JP2020104777A - Seat belt retractor - Google Patents

Abstract

To solve the problem associated with a conventional energy absorption pin provided with only the DEA function area that the pin may not be able to appropriately suppress pre-twist during operation of a pretensioner, therefore, all or part of the DEA function configured to obtain the additional load imparted by the pin may be lost due to the pre-twist.SOLUTION: A seatbelt retractor comprises: a pretensioner; and an EA pin 20 that passes through a locking base 14 and is inserted into an axial hole 4c of a spool 4. The pin 20 comprises: a region for suppressing twist deformation of torsion bar; and a region for applying a load in addition to a torsion bar load at EA (energy absorption by twisting of the torsion bar).SELECTED DRAWING: Figure 1

Description

The present invention relates to a seat belt retractor with a pretensioner used for vehicles such as automobiles, and particularly to a seat belt retractor having a torsion bar incorporated in a spool.

As a seat belt retractor with a pretensioner, a seat in which a torsion bar is inserted through an inner hole of a spool, one end of the torsion bar can be fixed to the spool, and the other end of the torsion bar can be locked to a frame of the seat belt retractor. Belt retractors are known. In an emergency such as a vehicle collision, the spool is rotationally driven by the pretensioner to wind up the seat belt. After that, the torsion bar is twisted by applying a force in the seat belt unwinding direction to the spool, the spool is gradually rotated, and the seat belt is gradually pulled out. As a result, a part of the kinetic energy applied to the body of the occupant is absorbed (EA) by the torsion of the torsion bar, and the impact is relieved.

In Patent Documents 1 to 3, as another additional EA mechanism that operates when the seat belt is pulled out due to the inertia of the occupant in the above-described emergency, an energy absorbing pin (disposed between the locking base and the spool ( In addition, in Patent Documents 1 and 3, a seat belt retractor including a wire is described.

In the seat belt retractor described in Patent Documents 1 to 3, when the seat belt is pulled out in an emergency, the spool rotates relative to the locked locking base in the seat belt withdrawing direction, so that the energy absorbing pin is It is pulled out from the spool while being bent and plastically deformed. The torsional deformation of the torsion bar and the bending plastic deformation of the energy absorbing pin (DEA pin) absorb the kinetic energy of the occupant when the seat belt is pulled out.

In Patent Document 2, in a retractor with a pretensioner driven by a torsion bar, a torsion bar torsion deformation suppressing member is provided in order to suppress a decrease in the pretensioner winding amount due to pretwisting of the torsion bar during pretensioner. It is provided.

JP 2002-59809 A JP, 2011-20488, A JP, 2003-25957, A

When the technique of Patent Document 1 is applied to a pretensioner driven by a torsion bar, not only the torsion bar is twisted by the pre-twisting when the pretensioner is operated, but also the pin is pulled out. This means that all or part of the DEA function set to obtain the additional load by the pin by the rotational phase difference between the predetermined spool and the locking base during EA operation is lost.

In Patent Document 2, a retractor equipped with a pretensioner driven by a torsion bar is used in order to prevent or reduce a reduction in the working take-up amount of the pretensioner due to pre-twisting of the torsion bar during operation of the pretensioner. Although a torsional deformation suppressing member is added, the torsional deformation suppressing member is supposed to use up the deformation allowance when the pretensioner operates, and does not assume the DEA function.

When trying to add an EA stopper function to a torsion bar drive pretensioner equipped with a DEA function, there is a case where the pre-twisting during the pretensioner cannot be properly suppressed with the conventional energy absorption pin equipped with only the DEA function area. Therefore, the pre-twisting consumes a part of the predetermined rotation amount until the EA stopper function is activated, and the EA stopper may be activated before the predetermined rotation amount EA is performed.

The present invention aims to solve such problems.

A seatbelt retractor of the present invention is a tubular spool having a frame that supports a spool and a locking base, and an inner hole and a flange that winds a seatbelt, and extends in a direction parallel to an axial direction. A spool having an axial hole for inserting a pin, a locking base that is disposed adjacent to the spool coaxially with the spool, and that is connected to the spool by a torsion bar, and is inserted into an inner hole of the spool and has one end with respect to the spool. A torsion bar that is non-rotatably connected to the locking base and the other end is non-rotatably connected to the locking base; and a pretensioner that rotates the locking base in the seatbelt winding direction. A seat belt retractor having a pretensioner having a housing adjacent to the flange of the spool and an EA pin inserted through the locking base into an axial hole of the spool, wherein the pin is a torsion bar screw. It is characterized by having a twist deformation suppression region and a region where a load is added to a torsion bar load during EA.

In one aspect of the present invention, the pin has a flange portion that is locked to the locking base on a proximal end side, and the pin has a large-diameter portion from the flange portion side toward the distal end side, and a middle diameter portion. It is a diameter part and a small diameter part.

In one aspect of the present invention, the pin has a flange portion that is locked to the locking base on a proximal end side, and the pin has a small diameter portion and a medium diameter portion from the flange portion side toward the distal end side. It is a part and a small diameter part.

The flange portion of the pin may be locked by another component integrated with the locking base.

According to the present invention, the pin has a torsion bar torsion deformation suppressing region for preventing and reducing a decrease in the working winding amount of the pretensioner due to pretwisting of the torsion bar during the pretensioner, and a torsion bar during EA. It has a region that functions as a DEA by adding a load to the bar load. Therefore, in each of the regions, a parameter that suppresses the load when the rotational phase difference between the spool and the locking base occurs (for example, the diameter of the pin) and a parameter that suppresses the amount of the rotational phase difference that causes the load (for example, the length of the pin). ) Can be adjusted individually.

It is a schematic sectional drawing of the seat belt retractor concerning an embodiment. It is a side view and a load characteristic view of a pin concerning an embodiment. It is a side view and a load characteristic view of a pin concerning a comparative example.

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

FIG. 1 is a vertical sectional view showing an example of a seat belt retractor of the present invention. In the figure, 1 is a seat belt retractor, 2 is a U-shaped frame, 3 is a seat belt, 4 is rotatably supported between both side walls of the U-shaped frame 2, and a spool for winding the seat belt 3 Is a deceleration sensing means that operates by sensing a large vehicle deceleration that occurs in the case of an emergency described above. A torsion bar 8 axially loosely fits and penetrates the center of the spool 4 and rotationally connects the spool 4 and the locking means 6, and 8 is a spring force of a spiral spring that causes the spool 4 to be constantly attached in the belt winding direction. A spring means 11 for urging, a pretensioner 11 for generating a belt winding torque by operating in the emergency described above, and a paddle wheel 12 for transmitting the seat belt winding torque of the pretensioner 11 to the spool 4.

The lock means 6 is provided with a locking base 14 which is rotatable integrally with the first torque transmission shaft 17 of the torsion bar 7 and which holds the pawl 13 in a swingable manner, and normally rotates integrally with the torsion bar 7. In an emergency, the deceleration sensing means 5 is actuated to stop and a relative rotation difference is generated between the deceleration sensing means 5 and the torsion bar 7 so that the pawl 13 is engaged with the internal teeth 19 on the side wall of the frame 2 and the seat belt of the locking base 14. A lock gear is provided to prevent rotation in the pull-out direction. A male screw shaft portion 15 is formed on the locking base 14, and a nut-shaped stopper member 16 that rotates integrally with the spool 4 is screwed onto the male screw shaft portion 15.

The torsion bar 7 is formed with a first torque transmitting portion 17 that engages with the locking base 14 in a relatively non-rotatable manner and a second torque transmitting portion 18 that engages with the spool 4 in a relatively non-rotatable manner. There is.

The spool 4 is constantly urged in the seat belt winding direction by the spring force of the spring means 8 via the torsion bar 7 and the second torque transmission portion 18 of the torsion bar 7.

A hexagonal portion as a non-circular portion is provided on the outer periphery of the locking base 14. The paddle wheel 12 is engaged with the hexagonal portion, and the paddle wheel 12 is mounted on the locking base 14 so as not to rotate in the circumferential direction.

By supplying a power transmission member made of synthetic resin or the like to the outer periphery of the paddle wheel 12 when the pretensioner operates, the paddle wheel 12 rotates and the locking base 14 rotates. This rotation is transmitted to the spool 4 via the torsion bar 7, whereby the spool 4 winds the seat belt 3 by a predetermined amount.

When the seat belt is not worn, the seat belt 3 is completely wound up by the urging force of the spring means 8. When the seat belt 3 is pulled out at a normal speed for wearing, the spool 4 rotates in the seat belt withdrawing direction, and the seat belt 3 is pulled out smoothly. After the tongue (not shown) slidably provided on the seat belt 3 is inserted and locked into a buckle (not shown) fixed to the vehicle body, the extra pulled seat belt 3 is wound around the spool 4 by the urging force of the spring means 8. As a result, the seat belt 3 fits to the extent that it does not give the passenger a feeling of pressure.

In the emergency described above, the seat belt retracting torque from the pretensioner 11 is transmitted to the spool 4, and the spool 4 retracts the seat belt 3 by a predetermined amount to remove the slack.

When the winding of the seat belt 3 progresses and the slack of the seat belt 3 is removed, the winding of the seat belt by the spool 4 stops. Thus, even after the slack of the seat belt 3 is removed, torque is applied to the torsion bar 7 from the pretensioner 11 in the seat belt winding direction, whereby the torsion bar 7 is twisted and pre-twisted. Occurs.

After that, the spool 4 starts to rotate in the seat belt withdrawing direction while twisting the torsion bar 7 by the force in the seat belt withdrawing direction applied to the spool 4 (EA operation). The locking base 14 connected to the spool 4 via the torsion bar 7 is prevented from rotating in the seat belt withdrawing direction by the pressure-holding action of the pretensioner 11. As a result, the spool 4 rotates (EA rotation) while twisting the torsion bar 7, and the seat belt is pulled out. The torsional deformation of the torsion bar 7 absorbs the kinetic energy of the forward movement of the occupant.

When the spool 4 rotates relative to the locking base 14, the stopper member 16 that rotates integrally with the spool 4 rotates relative to the externally threaded shaft portion 15 that is screwed together. Move to. Then, when the stopper member 16 comes into contact with the stepped portion on the proximal end side of the male screw shaft portion 15, further rotation of the stopper member 16 is blocked, so that rotation of the spool 4 is also blocked, and the rotation of the torsion bar 7 is prevented. The twisting stops.

The seat belt retractor 1 includes an elongated energy absorbing pin 20 extending in the axial direction of the spool 4. The energy absorbing pin 20 is slidably fitted in a slender axial hole 4c formed in the spool 4 at an eccentric position so as to extend in the axial direction and penetrates through the locking base 14. There is. A flange 20a is formed at the end of the energy absorbing pin 20 penetrating the locking base 14, and the flange 20a is locked to the locking base 14 to prevent the energy absorbing pin 20 from slipping out toward the spool 4 side. It has been blocked.

A guide groove 14a for guiding the energy absorbing pin 20 is formed at the penetrating position of the energy absorbing pin 20 on the side surface of the locking base 14 on the side facing the spool 4. The guide groove 14a is formed in an arc shape that is concentric with the locking base 14, and the arc length is such that the energy absorbing pin 20 is completely accommodated after the energy absorbing operation of the energy absorbing pin 20. It is set.

Before pulling out the pin 20 in the normal state, the energy absorbing pin 20 is not pulled out from the axial hole 4c of the spool 4 and has a linear shape. In the emergency described above, the rotation of the locking base 14 in the seat belt withdrawing direction is prevented, so that the torsion bar 7 is twisted and only the spool 4 rotates relative to the locking base 14 in the seat belt withdrawing direction. Then, withdrawal of the energy absorbing pin 20 from the axial hole 4c of the spool 4 starts. When the energy absorbing pin 20 is pulled out from the axial hole 4c, the energy absorbing pin 20 is bent at a right angle, and the pulled out energy absorbing pin 20 is guided by the guide groove 14a of the locking base 14 to be curved and deformed in an arc shape.

The total load due to the pulling resistance of the energy absorbing pin 20 from the axial hole 4c, the bending deformation of the energy absorbing pin 20, and the bending deformation of the energy absorbing pin 20 is applied to the seat belt. The limit load applied to the seat belt 3 at this time is a total of the torsional deformation load of the torsion bar 7 and the total load of the energy absorbing pin 20.

After the entire amount of the energy absorbing pin 20 is pulled out from the axial hole 4c, the torsion bar 7 is twisted to absorb energy.

The pin 20 is made of plastically deformable metal. In this embodiment, as shown in FIG. 2B, the pin 20 includes a large-diameter portion 21, a medium-diameter portion 22 having a diameter smaller than that of the large-diameter portion 21, and a large-diameter portion 21 from the flange portion 20a side toward the tip side. It has a small diameter portion 23 whose diameter is smaller than the middle diameter portion 22, or like the pin 20′ of FIG. 2(c), from the flange portion 20a side to the small diameter portion 24, the medium diameter portion 25, the small diameter portion. And a portion 26. The medium diameter portion 25 has a larger diameter than the small diameter portions 24 and 26.

It is preferable that the middle-diameter portion 22 of the pin 20 of FIG. It is preferable that the large-diameter portion 21 has a length of 10 to 40%, particularly 15 to 25%, of the length of the pin 20 inserted into the spool. It is preferable that the small-diameter portion 23 has a length of 10 to 40%, particularly 10 to 25% of the length of the pin 20 inserted into the spool.

The preferable ratio of each portion 24, 25, 26 of the pin 20' to the insertion length of the pin 20 in the spool is similar to that of each portion 21, 22, 23 of the pin 20'.

In the case of an ordinary seat belt retractor, the total length of the pins 20 and 20' is 20 to 50 mm, especially 30 to 45 mm, and the diameter of the medium diameter portions 22 and 25 is 2.0 to 4.0 mm, especially 2.8 to 3.5 mm. However, the present invention is not limited to this.

These pins 20 and 20 ′ have a torsion bar torsional deformation suppression region (C) for preventing and reducing a reduction in the working winding amount of the pretensioner due to pre-twisting of the torsion bar 7, and an EA. It sometimes has a region (B) that functions as a DEA by adding a load to the torsion bar load. Therefore, in each of the regions, a parameter that suppresses the load when the rotational phase difference between the spool and the locking base occurs (for example, the diameter of the pin) and a parameter that suppresses the amount of the rotational phase difference that causes the load (for example, the length of the pin). ) Can be adjusted individually.

When the pins 20 and 20′ are used, as shown in FIG. 2(a), by setting the portion that is deformed by pre-twisting (before EA), it is possible to prevent the decrease in the EA amount of the first step due to pre-twisting. ..

FIG. 3 shows a load curve when the pin 20 ″ is used for comparison. In this pin 20 ″, the tip side is a small diameter portion 28, and the flange portion 20 a side from the central portion is a medium diameter portion 27.

In the pin 20 ″, the portion a is deformed by pre-twisting, and the EA amount in the first stage decreases with respect to the target (indicated by the broken line in FIGS. 2 and 3 ). Therefore, the amount of movement of the occupant increases.

1 Seat Belt Retractor 3 Seat Belt 4 Spool 4b Support Surface 5 Deceleration Sensing Mechanism 6 Locking Means 7 Torsion Bar 8 Spring Means 13 Pawl 14 Rocking Base 20, 20' Energy Absorbing Pin 20a Flange 21 Large Diameter 22, 25 Medium Diameter Part 23, 24, 26 Small part

Claims (3)

A frame that supports the spool and the locking base,
A tubular spool having an inner hole and a flange for winding up a seat belt, the spool having an axial hole for inserting a pin extending in a direction parallel to the axial direction,
The locking base is disposed coaxially adjacent to the spool, and is connected to the spool by a torsion bar,
A torsion bar that is inserted into the inner hole of the spool, one end side of which is non-rotatably connected to the spool, the other end side of which is non-rotatably connected to the locking base, and which is twisted and deformed during EA;
A pretensioner for rotating the locking base in a seat belt winding direction, the pretensioner having a housing adjacent to the flange of the spool,
A seatbelt retractor having an EA pin inserted through the locking base into an axial hole of the spool,
The seatbelt retractor characterized in that the pin has a torsion bar torsional deformation suppression region and a region for applying a load to the torsion bar load during EA. The pin has a flange portion that is locked to the locking base on the base end side,
The seatbelt retractor, wherein the pin has a large-diameter portion, a medium-diameter portion, and a small-diameter portion from the flange side toward the tip side. The pin has a flange portion that is locked to the locking base on the base end side,
The seat belt retractor, wherein the pin has a small-diameter portion, a medium-diameter portion, and a small-diameter portion from the flange side toward the tip side.

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