tension applied to the webbing, the load can be supported by the lower layer made of the resin having high mechanical strength without deformation of the lower layer so that the webbing is prevented from contacting an edge of the metal plate at a folded back portion thereof. This allows the use of a resin having a low coefficient of friction for the top layer even though this resin is generally low in strength. Accordingly, the present invention can provide a good seatbelt through-anchor improved in the ease and smoothness of operation when the webbing is wound in and also in the feeling of operation when the webbing is wound out.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings, in which: FIG. 1 is a partly cross-sectional view of a seatbelt through-anchor according to one embodiment of the present invention; FIG. 2 is a vertical cross-sectional view of the seatbelt through-anchor, taken in the direction of arrows lI-Il of FIG. 1; FIG. 3 is a schematic illustration showing the construction of a three-point seat belt system; and FIG. 4 is a vertical cross-sectional view of a conventional seatbelt through-anchor.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENT Preferred examples of resins having high mechanical strength include reinforced polyamides, polyacetals and polypropylene, polycarbonates, and the like. On the other hand, polyolefin resins such as polyethylene and polypropylene, fluorinated resins and the like can be mentioned as preferred examples of resins having a low coefficient of friction, i.e., permitting good slidability.

The embodiment of the present invention will hereinafter be described with reference to the ac companying drawings.

A seatbelt through-anchor 1 depicted in FIG. 1 and FIG. 2 comprises a metal plate 2, which is provided at an upper end portion thereof with a through-hole 7 permitting insertion of a bolt 11 therethrough and on a side of a free end thereof with a slot defining a webbing slot 5 for insertion of a webbing 10 therethrough.

Outer surfaces on the side of the free end of the metal plate 2 are covered with a resin covering 8 molded integrally with the outer surfaces. The resin covering 8 has a double layer structure which is formed of a lower layer 3 made of a resin having high mechanical strength and a top layer 4 covering the lower layer 3 and made of a resin having low friction resistance and permitting good slidability.

The seatbelt through-anchor 1 can be produced, for example, in the following manner. First, as is illustrated in the right-hand half of FIG. 1, a resin having high mechanical strength is integrally molded with the metal plate 2 to form the lower layer 3 in such a way that the webbing 10 does not contact at least corner edges 9,9 of the metal plate 2, said corner edges 9,9 corresponding to a lower edge portion 30, as a webbing-contacting edge portion, of the webbing slot 5. The lower layer 3 covers the corner edges 9,9 of the metal plate 2 with the resin having high mechanical strength, on which corner edges 9,9 a tension applied to the webbing 10 is exerted. As a consequence, the folding angle for the webbing 10 at the folded back portion of the webbing 10 remains large so that the webbing 10 is prevented from contacting the corner edges 9,9.

Next, as is illustrated in the left-hand half of FIG. 1, a resin having low friction resistance and permitting good slidability is integrally molded on the side of the free end of the metal plate 2, including a peripheral edge of the webbing slot 5, in such a manner that the lower layer 3 is covered by the top layer 4.

The top layer 4 covers the lower edge portion 30 of the webbing slot 5 and also upper corner edges 9',9' of the metal plate 2, said upper corner edges 9',9' corresponding to an upper edge portion 31 of the webbing slot 5, whereby the sliding resistance of the webbing 10 is reduced on a sliding surface 6 of the lower edge portion 30 of the webbing slot 5 to permit smooth sliding for the webbing 10 and the webbing 10 is prevented from contacting the upper corner edges 9',9' of the metal plate 2.

The seatbelt through-anchor 1 can be mounted on a vehicle body, for example, in the following manner. As shown in FIG. 2, the seatbelt through-anchor 1 is swingably supported on the bolt 11 which extends through the through-hole 7 formed in the upper end portion.

When the through-anchor 1 is used in a threepoint seat belt system in which, like the conventional through-anchor, the webbing 10 is secured at one end portion thereof in the retractor 20, extends through the through-anchor 1 and is fastened at the opposite end portion thereof on the anchor plate 27 supported pivotally by the bolt 23 on the lower end portion of the center pillar 22 and an occupant is restrained in the seat 26 by latching the through-tongue 24, which is arranged at an intermediate portion of the webbing 10 between the anchor plate 27 and the through-anchor 21, in the buckle 25 disposed upright at the substantially central portion of the vehicle body, the webbing 10 extends as a retractor-side webbing 10a to the throughanchor 1 and, after being folded back at the webbing slot 5 of the through-anchor 1, extends further as an anchor-plate-side webbing 10b in a normal state of use as is shown in FIG. 2.

Namely, the webbing 10 is folded back by the lower edge portion 30 of the webbing slot 5 and slides longitudinally along the sliding surface 6 of the lower edge portion 30. Since the lower edge portion 30 is covered by the top layer 4 made of the resin permitting good slidability, for example, a polyolefin resin such as polyethylene or polypropylene, a fluorinated resin or the like, the folded back portion of the webbing 10 is able to slide smoothly in the webbing slot 5 and the webbing 10 can therefore be operated with ease when the webbing 10 is wound out or in.

If the webbing 10 is tensioned by a vehicular emergency or the like and the resulting load is exerted on the lower edge portion 30 of the webbing slot 5, the lower layer 3 made of the resin having high mechanical strength, such as a reinforced polyamide, polyacetal or polypropylene or a polycarbonate, can bear without deformation the load exerted on the lower edge portion 30 so that the webbing 10 can be prevented from contacting the corner edges 9,9 of the metal plate 2 at its folded back portion.

The seatbelt through-anchor 1 is thus applied with the resin covering 8 permitting good slidability and sufficient mechanical strength, thereby providing the seatbelt through-anchor 1 with good ease and smoothness of operation upon winding the webbing 10 and also with good feeling of operation upon winding out the webbing 10.

It is to be noted that the seatbelt throughanchor according to the present invention is not limited to the embodiment described above but can of course take various shapes. For example, the subject matter of the present invention can also be applied to a through-anchor resin-covered at only a peripheral edge portion of the slot although the entire surfaces of the free end portion of the metal plate are covered with the resins in the seatbelt anchor of the above embodiment.

Further, the seatbelt through-anchor according to the present invention is not limited to such a seatbelt through-anchor to be mounted on a center pillar as in the above embodiment but, of course, can be applied irrespective of the position where the webbing to be wound in the retractor is guided.

Claims

CLAIMS:

1. A seatbelt through-anchor defining therethrough a slot for changing the direction of a webbing to guide the webbing to a desired position, comprising a resin covering on a webbing-contacting edge portion of the slot, said resin covering being formed of (i) a lower layer made of a resin with high mechanical strength and molded integrally with the webbingcontacting edge portion and (ii) a top layer made of a resin having a low coefficient of friction, molded integrally with the lower layer and covering the lower layer.

2. A seatbelt through-anchor of claim 1, wherein the lower layer is made of a resin selected from reinforced polyamides, polyacetals and polypropylene and polycarbonates, and the top layer is made of a resin selected from polyolefin resins and fluorinated resins.

3. A seatbelt through-anchor comprising: a metal plate swingably fixable on a vehicle body; a through-hole defined in an upper end portion of the plate, through which a bolt can extend; a slot defined in a free end portion of the plate, through which a webbing can extend; and a resin covering on a webbing-contacting edge portion of the slot, said resin covering being formed of (i) a lower layer made of a resin with high mechanical strength and molded integrally with the webbingcontacting edge portion and (ii) a top layer made of a resin having a low coefficient of friction, molded integrally with the lower layer and covering the lower layer.

4. A seatbelt through-anchor of claim 3, wherein the lower layer is made of a resin selected from reinforced polyamides, polyacetals and polypropylene and polycarbonates, and the top layer is made of a resin selected from polyolefin resins and fluorinated resins.

5. A seatbelt through-anchor substantially as hereinbefore described with reference to, and as shown in, FIGS. l through 3 of the accompanying drawings.