JP2022154633A - seat belt retractor - Google Patents

Abstract

To provide a seat belt retractor allowing for confirming whether or not a coil spring is correctly assembled while securing a large area for a clutch to cover the coil spring.SOLUTION: The seatbelt retractor according to one embodiment comprises a coil spring 8 which is interposed between a winding drum 4 and a clutch 5 and is compressed when the winding drum 4 rotates relative to the clutch 5 in a pull-out direction. The clutch 5 includes a disk portion 51 that covers the coil spring 8 and an end surface of the winding drum 4. The disk portion 51 is provided with, as openings for exposure: at least one first opening (62, 63) exposing one or the other of spaces on both sides in a radial direction with respect to a central axis 80 of the coil spring 8 in a plane orthogonal to a support shaft 44, so as not to expose the coil spring 8 on the central axis 80 of the coil spring 8; and at least one second opening 64 exposing one end or the other end of the coil spring 8.SELECTED DRAWING: Figure 8

Description

The present invention relates to a seatbelt retractor mounted on a vehicle for pulling out and winding up webbing as a seatbelt.

2. Description of the Related Art Conventionally, a seat belt retractor is known that prevents webbing from being pulled out in an emergency such as a vehicle collision. In a seat belt retractor, a winding drum for winding webbing is rotatably accommodated between a pair of side walls of a housing.

For example, Patent Document 1 discloses a seat belt retractor 100 having a winding drum (referred to as "spool" in Patent Document 1) 110 and a clutch (referred to as "V gear" in Patent Document 1) 120 shown in FIG. disclosed. Note that the housing and the like are omitted in FIG. 14 .

A support shaft 111 protrudes from the end surface of the winding drum 110 , and the clutch 120 is supported by the support shaft 111 . A coil spring 130 is interposed between the winding drum 110 and the clutch 120 . The winding drum 110 is provided with a boss 112 inserted into one end of the coil spring 130 , and the clutch 120 is provided with a boss 121 inserted into the other end of the coil spring 130 . The coil spring 130 is stretched between the bosses 112 and 121 in a curved state.

The coil spring 130 urges the winding drum 110 to rotate relative to the clutch 120 in the winding direction A, and urges the clutch 120 to rotate relative to the winding drum 110 in the drawing direction B. . The biasing force of the coil spring 130 causes the clutch 120 to rotate integrally with the winding drum 110 in normal times.

On the other hand, the clutch 120 is prevented from rotating in the pull-out direction B by a locking mechanism (not shown) in case of emergency of the vehicle. As a result, the winding drum 110 rotates in the pull-out direction B while rotating relative to the clutch 120 and compresses the coil spring 130 . A pawl (not shown) (referred to as a “lock plate” in Patent Document 1) is movably held on the winding drum 110 . Relative rotation of the winding drum 110 with respect to the clutch 120 causes the pawl to operate and engage with internal teeth formed on a housing (referred to as a “frame” in Patent Document 1), thereby pulling the winding drum 110 in the pull-out direction B. rotation is blocked.

Clutch 120 covers end surfaces of coil spring 130 and winding drum 110 . Clutch 120 has a first opening 122 that exposes approximately half of coil spring 130 from the center to one end, and a first opening 122 that exposes approximately half of coil spring 130 from the center to one end of clutch 120 on the opposite side of winding drum 110 . A second opening 123 is provided to expose the end. Clutch 120 overlaps coil spring 130 by approximately one quarter of the length of coil spring 130 .

JP 2011-246013 A

If the clutch 120 is provided with the first opening 122 and the second opening 123 like the seat belt retractor 100 shown in FIG. You can check whether

However, since the first opening 122 is a large opening that exposes about half of the coil spring 130 to the opposite side of the clutch 120 from the winding drum 110 , the relative rotation between the clutch 120 and the winding drum 110 causes the coil spring 130 to be pulled out. When the coil spring 130 compresses or expands, the coil spring 130 may get caught on the edge of the first opening 122 to change the biasing force, or may fall off through the first opening 122 .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a seatbelt retractor that allows a clutch to secure a large area for covering a coil spring and to check whether the coil spring is correctly assembled.

In order to solve the above-described problems, a seat belt retractor of the present invention provides a housing having a pair of side walls facing each other, and a retractor for winding a webbing between the pair of side walls in the winding direction and the pulling direction of the webbing. It is rotatably supported by a winding drum and a support shaft protruding from the end face of the winding drum, and rotates integrally with the winding drum in normal times, and rotates in the pull-out direction in an emergency of the vehicle. A clutch that rotates relative to the winding drum that rotates in the pull-out direction by being blocked, and a clutch that rotates relative to the winding drum in the pull-out direction with respect to the clutch to operate the winding drum. A pawl interposed between the pawl for preventing rotation in the pull-out direction and the winding drum and the clutch, and having one end attached to the winding drum and the other end attached to the clutch, the clutch a coil spring that biases the winding drum against the winding drum in the direction of rotation in the winding direction, and is compressed by rotating the winding drum relative to the clutch in the pull-out direction; The clutch has a disk portion that covers the end surface of the coil spring and the winding drum, and the disk portion has an opening for exposing the disk portion to the opposite side of the winding drum. At least one first space that does not expose the coil spring on the central axis of the spring but exposes one or the other of the spaces on both sides in the radial direction with respect to the central axis of the coil spring on a plane perpendicular to the support shaft. An opening and at least one second opening exposing one end or the other end of the coil spring are provided.

According to the above configuration, the first opening provided in the disk portion of the clutch does not expose the coil spring to the side of the disk portion opposite to the winding drum on the central axis of the coil spring. As a result, even if the clutch secures a large area covering the coil spring, if the coil spring is erroneously assembled, the coil spring can be visually recognized through the first opening. The range of coil springs applied changes. Further, the disc portion of the clutch is provided with a second opening for exposing one end and/or the other end of the coil spring to the side of the disc portion opposite to the winding drum. The presence or absence can be confirmed. Therefore, it is possible to check whether the coil springs are correctly assembled while securing a large area for the clutch to cover the coil springs.

A size of the second opening in a central axis direction of the coil spring may be equal to or smaller than an outer diameter of the coil spring. At least one of the winding drum and the clutch is provided with a boss that is inserted into one end or the other end of the coil spring and supports the coil spring. The size of the second opening extending from the tip of the boss in the projecting direction of the boss may be equal to or smaller than the outer diameter of the coil spring. A length of overlap of the disc portion with the coil spring on the central axis of the coil spring may be 1/3 or more of a length of the coil spring. According to these configurations, the second opening provided in the disc portion exposes one end and/or the other end of the coil spring within a limited range to the side of the disc portion opposite to the winding drum. Therefore, it is possible to secure a large area for the clutch to cover the coil spring.

The at least one first opening may have two first openings located on both sides in the radial direction with respect to the central axis of the coil spring. If there is only one first opening, it is not possible to check for incorrect assembly when the coil spring can be assembled with a deviation away from the first opening. On the other hand, if the two first openings are positioned on both sides in the radial direction with respect to the center axis of the coil spring, it is possible to check any state of improper assembly of the coil spring. .

Advantageous Effects of Invention According to the present invention, it is possible to confirm whether or not the coil springs are correctly assembled while securing a large area for the clutch to cover the coil springs.

1 is a perspective view of a seat belt retractor according to an embodiment of the present invention; FIG. FIG. 2 is an exploded perspective view of the seat belt retractor shown in FIG. 1 ; 3 is an exploded perspective view of the winding drum unit; FIG. 3 is an exploded perspective view of the winding drum unit; FIG. It is the perspective view which looked at the clutch from the back side. It is the figure which looked at the state which removed the mechanism cover of the retractor for seatbelts shown in FIG. 1 from the left (vehicle sensors are shown in the cross section). (a) and (b) are views of the winding drum as seen from the left, (a) showing a state in which the pawl is in the non-engaging position, and (b) showing a state in which the pawl is in the engaging position. . (a) and (b) are views of the winding drum unit viewed from the left, (a) showing a state in which the clutch rotates integrally with the winding drum, and (b) shows a state in which the winding drum is pulled out from the clutch. It shows the state of relative rotation in the direction. (a) and (b) are views of the winding drum unit viewed from the left when the coil spring is incorrectly assembled. It is the figure which looked at the winding drum unit in the 1st modification from the left. It is the figure which looked at the winding drum unit in the 2nd modification from the left. It is the figure which looked at the winding drum unit in the 3rd modification from the left. It is the figure which looked at the winding drum unit in the 4th modification from the left. FIG. 10 is a side view of a winding drum and a clutch in a conventional seat belt retractor;

1 and 2 show a seat belt retractor 1 according to an embodiment of the present invention. This seatbelt retractor 1 is mounted on a vehicle to pull out and wind up a webbing 10 as a seatbelt, and to prevent the pulling out of the webbing 10 in an emergency such as a vehicle collision.

Specifically, the seat belt retractor 1 has a housing unit 1A, a winding drum unit 1B, a mechanism cover unit 1C, and a winding spring unit 1D. Hereinafter, for convenience of explanation, the direction of the axis (rotational axis) of the take-up drum unit 1B is referred to as the left-right direction (especially, the mechanism cover unit 1C side is left, and the take-up spring unit 1D side is right), and is perpendicular to the left-right direction. The lower left direction in FIG. 1 is called the front, and the opposite side is called the rear. In addition, the upper side of FIG. 1 perpendicular to the left-right direction and the front-rear direction is referred to as the upper side, and the lower side is referred to as the lower side.

The housing unit 1</b>A has a sheet metal housing 2 and a resin protector 26 attached to the housing 2 . The protector 26 has a rectangular tubular shape, and the webbing 10 is inserted through the inner side of the protector 26 .

The housing 2 has a U-shaped cross section, and includes a pair of side walls 21 and 22 facing each other in the left-right direction, a lower back plate 23 connecting the lower parts of the rear sides of the side walls 21 and 22, and the side walls 21. , 22 has an upper back plate 24 connecting the upper parts of the rear sides thereof. The protector 26 described above is attached to the upper back plate 24 .

A connecting bar 25 connects upper portions of the front sides of the side walls 21 and 22 . The side walls 21 and 22 are provided with openings 21a and 22a through which the winding drum unit 1B is inserted, respectively.

The winding drum unit 1</b>B has a winding drum 4 for winding the webbing 10 and a substantially disk-shaped clutch 5 attached to the left end surface of the winding drum 4 . The winding drum 4 is housed between the side walls 21 and 22 of the housing 2 so as to be rotatable in the winding direction A and the drawing direction B of the webbing 10 (see FIG. 6 for the winding direction A and the drawing direction B). ).

The winding drum 4 is manufactured by die casting of an aluminum alloy or the like, and includes a substantially cylindrical drum body 41 and substantially disk-shaped left and right ends 42 and 43 having a diameter larger than that of the drum body 41 . have The left end portion 42 is a portion that fits into the opening 21 a of the left side wall 21 of the housing 2 , and the right end portion 43 is a portion that fits into the opening 22 a of the right side wall 22 of the housing 2 . The clutch 5 is larger than the opening 21a and positioned outside the left side wall 21. As shown in FIG.

Internal teeth 21b are formed around the opening 21a of the left side wall 21 of the housing 2 . A left end portion 42 of the winding drum 4 fitted in the opening 21a holds a pawl 7 as shown in FIG. 7(a). The left end portion 42 is provided with a recess 42a that opens to the peripheral surface of the left end portion 42, and the pawl 7 is inserted into the recess 42a.

A plurality of (three in the illustrated example) engaging claws 72 are formed on the pawl 7 . The pawl 7 has an engagement position where the engagement claw 72 meshes with the inner tooth 21b shown in FIG. 7B and a non-engagement position where the engagement claw 72 shown in FIG. move to and from the alignment position.

The pawl 7 has an operation shaft 71 projecting leftward. The pawl 7 moves between the disengaged position and the engaged position by operating the operating shaft 71 with the clutch 5 .

As shown in FIGS. 3 and 4, a support shaft 44 protrudes from the left end surface of the winding drum 4 (the outer surface of the left end portion 42) along the axis (rotational axis) of the winding drum 4. A support shaft 45 protrudes from the right end surface of the take-up drum 4 (the outer surface of the right end portion 43 ) along the axis of the take-up drum 4 .

Returning to FIG. 2, the take-up spring unit 1D is attached to the right side wall 22 of the housing 2. As shown in FIG. The take-up spring unit 1D rotatably supports the support shaft 45 of the take-up drum 4 and imparts a biasing force to rotate the take-up drum 3 in the take-up direction A to the support shaft 45 . Since the configuration of the take-up spring unit 1D is well known, detailed description thereof will be omitted.

The mechanism cover unit 1C is attached to the left side wall 21 of the housing 2. As shown in FIG. The mechanism cover unit 1C rotatably supports the support shaft 44 of the winding drum 4 via a cap 35 which will be described later.

The mechanism cover unit 1</b>C has a mechanism cover 31 that covers the clutch 5 and the left side wall 21 of the housing 2 and a vehicle sensor 32 attached to the mechanism cover 31 . The left side wall 21 is also provided with an opening 21c for the vehicle sensor 32 below the opening 21a. The vehicle sensor 32 is for detecting that the acceleration of the vehicle has changed significantly (during a first emergency (for example, during a vehicle collision)).

The mechanism cover 31 is formed with internal teeth 31 a defining an inner peripheral surface having a diameter smaller than that of the clutch 5 . This internal tooth 31a is for engaging with a locking arm 33 attached to the clutch 5, as shown in FIG. The locking arm 33 constitutes a webbing sensor for detecting that the webbing 10 has been suddenly pulled out (second emergency) together with a coil spring 34 which will be described later.

The clutch 5 is supported by the support shaft 44 described above. The clutch 5 is made of resin, and has a disk portion 51 that is penetrated by the support shaft 44 and covers the left end surface of the winding drum 4 (the outer surface of the left end portion 42 ), and a peripheral wall 52 along the periphery of the disk portion 51 . have. As shown in FIG. 8( a ), the disk portion 51 has a larger diameter than the left end portion 42 of the winding drum 4 .

In the present embodiment, as shown in FIGS. 3 and 4, the disc portion 51 has a flat plate shape, and the distance from the back surface of the disc portion 51 to the end face on the right side of the peripheral wall 52 (on the winding drum 4 side) is greater than the distance. , the distance from the surface of the disk portion 51 to the left end face of the peripheral wall 52 is long. However, the shape of the clutch 5 can be changed as appropriate.

A tubular portion 53 is provided at the center of the disk portion 51 , and the support shaft 44 is fitted into the tubular portion 53 . The tip of the support shaft 44 protrudes leftward from the tubular portion 53 , and the cap 35 having a diameter larger than the inner diameter of the tubular portion 53 is attached to this tip. Further, as shown in FIG. 6, the disc portion 51 is provided with a guide hole 61 for operating the operation shaft 71 of the pawl 7 described above.

As shown in FIGS. 3 and 4, a coil spring 8 is interposed between the winding drum 4 and the clutch 5 . In this embodiment, the left end portion 42 of the winding drum 4 is provided with a recess 42b that opens to the outer surface of the left end portion 42 (the left end surface of the winding drum 4). A spring 8 is arranged. The disc portion 51 of the clutch 5 forms a housing chamber for the coil spring 8 together with the concave portion 42b, and covers the coil spring 8. As shown in FIG.

The concave portion 42b has a fitting portion 42c (see FIG. 8A) having a width approximately equal to the outer diameter of the coil spring 8, and one end portion of the coil spring 8 is inserted into the fitting portion 42c to hold the coil spring. One end of the coil spring 8 is attached to the winding drum 4 by bringing the end of the coil spring 8 into contact with one surface of the fitting portion 42c.

On the other hand, as shown in FIG. 4 , a support portion 58 for supporting the other end portion of the coil spring 8 is provided on the rear surface of the disk portion 51 of the clutch 5 . The other end of the coil spring 8 is attached to the clutch 5 by supporting the other end of the coil spring 8 on the support portion 58 .

In this embodiment, as shown in FIG. 5, the support portion 58 is box-shaped, and the other end portion of the coil spring 8 is inserted into the support portion 58 . More specifically, the support portion 58 includes a main plate 58a that abuts on the end of the coil spring 8, a pair of side plates 58b and 58c that sandwich the other end of the coil spring 8 in the direction along the disk portion 51, and the coil spring 8. It has a bottom plate 58d located on the right side of the end (on the winding drum 4 side).

However, the support portion 58 does not necessarily have to be box-shaped, and is inserted into the other end portion of the coil spring 8 to hold the other end portion of the coil spring 8 in the same manner as the conventional seat belt retractor 100 shown in FIG. It may be a supporting boss 121 .

As shown in FIG. 8A, the coil spring 8 is stretched between the fitting portion 42c and the support portion 58 in a curved state. The coil spring 8 urges the winding drum 4 to rotate with respect to the clutch 5 in the winding direction A, and urges the clutch 5 to rotate with respect to the winding drum 4 in the pull-out direction B. . The biasing force of the coil spring 8 causes the clutch 5 to rotate integrally with the winding drum 4 in normal times.

External teeth 52 a for engaging with the vehicle sensor 32 are formed on the outer peripheral surface of the peripheral wall 52 of the clutch 5 . When the acceleration of the vehicle changes significantly, the vehicle sensor 32 operates as indicated by the two-dot chain line in FIG. 6 and engages the external teeth 52a. As a result, rotation of the clutch 5 in the pull-out direction B is blocked.

The locking arm 33 described above has a generally arcuate shape. A rocking shaft 54 is provided on the surface of the disk portion 51 for rockably supporting the substantially center of the locking arm 33 . A spring receiver 55 facing one end of the locking arm 33 is provided on the surface of the disc portion 51 , and the coil spring 34 is arranged between the spring receiver 55 and one end of the locking arm 33 . there is Further, stoppers 56 and 57 are provided on the surface of the disc portion 51 so as to sandwich the other end portion of the locking arm 33 .

When the webbing 10 is abruptly pulled out, inertial force causes a delay in rotation of the locking arm 33 with respect to the clutch 5, causing the locking arm 33 to swing. portion is separated from the stopper 56 and engages with the internal teeth 31 a of the mechanism cover 31 and abuts against the stopper 57 . As a result, rotation of the clutch 5 in the pull-out direction B is blocked.

When the rotation of the clutch 5 in the pull-out direction B is blocked by the engagement between the vehicle sensor 32 and the external tooth 52a or the engagement between the locking arm 33 and the internal tooth 31a (that is, in the first emergency or the second emergency ), the winding drum 4 rotates in the pull-out direction B while rotating relative to the clutch 5, and compresses the coil spring 8, as shown in FIG. 8(b). In this embodiment, the coil spring 8 becomes linear at this time.

When the winding drum 4 rotates relative to the clutch 5 in the pull-out direction B, the operating shaft 71 of the pawl 7 is operated by the guide hole 61, thereby operating the pawl 7 as shown in FIG. 7(a). It moves from the disengaged position to the engaged position shown in FIG. 7(b). As a result, rotation of the winding drum 4 in the pull-out direction B is prevented.

As shown in FIG. 8( a ), the disc portion 51 of the clutch 5 has two first openings 62 , 63 and 1 as openings for exposing the disc portion 51 to the opposite side of the winding drum 4 . Two second openings 64 are provided. The first openings 62 , 63 and the second opening 64 expose the winding drum 4 side of the disk portion 51 to be visible from the opposite side of the disk portion 51 to the winding drum 4 . The first openings 62 and 63 are located on both radial sides of the central axis 80 of the coil spring 8 , and the second opening 64 is located at a position corresponding to the other end of the coil spring 8 .

The first openings 62 are formed in spaces on both sides in the radial direction with respect to the center axis of the coil spring 8 on a plane orthogonal to the support shaft 44 (in this embodiment, both spaces are part of the space within the recess 42b). One side of the disk portion 51 is exposed on the opposite side of the winding drum 4 , and the first openings 63 are formed on both sides in the radial direction of the center axis 80 of the coil spring 8 on a plane orthogonal to the support shaft 44 . The other side of a certain space is exposed on the opposite side of the winding drum 4 of the disc portion 51 . Both of the first openings 62 and 63 do not expose the coil spring 8 to the side of the disk portion 51 opposite to the winding drum 4 on the central axis 80 of the coil spring 8 .

Therefore, when the coil spring 8 is compressed or expanded by the relative rotation between the clutch 5 and the winding drum 4, even if the coil spring 8 moves to the left side (toward the disk portion 51), it contacts the disk portion 51. , the edges of the first openings 62 and 63 can be prevented from being caught.

In this embodiment, both the first openings 62 and 63 are rectangular and parallel to the central axis 80 of the coil spring 8 . Also, in this embodiment, the distance between the first openings 62 and 63 is approximately equal to the outer diameter of the coil spring 8 . Therefore, the coil spring 8 is not visible through the first openings 62 and 63 when viewed from the axial direction of the winding drum 4 .

The second opening 64 exposes the other end of the coil spring 8 to the side of the disk portion 51 opposite to the winding drum 4 . In this embodiment, the size of the second opening 64 in the direction of the central axis 80 of the coil spring 8 is equal to or smaller than the outer diameter of the coil spring 8 . Therefore, it is possible to prevent the coil spring 8 from coming off through the second opening 64 .

As described above, the support portion 58 that supports the other end of the coil spring 8 is the boss 121 that is inserted into the other end of the coil spring 8, similar to the conventional seat belt retractor 100 shown in FIG. In that case, the size of the second opening 64 extending from the tip of the boss 121 toward the projecting direction of the boss 121 in the direction of the center axis 80 of the coil spring 8 may be equal to or smaller than the outer diameter of the coil spring 8 . Even in this case, it is possible to prevent the coil spring 8 from coming off through the second opening 64 . When the boss 121 is inserted into the other end of the coil spring 8 , the second opening 64 allows the other end of the coil spring 8 to be positioned opposite to the winding drum 4 of the disc portion 51 in the area where the boss 121 exists. It may or may not be exposed to the side. That is, the overall size of the second opening 64 in the direction of the central axis 80 of the coil spring 8 may be equal to or larger than the outer diameter of the coil spring 8 .

In any case, it is desirable that the length over which the disc portion 51 overlaps the coil spring 8 on the central axis 80 of the coil spring 8 is ⅓ or more of the length of the coil spring 8 .

As described above, in the seat belt retractor 1 of the present embodiment, the first openings 62 and 63 provided in the disk portion 51 of the clutch 5 allow the coil spring 8 to move toward the disk portion 51 on the center axis 80 of the coil spring 8 . The second opening 64 provided in the disk portion 51 is not exposed on the side opposite to the winding drum 4 of the disk portion 51, and the other end portion of the coil spring 8 is held within a limited range by the winding drum 4 of the disk portion 51. Since it is exposed on the opposite side, it is possible to secure a large area for the clutch 5 to cover the coil spring 8 .

Moreover, if the coil spring 8 is incorrectly assembled as shown in FIGS. 9A and 9B, the coil spring 8 is visible through the first opening 62 or the first opening 63. Furthermore, the presence or absence of the coil spring 8 can be confirmed through the second opening 64 . Therefore, it can be confirmed whether the coil spring 8 is correctly assembled.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the gist of the present invention.

For example, the distance between the first openings 62 and 63 may be smaller than the outer diameter of the coil spring 8, as in a first modified example shown in FIG. In other words, part of the coil spring 8 may be seen through the first openings 62 and 63 . In this case, when the coil spring 8 is assembled incorrectly, the range of the coil spring 8 visually recognized through the first openings 62 and 63 changes.

Further, as in the second modification shown in FIG. 11, the position of the first opening 62 and the position of the first opening 63 in the axial direction of the coil spring 8 may be deviated, or the sizes of the first openings 62 and 63 may be different. may differ from each other. Alternatively, one of the first openings 62 and 63 may be continuous with the second opening 64 as in the third modification shown in FIG. Furthermore, both of the first openings 62 and 63 may be positioned on one side in the radial direction with respect to the central axis 80 of the coil spring 8, as in a fourth modification shown in FIG.

Alternatively, although illustration is omitted, only one of the first openings 62 and 63 may be provided in the disc portion 51 of the clutch 5 . However, when both of the first openings 62 and 63 are located on one side in the radial direction with respect to the central axis 80 of the coil spring 8, or when there is only one first opening, the coil spring 8 is positioned from the first opening. When it is possible to assemble with a deviation in the direction of separation, the erroneous assembly cannot be ascertained. On the other hand, if the two first openings 62 and 63 are positioned on both sides in the radial direction with respect to the central axis 80 of the coil spring 8 as in the above-described embodiment or the first to third modifications, the coil spring 8 may be misaligned. It can be checked in any state of assembly.

Although not shown, the second opening 64 is positioned on the disk of the clutch 5 so that one end of the coil spring 8 attached to the winding drum 4 is exposed on the side of the disk portion 51 opposite to the winding drum 4 . It may be provided in the portion 51 . Even in this case, the size of the second opening 64 in the direction of the central axis 80 of the coil spring 8 is equal to or less than the outer diameter of the coil spring 8. Therefore, it is possible to prevent the coil spring 8 from coming off through the second opening 64 . In this case, in the above-described embodiment, the locking arm 33 overlaps one end of the coil spring 8 when viewed from the axial direction of the winding drum 4, but before the locking arm 33 is attached, the second opening The presence or absence of the coil spring 8 can be confirmed through 64 .

Alternatively, the disk portion 51 of the clutch 5 may be provided with both a second opening 64 exposing one end of the coil spring 8 and a second opening 64 exposing the other end of the coil spring 8 . Even if both the second opening 64 for exposing one end of the coil spring 8 and the second opening 64 for exposing the other end of the coil spring 8 are provided, the disc portion 51 is positioned on the central axis 80 of the coil spring 8 . It is desirable that the length of overlap with the coil spring 8 is ⅓ or more of the length of the coil spring 8 .

When the second opening 64 exposes one end of the coil spring 8, the coil spring 8 is attached to the winding drum 4 in place of the fitting portion 42c, similar to the conventional seat belt retractor 100 shown in FIG. A boss 112 may be provided that is inserted into one end to support one end of the coil spring 8 . In this case, the size of the second opening 64 extending from the tip of the boss 112 toward the projecting direction of the boss 112 in the direction of the center axis 80 of the coil spring 8 may be equal to or less than the outer diameter of the coil spring 8 . Even in this case, it is possible to prevent the coil spring 8 from coming off through the second opening 64 .

When the boss 112 is inserted into one end of the coil spring 8 , the second opening 64 is arranged so that the one end of the coil spring 8 is positioned on the opposite side of the disk portion 51 from the winding drum 4 in the area where the boss 112 exists. May or may not be exposed. That is, the overall size of the second opening 64 in the direction of the central axis 80 of the coil spring 8 may be equal to or larger than the outer diameter of the coil spring 8 .

When the second opening 64 exposes one end of the coil spring 8 , regardless of whether the fitting portion 42 c or the boss 112 is employed, the disk portion 51 of the clutch 5 is provided with the coil spring 8 as well as other components. Regardless of whether or not the second opening 64 for exposing the end portion is provided, the length over which the disc portion 51 overlaps the coil spring 8 on the central axis 80 of the coil spring 8 is 1/1 of the length of the coil spring 8. 3 or more is desirable.

The winding drum 4 does not necessarily have to be a single piece. For example, the winding drum 4 includes a casting provided with a central hole that opens in one direction in the axial direction corresponding to the drum body 41 and the right end 43, and one end connected to the casting at the bottom of the central hole. and a component corresponding to the left end 42 to which the other end of the torsion bar is coupled. In this case, when the pawl 7 is moved to the engaging position in an emergency, the winding drum 4 of the part corresponding to the left end portion 42 is prevented from rotating in the pull-out direction B, and the webbing 10 is pulled by the occupant. When the output exceeds a predetermined value, the torsion bar is twisted to rotate the casting corresponding to the drum body 41 and the right end portion 43 in the drawing direction B of the winding drum 4, thereby drawing the webbing 10 with a predetermined drawing force. occupant impact energy is absorbed. Further, when the winding drum 4 is configured as described above, a part of the torsion bar may constitute the support shaft 44, or the support shaft 45 may be a casting corresponding to the drum body 41 and the right end portion 43. It may be composed of separate parts instead of being integrated with.

Reference Signs List 1 seat belt retractor 10 webbing 2 housing 21, 22 side wall 4 winding drum 44, 45 support shaft 5 clutch 51 disk portion 52 peripheral wall 62, 63 first opening 64 second opening 7 pawl 8 coil spring 80 center shaft 112, 121 boss

Claims (5)

a housing having a pair of side walls facing each other;
a winding drum that winds up the webbing and is housed between the pair of side walls so as to be rotatable in the winding direction and the drawing-out direction of the webbing;
It is supported by a support shaft protruding from the end surface of the winding drum, rotates integrally with the winding drum during normal operation, and rotates in the pulling-out direction when the vehicle is in an emergency by being prevented from rotating in the pulling-out direction. a clutch that rotates relative to the winding drum;
a pawl that operates when the winding drum rotates relative to the clutch in the pull-out direction to prevent rotation of the winding drum in the pull-out direction;
One end is attached to the winding drum and the other end is attached to the clutch, interposed between the winding drum and the clutch, to move the winding drum with respect to the clutch in the winding direction. and a coil spring that is compressed by rotating the winding drum relative to the clutch in the pull-out direction,
the clutch has a disk portion covering end surfaces of the coil spring and the winding drum;
The disk portion has an opening for exposing the disk portion to the side opposite to the winding drum, and the coil spring is not exposed on the central axis of the coil spring, and the coil spring is not exposed on the plane orthogonal to the support shaft. At least one first opening exposing one or the other of the spaces on both sides in the radial direction with respect to the central axis of the coil spring, and at least one second opening exposing one end or the other end of the coil spring A retractor for a seat belt, characterized in that it is provided with a 2. The seatbelt retractor according to claim 1, wherein the size of said second opening in the central axis direction of said coil spring is equal to or smaller than the outer diameter of said coil spring. At least one of the winding drum and the clutch is provided with a boss that is inserted into one end or the other end of the coil spring and supports the coil spring. 2. The seatbelt retractor according to claim 1, wherein the size of said second opening extending from the tip of said boss in the projecting direction of said boss is equal to or smaller than the outer diameter of said coil spring. 2. The seatbelt retractor according to claim 1, wherein the length of overlap of the disk portion with the coil spring on the central axis of the coil spring is 1/3 or more of the length of the coil spring. 3. The seatbelt retractor according to claim 1, wherein the at least one first opening has two first openings positioned on both sides in the radial direction with respect to the central axis of the coil spring.

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