JPH1035411A - Seat belt retractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt retractor provided with a good energy absorbing mechanism, by which occupant initial constraint performance can be improved and collision energy working on an occupant body can be efficiently absorbed in a case of a vehicle collision. SOLUTION: A seat belt retractor 100 is provided with a torsion bar 2 which is installed in a retractor base 1 rotationally and is prevented from rotating in the webbing pulling out direction in case of a vehicle emergency, a cylindrical bobbin 3 which winds a webbing around itself and is supported in the torsion bar 2 rotationally, an energy absorbing mechanism 200 which is mainly constructed of the torsion bar 2 and is formed between the bobbin 3 and a locking plate 5, and a shear pin 50 which is arranged between the torsion bar 2 and the bobbin 3 so as to perform shearing with the predetermined torque. When the locking plate 5 and the bobbin 3 are rotated relatively, a shear pin 50 is broken, and subsequently, the torsion bar is torsionally deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retractor (winding device) for a seat belt device, and more particularly to a seat belt retractor having an energy absorbing mechanism.

[0002]

2. Description of the Related Art Conventionally, in a seat belt retractor for holding a vehicle occupant or the like safely in a seat, a retractor is physically locked by inertial sensing means that responds to sudden acceleration, collision or deceleration. An emergency lock retractor that has an emergency lock mechanism and effectively and safely restrains an occupant is used.

[0003] Such an emergency lock type retractor is disclosed in, for example, Japanese Patent Application Laid-Open No. 50-79024 and Japanese Patent Publication No.
As in the seat belt retractor disclosed in Japanese Patent Publication No. 21624 and Japanese Utility Model Publication No. 2-45088, an engaging member disposed at one end of a winding shaft on which webbing is wound is provided with a retractor base in a vehicle emergency. There is a type provided with a lock means which can be engaged with the engaged portion to prevent the winding shaft from rotating in the webbing withdrawing direction.

[0004] In the locking means, a locking mesh portion formed in a winding shaft through-hole of the retractor base through which the winding shaft passes, or an internal gear plate provided in parallel with the winding shaft through-hole. While the formed ratchet teeth are used as the engaged portion, a lock plate or a locking claw that rotates together with the winding shaft is used as the engaging member. Are engaged to prevent the take-up shaft from rotating in the webbing withdrawing direction.

On the other hand, when the impact force due to the collision is extremely large, the webbing tension increases with the passage of time after the collision, so that the occupant's body suddenly decelerates, and the load applied from the webbing to the occupant is extremely low. growing. Therefore, when the load acting on the webbing is equal to or greater than a predetermined value, the seat belt is extended by a predetermined amount to provide an energy absorbing mechanism for absorbing an impact generated on the occupant's body, thereby making the occupant's body more reliable. There have been proposed various types of seat belt devices for protecting the vehicle. As an example of a seat belt retractor having such a structure, an "energy absorbing device for a safety belt" described in Japanese Patent Application Laid-Open No. 46-7710 is known.

[0006] The energy absorbing device includes a winding member serving as a portion to which the energy absorbing device transmits force, and a holder (bobbin) rotatable relative to the winding member. A torsion bar (energy absorbing mechanism) is arranged between the holder and the winding member. Therefore, after the rotation of the take-up shaft is stopped in the event of a vehicle emergency, when a load is further applied to the locking means, the torsion bar is twisted around its own axis, so that the collision energy acting on the occupant's body is reduced. It is absorbed as deformation work of the torsion bar.

[0007]

However, the impact at the time of a collision differs depending on the vehicle structure, and in order to sufficiently protect the occupant's body, the load of the energy absorbing load (the load acting on the webbing) must be adjusted in accordance with the characteristics of the vehicle. It is necessary to obtain an arbitrary load characteristic by changing the curve. However, in the case of the energy absorbing mechanism using the plastic deformation means such as the above-mentioned torsion bar, since the deformation load of the plastic deformation means is substantially constant, the energy absorption load is substantially constant over the entire operation range.

That is, the initial restraint performance of the occupant immediately after the collision is determined by the deformation load of the plastic deformation means.
Therefore, in a retractor equipped with an energy absorbing mechanism, in order to improve the initial restraint performance immediately after a collision and reduce the amount of movement of the occupant, for example, hold the webbing in an emergency and extend the webbing from the retractor. A blocking mechanism must be combined.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and improve the initial restraint performance of the occupant, and efficiently absorb the collision energy acting on the occupant's body at the time of a vehicle collision. An object of the present invention is to provide a seat belt retractor having an energy absorbing mechanism.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a winding shaft which is rotatably mounted on a retractor base and is prevented from rotating in a webbing withdrawing direction in the event of a vehicle emergency. A cylindrical bobbin rotatably supported by the winding shaft, plastic deformation means for relatively rotatably engaging the winding shaft and the bobbin with a predetermined load, and between the winding shaft and the bobbin. This is achieved by a seat belt retractor provided with a shear pin disposed and shearing at a predetermined torque.

In the present invention, the bobbin rotatably supported by the winding shaft is not permanently fixed to the winding shaft, but is always rotatably supported by the winding shaft. The bobbin or the bobbin that rotates together with the winding shaft in a normal use state, but is rotatably supported with respect to the winding shaft when a predetermined load or more is applied. Including.

Therefore, preferably, the plastic deformation means comprises:
At one end, it is attached so as to rotate integrally with the bobbin, and at the other end, it is twisted in response to being prevented from rotating in the webbing withdrawal direction, thereby absorbing collision energy acting on the occupant's body as deformation work. It is constituted by a winding shaft as a torsion bar. The shear pin is configured to break after the winding shaft and the bobbin rotate relative to each other by a predetermined angle.

[0013] The shearing pin is configured to apply a resistance to the rotating torque during the relative rotation of the winding shaft and the bobbin by a predetermined angle, and then to be broken.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a seat belt retractor according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front vertical sectional view of a seat belt retractor 100 according to an embodiment of the present invention, and FIG.
FIG. 2 is an exploded perspective view of a main part of the seat belt retractor 100 shown in FIG.

The seat belt retractor 100
Is a columnar torsion bar 2 which is a winding shaft rotatably attached to the retractor base 1 and has a disk-shaped locking plate 5 attached at least at one end, and a webbing withdrawal direction of the locking plate 5 in the event of a vehicle emergency. Emergency lock means 30 for preventing rotation of
0, a cylindrical bobbin 3 on which webbing is wound and which is attached to the other end of the torsion bar 2 so as to rotate integrally therewith; the locking plate 5 and the bobbin 3
And a lock piece 15 provided on a guide portion 13 formed at the opposite portion of the lock member.

The retractor base 1 has a substantially U-shaped cross section, and a torsion bar 2 combined with the bobbin 3 is rotatably bridged between the opposed side plates 1a and 1b. . The other end of the torsion bar 2, the webbing known winding spring device in the winding take the direction (direction of arrow X ₁₎ is normally urged to the torsion bar 2 (not shown) is disposed.

A substantially annular internal tooth ratchet 2 is provided outside the shaft through hole 20 provided in the side plate 1a.
1 are arranged side by side, and engagement inner teeth 25 are formed on the inner peripheral edge of the internal tooth ratchet 21. The internal tooth ratchet 21 is riveted by a rivet 26 that fits a hole 22 formed on the peripheral edge of the shaft through hole 20 and a hole 23 provided on the outer peripheral edge of the internal tooth ratchet 21. .

That is, in the event of a vehicle emergency, the locking plate 5
In order to prevent the webbing from rotating in the pulling-out direction, the engaged portion of the emergency locking means 300 to be engaged with an engagement member described later is constituted by the engagement inner teeth 25. The bobbin 3 supported on the retractor base 1 via the torsion bar 2 has a substantially cylindrical shape obtained by combining an aluminum alloy or a steel and a resin. A slit opening 3a penetrating in the radial direction is provided for inserting and holding the portion.

At both ends in the axial direction of the bobbin 3, square holes 3 are provided.
1 and a round hole 32 are respectively formed through. Further, a retainer 40 to be fitted into a shaft through hole of the side plate 1b is mounted on an end of the bobbin 3 on the side of the take-up spring device (not shown) in which the square hole 31 is formed. Further, the round hole 3
At the end of the bobbin 3 on the side of the emergency lock means 300 formed with 2, a guide groove 11 having a C-shaped bottomed groove is engraved along the outer peripheral edge thereof. Also, the guide groove 11
As shown in FIG. 3, a guide groove 12 which forms a guide portion 13 together with the guide groove 11 is formed on the inner surface of the locking plate 5 which faces the end of the bobbin 3 where the groove is formed. . The guide portion 13 has a curvature corresponding to the curvature of the guide grooves 11 and 12, and
An approximately cocoon-shaped lock piece 15 slidable along the inner wall surfaces of 1 and 12 is provided.

As shown in FIG. 4B, the guide groove 11 extends from the initial end 11A to the end 11A of the guide groove 11.
B is set to be approximately three quarters of the outer peripheral distance of the bobbin 3, and the groove width is set to the lock piece 15 over the entire area.
Wider than the width. As shown in FIG. 4A, the guide groove 12 is set such that the distance from the initial end 12A to the end 12B of the guide groove 12 is substantially three-fourths of the outer circumference of the locking plate 5. And the initial end 12
On the A side, a wide portion 12a having a groove width larger than the width of the lock piece 15 is formed, and on the end portion 12B side, a narrow portion 12b which is a deformed portion having a groove width smaller than the width of the lock piece 15 is formed.

The set distance between the guide grooves 11 and 12 can be appropriately selected. Further, the ratio between the wide portion 12a and the narrow portion 12b is appropriately selected. Therefore, the lock piece 15 is relatively movable with respect to the bobbin 3 over the entire area of the guide groove 11, and is relatively movable with respect to the locking plate 5 at the wide portion 12 a of the guide groove 12.
On the other hand, in the narrow portion 12b of the guide groove 12, when a predetermined force or more is applied to the lock piece 15, the narrow portion 12b is pushed or expanded or cut to deform the narrow portion 12b. The lock piece 15 is movable relative to the locking plate 5.

However, between the bobbin 3 and the locking plate 5, a shear pin 50 for shearing with a predetermined torque is provided.
Are arranged. The shear pin 50 penetrates through the through hole 5 b of the locking plate 5 and is fitted in the locking hole 3 b of the bobbin 3, and regulates the relative rotation of the bobbin 3 with respect to the locking plate 5. When a rotation torque greater than a predetermined value acts between the bobbin 3 and the locking plate 5, the shear pin 50 is sheared, and the bobbin 3 can be rotated relative to the locking plate 5.

Further, on the outer surface of the locking plate 5, a support shaft 7 on which a pawl 16 which is an engagement member engageable with the engagement internal teeth 25 is pivotally supported so as to swing and protrude is provided. In addition, a rotation support shaft 6 of the torsion bar 2 penetrating through the locking plate 5 protrudes to rotatably support the bobbin 3. Here, the bobbin 3 or the locking plate 5 is formed as a through groove which penetrates the guide groove 11 or 12 in the thickness direction on a separately formed disk member, and these disk members are respectively formed on the bobbin 3 or the locking plate. It is good also as a structure which is integrated with 5 at the time of assembly. A configuration in which only one of the guide groove 11 and the guide groove 12 is formed is also suitable.

The locking plate 5 has a pole 16
Is rotated in the direction in which it engages with the engagement internal teeth 25, the pole 16 e (see FIG. 2) on the opposite side to the swing side end of the pole 16 is positioned, and so,
When a large load is applied to the pole 16, the pole 16 has a pressure receiving surface 4 that receives the load. At both ends in the axial direction of the torsion bar 2, a prismatic portion 2 a sized so as to be press-fittable into the square hole 5 a of the locking plate 5, and press-fit into the square holes 31 and 40 a of the bobbin 3 and the retainer 40. A prismatic portion 2b set to a size that can be combined is formed.
Therefore, the rotation support shaft 6 of the torsion bar 2 and the prism-shaped portion 2
Each of the shafts b is rotatably supported by a shaft support portion 34b of a gear case 34 described later and a retainer 40 inserted into a shaft through hole of the side plate 1b. The retainer 40
Is rotatably supported via a ring-shaped bearing bush 41 fitted between the side plate 1b. In the present embodiment, the prisms 2a and 2b and the square holes 5a, 31 and 4 are used.
0a is a hexagonal shape, but is not limited to this.

Outside the locking plate 5, a ratchet wheel 18 as a lock operating means for operating the emergency locking means 300 in the event of a vehicle emergency is provided so as to be rotatable relative to the locking plate 5. Therefore, between the bobbin 3 and the locking plate 5, an energy absorbing mechanism 200 using plastic deformation means mainly composed of the torsion bar 2 is formed. That is,
When a load of a predetermined value or more (in the direction in which the bobbin 3 is rotated) is applied to the locking plate 5 in a state where the webbing is prevented from being pulled out by the emergency locking means 300, first, a rotation torque of a predetermined value or more is applied to the shear pin 50. The torsion bar 2 twists around its own axis to rotate the bobbin 3 under a predetermined torque after a part of the kinetic energy possessed by the occupant is absorbed by the action of the shear pin 50 being sheared. Can be done. Therefore, although the rotation of the locking plate 5 in the webbing withdrawing direction is prevented by the emergency locking means 300, a predetermined amount of webbing can be withdrawn under a predetermined webbing tension, and the torsion bar 2 is torsionally deformed. By doing so, the kinetic energy of the occupant can be absorbed.

Furthermore, when the bobbin 3 and the locking plate 5 rotate relative to each other by a predetermined angle or more and the torsion bar 2 is twisted, a predetermined force or more acts on the lock piece 15 reaching the narrow portion 12b of the guide groove 12. As a result, the lock piece 15 disposed on the guide portion 13 is
2b by expanding or shaving the narrow portion 12b
Are relatively moved with respect to the locking plate 5 while deforming. Therefore, the guide portion 13 and the lock piece 15
Accordingly, the collision energy acting on the occupant's body can be absorbed as deformation work.

As can be understood from FIG. 1, when the torsion bar 2, the locking plate 5, the bobbin 3, the lock piece 15, and the retainer 40 are mounted on the retractor base 1, both axial ends of the torsion bar 2 are provided. The prismatic portion 2a and the prismatic portion 2b in the portion are square holes 31 and 4
0a and the square hole 5a are press-fitted respectively.
In a normal use state, the bobbin 3 rotates integrally with the locking plate 5. As described above, the relative rotation of the bobbin 3 with respect to the locking plate 5 is also restricted by the shear pin 50.

Further, a gear case 34 disposed outside the inertia plate 30 has a shaft support portion 34b for rotatably supporting the rotation support shaft 6 of the torsion bar 2 at the center thereof.
Is provided, and the bottom surface of the shaft support portion 34b is a positioning surface of the torsion bar 2 in the axial direction. A box-shaped storage section 43 for storing vehicle acceleration detecting means (not shown) is provided below the gear case 34, and a sensor cover 35 is provided outside the side plate 1a that covers the gear case 34. .

Next, the seat belt retractor 1
The operation of 00 will be described. First, in a normal use state, the ratchet wheel 18 engaged with the locking plate 5 is rotatable integrally with the locking plate 5, and the emergency locking means 300 is in a non-operating state. Therefore, the retractor 100 is capable of winding the webbing by the urging force of a winding spring device (not shown) and pulling out the webbing against the spring force.

Next, when a certain degree of deceleration such as sudden braking occurs in the vehicle, the occupant moves forward, the webbing is pulled out, and the bobbin 3 causes the torsion bar 2 and the locking plate 5 to move beyond a predetermined amount. When the rotating force of the shocking webbing unwinding direction (direction of arrow X ₂₎ is acting, the inertia plate 30 rotates delay occurs with respect to the rotation of the webbing pull-out direction of the locking plate 5 receives the inertial force. Then, the inertia plate 30 operates a lock arm (not shown) to lock the ratchet wheel 18 to the gear case 34.

[0031] As a result, the ratchet wheel 18 causes a rotation delay with respect to the locking plate 5 which rotates in the webbing pull-out direction, the direction of engagement (arrow in FIG Y ₁ direction) of the engaging internal teeth 25 of the pawl 16 The emergency locking means 300 is operated since the rocking operation is performed. Also, the ratchet wheel 18, by the vehicle acceleration sensing means senses the acceleration of the vehicle (not shown), a rotation delay with respect to the locking plate 5 which rotates in the webbing pull-out direction (FIG. 2 in direction of arrow X ₂₎ As a result, the pawl 16 can be pivotally rotated in the direction of engagement with the engagement internal teeth 25.

[0032] Thus, the pole 16 when moving to the position where the positive engagement between the engaging internal teeth 25, rotation of the direction of arrow X ₂ of the locking plate 5 that pivotally supports the pawl 16 is locked. At this time, the torsion bar 2 having one end connected to the locking plate 5 via the square hole 5a and the other end connected to the bobbin 3 via the square hole 31 does not receive a predetermined or more torsional force. The torsion bar 2 is not torsionally deformed.

[0033] Thus, the rotation of the direction of arrow X ₂ of the bobbin 3 is also locked, extended out of the webbing is prevented. Then, in this state, when a large tension is further applied to the webbing, the bobbin 3 to which one end of the webbing is locked starts to rotate, and the shear pin 50 is first sheared.
After a part of the kinetic energy possessed by the occupant is absorbed, the torsion bar 2 having one end connected to the locking plate 5 whose rotation is locked is twisted around its own axis, so that the function as an energy absorbing mechanism is achieved. Works.

Therefore, as shown in FIG. 8, the load curve of the energy absorbing load (load acting on the webbing) with respect to the webbing extension immediately after the collision rises sharply by shearing the shear pin 50. State. That is, the amount of energy absorbed by the shear pin 50 in the hatched portion in the figure is combined with the load curve indicated by the broken line in FIG. The amount of absorption can be increased temporarily. By changing the shear strength of the shear pin 50, the energy absorption amount of the energy absorbing mechanism 200 can be changed.

Further, as shown in FIG. 4, when a larger tension is applied to the webbing, the lock piece 15 is positioned at the initial end 11A of the guide groove 11 and the initial end 12A of the guide groove 12. ing. Then, the torsion bar 2 is torsionally deformed, and the length of the guide groove 11 (3 /
When the bobbin 3 is rotated with respect to the locking plate 5 in the direction of the arrow T in the figure and the lock piece 15 slides in the guide groove 11 and relatively moves in the direction of the arrow S at an angle corresponding to 4 rotations). As shown in FIG. 5, the lock piece 15 reaches the end portion 11B of the guide groove 11.

When the bobbin 3 is rotated in the direction of the arrow T in the figure, the lock piece 15 urged against the terminal end 11B of the guide groove 11 is moved to the initial end 12A of the guide groove 12 of the locking plate 5. Then, the sliding starts, and accordingly, it moves in the wide portion 12a of the guide groove 12 in the direction of arrow T in the figure to the position shown in FIG. During this time, the bobbin 3 is rotated about 405 degrees in the direction of the arrow T with respect to the locking plate 5 (for example, the extension amount of the webbing is 150 mm). Since only the sliding movement of the torsion bar 2 around the axis of the torsion bar 2 is absorbed, the collision energy acting on the occupant's body is merely absorbed as the work is slid only in the wide portion 12a of the guide groove 12 and the guide groove 12. That is, since the torsional deformation torque of the torsion bar 2 is substantially constant, the energy absorption torque is substantially constant over the entire operating range. Therefore, as shown in FIG. 8, the load curve of the energy absorbing load (the load acting on the webbing) with respect to the amount of webbing extension is in a proportional state having substantially the same slope.

Further, when the bobbin 3 rotates in the direction of arrow T in the figure and the torsion bar 2 is twisted, a predetermined force or more acts on the lock piece 15 reaching the narrow portion 12b of the guide groove 12. Then, the lock piece 15 pushes or narrows the narrow portion 12b to form the narrow portion 12b.
While deforming b, it moves in the narrow portion 12b of the guide groove 12 in the direction of arrow T in the figure to the end portion 12B shown in FIG.

That is, the bobbin 3 rotates about 405 degrees to about 540 degrees in the direction of arrow T with respect to the locking plate 5 (for example, the extension of the webbing is 150 to 2).
(00 mm), the collision energy acting on the occupant's body can be absorbed as deformation work also by the deformation of the narrow portion 12b by the lock piece 15. Therefore, the load curve of the energy absorption load changes to a slope obtained by combining the torsion of the torsion bar 2 and the deformation (including the frictional force) of the narrow portion 12b as shown in FIG.

In this manner, the lock piece 15 is
When the bobbin 3 reaches the second end portion 12B, relative rotation of the bobbin 3 with respect to the locking plate 5 is regulated by the lock piece 15, so that further twisting of the torsion bar 2 is prevented. As described above, in the seat belt retractor 100 of the present embodiment, after the pawl 16 is engaged with the engagement internal teeth 25 in the event of a vehicle emergency, the rotation of the locking plate 5 is once blocked by the emergency locking means 300. When a predetermined tension or more is applied to the webbing, the shear pin 50 is sheared in response to the rotation of the bobbin 3, so that the energy absorption load rises sharply, and the torsion bar 2 is twisted. The webbing can be extended, and operates as an energy absorbing mechanism. Further, when the bobbin 3 and the locking plate 5 rotate relative to each other by a predetermined angle (about 405 degrees in the present embodiment), the bobbin 3 is rotated while the lock piece 15 deforms the narrow portion 12b. Is the combined load of the torsion bar 2 and the deformation of the narrow portion 12b.

Therefore, by changing the shape and the material,
Of the webbing extension by appropriately changing the set distance of the guide grooves 11 and 12, the ratio of the wide portion 12a to the narrow portion 12b, the groove width of the narrow portion 12b, and the like. It is easy to change the load curve of the load. In particular, by using the shear pin 50, the shear load of the shear pin 50 is used to absorb the kinetic energy of the occupant, and the energy absorption load at the start of energy absorption can be temporarily increased. It is possible to improve the initial restraint performance and reduce the moving amount of the occupant.

Therefore, it is possible to obtain a desired energy characteristic according to the vehicle characteristics, and it is possible to constitute a good energy absorbing mechanism capable of efficiently absorbing the collision energy acting on the occupant's body at the time of a vehicle collision. . Further, since the shear pin 50 in the above embodiment penetrates through the through hole 5b of the locking plate 5 without play, the shear pin 50 is immediately sheared when the bobbin 3 and the locking plate 5 are relatively rotated. On the other hand, if the through-hole 5b is formed of, for example, a long hole and the shear pin 50 is penetrated with play, the shear pin 50 is sheared after the bobbin 3 and the locking plate 5 rotate relative to each other by a predetermined angle. , Bobbin 3
While the and the locking plate 5 rotate relative to each other by a predetermined angle, only the energy absorbing load due to the torsion of the torsion bar 2 is applied.

Therefore, as shown in FIG. 9, the load curve of the energy absorption load (the load acting on the webbing) with respect to the webbing extension amount, as shown in FIG. Is rapidly raised by shearing.
That is, the shear strength of the shear pin 50 with respect to the peak load is
The energy absorption load of the torsion bar 2 can be reduced by the large amount. For this reason, the shear pin 50 can be made thin and compact. However, compared to the case where the shear pin 50 penetrates through the through-hole 5b without play, in this case, the initial restraint performance immediately after the collision is reduced, so that the effect is exhibited in combination with the pretensioner or the like.

Further, by forming the shear pin 50 with a soft material such as aluminum, raw iron wire, resin or the like, the amount of webbing extension until the shear pin 50 breaks and energy absorption is completed can be set large. Can be. Further, as shown in FIG. 10A, the opening of the locking hole 3b and the opening of the through hole 5b are each subjected to C-chamfering so that the sharpness to the shear pin 50 is intentionally deteriorated.
The amount of webbing extension until the shear pin 50 breaks and energy absorption is completed can be increased.
That is, when a rotation torque greater than a predetermined value acts between the bobbin 3 and the locking plate 5, a large shearing force cannot be applied to the shearing pin 50, and as shown in FIG. 50 breaks apart torn apart and cannot be broken immediately.

Further, as shown in FIG. 11 (a), a relief portion 5c is provided in the opening of the through hole 5b, and the shear pin 50 is plastically deformed and then sheared, whereby the shear pin 50 is sheared.
It is also possible to increase the amount of webbing extension until breakage occurs and energy absorption is completed. That is, bobbin 3
When a rotation torque equal to or more than a predetermined value acts between the shear pin 50 and the locking plate 5, the shear pin 50 is not immediately sheared.
As shown in FIG. 1 (b), it is broken after being plastically deformed.

The position of the shear pin 50 that passes through the locking plate 5 and is fitted to the bobbin 3 is changed, and the shear pin 50 passes through at least one of the guide grooves 11 and 12. With such a configuration, the lock piece 15 disposed on the guide portion 13 can interfere with the shear pin 50, and the load curve of the energy absorbing load with respect to the amount of extension of the webbing can be changed.

That is, after the shear pin 50 is broken by the application of a rotational torque greater than a predetermined value, the bobbin 3 and the locking plate 5 rotate relative to each other, and the lock piece 15
When the lock piece is moved inside, the debris of the sheared pin 50 and the lock piece interfere with each other, and the energy absorption load can be changed by the resistance. The configuration of the guide portion in the above embodiment is not limited to the configuration of the guide groove 11 and the guide groove 12, and it goes without saying that various configurations can be adopted. For example, a wide portion and a narrow portion may be provided in the guide groove 11, and the groove width of the guide groove 12 may be wider than the width of the lock piece 15 in the entire region.

Further, if the width of the guide groove is narrowed at the initial position, it is possible to prevent rattle of the lock piece and to prevent rattle. In this case, if a taper portion is provided on the insertion side of the lock piece, assembly is easy. Further, the plastic deformation means in the present invention does not necessarily need to combine the torsion bar and the guide portion, as in the seat belt retractor 100 of the above embodiment, and bears the energy absorbing load by only one of the plastic deformation. It is also possible. Further, the plastic deformation means is not limited to the structure of the torsion bar and the guide. If the torsion bar has a sufficient allowable torsion angle, the vehicle collision ends before the torsion bar is twisted, so that the plastic deformation means is provided with the stopper mechanism (guide groove 1).
It is not necessary to prevent the torsion bar from being twisted more than a predetermined amount by the lock pieces 1 and 12 and the lock piece 15).

The emergency locking means is not limited to the configuration in the above embodiment, but can be variously modified. For example, the inertia sensing means which operates in the event of a vehicle emergency includes a vehicle body acceleration sensing means and a webbing. A configuration including only one of the acceleration sensing means may be employed. Further, the configuration of the shear pin disposed between the winding shaft and the bobbin and shearing the bobbin with a predetermined torque is also different from the bobbin 3 as in the above embodiment.
The configuration is not limited to the configuration disposed between the locking plate 5 and the locking plate 5. For example, the configuration may be such that the body of the bobbin penetrates inward in the radial direction and is fitted to the torsion bar. Alternatively, the same effect as the shear pin 50 can be obtained by fitting a columnar shear pin integrally formed with the bobbin into a hole of the locking plate.

[0049]

As described above, in the seat belt retractor of the present invention, by disposing the shear pin between the winding shaft and the bobbin, the shear load of the shear pin causes the kinetic energy of the occupant. Therefore, the energy absorption load characteristics can be arbitrarily changed in accordance with the vehicle characteristics only by changing the material and shape of the shear pin, the mounting state, and the like.

Further, by using the shear pin, the energy absorption load at the time of starting the energy absorption or immediately after the energy absorption can be temporarily increased, so that the initial restraint performance immediately after the collision is improved and the movement amount of the occupant is reduced. can do. Therefore, it is possible to improve the initial restraint performance of the occupant, obtain an arbitrary load characteristic according to the vehicle characteristics, and efficiently absorb the collision energy acting on the occupant's body at the time of a vehicle collision. A seat belt retractor provided with a mechanism can be provided.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view of a seat belt retractor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part of the seat belt retractor shown in FIG.

FIG. 3 is a perspective view of a main part of the locking plate shown in FIG. 1;

FIG. 4 is an explanatory diagram for explaining the operation of the energy absorbing mechanism of the seat belt retractor shown in FIG. 1,
(a) is an AA sectional view in FIG. 1, and (b) is a BB sectional view in FIG. 1.

FIG. 5 is an explanatory diagram for explaining an operation of an energy absorbing mechanism of the seat belt retractor shown in FIG. 1;

FIG. 6 is an explanatory diagram for explaining an operation of the energy absorbing mechanism of the seat belt retractor shown in FIG. 1;

7 is an explanatory diagram for explaining the operation of the energy absorbing mechanism of the seat belt retractor shown in FIG.

8 is a graph showing a relationship between a webbing extension amount and an energy absorption load in the seat belt retractor shown in FIG.

FIG. 9 is a graph showing a relationship between a webbing extension amount and an energy absorption load in a seat belt retractor based on another embodiment.

FIG. 10 is an enlarged cross-sectional view of a main part for explaining a broken state of a shear pin in a seat belt retractor based on another embodiment.

FIG. 11 is an enlarged cross-sectional view of a main part for describing a broken state of a shear pin in a seat belt retractor based on another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Retractor base 2 Torsion bar 3 Bobbin 5 Locking plate 11 Guide groove 12 Guide groove 13 Guide part 16 Pole 50 Shear pin 100 Retractor for seat belt 200 Energy absorption mechanism 300 Emergency locking means

Claims (1)

[Claims] 1. A winding shaft rotatably attached to a retractor base and prevented from rotating in a webbing withdrawal direction in the event of a vehicle emergency, a webbing wound thereon and rotatably supported by the winding shaft. A cylindrical bobbin, plastic deformation means for engaging the winding shaft and the bobbin so as to be rotatable relative to each other with a predetermined load, and a shear pin disposed between the winding shaft and the bobbin and shearing with a predetermined torque. With seat belt retractor.