JPH10194084A - Seat belt retractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt provided with a good energy absorbing mechanism capable of increasing the torsional limit of a torsion bar, preventing breakage of the torsion bar and preventing the bobbin from slipping out. Provide retractors for SOLUTION: A bobbin 3 around which a webbing is wound, a locking base 5 which is engaged with a retractor base 1 in a vehicle emergency and is prevented from rotating in a webbing pull-out direction, and a retractor base which is inserted through the bobbin 3. 1 and a torsion bar 2 integrally connected to the bobbin 3 at one end and a locking base 5 at the other end. The locking base side end of the bobbin 3 is connected to the other end of the torsion bar 2 via a fitting recess 9 formed to receive a cylindrical boss 8 protruding from the bobbin side end surface of the locking base 5. A bearing bush 10 is rotatably supported on the end side so as to be relatively rotatable, and a bearing bush 10 for improving slidability is fitted to these bearing portions.

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, a lock member provided at one end of a winding shaft on which webbing is wound is provided with a retractor base cover in a vehicle emergency. There is one provided with a lock means that can be engaged with an engaging 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. The formed ratchet teeth are used as engaged parts, while a lock plate or a locking claw that rotates together with the winding shaft is used as a lock member. In addition, it is configured to prevent the winding 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.

In the above energy absorbing device, a winding member (bobbin) for a portion where the energy absorbing device transmits a force.
And a holder (retractor base) rotatable relative to the winding member, and a torsion bar (plastic deformation means) is disposed between the holder and the winding member. ing. In the event of a vehicle emergency, a gear (locking member) provided at one end of the torsion bar is locked by a locking lever, and is non-rotatably connected to the holder. On the other hand, the other end of the torsion bar is non-rotatably connected to the winding member in advance. Therefore, when torque in the webbing pull-out direction is further applied to the winding member, the torsion bar is twisted around its own axis and plastically deforms, so that the collision energy acting on the occupant's body is absorbed as deformation work of the torsion bar. Is done.

[0007]

When an energy absorbing device for a safety belt described in Japanese Patent Application Laid-Open No. 46-7710 is used for an automatic safety belt (emergency locking retractor), both ends of a torsion bar are used. Since the portion is rotatably supported by the holder block, the winding member on which the webbing is wound is rotatably attached to the holder block.

However, when the winding member receives a large force in the webbing pull-out direction due to the load acting on the webbing, a shearing force is applied between both ends of the torsion bar supported by the holder block and the support portion of the holder block. As a result, there is a possibility that both ends of the torsion bar are sheared and the winding member comes off the holder block.

Further, depending on the supporting state of one end of the winding member rotatably supported by the gear, when the winding member receives a large force in the webbing pull-out direction due to the load acting on the webbing, the holder block may be used. In some cases, a bending force is applied to the torsion bar due to a force that pushes and spreads both side plates of the torsion bar. Therefore, the torsion bar to which the bending force is applied together with the torsion force has a twist limit lower than a predetermined value.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and it is possible to increase the torsional limit of the torsion bar, prevent the torsion bar from breaking, and prevent the bobbin from slipping out. An object of the present invention is to provide a seat belt retractor having a good energy absorbing mechanism.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bobbin around which a webbing is wound, a locking member which is engaged with a retractor base in a vehicle emergency and is prevented from rotating in a webbing withdrawing direction, A torsion bar, which is rotatably supported by the retractor base through the bobbin, is integrally connected to the bobbin at one end, and is integrally connected to the lock member at the other end. A seat belt retractor comprising: a lock member side end of the bobbin, a fitting recess formed to receive a cylindrical boss protruding from a bobbin side end surface of the lock member. A bearing bush that is rotatably supported relative to the other end side of the torsion bar through the intermediary of the torsion rod and that at least supports a contact portion between the bobbin and the lock member at the shaft support portion. It has been achieved by a seat belt retractor according to claim.

According to the above construction, when the bobbin receives a large force in the webbing withdrawal direction due to the load acting on the webbing, the end of the bobbin on the lock member side is pulled through the boss of the lock member and the bearing bush in the webbing withdrawal direction. , The bending force and the shearing force do not act on the torsion rod passing through the bobbin. In addition, when a bearing bush that enhances slidability is fitted to a shaft support between the bobbin and the lock member, the torsion rod is twisted to cause relative rotation between the bobbin and the lock member. The energy absorption load can be stabilized by reducing the frictional resistance of the shaft support.

Preferably, the bearing bush is made of a plastic having excellent slidability, such as polyoxymethylene or fluorine resin, or a hard, smooth metal such as stainless steel or a bearing metal. Further, the object of the present invention is to provide a bobbin around which a webbing is wound, a locking member which is engaged with a retractor base in a vehicle emergency to prevent rotation in a webbing withdrawing direction, and a bobbin that is inserted through the bobbin to re-insert the webbing. A seat belt retractor having a torsion bar rotatably supported by a tractor base and integrally connected to the bobbin at one end and integrally connected to the lock member at the other end Wherein the torsion rod is provided through a fitting recess formed in a lock member side end of the bobbin to receive a cylindrical boss portion protruding from the bobbin side end surface of the lock member. A bearing bush that is rotatably supported relative to the other end of the shaft and that can be compressed and deformed by at least a predetermined bearing load is fitted into at least a shaft support at a contact portion between the bobbin and the lock member. A seat belt retractor characterized in that an outer peripheral portion of a lock member side end of the bobbin is opposed to an inner peripheral edge of a through hole opened in a side plate of the retractor base. You.

According to the above construction, when the bobbin receives a large force in the webbing withdrawal direction due to the load acting on the webbing, the lock member side end of the bobbin is moved through the boss of the lock member and the bearing bush in the webbing withdrawal direction. Is restricted, so that no bending force or shearing force acts on the torsion rod passing through the bobbin during the energy absorbing operation. In addition, after the energy absorption operation is completed, the bearing bush is compressed and deformed by a predetermined bearing load or more, so that the outer peripheral portion of the bobbin comes into contact with the inner peripheral edge of the retractor base and the movement in the webbing pull-out direction is regulated. In addition, the bobbin can be prevented from falling out of the retractor twice.

Preferably, the inner peripheral edge of the through hole is opposed to the outer peripheral portion of the bobbin at the locking base side end by drawing, burring, or semi-shearing inward of the retractor.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of 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 a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of a main part of the seat belt retractor 100 shown in FIG. 3 is FIG.
FIG. 4 is a perspective view of a main part of the locking base 5 shown in FIG.

The seat belt retractor 100 of the first embodiment has a substantially cylindrical bobbin 3 around which webbing is wound, and is rotatably supported by the retractor base 1 through the bobbin 3. On one end side (right side in FIG. 1), the bobbin 3 is integrally connected, and on the other end side (in FIG. 1,
On the left side), a cylindrical torsion bar 2 integrally connected to the disc-shaped locking base 5 and an emergency locking means 300 for preventing the locking base 5 serving as a locking member from rotating in the webbing pull-out direction in a vehicle emergency. And

The retractor base 1 is formed by press-forming a metal plate so that left and right side plates 1a and 1b rise from both sides of a back plate 1c fixed to a vehicle body and have a substantially U-shaped cross section. A torsion bar 2 combined with the bobbin 3 is rotatably bridged at a position facing the left and right side plates 1a and 1b. One end of the torsion bar 2 into which the side plate 1b of the retractor base 1 is inserted is provided with the torsion bar 2
A known take-up spring device (not shown) that constantly urges the bobbin 3 in the webbing take-up direction via the control unit is provided.

At one end of the torsion bar 2, there is provided a bobbin connecting portion 2a which can rotate integrally with the bobbin 3, and at the other end, a locking base which can rotate integrally with the locking base 5. It has a coupling portion 2b. Each of these connecting portions 2a and 2b has a cross-sectional shape formed into a hexagon. The bobbin coupling portion 2a has a hexagonal cross section, and is inserted into a hexagonal cross-section insertion hole 40a of a retainer 40 fitted into a hexagonal cross section fitting concave portion 3a formed at one end of the bobbin 3. , So that it is integrally rotatable with the bobbin 3. The retainer 40 is rotatably supported by the side plate 1b via a bush 41.

The locking base coupling portion 2b has a hexagonal cross section, and is inserted into a hexagonal cross section insertion hole 8a of a cylindrical boss portion 8 protruding from the bobbin-side end surface of the locking base 5. It is integrally rotatable with the locking base 5 (see FIG. 3). A fitting recess 9 for receiving the boss 8 of the locking base 5 is formed in the locking base side end of the bobbin 3. The fitting recess 9 is provided to the torsion bar 2 through the fitting recess 9. It is pivotally supported so as to be relatively rotatable.

Further, a hollow cylindrical bearing bush 10 is fitted on a shaft support between the boss 8 and the fitting recess 9. The bearing bush 10 for improving the slidability is made of a highly slidable plastic such as polyoxymethylene or fluororesin, or a hard and smooth metal such as stainless steel or a bearing metal. The frictional resistance between the outer peripheral surface of the inner surface 8 and the inner peripheral surface of the fitting recess 9 is reduced. Preferably, the bearing bush 10 is lightly press-fitted and fixed to at least one of the boss 8 or the fitting recess 9.

That is, the bearing bush 10 fitted between the boss portion 8 and the fitting concave portion 9
The rattling between the and the fitting recess 9 can be absorbed, and generation of abnormal noise can be prevented. It should be noted that a plurality of rib projections 71 are protruded on the inner peripheral surface, such as a hollow cylindrical bearing bush 70 shown in FIG. Can be.

The torsion bar 2 is connected to the connecting portions 2a and 2b.
This is an energy absorbing mechanism configured to absorb the impact energy acting on the occupant's body by causing a twisting deformation between the coupling portions 2a and 2b by applying a rotation torque greater than or equal to a predetermined value therebetween. . In the present invention,
The locking base 5 which is a locking member in the event of a vehicle emergency
Various known structures can be adopted as a specific configuration of the emergency locking means 300 for restricting the rotation of the emergency locking device 300 in the webbing pull-out direction. For example, in the case of the first embodiment,
As shown in FIG. 2, the support shaft 7 of the locking base 5
A pole 16 having a locking tooth 16a at the tip is rotatably supported. Outside the through hole 20 opened in the side plate 1a, an internal tooth ratchet 21 having an engagement internal tooth 25 on the inner periphery capable of meshing with the locking tooth 16a is arranged in parallel.

The emergency locking means 300 provided in the sensor cover 35 is used for urging the pole 1 when the vehicle is in an emergency.
The engagement teeth 16a of the sixth engagement teeth engage with the engagement internal teeth 25 of the internal ratchet 21, thereby preventing the locking base 5 from rotating in the webbing pull-out direction.
Next, the seat belt retractor 1 of the first embodiment is described.
The operation of 00 will be described.

The emergency locking means 30 in the event of a vehicle emergency such as a collision
When 0 operates, the locking base 5 connected to the other end of the torsion bar 2 is prevented from rotating in the webbing withdrawing direction. Then, when a rotation torque equal to or more than a predetermined value acts on one end of the torsion bar 2 via the bobbin 3 due to a load acting on the webbing, the torsional deformation of the torsion bar 2 starts and the impact energy is absorbed.

At the time of this shock energy absorbing operation, the locking base side end of the bobbin 3 rotates relative to the torsion bar 2, but the locking base 5 through the bearing bush 10 having good slidability. The bobbin 3 in which the fitting concave portion 9 is rotatably supported by the boss portion 8 can smoothly slide. Therefore, the energy absorption load absorbed by the torsion bar 2 torsionally deforming stably changes according to the torsion angle.

When the impact energy absorbing operation is completed (when the webbing wound around the bobbin 3 is fully unwound by the energy absorbing operation), the bobbin 3 is pulled out by the load acting on the webbing (in FIG. 1). ,
Under the large force (upward), the locking base 5 which is locked to the side plate 1a of the retractor base 1 via the pawl 16 and the internal teeth ratchet 21 tends to shift. However, the end of the bobbin 3 on the locking base side is restricted from moving in the webbing withdrawing direction with respect to the locking base 5 via the boss portion 8 and the bearing bush 10. There is no deviation in the direction. Therefore, the bending force and the shearing force do not act on the torsion bar 2 due to the displacement of the bobbin 3 and the locking base 5 in the webbing withdrawing direction.

That is, the seat belt retractor 100 of the first embodiment does not apply a bending force and a shearing force to the torsion bar 2 torsionally deformed, and the torsion of the torsion bar 2 is prevented. The limit amount can be increased, and it is possible to prevent the torsion bar 2 from being damaged by the excessive load acting on the webbing and the bobbin 3 from coming out of the retractor.

FIG. 5 is a front vertical sectional view of a main part of a seat belt retractor 110 according to a second embodiment of the present invention. The same components as those of the seat belt retractor 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The seatbelt retractor 110 of the second embodiment has a substantially cylindrical bobbin 43 around which webbing is wound, and is rotatably supported by the retractor base 41 through the bobbin 43 and has one end side. (Not shown), the bobbin 43 is integrally connected to the
At the other end (the left side in FIG. 5), a cylindrical torsion rod 2 integrally connected to the disc-shaped locking base 45, and prevents the locking base 45 from rotating in the webbing pull-out direction in a vehicle emergency. An emergency lock device 300 and a stopper device 400 provided at a portion where the locking base 45 and the bobbin 43 are opposed to each other are provided.

The inner peripheral edge 50 of the through-hole opened in the side plate 41a of the retractor base 41 is drawn inwardly into the retractor, so that the bobbin 4
3 is opposed to the outer peripheral portion 43b of the locking base side end. The outer peripheral portion 43b is provided with the locking base 4
5 has a larger diameter than the outer peripheral portion 45b, and extends toward the locking base along the outer peripheral surface of the outer peripheral portion 45b.

The locking base coupling portion 2b of the torsion bar 2 is provided with a through hole 4 having a hexagonal cross section of the locking base 45.
By being inserted into 5a, it is integrally rotatably connected to the locking base 45. A fitting recess 49 for receiving the boss 48 of the locking base 45 is provided at the locking base side end of the bobbin 43. The fitting recess 49 is provided to the torsion bar 2 through the fitting recess 49. It is pivotally supported so as to be relatively rotatable.

Further, the boss portion 48 and the fitting concave portion 49
A hollow cylindrical bearing bush 65 is fitted to the shaft support between the two. The bearing bush 65 is made of plastic having excellent slidability, for example, polyoxymethylene or fluororesin, and is crushed and compressively deformable when a predetermined or more bearing load is applied to the shaft support. The frictional resistance between the outer peripheral surface of the boss portion 48 and the inner peripheral surface of the fitting concave portion 49 in the shaft support portion is reduced. The bearing bush 6
5 is preferably lightly press-fitted and fixed to at least one of the boss portion 48 or the fitting concave portion 49.

That is, the boss portion 48 and the fitting concave portion 49
The bearing bush 65 fitted between the boss portions 48 is similar to the bearing bush 10 of the first embodiment.
The rattling between the and the fitting recess 49 can be absorbed, and generation of abnormal noise can be prevented. If the bearing bush can be compressed and deformed when a predetermined bearing load or more is applied, the bearing bush 6
5 can also be formed of a metal having a smooth surface such as stainless steel or a bearing metal. In this case, for example, a plurality of deformed portions are appropriately protruded on at least one of the inner circumferential surface and the outer circumferential surface of the metal cylindrical member, and the deformed portions are crushed when a predetermined or more bearing load is applied. Good.

A stopper means 400 for preventing the rotation of the bobbin 43 in the webbing withdrawing direction when the amount of twist of the torsion bar 2 exceeds a predetermined amount is formed on the bobbin-side end face of the locking base 45. A guide groove 60 which is a C-shaped bottomed groove, and a C-shaped guide groove 61 formed in a lock plate 54 which is press-fitted and fixed to the locking base side end surface of the bobbin 43 so as to face the guide groove 60.
And a lock piece 62 formed in a substantially cocoon shape slidable along the inner wall surfaces of the guide grooves 60 and 61, and a range in which the lock piece 62 can slide with respect to the guide grooves 60 and 61. Then locking base 45 and bobbin 4
And 3 are relatively rotatable. The lock plate 5
Reference numeral 4 denotes a steel plate annular member formed separately from the bobbin 43 made of an aluminum alloy.

Next, the operation of the seat belt retractor 110 of the second embodiment will be described. When the emergency locking means 300 operates in the event of a vehicle emergency such as a collision, the locking base 45 connected to the other end of the torsion bar 2 is prevented from rotating in the webbing pull-out direction. Then, when a rotation torque equal to or more than a predetermined value acts on one end side of the torsion bar 2 via the bobbin 43 due to a load acting on the webbing, the torsion deformation of the torsion bar 2 starts and the impact energy is absorbed.

At the time of this shock energy absorbing operation, the locking base side end of the bobbin 43 rotates relative to the torsion bar 2, but the locking base 45 through the bearing bush 65 having good slidability. Boss part 4
The bobbin 43 in which the fitting concave portion 49 is rotatably supported by 8 can slide smoothly. Therefore, the energy absorption load absorbed by the torsion bar 2 torsionally deforming stably changes according to the torsion angle.

When the impact energy absorbing operation is completed (ie, when the torsion amount of the torsion bar 2 reaches a predetermined amount or more and the stopper means 400 is operated), the load acting on the webbing causes the bobbin 43 to move. When a large force is applied in the webbing withdrawing direction (upward in FIG. 5), the locking base 45 that is locked to the side plate 41a of the retractor base 41 via the pawl 16 and the internal ratchet 21 is likely to shift. . However, the locking base side end of the bobbin 43 is connected to the boss 48 and the bearing bush 65.
The movement of the locking base 45 with respect to the locking base 45 in the webbing pulling-out direction is restricted through the, so that the bobbin 43 does not shift with respect to the locking base 45 in the webbing pulling-out direction. Therefore, a bending force and a shearing force do not act on the torsion bar 2 due to the displacement of the bobbin 43 and the locking base 45 in the webbing withdrawing direction.

Therefore, similarly to the seat belt retractor 100 of the first embodiment, a bending force and a shearing force act on the torsion bar 2 inserted through the bobbin 43 by a load acting on the webbing. The twist limit of the torsion bar 2 can be increased, and the bobbin 43 can be prevented from falling out of the retractor due to an excessive load acting on the webbing.

Further, in the seat belt retractor 110 of the second embodiment, when a bearing load exceeding a predetermined level is applied, the bearing bush 65 is crushed and deformed by compression. Therefore, the locking base 45 is moved in the webbing pull-out direction by an excessive load acting on the webbing, and the outer peripheral portion 45b of the locking base 45 is moved to the internal ratchet 2.
Before being locked to the first or side plate 41a, the outer peripheral portion 43b of the bobbin 43 abuts on the inner peripheral edge 50 of the retractor base 41 to restrict the movement in the webbing pull-out direction. Therefore, an excessive load in the webbing pull-out direction is applied to the boss portion 48 of the locking base 45 via the bobbin 43.
The boss portion 48 only needs to have a thickness having a strength required in design.

That is, since the boss portion 48 of the locking base 45 in the second embodiment does not require a large safety factor, it can be made thinner than the boss portion 8 in the first embodiment. Therefore, the locking base 4
There is a space in the opposing portion between the bobbin 5 and the bobbin 43, and the stopper means 400 as described above can be arranged without difficulty.

In the second embodiment, the side plates 41
The inner periphery 50 protrudes inwardly of the retractor by performing drawing on the entire periphery of the through hole a, and faces the outer peripheral portion 43 b of the bobbin 43 on the locking base side end. Burring or semi-shearing is applied to the entire periphery of the hole to protrude inward into the retractor and the bobbin 43
May be provided with an inner peripheral edge 50 facing the outer peripheral portion 43b.
Further, the structure of the stopper means is the same as that of the second embodiment.
The present invention is not limited to the configuration including the U-shaped guide grooves 60 and 61 and the lock piece 62, and may employ various configurations.

The seatbelt retractor of the present invention is not limited to the configuration of the bobbin, the torsion bar, the bearing bush and the like in each of the above embodiments, but may take various forms. is there. For example, the bearing bush 10 (60) in each of the above embodiments includes the boss 8 (48) of the locking base 5 (45) and the bobbin 3 (43).
Although it is a hollow cylindrical member fitted to the shaft support between the fitting recesses 9 (49), the bearing bush of the present invention is not limited to this.

For example, like the bearing bush 70 of the seat belt retractor 120 according to the third embodiment of the present invention shown in FIG. 6, the outer peripheral surface of the boss 8 of the locking base 5 and the fitting recess of the bobbin 53 are provided. 59 has a cylindrical portion 71 interposed between the inner peripheral surface of the bobbin 53 and a flange portion 72 interposed between the locking base side end surface of the bobbin 53 and the bobbin side end surface of the locking base 5. be able to.

In this case, since the bearing bush 70 having good slidability is interposed over the entire contact portion between the locking base 5 and the bobbin 53, the locking base side end of the bobbin 43 is screwed. During the impact energy absorbing operation of rotating relative to the torsion bar 2, the locking base side end surface of the bobbin 43 can also smoothly slide with respect to the bobbin side end surface of the locking base 5. Therefore, the energy absorption load absorbed by the torsion bar 2 torsionally deforming can be more stably changed according to the torsion angle.

Further, in the emergency locking means in each of the above embodiments, the pawl rotatably supported by the locking member is locked to the engaged portion of the retractor so that the locking member can be rotated in the webbing pull-out direction. However, the present invention is not limited to this. Locking means may be provided by providing latch teeth on the lock member and pivotally supporting the pawl on the retractor.

[0046]

According to the seat belt retractor of the present invention as described above, when the bobbin receives a large force in the webbing pull-out direction due to the load acting on the webbing,
Since the end of the bobbin on the lock member side is restricted from moving in the webbing withdrawal direction via the boss of the lock member and the bearing bush, when the bobbin receives a large force in the webbing withdrawal direction due to the load acting on the webbing. Also,
No bending or shearing force acts on the torsion bar passing through the bobbin.

Further, a bearing bush for improving the slidability is fitted to a shaft support between the bobbin and the lock member, so that the torsion bar is twisted and relative rotation between the bobbin and the lock member is performed. The energy absorption load can be stabilized by reducing the frictional resistance of the shaft support when it occurs. or,
A bearing bush that can be compressed and deformed by a predetermined bearing load or more is fitted on a shaft support between the bobbin and the lock member, and an outer peripheral portion of a lock member side end of the bobbin is attached to a side plate of the retractor base. After the energy absorption operation is completed, the bearing bush is compressed and deformed by the bearing load exceeding a predetermined value by facing the inner peripheral edge of the opened through hole, and the outer peripheral portion of the bobbin contacts the inner peripheral edge of the retractor base and webbings. Since the movement in the pull-out direction is restricted, the bobbin can be prevented from falling out of the retractor twice.

Therefore, the torsion limit of the torsion bar can be increased, and the torsion bar can be prevented from being broken by the excessive load acting on the webbing and the bobbin coming out of the retractor. It is possible to provide a seat belt retractor having a simple energy absorbing mechanism.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view of a seat belt retractor according to a first 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 base shown in FIG. 2;

FIG. 4 is an overall perspective view showing a modified example of the bearing bush shown in FIG.

FIG. 5 is a front longitudinal sectional view of a main part of a seat belt retractor according to a second embodiment of the present invention.

FIG. 6 is a front vertical sectional view of a main part of a seat belt retractor according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Retractor base 2 Torsion rod 3 Bobbin 5 Locking base 8 Boss part 9 Fitting recess 10 Bearing bush 21 Internal ratchet 100 Retractor for seat belt 300 Emergency locking means

Claims (2)

[Claims] 1. A bobbin on which webbing is wound, a lock member engaged with a retractor base in a vehicle emergency to prevent rotation in a webbing pull-out direction, and a bobbin inserted through the bobbin to rotate on the retractor base. A seat belt retractor that is freely supported and includes a torsion bar integrally connected to the bobbin at one end and the lock member at the other end. The other end of the torsion rod is provided through a fitting recess formed by receiving a cylindrical boss protruding from the bobbin-side end surface of the bobbin. And a bearing bush for improving slidability is fitted in at least a bearing portion at a contact portion between the bobbin and the lock member. Retractor belt. 2. A bobbin around which a webbing is wound, a lock member which is engaged with a retractor base in a vehicle emergency to prevent rotation in a webbing pull-out direction, and rotates through the bobbin through the retractor base. A seat belt retractor that is freely supported and includes a torsion bar integrally connected to the bobbin at one end and the lock member at the other end. The other end of the torsion rod is provided through a fitting recess formed by receiving a cylindrical boss protruding from the bobbin-side end surface of the bobbin. A bearing bush that is rotatably supported with respect to the bearing and that can be compressed and deformed by a bearing load greater than or equal to a predetermined value is fitted in at least a bearing portion at a contact portion between the bobbin and the lock member. , The outer peripheral portion of the lock member side end portion of the bobbin, the retractor for a seat belt, characterized in that it is an inner peripheral edge facing the retractor base of the through hole is opened in the side plate.