JP2004231019A - Retractor for seat belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily set various energy absorption characteristics with a simple structure. <P>SOLUTION: The retractor for a seat belt has: a retractor base; a bobbin 3; a torsion bar 11; a locking head 12; an emergency lock means; a bending element rotating with the bobbin 3; and a cover integrally rotating with the locking head. A drawing mechanism 31 formed on the cover makes the bending element passing by a radially bent route 32 and it is locally plastically deformed when the bending element is relatively rotated against the locking head. The drawing mechanism 31 is constituted by a claw part 35 and pressing parts 36 positioned at front and rear sides of the claw part. A terminal end 20B of the bending element 20 is formed so as to gradually become narrow as it advances to a terminal end by obliquely cutting an edge part in a width direction positioned at a tip end side of the claw part 35. The claw part is formed so as to become wider as it advances from a base side to a tip end side. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seatbelt retractor provided with an energy absorbing mechanism for alleviating a load received by an occupant from a webbing during a vehicle collision.
[0002]
[Prior art]
2. Description of the Related Art A retractor that winds up a webbing of a seat belt device generally includes an emergency lock mechanism that physically locks a drawer of the webbing at the time of a vehicle collision. Also, when the impact force due to the collision is extremely large, the tension of the emergency locked webbing gradually increases with the passage of time after the collision due to the inertial movement of the occupant, and a sudden load is applied to the occupant's body from the webbing. become. For this reason, in this type of retractor, when the load acting on the webbing is equal to or greater than a predetermined value, the emergency locked webbing is allowed to be fed out by a predetermined amount, and the impact given to the occupant's body is absorbed. It is common to provide such an energy absorbing mechanism.
[0003]
As this kind of energy absorbing mechanism, there is known an energy absorbing mechanism that absorbs energy by using plastic deformation of a torsion bar (torsion bar) in a torsional direction (for example, see Patent Document 1).
[0004]
In such an energy absorbing mechanism using a torsion bar, when excessive torque acts on the bobbin around which the webbing is wound in the pulling-out direction of the webbing, the torsion bar is twisted and plastically deformed, so that the collision energy acting on the occupant's body is reduced. Is absorbed as deformation work of the torsion bar.
[0005]
Incidentally, the impact at the time of the collision varies depending on the vehicle structure and the like. Therefore, in order to sufficiently protect the occupant's body, it is desired that, for example, a set load at which the energy absorbing mechanism starts operating and a shock absorbing characteristic can be freely set in accordance with a vehicle structure or the like.
[0006]
When the emergency locked webbing is pulled out by the action of the energy absorbing mechanism, the occupant moves in the collision direction accordingly. At that time, in order to prevent the occupant's body from colliding with the vehicle interior wall, etc., in recent vehicles, in the event of a vehicle emergency, the vehicle swells between the occupant and the vehicle interior wall, etc., and receives the occupant's body. An SRS airbag system for protecting the body of a passenger is equipped, and measures to improve occupant safety in cooperation with a seat belt device have become widespread. When such an SRS airbag system is provided, there is also a demand that the characteristics of the energy absorbing mechanism in the retractor have various changes in order to safely and maximize the effect of the SRS airbag system. Is coming out.
[0007]
For example, in the early stage of the collision before the occupant comes into contact with the inflated airbag, a large energy absorption load is secured to minimize the movement of the occupant, and during the late collision when the airbag begins to restrain the occupant, the energy absorption load is increased. Lowering the airbag system and entrusting occupant protection to the airbag system.
[0008]
Thus, from the viewpoint of optimizing the energy absorbing load according to the difference in the vehicle structure and sharing the role with the SRS airbag system, the energy absorbing mechanism should have a change in the characteristics such as the energy absorbing load. There is a growing need for flexibility and design flexibility.
[0009]
In recent years, with the improvement of collision safety, seat belts also have energy absorbing characteristics such as "high EA load in the early stage of collision and low EA load in the latter half (after the belt has been extended to some extent)". The desired case has come out. This is because, instead of simply pulling out the belt with a constant load, the load is changed to further improve safety.
[0010]
In this regard, the torsion bar is twisted with a predetermined load (torque), and it is difficult to change the load. In particular, since a shaft member such as a torsion bar becomes harder as it is twisted, it is deformed while the torsional torque increases, and the torque cannot be changed midway.
[0011]
Therefore, in the retractor described in Patent Document 1, a combination of a torsion bar and a hollow pipe is used as an energy absorbing member, and the torsion bar is deformed in the torsion direction and the plastic deformation in the radial direction of the end of the hollow pipe is used to reduce the impact energy. So that it absorbs. In this retractor, a hollow pipe is provided separately from the torsion bar, and energy is absorbed by a combination of both. Therefore, it is possible to flexibly cope with a change in energy absorption characteristics.
[0012]
[Patent Document 1]
JP 2001-294125 A
[Problems to be solved by the invention]
However, in the technique of Patent Document 1, a hollow pipe is used as an energy absorbing member other than the torsion bar, and the end of the hollow pipe is simply formed radially outward with a projection formed at the end of the torsion bar. Since the energy is absorbed by plastically deforming convexly, there is a problem that the structure is complicated and it is difficult to set the energy absorption characteristics.
[0014]
The present invention has been made in consideration of the above circumstances, and has as its object to provide a seatbelt retractor that can easily set various energy absorption characteristics with a simple structure.
[0015]
[Means for Solving the Problems]
A retractor according to a first aspect of the present invention includes a retractor base, a bobbin wound with webbing and rotatably supported by the retractor base, and disposed in a central cavity of the bobbin. Bar as a first energy absorbing member coupled to one end of the torsion bar, a locking head rotatably supported by the retractor base and coupled to the other end of the torsion bar in the axial direction, and the locking in an emergency. By locking the head to the retractor base, emergency locking means for preventing the rotation of the bobbin in the webbing pull-out direction via the torsion bar, and by forming a metal band plate into a substantially semi-annular curved shape, The bobbin is wound around the outer periphery of the other end in the axial direction, and the distal end in the circumferential direction is fixed to the bobbin so that the bobbin and the bobbin are fixed. A rotating bending element as a second energy absorbing member, a cover integrally coupled to the locking head and covering the outer periphery of the other end of the bobbin in the axial direction from above the bending element, and integrally formed with the cover. When the locking head is locked by the emergency locking means and the bobbin rotates with the torsional deformation of the torsion bar and the bending element rotates relative to the locking head, the bending element has a radius Handle means for passing through a path bent in the direction and locally deforming plastically, and the handle means is protruded in a cantilever shape parallel to the axial direction of the bobbin and is provided on the inner peripheral side of the bending element. Inserted, bending element rotates relative to locking head When the bending element is formed, the bent path is formed between the claw that plastically deforms the bending element outward in the radial direction and the claw positioned before and after the claw. A pressing portion that presses the deformed portion toward the initial shape position, and the end portion of the bending element is formed by obliquely cutting an edge in the width direction located on the tip side of the claw portion. , The width is gradually reduced toward the end.
[0016]
A retractor according to a second aspect of the present invention is characterized in that, in the first aspect, the claw portion is formed so as to become wider from the root side to the tip side.
[0017]
In the retractor of the present invention, a bending element formed by bending a metal strip into a substantially semi-annular shape is used as the second energy absorbing member, and the bending element is handled according to a bending path by a handling means provided on the cover. The energy absorption characteristics can be easily and variously set according to the width and thickness of the bending element, the manner of setting the bending path of the handling means, and the like. Moreover, since the handling means for deforming the bending element is formed on a cover which is a member separate from the torsion bar, the structure is simple, and the processing and assembly can be simplified.
[0018]
In addition, the handling means is constituted by a cantilevered claw portion and a pressing portion, and the shape of the end portion of the bending element for absorbing energy is obtained by obliquely cutting the edge in the width direction located on the tip side of the claw portion. Since it is formed so that it gradually becomes narrower toward the end, it is possible to ensure that the bending element is hooked on the claw until it reaches the final end, and that the bending element is securely deformed to the final end As a result, the energy absorption characteristics can be stabilized. In this case, by forming the claw portion in a shape that becomes wider as going from the root side to the tip side, it is possible to further ensure that.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the retractor of the embodiment, FIG. 2 is an exploded perspective view of a main part thereof, FIG. 3 is a perspective view of a bending element as a second energy absorbing member, and FIG. FIG. 3 is a cross-sectional view taken along the arrow A, and FIG.
[0020]
The retractor 1 has two side plates 2A and 2B parallel to each other, and a retractor base 2 fixed to a vehicle body, and webbing (not shown) wound around an outer peripheral portion, and both side plates 2A of the retractor base 2; A bobbin 3 rotatably supported between 2B, a pretensioner mechanism 4 for forcibly rotating the bobbin 3 in a winding direction of the webbing to remove slack of the webbing in the event of a collision, and mounting and releasing the webbing And a take-up spring mechanism 5 for applying a biasing force to the bobbin 3 to remove the slack of the webbing at this time. The pretensioner mechanism 4 and the take-up spring mechanism 5 are attached to one side plate 2A of the retractor 1 that supports one end of the bobbin 3.
[0021]
Further, the retractor 1 is disposed coaxially with the bobbin 3 in the center cavity 3A of the bobbin 3, and has a first axial end coupled to one end of the bobbin 3 in the axial direction (spline coupling in the illustrated example). And a rocking head (tread) rotatably supported by the other side plate 2B of the retractor base 2 and coupled (spline-coupled in the illustrated example) to the other axial end of the torsion bar 11. An emergency locking means 13 for locking the locking head 12 to the retractor base 2 in an emergency to prevent the bobbin 3 from rotating in the webbing pull-out direction via the torsion bar 11, and an axis of the bobbin 3. Is wound around the outer circumference of the other end in the direction, and the distal end portion 20A in the circumferential direction is fixed to the hook 3B formed on the bobbin 3. A bending element 20 serving as a second energy absorbing member that rotates together with the bobbin 3, and a metal press that is integrally connected to the locking head 12 and covers the outer periphery of the other end of the bobbin 3 in the axial direction from above the bending element 20. After the cover 30 made of a molded product, the torsion bar 11 as the first energy absorbing member, and the bending element 20 as the second energy absorbing member are sufficiently deformed to the last, the rotation of the bobbin 3 is finally completed. A stopper ring 40 which locks and prevents further withdrawal of the webbing.
[0022]
The torsion bar 11 is formed of a plastically deformable metal rod. When a predetermined or more torsional force acts between both ends, the torsion bar 11 is plastically deformed, and absorbs energy as a work of deformation. The stopper ring 40 is assembled so as to rotate integrally with the bobbin 3 by inserting its own three projections 41 into the concave portion 3C formed on the end face of the bobbin 3 so as to be freely slidable in the axial direction. The male screw of the boss 12A is screwed with a predetermined clearance 42 to the substrate 12B of the locking head 12. When the bobbin 3 rotates relative to the locking head 12, the stopper ring 40 rotates together with the bobbin 3, thereby being displaced in the axial direction by the lead action of the screw portion, and moving by the clearance 42. At this point, the locking head 12 comes into contact with the substrate 12 </ b> B, and functions to prevent further rotation of the bobbin 3.
[0023]
As shown in FIG. 3, the bending element 20 is formed by bending a metal band plate into a substantially semi-annular shape, and the hook 20B is hooked so that the distal end portion 20A can be hooked on the hook 3B on the bobbin 3 side. It is bent. In addition, the range of the predetermined length of the terminal portion 20B is formed so that one edge portion 21 is obliquely cut so that the width gradually decreases toward the terminal portion.
[0024]
The bending element 20 absorbs the impact energy acting on the webbing by successively handling (laddering) each part in the circumferential direction in order. ) A mechanism section (handle means) 31 is provided.
[0025]
As shown in FIG. 4, the handling mechanism 31 provided on the cover 30 rotates the bobbin 3 with the torsional deformation of the torsion bar 11 in a state in which the locking head 12 is locked by the emergency locking means, and causes bending. When the element 20 is relatively rotated with respect to the locking head 12, the bending element 20 is caused to pass through a path 32 bent in the radial direction to locally plastically deform. That is, the handle mechanism 31 is protruded in a cantilever shape parallel to the axial direction of the bobbin 3 and inserted into the inner peripheral side of the bending element 20, and when the bending element 20 rotates relative to the locking head 12. The bent path 32 is formed between a claw 35 for plastically deforming the bending element 20 to protrude radially outward and a claw 35 positioned before and after the claw 35, and the bending element 20 is formed. And a pressing portion 36 for pressing the convexly deformed portion 25 toward the initial shape position.
[0026]
In the initial shape, the bending element 20 has, at a position close to the distal end portion 30A, a portion 25 that is deformed outward in the radial direction in which the claw portion 35 is inserted on the inner peripheral side. The claw portion 35 of the cover 30 is inserted inside. Further, the portions of the claw portion 35 and the pressing portion 36 that rub against the bending element 20 are rounded so as not to have corners.
[0027]
As shown in FIG. 4 (b), the bending element 20 has a bobbin 3 in a direction in which the edge 21 of the end portion 20B is obliquely cut is positioned on the tip side of the cantilever claw 35. It is set on the outer circumference of. In this case, the right and left side edges in the protruding direction of the claw portion 35 on the cover 30 that handles the bending element 20 have a predetermined angle θ (exaggerated in the figure) so that the claw portion 35 on the cover 30 side becomes wider from the base 35a side to the tip end 35b side. It is drawn large, but is actually slanted by a smaller angle).
[0028]
Next, the operation will be described.
During normal running of the vehicle, for example, the torsion bar 11, the locking head 12, the cover 30, the bending element 20, and the stopper ring 40 rotate integrally via the bobbin 3, thereby pulling out and winding the webbing. Is performed.
[0029]
Next, for example, when the vehicle collides with an obstacle, a collision sensor detects the collision, and a control unit (not shown) operates the pretensioner mechanism 4 to rotate the bobbin 3 in the webbing winding direction, thereby loosening the webbing. And restrain the occupant in the seat. In addition, the emergency locking means 13 is activated by the deceleration or sudden withdrawal of the webbing, the locking head 12 is locked by the retractor base 2, and the webbing is not pulled out.
[0030]
When a strong pull-out load greater than a preset value acts on the webbing due to the recoil of the occupant, the locking head 12 is already locked to the retractor base 2, so that the other axial side of the torsion bar 11 may rotate. Although not possible, the other end rotates while torsionally deforming the torsion bar 11, and rotates the bobbin 3 relative to the locking head 12 so that the webbing is pulled out to reduce the impact acting on the occupant.
[0031]
At the same time, with the relative rotation of the bobbin 3 with respect to the locking head 12, a phase shift between the handling mechanism 31 of the cover 30 and the bending element 20 starts, and the bending element 20 is handled by the claw 35 and the pressing portion 36 of the cover 30. Meanwhile, the bobbin 3 rotates with respect to the locking head 12.
[0032]
FIG. 5 shows how the relative rotation position between the bobbin 3 and the cover 30 (the locking head 12) changes, and how the bending element 20 is deformed. The relative rotation proceeds in the order of (a) to (h), and the bending element 20 passes through the handling mechanism 31 while locally deforming to be convex in the radial direction. Then, by the plastic deformation of the torsion bar 11 and the bending element 20 at this time, the webbing is drawn out while absorbing energy.
[0033]
At this time, when the deformation of the bending element 20 is completed, the end portion 20B of the bending element 20 passes through the handling mechanism portion 31. However, the shape of the end portion 20B of the bending element 20 is changed to the width located at the tip 35b side of the claw portion 35. The edge 21 in the direction is cut obliquely so that it gradually narrows toward the end, that is, it is formed so as to be close to the base 35a of the claw 35, so that bending is performed. Even if the element 20 is slightly shifted in the direction in which it escapes from the base 35a of the claw portion 35 of the cover 30 while being handled, the claw portion 35 is surely hooked to the final end. Can be reliably handled by the claw portion 35, and the energy absorption characteristics can be stabilized. In particular, in this case, since the claw portion 35 is formed in a shape that becomes wider from the base 35a side to the tip end 35b side, the bending element 20 can be more reliably handled to the final end.
[0034]
When the bobbin 3 rotates relative to the locking head 12, the stopper ring 40 slides toward the substrate 12 of the locking head 12, and finally the bending element 20 is handled and the stopper ring 40 is removed from the mechanism 31. Stroke is limited by the contact of the substrate 40 with the substrate 12B of the locking head 12, whereby the rotation of the bobbin 3 is locked.
[0035]
As described above, in the event of a vehicle emergency, the emergency locking means operates to lock the webbing withdrawal, and when the load acting on the bobbin 3 in the webbing withdrawal direction exceeds a predetermined value, both the torsion bar 11 and the bending element 20 absorb energy. Operates as a mechanism to absorb impact energy in the event of a vehicle emergency. Therefore, as shown in FIG. 6A, the energy absorbing load of the entire retractor 1 is the energy absorbing load f1 when the torsion bar 11 undergoes torsional deformation and the energy absorbing load f1 when the bending element 20 undergoes plastic deformation. When the torsion bar 11 absorbs energy in the event of a vehicle emergency only by torsional deformation as shown in (b), the energy absorption load is reduced by the amount absorbed by the bending element 20 as shown in FIG. And it is easy to secure a high energy absorption load.
[0036]
Further, as shown in (a), the energy absorption area A2 due to the plastic deformation of the bending element 20 can be set independently of the energy absorption area A1 due to the torsional deformation of the torsion bar 11. For example, by setting the energy absorption region A2 due to the plastic deformation of the bending element 20 so as to overlap a part of the energy absorption region A1 due to the torsional deformation of the torsion bar 11, a part of the energy absorption region due to the torsional deformation of the torsion bar 11 is formed. Therefore, a high energy absorption load is secured by summing the two energy absorption loads. In addition, as long as the two energy absorption regions do not overlap, a low energy absorption load can be set only by the energy absorption effect due to the torsional deformation of the torsion bar 11. In this manner, the energy absorbing mechanism of the seat belt retractor can have an energy absorbing characteristic in which the energy absorbing load changes during operation.
[0037]
Further, the adjustment of the energy absorbing load of the entire retractor 1 involves not only the change of the shaft diameter and the material of the torsion bar 11 but also the change of the size, shape, and material of the portion where the bending element 20 undergoes plastic deformation. Since various elements are involved, a desired energy absorbing load can be realized by changing the design of the remaining elements without relying on, for example, an increase in the shaft diameter of the torsion bar 11 or a change in material. is there. That is, the energy absorption load can be easily set higher without sacrificing the compactness of the retractor 1 by reducing the diameters of the torsion bar 11 and the bobbin 3 of the retractor 1.
[0038]
When the dimensions and materials of both the torsion bar 11 and the bending element 20 can be changed, the adjustment of the energy absorption load and the adjustment of the energy absorption range are performed on both, so that the specific structure according to the difference in the vehicle structure and the like can be obtained. It can easily respond to demands for various energy characteristics and flexibly respond to various needs. Therefore, the energy absorption performance can be improved without sacrificing the compactness of the retractor 1, and the seat belt device can be downsized, and the occupant safety can be improved by improving the energy absorption characteristics. Can be.
[0039]
Further, in the retractor 1 of the above embodiment, the bending element 20 formed by bending the metal strip into a substantially semi-annular shape is used as the second energy absorbing member next to the torsion bar 11, and the handle mechanism provided on the cover 30 is provided. By using the bending element 20, the energy is absorbed by handling the bending element 20, so that the degree of freedom of design can be expanded as compared with the conventional one in which the torsion bar 11 is provided with a projection for deforming the energy absorbing member. It can be easily performed, and the structure can be simplified and the processing and assembly can be simplified.
[0040]
【The invention's effect】
As described above, according to the present invention, a bending element formed by bending a metal strip into a substantially semi-annular shape is used as the second energy absorbing member next to the torsion bar, and the bending is performed by the gripping means provided on the cover. Since the energy is absorbed by handling the element, the energy absorption characteristics can be easily and variously set depending on the width and thickness of the bending element, the manner of setting the bending path of the handling means, and the like. In addition, since the handling means for deforming the bending element is formed on the cover, which is a separate member from the torsion bar, it is easy to expand the degree of freedom of design, simplifying the structure and simplifying the processing and assembly. Can be achieved.
[0041]
In addition, the handling means is constituted by a cantilevered claw portion and a pressing portion, and the shape of the end portion of the bending element for absorbing energy is obtained by obliquely cutting the edge in the width direction located on the tip side of the claw portion. Since the width is gradually reduced toward the end, the bending element can be surely deformed up to the final end, and the energy absorption characteristics can be stabilized. Further, by forming the claw portion in a shape that becomes wider from the base side to the tip side, it is possible to further assure the reliability and to realize a seat belt device that can exhibit stable energy absorption characteristics. Can be.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a retractor according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view showing a configuration of a main part of the retractor of FIG.
FIG. 3 is a perspective view showing a configuration of a bending element in the retractor of FIG.
4A is a sectional view taken along the line AA of FIG. 1, and FIG. 4B is a view taken along the line BB of FIG.
FIGS. 5A to 5H are cross-sectional views showing a change in a relative rotational position between a bobbin and a cover of the retractor and a deformation of a bending element.
6A and 6B are characteristic diagrams of a retractor, wherein FIG. 6A is a characteristic diagram of a retractor according to an embodiment of the present invention, and FIG. 6B is a characteristic diagram of a conventional retractor.
[Explanation of symbols]
Reference Signs List 1 retractor 2 retractor base 3 bobbin 11 torsion bar 12 locking head 13 emergency locking means 20 bending element 20A distal end 20B terminal end 21 edge 30 cover 31 handling mechanism 32 bent path 35 claw 35a root 35b distal end 36 pressing part

Claims (2)

A retractor base, a bobbin wound with webbing rotatably supported by the retractor base, a first bobbin disposed in a central cavity of the bobbin, and having one axial end coupled to one axial end of the bobbin. A torsion bar as an energy absorbing member, a locking head rotatably supported by the retractor base and coupled to the other axial end of the torsion bar, and locking the locking head to the retractor base in an emergency. Emergency locking means for preventing the rotation of the bobbin in the webbing withdrawal direction via the torsion bar, and a metal band plate is formed into a substantially semi-circular curved shape, and the outer periphery of the bobbin in the axial direction at the other end is formed. A second energy absorbing portion that is wound around and rotates with the bobbin by fixing its circumferential end to the bobbin And a cover that is integrally formed with the locking head and that covers the outer periphery of the other end of the bobbin in the axial direction from above the bending element, and that the locking head is formed integrally with the cover. When the bobbin rotates with the torsional deformation of the torsion bar in a state locked by the locking means and the bending element rotates relative to the locking head, the bending element passes through the bending element in a path bent in the radial direction. And means for locally deforming plastically,
The handling means is protruded in a cantilever shape parallel to the axial direction of the bobbin and inserted into the inner peripheral side of the bending element. When the bending element rotates relative to the locking head, the bending element has a radius Forming a bent path between the claw portion to be plastically deformed outward in the direction and the claw portion located before and after the claw portion, and setting the convexly deformed portion of the bending element to an initial shape position. And a pressing section that presses toward
The end portion of the bending element is formed so that the widthwise edge located on the tip side of the claw portion is obliquely cut so that the width gradually decreases toward the end. Seat belt retractor. The retractor for a seat belt according to claim 1, wherein the claw portion is formed so as to become wider from a root side to a tip side.

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