JP2006240618A - Seat belt retractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat belt retractor equipped with a spindle shaft functioning as a torsion bar, capable of absorbing the kinetic energy of a seat occupant when a vehicle encounters an emergency case and restraining finally the occupant by webbing certainly. <P>SOLUTION: The seat belt retractor is furnished with a fastening mechanism 8 which admits a twisting deformation of the spindle shaft 4 until the specified value is attained by the twisting deformation rotational amount of one end of the spindle shaft 4 relative to a part near the other end when the vehicle encounters an emergency case, and when the twisting deformation rotational amount has attained the specified value, fastens a part near the other end of the spindle shaft 4 and a takeup drum 3 in such a manner as not able to make relative rotation. One end of the spindle shaft 4 and the takeup drum 3 engage each other through a cap 35 in such a manner as not able to make relative rotation. The fastening mechanism 8 is furnished with a ring member 70 fitted on a part near the other end of the spindle shaft 4 and fitted in a spline-shaped fitting hole in the takeup drum 3 in such a manner as not able to make relative rotation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a seat belt retractor, and particularly absorbs energy applied to the occupant by torsional deformation of a spindle shaft that functions as a torsion bar in the event of a vehicle emergency, and finally restrains the occupant reliably with webbing. The present invention relates to a seat belt retractor.

  Conventionally, in a seat belt retractor installed in an automobile, in the event of a vehicle emergency such as a vehicle collision, the take-up drum is locked in a non-rotatable direction in the webbing pull-out direction by an emergency lock mechanism, preventing webbing from being drawn from the take-up drum. It is supposed to be.

  By the way, when the deceleration of the vehicle becomes very large in a vehicle emergency, the load that the occupant receives from the webbing becomes very large, which is not desirable. Therefore, in recent seat belt retractors, when the rotation of the take-up drum is substantially locked by the emergency lock mechanism and the load acting on the webbing increases, the energy is absorbed by the energy absorbing means while allowing the take-up drum to rotate. Absorbs and reduces the impact on the passenger.

  For example, Patent Literature 1 and Patent Literature 2 disclose a seat belt retractor in which a deformable member as the energy absorbing means is mounted along the outer peripheral surface of a winding drum. In this seat belt retractor, when the vehicle is in an emergency, the take-up drum is locked so as not to rotate by an emergency lock mechanism, and when a large load is applied to the webbing, the deformable member is deformed in the diameter reducing direction and energy is absorbed through the deformation. It has become so. However, this type of seat belt retractor has a complicated structure and is difficult to assemble.

  On the other hand, Patent Document 3 discloses a seat belt retractor to which a torsion bar (torsion bar) as the energy absorbing means is applied. In this seat belt retractor, the torsion bar is inserted into the take-up drum, and one end of the torsion bar is connected to the take-up drum so as not to be relatively rotatable.

  A head portion is formed at the other end portion of the torsion bar, and when a predetermined load (for example, 4KN) is applied to the webbing in a state where the head portion is locked to be non-rotatable by an emergency lock mechanism in the event of a vehicle emergency, The torsion bar is twisted and deformed by rotating one end portion thereof together with the winding drum, and energy is absorbed through the torsional deformation. The seat belt retractor to which this torsion bar is applied is excellent in that the structure is simple and the assembly is easy, the energy absorption performance is stable and the reliability is high.

JP 7-277136 A JP-A-7-101310 Japanese Patent Laid-Open No. 6-156684

  However, the seat belt retractor of Patent Document 3 is very large for webbing because, in the event of a vehicle emergency, the emergency lock mechanism only locks the head portion of the torsion bar and does not lock one end portion of the torsion bar. Even when a load is applied, the rotation of the take-up drum is not constrained, so the torsion bar continues to twist and deforms, the webbing feed amount exceeds the limit value, or the torsion bar breaks and loses the body restraint function There is. In particular, when a vehicle collides with a ball or the like, the torsion bar is easily broken when it is repeatedly torsionally deformed.

  An object of the present invention is to absorb the kinetic energy of an occupant and finally restrain the occupant with webbing in a vehicle emergency in a seat belt retractor having a spindle shaft that functions as a torsion bar. .

  A seat belt retractor according to a first aspect of the present invention includes a winding drum for winding a webbing, and a spindle shaft whose one end is engaged with the winding drum so as not to be relatively rotatable and functions as a torsion bar. In a seat belt retractor that absorbs energy by torsional deformation of the spindle, the torsion of the spindle shaft until the torsional deformation rotation amount with respect to the vicinity of the other end of one end of the spindle shaft in a vehicle emergency is a predetermined value. A fastening mechanism for allowing deformation and fastening the vicinity of the other end of the spindle shaft and the winding drum so as not to rotate relative to each other when the torsional deformation rotation amount reaches a predetermined value; The winding drum is engaged with the winding member through a cap member so as not to rotate relative to the winding drum, and the winding drum has a spline shape having a radial recess. A fitting hole is formed, and the fastening mechanism includes a ring member that is externally screwed into the vicinity of the other end of the spindle shaft and is fitted in a spline-like fitting hole of the take-up drum so as not to be relatively rotatable. It is characterized by having.

  Accordingly, the ring member can be rotated relative to the spindle shaft together with the take-up drum until the torsion deformation rotation amount of the spindle shaft reaches a predetermined value in a vehicle emergency, and the spindle shaft is allowed to twist. When the torsional deformation rotation amount reaches a predetermined value, the ring member is screwed and fastened to the vicinity of the other end of the spindle shaft, and the vicinity of the other end of the spindle shaft and the winding drum are connected via the ring member. It can be fastened so as not to be relatively rotatable.

  The seat belt retractor according to the second aspect of the invention is a seat belt retractor that absorbs energy through torsional deformation of a torsion bar in a vehicle emergency, and a winding drum that winds webbing, and the winding drum. A spindle shaft which is disposed so as to be inserted into the drum and whose one end is engaged with the take-up drum in a relatively non-rotatable manner and has a torsion bar portion, and a portion in the vicinity of the other end of the spindle shaft are locked in a non-rotatable manner in a vehicle emergency The winding drum and one end of the spindle shaft rotate integrally due to the emergency locking means and the tension applied to the webbing after the emergency locking means is actuated to twist the webbing in the direction near the other end of the one end of the spindle shaft. The torsional deformation of the spindle shaft is allowed until the torsional deformation rotation amount reaches a predetermined value, and the torsional deformation rotation amount is a predetermined value. And a fastening mechanism for fastening the vicinity of the other end of the spindle shaft and the winding drum so as not to rotate relative to each other, and the one end of the spindle shaft and the winding drum cannot be rotated relative to each other via a cap member. A spline-like fitting hole having a radial recess is formed in the take-up drum, and the fastening mechanism locks the vicinity of the other end of the spindle shaft so that it cannot rotate in the event of a vehicle emergency. And a ring member that is externally screwed into a ratchet wheel that constitutes a part of the emergency locking means and is fitted in a spline-like fitting hole of the winding drum so as not to be relatively rotatable. is there.

  Therefore, the torsional deformation of the spindle shaft is allowed by allowing the ring member to rotate relative to the ratchet wheel together with the winding drum until the torsional deformation rotation amount of the spindle shaft reaches a predetermined value in the event of a vehicle emergency, When the torsional deformation rotation amount reaches a predetermined value, the ring member is screwed and fastened to the ratchet wheel, and the vicinity of the other end of the spindle shaft and the winding drum are made relative to each other via the ring member and the ratchet wheel. It can be fastened so that it cannot rotate.

  A seat belt retractor according to a third aspect of the present invention is the seat belt retractor according to the first or second aspect, wherein the ring member is fitted into the winding drum so as to be relatively movable in the axial direction. It is. Therefore, when the ring member rotates relative to the spindle shaft or the ratchet wheel, the ring member can be allowed to move in the axial direction, and expansion and contraction due to torsional deformation of the spindle shaft can be allowed. Other effects similar to those of the first or second invention are achieved.

  A seat belt retractor according to a fourth invention is the seat belt retractor according to the second invention, wherein the fastening mechanism fastens the vicinity of the other end of the spindle shaft and the winding drum by bringing the ring member into contact with the ratchet wheel. It is a feature. Therefore, when the torsional deformation rotation amount reaches a predetermined value in the event of a vehicle emergency, the ring member and the ratchet wheel come into contact with each other, and the vicinity of the other end of the spindle shaft is wound around the ring member and the ratchet wheel. The drum is securely fastened. Other effects similar to those of the second invention are achieved.

  According to the seat belt retractor of the first invention, the fastening mechanism is externally screwed into the vicinity of the other end of the spindle shaft and is fitted into the spline-like fitting hole of the take-up drum so as not to be relatively rotatable. Since the ring member is provided, the ring member can be rotated relative to the spindle shaft together with the take-up drum until the torsional deformation rotation amount of the spindle shaft reaches a predetermined value in the event of a vehicle emergency. When the torsional deformation rotation amount reaches a predetermined value, the ring member is screwed and fastened to the vicinity of the other end of the spindle shaft, and the other end of the spindle shaft is The winding drum can be securely fastened so as not to be relatively rotatable.

  According to the seat belt retractor according to the second invention, the fastening mechanism is externally screwed onto the ratchet wheel that constitutes a part of the emergency lock means that locks the vicinity of the other end of the spindle shaft so as not to rotate in the event of a vehicle emergency. In addition, since the ring member is fitted in the spline-like fitting hole of the winding drum so as not to be relatively rotatable, the ratchet wheel is mounted on the ratchet wheel until the torsional deformation rotation amount of the spindle shaft reaches a predetermined value in a vehicle emergency. On the other hand, the ring member can be relatively rotated together with the take-up drum to allow torsional deformation of the spindle shaft, and when the torsional deformation rotation amount reaches a predetermined value, the ring member is screwed and fastened to the ratchet wheel. Thus, the vicinity of the other end of the spindle shaft and the winding drum can be reliably fastened through the ring member and the ratchet wheel so as not to be relatively rotatable.

  According to the seat belt retractor according to the third aspect of the invention, the same effect as in the first or second aspect of the invention can be obtained, but the ring member is fitted into the winding drum so as to be relatively movable in the axial direction. Therefore, when the ring member rotates relative to the spindle shaft or the ratchet wheel, the ring member can be allowed to move in the axial direction, and the spindle shaft can be allowed to expand and contract due to torsional deformation. Become.

  According to the seat belt retractor according to the fourth aspect of the present invention, the same effect as that of the second aspect of the invention can be obtained. However, the fastening mechanism is configured such that the ring member and the vicinity of the other end of the spindle shaft are wound by bringing the ring member into contact with the ratchet wheel. Since the torsional deformation rotation amount reaches a predetermined value in the event of a vehicle emergency, the ring member and the ratchet wheel are brought into contact with each other and the other of the spindle shaft is interposed via the ring member and the ratchet wheel. The vicinity of the end and the winding drum can be more securely fastened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present embodiment is an example in which the present invention is applied to a seat belt retractor that absorbs energy through torsional deformation of a spindle shaft that functions as a torsion bar in the event of a vehicle emergency such as a vehicle collision. In addition, front and rear, right and left in FIG.

  As shown in FIGS. 1 to 3, the seat belt retractor 1 includes a metal housing 2 fixed to the vehicle body, a winding drum 3 that is attached to the housing 2 and winds the webbing W, and a winding drum 3. A spindle shaft 4 disposed so as to be inserted and having a left end engaged with the winding drum 3 so as not to rotate relative to the winding drum 3, and a rotation biasing mechanism 5 that constantly biases the winding drum 3 in the winding direction. And a forcible take-up mechanism 6 that forcibly rotates the take-up drum 3 in the take-up direction in the event of a vehicle emergency such as a vehicle collision, and the right end portion of the spindle shaft 4 cannot rotate in the event of a vehicle emergency. The emergency lock mechanism 7 that locks the spindle shaft 4 and the torsional deformation of the spindle shaft 4 until the torsional deformation amount of the left end portion of the spindle shaft 4 near the right end reaches a predetermined value in the event of a vehicle emergency. The amount of rotation And a fastening mechanism 8 for fastening the right end part near the winding drum 3 of the spindle shaft 4 to rotate relative when.

  As shown in FIGS. 1 to 3, the housing 2 includes a left side wall 10, a right side wall 11, a rear wall portion 12 connecting the left side wall 10 and the rear upper end portion of the right side wall 11, a left side wall 10 and a right side wall. A connecting plate portion 13 that connects the rear lower portion 11 is integrally formed, and a mounting plate 13a that is fixed to the rear wall portion 12 and the connecting plate portion 13 and extends downward is fixed to the vehicle body with a bolt or the like. The front upper ends of the left side wall 10 and the right side wall 11 are connected by a bar member 14 facing in the left-right direction.

  Circular openings 15 and 16 having a diameter smaller than that of the winding drum 3 are formed concentrically on the left side wall 10 and the right side wall 11, and a pawl 60 and a holder 67 of the emergency lock mechanism 7 are provided at the lower right side of the right side wall 11. Is installed. A rectangular opening 17 is formed between the rear wall portion 12 and the connecting plate portion 13. Although not shown, when the webbing W is almost wound around the winding drum 3, the diameter of the webbing W increases. The end portion reaches the opening 17 so as not to interfere with the housing 2.

  As shown in FIGS. 1 to 3 and FIGS. 5 to 7, the winding drum 3 includes a body portion 20 around which a webbing W is wound, a port portion 21, and a starboard portion 22. In the axial center portion, a left-right insertion hole 23 through which the spindle shaft 4 is inserted is formed. A spline hole 24 is formed in the port portion 21, and an insertion hole 25 communicating with the insertion hole 23 and the spline hole 24 and having a larger diameter than the insertion hole 23 is formed at the left end portion of the winding drum 3. Has been.

  The starboard-shaped portion 22 is formed to be wide on the left and right sides, and a spline-like fitting hole 26 that communicates with the insertion hole 23 and has a larger diameter than the insertion hole 23 is formed at the center portion thereof. The ring member 70 of the fastening mechanism 8 is fitted so as not to be relatively rotatable and to be relatively movable left and right. Further, a webbing insertion opening 27 for fitting and fixing the proximal end of the webbing W is formed in the body part 20.

  As shown in FIGS. 1 and 4 to 7, the spindle shaft 4 includes a torsion bar portion 30 that is torsionally deformed when a torsional torque exceeding a predetermined level is applied, and a knurled shaft portion on the left end side of the torsion bar portion 30. 31, a spline shaft portion 32 on the right end side of the torsion bar portion 30, and a connecting shaft portion 33 on the right end side of the spline shaft portion 32, and the knurled shaft portion 31 is interposed via the cap member 35. The ratchet wheel 50 of the emergency lock mechanism 7 is connected to the spline shaft portion 32 so as not to be relatively rotatable.

  The cap member 35 includes a spline-shaped engaging portion 36, a cylindrical portion 37 extending rightward from the engaging portion 36, and a knurled hole 38 formed in the cylindrical portion 37. Is engaged with the spline hole 24 of the winding drum 3, the cylindrical portion 37 is fitted into the insertion hole 25, and the knurled shaft portion 31 of the spindle shaft 4 is engaged with the knurled hole portion 38. Further, the cap member 35 is integrally formed with a connecting shaft portion 39 having a square section extending leftward from the engaging portion 36, and this connecting shaft portion 39 is operatively connected to the forced winding mechanism 6 and the rotation urging mechanism 5. It is connected to.

  Although not shown, the cylindrical portion of the base end portion of the webbing W is externally fitted to the torsion bar portion 30 of the spindle shaft 4, and the webbing W extends from the torsion bar portion 30 to the body portion 20 of the winding drum 3. The webbing insertion opening 27 extends and is wound around the body portion 20.

  As shown in FIGS. 1 to 3, the rotation urging mechanism 5 is a spring spring (not shown) housed in a spring housing cap 40 fixed to the casing 41 of the forced winding mechanism 6, and has a connecting shaft portion. The forced winding mechanism 6 has a gas generator 43 that generates pressurized gas in the event of a vehicle emergency, and is generated by the gas generator 43 provided in the casing 41. A gas pressure drive mechanism (not shown) is provided for rotating the winding drum 3 in the winding direction via the cap member 35 by gas pressure. Since the rotation urging mechanism 5 and the forced winding mechanism 6 are well known, detailed description thereof will be omitted.

  The emergency lock mechanism 7 will be described.

  As shown in FIGS. 1 to 4, the emergency lock mechanism 7 includes a ratchet wheel 50 that is connected to the spline shaft portion 32 of the spindle shaft 4 so as not to be relatively rotatable, and a ratchet wheel 50 in response to a sudden withdrawal of the webbing W. And a second lock mechanism for locking the rotation of the ratchet wheel 50 in response to sudden deceleration in the event of a vehicle emergency. The emergency lock mechanism 7 is covered with a cover member 7 a that is fixed to the right side wall 11 of the housing 2.

  As shown in FIGS. 4 and 5, the ratchet wheel 50 includes a gear portion 53 having a ratchet gear 54 formed on the outer peripheral portion, and a guide portion 55 that is smaller in diameter than the gear portion 53 and provided on the left side of the gear portion 53. And a cylindrical portion 56 having a smaller diameter than the guide portion 55 and extending to the left from the guide portion 55 are integrally formed, and the spline of the spindle shaft 4 is inserted into the spline hole 58 formed in the gear portion 53 and the guide portion 55. The shaft portion 32 is engaged. The gear portion 53 is disposed on the right side of the right side wall 11 of the housing 2, and the guide portion 55 is provided on the peripheral surface portion of the circular opening 16 formed in the right side wall 11 via a ring-shaped synthetic resin bearing 57. A ring member 70 is externally screwed onto the cylindrical portion 56 and is rotatably supported.

  The first locking mechanism is pivotally supported by a pawl 60 pivotally supported by a shaft portion 19 fixed to the right side wall 11 of the housing 2 and engageable with a ratchet gear 54, and a connecting shaft portion 33 of the spindle shaft 4. A clutch member 62 formed with a guide portion 62a for guiding the pawl 60 in the engagement / disengagement direction with respect to the ratchet gear 54, and a cylindrical portion 62b of the clutch member 62 connected to the connecting shaft portion 33. A lock arm base 66 and a protrusion 64a which is supported by the lock arm base 66 so as to be swingable and engages with an internal tooth 62c formed in the cylindrical portion 62b of the clutch member 62. 64a, a locking arm 64 biased so as not to engage with the internal teeth 62c, a locking gear 65 pivotally supported by the connecting shaft 33 and prevented by the rivet 61, and a locking arm It is composed of abutting locking gear 65 frictionally coupled lock arm guide (not shown) or the like 64.

  In a normal state, the pawl 60 is urged by a torsion spring 63 to a non-engagement position where the pawl 60 is not engaged with the ratchet gear 54, and when the webbing W is suddenly pulled out and the connecting shaft portion 33 is rotated, the lock arm The rotation delay of the locking gear 65 is caused with respect to the base 66, and the lock arm guide is also delayed. As a result, the lock arm 64 rotates against the spring force, and the protrusion 64a engages with the internal teeth 62c. . Then, the clutch member 62 is rotated, guided by the guide portion 62 a of the clutch member 62, and the pawl 60 rotates against the urging force of the torsion spring 63 to engage with the ratchet gear 54, and the ratchet wheel 50. At the same time, the rotation of the spline shaft portion 32 of the spindle shaft 4 is locked.

  The second lock mechanism is pivotally supported by the connecting shaft portion 33 on the right side of the pawl 60, the clutch member 62, the lock arm base 66, the lock arm 64, and the lock arm 64, which is the same as the first lock mechanism, and is prevented from being removed by the rivet 61. A locking gear 65, a holder 67 fixed to the right side wall 10 of the housing 2, a spherical inertia mass body 68 accommodated in the holder 67, a swingable connection to the holder 67, and an engagement with the locking gear 65. A swing lever 69 is provided.

  In the normal state, the locking gear 65 rotates integrally with the connecting shaft portion 33 of the spindle shaft 4 via frictional force, and when the vehicle suddenly decelerates, the inertia mass body 68 accommodated in the holder 67 moves, The swing lever 69 swings and engages with the locking gear 65, and the rotation of the locking gear 65 is locked. Then, by the relative rotation of the lock arm 64 with respect to the lock arm guide of the locking gear 65, the projection 64a engages with the internal teeth 62c and the clutch member 62 rotates, and the spline shaft of the spindle shaft 4 together with the ratchet wheel 50 as described above. The rotation of the part 32 is locked.

  The fastening mechanism 8 will be described. As shown in FIGS. 1, 5, and 7 to 9, the fastening mechanism 8 is connected to the cylindrical portion 56 of the ratchet wheel 50 that is connected to the spline shaft portion 32 of the spindle shaft 4 so as not to be relatively rotatable via a screwing mechanism 75. And a ring member 70 that is externally screwed. The ring member 70 is fitted in the fitting hole 26 of the winding drum 3 and is provided so as not to rotate relative to the winding drum 3 and to be relatively movable in the axial direction (left and right direction).

  The screwing mechanism 75 includes a female screw portion 76 formed on the inner periphery of the ring member 70 and a male screw portion 77 formed on the outer periphery of the ratchet wheel 50 cylindrical portion 56 and screwed into the female screw portion 76. The male threaded portion 77 of the cylindrical part 56 and the female threaded part 76 of the ring member 70 are formed as positive threads, and when the ring member 70 rotates with respect to the cylindrical part 56 in the direction indicated by the arrow A in FIG. 8, the right end surface of the ring member 70 comes into contact with the left end surface of the guide portion 55 of the ratchet wheel 50, and as shown in FIG. Are integrated to make relative rotation impossible.

  In this fastening mechanism 8, in the event of a vehicle emergency, the spindle shaft 4 is rotated until the torsional deformation rotation amount of the knurled shaft portion 31 of the spindle shaft 4 with respect to the spline shaft portion 32 reaches a predetermined value at which the ring member 70 cannot rotate. When the torsion bar portion 30 of the torsion bar portion 30 is allowed torsional deformation and the torsional deformation rotation amount reaches a predetermined value, the spline shaft portion 32 of the spindle shaft 4 and the winding drum 3 are connected to each other by the ring member 70 and the ratchet wheel. 50 is configured to be fastened so as not to be relatively rotatable.

  Here, the rotation speed at which the ring member 70 can rotate with respect to the cylindrical portion 56 until the right end surface of the ring member 70 contacts the left end surface of the guide portion 55, that is, the torsional deformation rotation amount is determined by the ring member 70. At the time of assembly, the retracting member 70 can be easily set by rotating the retracting member 70 in a direction opposite to the above from the state in which the right end surface of the ring member 70 is in contact with the left end surface of the guide portion 55. In this case, it is desirable that a resin coating is applied to the cylindrical portion 56 so that the ring member 70 is not easily rotated, and a frictional force is applied between the cylindrical portion 56 and the ring member 70 to some extent.

  Next, the action of the seat belt retractor 1 will be described with reference to the load characteristics acting on the webbing W in FIG.

  In a normal state, since the emergency lock mechanism 7 does not operate, the webbing W can be freely pulled out from the take-up drum 3 and set on the waist or chest of an occupant seated on the seat.

  In the state where the webbing W is set on the occupant's body, in the event of a vehicle emergency such as a vehicle collision, the winding drum 3 is forcibly rotated in the winding direction by the forced winding mechanism 6 and the slack webbing W is wound up. The emergency lock mechanism 7 locks the spline shaft portion 32 of the spindle shaft 4 in a non-rotatable manner, and then the webbing W wound around the winding drum 3 is tightened. After that, the webbing W is unwound and the load acting on the webbing W increases.

  Thereafter, when the feeding amount of the webbing W becomes L1 and the load acting on the webbing W reaches a predetermined W1, the torsion bar portion 30 of the spindle shaft 4 is twisted and deformed, and the locked spline shaft portion of the spindle shaft 4 is The knurled shaft portion 31 rotates with the winding drum 3 with respect to 32, the kinetic energy of the occupant is absorbed through the torsional deformation of the torsion bar portion 30, and the load acting on the occupant from the webbing W gradually increases from W1. The webbing W is fed out while increasing. At this time, the ring member 70 that rotates together with the winding drum 3 moves to the right side through the state shown in FIG.

  Normally, all kinetic energy is absorbed until the webbing feed amount reaches L2. However, if the load acting on the webbing W becomes W2 and the torsional deformation rotation amount of the torsion bar portion 30 of the spindle shaft 4 reaches a predetermined value, as shown in FIG. The surface abuts against the left end surface of the guide portion 55, the ring member 70 is integrated with the ratchet wheel 50, and the spline shaft portion 32 is fastened to the winding drum 3 through the ratchet wheel 50 and the ring member 70 so as not to be relatively rotatable. The torsion bar 30 is prevented from being broken. Thus, the winding drum 3 is completely rotationally restrained, the feeding of the webbing W is prevented, and the occupant is reliably restrained by the webbing W.

  As described above, according to the seat belt retractor 1, since the fastening mechanism 8 is provided, after the emergency lock mechanism 7 is actuated, twisting of the knurled shaft portion 31 of the spindle shaft 4 in the webbing pull-out direction with respect to the spline shaft portion 32 is performed. Torsional deformation of the torsion bar portion 30 is allowed until the deformation rotation amount reaches a predetermined value. When the torsion deformation rotation amount reaches a predetermined value, the spline shaft portion 32 of the spindle shaft 4 and the winding drum 3 are connected. It can be fastened so as not to be relatively rotatable.

  As a result, even when a large load is applied to the webbing W in an emergency of the vehicle, or even when the vehicle collides a plurality of times at once and the spindle shaft 4 is repeatedly torsionally deformed, the kinetic energy of the occupant is absorbed and the spindle shaft 4 can be surely prevented, and finally the occupant can be reliably restrained by the webbing W, so that the occupant can be surely prevented from secondary collision with the steering wheel, the front window, etc. Can be secured. The loads W1 and W2 can be appropriately set by appropriately designing the length, diameter, material, torsional deformation rotation allowable value (predetermined value) and the like of the torsion bar portion 30. .

  In addition, the fastening mechanism 8 is externally screwed into the cylindrical portion 56 of the ratchet wheel 50 engaged with the spline shaft portion 32 of the spindle shaft 3 so as not to be relatively rotatable, and is internally fitted to the winding drum 3 so as not to be relatively rotatable. Since the ring member 70 is provided, the above operation can be reliably realized with a simple structure, and the ring member 70 is fitted into the winding drum 3 so as to be relatively movable in the axial direction. Therefore, when the ring member 70 rotates relative to the ratchet wheel 50, the ring member 70 can be allowed to move to the right, and the spindle shaft 4 can be allowed to expand and contract due to torsional deformation.

  Further, since the fastening mechanism 8 fastens the spline shaft portion 32 of the spindle shaft 4 and the winding drum 3 by bringing the ring member 70 into contact with the ratchet wheel 50, the torsional deformation rotation amount is reduced in a vehicle emergency. When the predetermined value is reached, the ring member 70 and the ratchet wheel 50 are brought into contact with each other, and the spline shaft portion 32 of the spindle shaft and the winding drum 3 are more securely fastened via the ring member 70 and the ratchet wheel 50. can do.

  In the fastening mechanism 8 of the seat belt retractor 1, the cylindrical portion 56 of the ratchet wheel 50 and the threaded portion of the ring member 70 are formed as reverse threads, and the ring member 70 is shown in FIG. When the ring member 70 is rotated in the direction indicated by A, the ring member 70 is moved to the left, and the ring member 70 is brought into contact with the take-up drum 3, whereby the spline of the spindle shaft 4 is connected via the ring member 70 and the ratchet wheel 50. You may comprise so that the axial part 32 and the winding drum 3 may be fastened.

  Of course, various emergency lock mechanisms other than the emergency lock mechanism 7 of the above-described embodiment can be applied to the emergency lock mechanism that locks the vicinity of the other end of the spindle shaft in a non-rotatable manner. Of course, various structures can be applied to the winding drum 3, the rotation biasing mechanism 5, the forced winding mechanism 6, and the like.

  In addition, the seat belt retractor according to the present invention is not limited to the one described in the above embodiment, and various modifications can be added without departing from the gist of the present invention and applied to various types of seat belt retractors. Can do.

It is a disassembled perspective view of the seatbelt retractor which concerns on embodiment of this invention. It is a perspective view from the upper left side of a seatbelt retractor. It is a perspective view from the upper right side of a seatbelt retractor. It is a principal part perspective view of a seatbelt retractor. It is principal part sectional drawing of a seatbelt retractor. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is the VII-VII sectional view taken on the line of FIG. It is principal part sectional drawing of a seatbelt retractor. It is principal part sectional drawing of a seatbelt retractor. It is a load characteristic figure which acts on webbing.

Explanation of symbols

W Webbing 1, 1A, 1B Seat belt retractor 3, 3A, 3B Winding drum 4, 4B Spindle shaft 7 Emergency lock mechanism 8, 8A, 8B Fastening mechanism 30 Torsion bar 50, 50A, 50B Ratchet wheel 70 Ring member 75, 80, 85 screwing mechanism

Claims (4)

A winding drum for winding the webbing and a spindle shaft whose one end is engaged with the winding drum so as not to rotate relative to each other so as to function as a torsion bar so as to absorb energy by torsional deformation of the spindle shaft in a vehicle emergency. In the seat belt retractor
The torsional deformation of the spindle shaft is allowed until the torsional deformation rotation amount with respect to the vicinity of the other end of the one end portion of the spindle shaft in a vehicle emergency, and the torsional deformation rotation amount has reached the predetermined value. Sometimes, a fastening mechanism is provided for fastening the vicinity of the other end of the spindle shaft and the winding drum so as not to be relatively rotatable,
One end portion of the spindle shaft and the winding drum are engaged with each other through a cap member so as not to be relatively rotatable,
The winding drum is formed with a spline-like fitting hole having a radial recess,
The fastening mechanism includes a seat belt that includes a ring member that is externally screwed into the vicinity of the other end of the spindle shaft and is fitted in a spline-like fitting hole of the winding drum so as not to be relatively rotatable. Retractor. In a seat belt retractor that absorbs energy through torsional deformation of a torsion bar in a vehicle emergency,
A winding drum for winding the webbing;
A spindle shaft that is disposed so as to be inserted through the winding drum, has one end engaged with the winding drum in a relatively non-rotatable manner, and has a torsion bar portion;
Emergency locking means for locking the vicinity of the other end of the spindle shaft to be non-rotatable in a vehicle emergency;
The winding drum and one end of the spindle shaft rotate integrally by the tension applied to the webbing after the operation of the emergency locking means, and the torsional deformation rotation amount in the webbing pull-out direction with respect to the vicinity of the other end of the one end of the spindle shaft The spindle shaft is allowed to torsionally deform until a predetermined value is reached, and when the torsional deformation rotation amount reaches a predetermined value, the vicinity of the other end of the spindle shaft and the winding drum are fastened so as not to be relatively rotatable. A fastening mechanism,
One end portion of the spindle shaft and the winding drum are engaged with each other through a cap member so as not to be relatively rotatable,
The winding drum is formed with a spline-like fitting hole having a radial recess,
The fastening mechanism is externally screwed onto a ratchet wheel that forms part of an emergency lock means that locks the vicinity of the other end of the spindle shaft in a non-rotatable manner in the event of a vehicle emergency, and is fitted into a spline-like fitting hole in the winding drum. A seat belt retractor comprising a ring member fitted in such a manner as to be relatively non-rotatable.   The seat ring retractor according to claim 1 or 2, wherein the ring member is fitted into the winding drum so as to be relatively movable in the axial direction. The seat belt retractor according to claim 2, wherein the fastening mechanism fastens the vicinity of the other end of the spindle shaft and the winding drum by bringing the ring member into contact with the ratchet wheel.

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