KR101596769B1 - Retractor for Seat Belt Preventing Deviate for Lock Pawl - Google Patents

Abstract

The present invention relates to a retractor for a seat belt with improved reliability of an overshoot releasing function. According to one embodiment of the present invention, a retractor for a seat belt includes: a frame having a spool hole and an inner gear formed around an inner circumference of the spool hole; a spool formed inside the frame to rotate and having a cam hole on the other surface; a torsion bar formed inside the spool and rotating with the spool by sharing a rotary shaft of the spool; and an overshoot releasing module rotating the other side of the torsion bar by rotating with the spool. The overshoot releasing module includes: a lock pawl member formed on the other surface of the spool, received in a lock pawl chamber forming a space open toward the outer side of the spool to be moved, and engaged with the inner gear of the spool hole and formed on the surface toward the outer side of the spool; a rod coupler engaged with the other end of the torsion bar and transmitting the torque of the torsion bar to the spool; a lock pawl holder formed on the other surface of the rod coupler, rotating according to the rotation of the rod coupler, and having a cam protrusion penetrating through the cam hole of the spool and limiting the projection of the lock pawl member according to the rotation; and a reverse rotation preventing unit preventing the reverse rotation of the lock pawl holder.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a retractor for a seat belt,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretensioner, and more particularly, to a retractor for a seat belt in which separation of a pawl member, in which reliability of an overshoot mitigation function is improved, is prevented.

When a person is riding on a vehicle or an apparatus, various safeguards are provided in order to prevent the person aboard from colliding with the vehicle or other object from leaving the vehicle or apparatus.

Typically, a seat belt is used to stably fix the lower abdomen and the chest of a person aboard the vehicle or mechanism using the seat belt. However, the degree of collision with the vehicle or with other objects increases beyond the reference level, so that the seat belt often fails to function, and in such a case, the safety of a person aboard the vehicle or apparatus is deteriorated.

Accordingly, various techniques have been developed so that the seat belt performs its function even when the degree of collision with the vehicle or with other objects is large. Among them, Retractor is the technology that is currently attracting attention.

The retractor is provided with a pre-tensioner for increasing the function and effect of the seat belt by introducing a webbing of the seat belt when the vehicle collides with a vehicle or another object, and a pretensioner And an ELR actuating part for locking one side of the spool so as not to be drawn out.

The operation of this pretensioner and the ELR actuating part can be confirmed by a graph expressing the collision performance of the vehicle, that is, a graph showing the load change applied to the occupant's body shown in Fig.

That is, the load change graph R expressing the crash performance of the vehicle shown in FIG. 1 is expressed by a load curve acting on the occupant when the pretensioner is in the preceding operation and a load curve acting on the occupant when the ELR operation portion is performing the following operation , Which confirms the operation of the pretensioner and the ELR actuator.

More specifically, the operation of the pretensioner and the ELR operation unit will be described with reference to FIG.

Generally, the pretensioner operates the piston located in the cylinder using the energy generated when the gas explodes, and the structure associated with the piston is activated as the piston is operated to rotate the spool in the reverse direction, thereby limiting the forward movement of the occupant Lt; / RTI > Therefore, the time-related numerical values shown in FIG. 1 are only displayed for example, and the numerical values for the time are also indicated to be the same for 15 to 25 milliseconds in FIG. - the load acting on the occupant gradually increases as the load curve in the vicinity increases.

However, due to the gas remaining in the cylinder after the gas has exploded in the pretensioner, an overshoot phenomenon occurs.

At this time, the overshoot phenomenon is a phenomenon in which the load sharply increases in the vicinity of 30 [ms] compared with the ideal load change graph (I) indicated by a dotted line in Fig. 1. In more detail, This is because the initial operating load of the load limiter is increased due to the pressure of the gas remaining in the cylinder when the load limiter provided to mitigate the load acting on the passenger after the webbing is locked.

Also, since the operation of the ELR operation portion is delayed due to the structural limit of the retractor after the gas explodes in the pretensioner, a locking deep phenomenon occurs.

At this time, the locking dip phenomenon is a phenomenon in which the load sharply decreases in the vicinity of 20 [ms] with respect to the ideal load change graph (I) indicated by a dotted line in Fig. 1. In more detail, There is a delay between the operation of the pretensioner and the operation of the ELR actuating part because the ELR actuating part is provided adjacent to the other end opposite to the one end of the spool with the pretensioner provided adjacent to one end of the spool It is because there is not.

As described above, when the locking depression phenomenon and the overshoot phenomenon occur sequentially in the operation of the pretensioner and the ELR operation unit, unlike the ideal load change graph I indicated by the dotted line in FIG. 1, the load applied to the body of the occupant A load is applied to the occupant, such as a steeply decreasing or increasing load change graph (R).

If such a suddenly changing load is applied to the occupant, the occupant will be exposed to the risk of unexpected injury, and further research and development is under way to solve such a problem.

Korean Patent No. 10-1261848

SUMMARY OF THE INVENTION It is an object of the present invention to provide a retractor for a seat belt in which a pawl member is prevented from being separated from the seat cushion to prevent a locking deep phenomenon and an overshoot phenomenon It is an assignment.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, a spool hole is formed on the opposite side of a side where a pretensioner is located, and a frame having an internal gear around an inner circumferential surface of the spool hole; A spool rotatably provided in the frame so that the webbing is wound or unwound, and a cam hole is formed on the other side; A torsion bar provided on the inside of the spool and rotated together with the spool by sharing a rotation axis of the spool; And an overshoot mitigation module which is provided on the other side of the spool and rotates together with the spool to rotate the other side of the torsion bar after the pretensioner fixes one side of the torsion bar, A gear tooth formed on the other side surface of the spool and movably received in a pawl chamber forming a space open toward the outside of the spool, the gear teeth meshing with the internal gear of the spool hole on a surface facing the outside of the spool, A pawl member protruding selectively outwardly of the spool and engaging with the inner gear to restrict rotation of the spool; A rod coupler engaged with the other end of the torsion bar and transmitting the rotational force of the torsion bar to the spool; A pawl holder provided on the other side of the rod coupler and rotatable in accordance with rotation of the rod coupler and having a cam protrusion penetrating the cam hole of the spool and restricting the projection of the pawl in accordance with rotation; A retractor for a seat belt is disclosed in which a pawl member including a reverse rotation preventing portion for preventing reverse rotation of the pole holder is prevented from being released.

Wherein the pawl chamber is formed to communicate with the cam hole, the pawl member includes a cam groove receiving the cam protrusion at a position communicating with the cam hole, and the cam protrusion is rotated by the rotation of the pole holder, And the protrusion of the pawl member may be limited as the pawl member is received therein.

Wherein the reverse rotation preventing portion includes: a hook formed around the pole holder; The hook may be formed at a position corresponding to the periphery of the pole holder on the other side surface of the spool, and may be configured to restrict the rotation of the pawl holder by hooking the hook.

The hook and the latching jaw do not restrict rotation when the pole holder rotates forward and may be inclined in one direction so as to restrict rotation when the pole holder rotates in the reverse direction.

A rotation protrusion protruding from a surface of the pole holder in contact with the rod coupler is formed and a rotation groove formed in a surface of the rod coupler in contact with the rotation protrusion for receiving the rotation protrusion may be formed.

The rotation groove may be formed to have a wider width than the rotation protrusion such that a space is formed between the rotation protrusion and the rotation groove in the rotation direction thereof.

According to the retractor for a seat belt in which the pawl member of the present invention is prevented from being released, the following effects can be obtained.

First, the one side of the torsion bar is fixed by the pretensioner, and the other side of the torsion bar is rotated by the overshoot easing module, thereby being able to prevent the locking deep phenomenon and the overshoot phenomenon .

Second, since the pawl holder having the cam protrusion for fixing the pawl member is prevented from rotating in the reverse direction, it is possible to prevent the pawl from being detached and the spool being fixed even if an unexpected impact is applied.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

The foregoing summary, as well as the detailed description of the preferred embodiments of the present application set forth below, may be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown preferred embodiments in the figures. It should be understood, however, that this application is not limited to the precise arrangements and instrumentalities shown.
FIG. 1 is a graph showing changes in load applied to a body of a passenger when a conventional retractor for a seat belt is operated; FIG.
2 is a perspective view showing a retractor for a seat belt according to an embodiment of the present invention;
FIG. 3 is an exploded perspective view showing a connection structure between the components of FIG. 2; FIG.
4 is a cross-sectional perspective view showing a state in which respective components of the pretensioner of FIG. 3 are coupled;
5 is a side view showing a state in which the rocker is protruded by pushing the trigger while the rack gear of FIG. 4 is being moved;
FIG. 6 is a perspective view illustrating a state in which the torsion bar is rotated according to rotation of the pinion gear of FIG. 3;
7 is a side view showing a state where a pawl member and a cam projection are separated from each other in a retractor for a seat belt according to an embodiment of the present invention;
FIG. 8 is a side view showing a state in which the pawl member and the cam protrusion of FIG. 7 are combined;
9 is an exploded perspective view showing a pawl holder and a rod coupler of a retractor for a seat belt according to an embodiment of the present invention;
Fig. 10 is a side view showing the hook of the pawl member and the engagement jaw of the spool of Fig. 9. Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In describing the present embodiment, the same designations and the same reference numerals are used for the same components, and further description thereof will be omitted.

FIG. 2 is a perspective view showing a state of a retractor for a seat belt (hereinafter, referred to as a seat belt retractor for convenience of explanation) in which a release of a pawl member is prevented according to an embodiment of the present invention. FIG. 3 is an exploded perspective view showing a connection structure between the components of the retractor according to the present embodiment, and FIG. 4 is a sectional perspective view showing a state in which the pretensioner is engaged.

2 to 4, a retractor 1 for a seat belt includes a frame 10, a spool (not shown) rotatably provided on the frame 10 and configured to wind or loosen a webbing (20).

A pretensioner 100 is provided on one side of the frame 10. The pretensioner 100 includes a housing 110, a pinion gear 170, a gas generator 140, a transfer pipe 130, a ball member 160, and a rack gear 120 .

Referring to FIG. 3, the housing 110 includes a base housing 110a and a cover housing 110b, and an accommodation space S is formed between the base housing 110a and the cover housing 110b. The pinion gear 170 is inserted into the receiving space S through the through hole 112 of the housing 110 while being connected to the rotating shaft of the spool 20.

In this state, the rack gear 120 and the rotary roller 150 are received in the receiving space S, one side of which is connected to the gas generator 140, And is connected to the accommodation space S. A plurality of the ball members 160 are accommodated in the transfer tube 130.

The connection structure between the components has been described above, and each component will be described in more detail below.

As described above, the pretensioner 100 according to the present embodiment includes a housing 110 including a base housing 110a and a cover housing 110b (see FIG. 3), a pinion gear 170, a gas generator 140, a transfer tube 130, a ball member 160 (see FIG. 3), and a rack gear 120.

The pinion gear 170 is provided with a plurality of gear teeth 172 so as to be meshed with the gear teeth 122 formed on the rack gear 120.

4 and 5, the rack gear 120 may be formed to form a part of an arc, and the pinion gear 170 may be positioned at a center of curvature thereof. A gear teeth 172 may be formed on the surface of the rack gear facing the center of curvature.

The gas generator 140 is a component that generates an explosive force in response to an external impact.

One side of the transfer pipe 130 is connected to the gas generator 140 and the other side of the transfer pipe 130 is connected to the accommodation space S by forming an opening 132. A plurality of ball members 160 may be provided in the transfer pipe 130 to be transferred to the accommodation space S by the explosion of the gas generator 140.

That is, when an impact is applied from the outside of the object on which the present pretensioner 100 such as a vehicle is installed, an explosive force is generated by a gunpowder or the like provided inside, and the explosive force is transmitted to the ball member 160 provided in the transfer pipe 130 . Therefore, the ball member 160 can be transferred to the rack gear 120 side of the accommodation space S.

The rack gear 120 is fixed to the accommodation space S by a first fixing member 125 and a second fixing member 126. The rack gear 120 is fixed to the receiving space S by a ball member The first fixing member 125 and the second fixing member 126 are broken by being pushed by the first fixing member 160 so that the rack gear 120 can move.

That is, the rack gear 120 is initially fixed to the accommodation space S without being engaged with the pinion gear 170, and is fixed by the kinetic energy of the ball member 160 due to external impact And is engaged with the pinion gear 170. And the pinion gear 170 can be rotated in the direction in which the webbing is pulled by the residual thrust of the ball member 160. [

Meanwhile, the pretensioner 100 according to the present embodiment may include a locker 190 and a trigger 180, as shown in FIGS.

The rack gear 120 is moved by the explosion of the gas generator 140 and can be moved in the opposite direction by recoil at the end after the residual thrust of the ball member 160 due to the explosion of the gas generator 140 disappears, The pinion gear 170 engaged with the rack gear 120 can also be rotated in the opposite direction.

The locker 190 is a component that prevents the rack gear 120 and the pinion gear 170 engaged with the rack gear 120 from moving and rotating in the opposite direction.

The trigger 180 is fixed to the rack gear 120 so that the rack gear 120 is kept stationary before the rack gear 120 is moved by the gas generator 140, And is configured to release the locker 190 when it is rotated by the explosion force of the generator 140.

5, when the rack gear 120 is moved by the pressure of the ball member 160 due to the explosion of the gas generator 140, the rack gear 120 is rotated by the trigger 180 And the rotated trigger 180 disengages the locker 190, and the locker 190 can be protruded by the spring 198.

When the rack gear 120 is moved in the opposite direction by the recoil or the like, the protruded locker 190 is inserted between the gear teeth 122 of the rack gear 120 and the gear teeth 172 of the pinion gear 170 So that it is possible to prevent the pinion gear 170 from rotating in the opposite direction.

Therefore, when the webbing is re-drawn by reducing the force transmitted by the explosion of the gas generator after the pretensioner is operated, one side of the torsion bar 25, which is the rotating shaft of the spool 20, It is possible to prevent the draw-out.

At this time, an overshoot phenomenon in which the load applied to the body of the driver suddenly increases at the moment when one side of the torsion bar 25 is fixed may occur, so that the side of the torsion bar 25 is rotated a little after the pretensioner is operated Thereby minimizing the overshoot phenomenon.

The overshoot mitigation module 200 of this embodiment is a component that minimizes the overshoot phenomenon by allowing the torsion bar 25 to be rotated somewhat after the pretensioner is operated to minimize the overshoot phenomenon as described above .

6 to 10, the overshoot mitigation module 200 of the retractor for a seat belt according to the present embodiment includes a pawl member 220, a rod coupler 240, a pole holder 250, Prevention part 260 may be included.

6 is a view showing a state in which the torsion bar 25 is rotated according to the rotation of the pinion gear 170, and FIG. 7 is a view showing the state of the pawl member 220 and the cam protrusion 252. 8 and 9 are views showing a state in which the pawl member 220 is fixed according to the operation of the cam protrusion 252. Figs. 10 and 11 show the pawl holder 250, the rod coupler 240, Preventing unit 260 shown in Fig.

Meanwhile, as described above, the rack gear 120 rotates the pinion gear 170, and the torsion bar 25 axially coupled to the pinion gear 170 is also rotated.

The torsion bar 25 is provided to transmit a rotational force to the overshoot easing module 200 provided on the other side of the frame 10. [

To this end, a rod coupler 240 may be coupled to the other end of the torsion bar 25. [

That is, gear teeth are formed at the other end of the torsion bar 25, and the rod coupler 240 has a hole 242 formed at the center thereof with a gear tooth to which the other end of the torsion bar 25 is inserted, .

The rod coupler may be coupled to an inner surface of the other side surface of the spool 20 to transmit the rotational force of the torsion bar 25 to the spool 20.

A spool hole 230 corresponding to the other shape of the spool 20 is formed on the other side of the frame 10. An inner gear 232 having a plurality of gear teeth is formed on the inner peripheral surface of the spool hole 230 (See FIG. 3).

7, a pawl member 220 may be provided. The pawl member 220 may be movably received in the pawl chamber 22 formed on the other side of the spool 20. At this time, the pole chamber 22 may be formed at a position facing the inner gear 232 of the spool hole 230 on the other side of the spool 20.

The pole chamber 22 may be a space formed on the other side of the spool 20 and opened toward the outer periphery of the spool 20.

The pawl member 220 is received in the pawl chamber 22 so as to protrude into the open portion of the pawl chamber 22 or to be movable in the opposite direction to the outside of the pawl chamber 22, A gear tooth 222 that is engaged with an internal gear 232 of the spool hole 230 formed on the other side of the frame 10 may be formed on a surface facing the gear shaft 222.

At this time, the pawl member 220 may be formed so as not to be spaced apart from the pawl chamber 22 in a direction in which the spool 20 is rotated in the pawl chamber 22.

The pawl member 220 may be selectively protruded in the pawl chamber 22 to engage with the inner gear 232. The spool 20 is fixed to the frame 10 by interference with the pawl chamber 22 as the pawl member 220 is engaged with the inner gear 232 of the frame 10, Lt; / RTI >

A cam hole 24 formed in a pole holder 250 described later may be formed on the other side of the spool 20.

At this time, the cam hole 24 may be formed to be partially in communication with the pole chamber 22.

When the pawl member 220 is received in the pawl chamber 22, a cam groove 242 is formed in a portion of the pawl member 220 which is connected to the cam hole 24, 224 may be formed.

6 and 9, the pole holder 250 is provided on the other side of the rod coupler 240 and rotatably supports the rod coupler 240 and the rod coupler 240 so as to be rotated according to the rotation of the rod coupler 240. [ Can be combined.

At this time, a rotation protrusion 254 protrudes from the surface of the pole holder 250 in contact with the rod coupler 240, and the surface of the rod coupler 240, which is in contact with the rotation protrusion 254, A rotation groove 244 for receiving the rotation shaft 254 may be formed.

The rotation protrusion 254 may be received in the rotation groove 244 to transmit the rotational force of the rod coupler 240 to the pole holder 250.

The rotation groove 244 may be formed to be wider than the rotation protrusion 254 so that a space is formed between the rotation protrusion 254 and the rotation groove 244 in the rotation direction.

A cam protrusion 252 may be formed on the other side of the pole holder 250 to penetrate the cam hole 24 formed on the other side of the spool 20. At this time, the cam protrusion 252 may be formed to have a smaller size than the cam hole 24 so as to be movable in the rotation direction of the pole holder 250 in the cam hole 24.

Meanwhile, the pole holder 250 receiving the rotational force of the rod coupler 240 may also be rotated. At this time, the cam protrusion 252 is also moved in the cam hole 24 to be accommodated in the cam groove 224 of the pawl member 220, thereby restricting the movement of the pawl member 220.

7, when the cam protrusion 252 is in a position away from the cam groove 224, the movement of the pawl member 220 is free, and as shown in FIG. 8, The movement of the pawl member 220 can be restricted when the cam protrusion 252 is accommodated in the cam groove 224 of the pawl member 220 according to the movement of the pawl holder 250.

When the rod coupler 240 and the pole holder 250 are rotated according to the rotation of the torsion bar 25, the cam protrusion 252 is received in the cam groove 224 and the movement of the pole holder 250 The rotation of the other side of the torsion bar 25 is not restricted.

Therefore, the spool 20 can be rotated slightly by the torsion action of the torsion bar 25, and the overshoot phenomenon can be minimized.

The cam protrusion 252 is disengaged from the cam groove 224 by the external impact and the pawl member 220 protrudes from the cam groove 224, 20 may be restricted in rotation.

Therefore, in the present embodiment, when the pole holder 250 is rotated so that the cam protrusion 252 is received in the cam groove 224, the reverse rotation in the opposite direction is restricted, Rotation preventing portion 260 that excludes the possibility of being detached from the base portion 224.

The reverse rotation preventing portion 260 may include a hook 262 and a stopping jaw 264, as shown in FIG.

The hook is formed on an outer circumferential surface of the pole holder 250. The hook is formed at a position corresponding to the periphery of the hook 262 of the pole holder 250 on the inner side of the other side of the spool, The hook 262 may be hooked upon the reverse rotation of the pawl holder 250 to limit the rotation of the pawl holder 250.

At this time, the rotation direction of the pawl holder 250 in the direction in which the cam protrusion 252 is received in the cam groove 224 is referred to as forward rotation, and the rotation in the opposite direction is referred to as reverse rotation.

At this time, the hook 262 and the latching jaw 264 do not restrict the rotation when the pole holder 250 rotates in the normal direction, and when the pole holder 250 rotates in the reverse direction, And the opposite side may be formed to form a step.

Accordingly, when the pawl holder 250 rotates in the forward direction, the hook 262 is inclined to exceed the stopping jaw 264 so that rotation is not restricted. When the pawl holder 250 rotates in the reverse direction, The cam protrusion 252 is prevented from being detached while the cam protrusion 252 is accommodated in the cam groove 224 because the rotation of the pawl holder 250 is restricted by engaging the engaging protrusion 262 with the engaging protrusion 264, The operation of the mitigation function can be more reliable.

Since the rotation groove 244 is formed to be wider than the rotation protrusion 254 and a space is formed between the rotation groove 244 and the rotation protrusion 254, When the torsion bar 25 is rotated in the reverse direction due to an unexpected impact and operation in a state where the hook 262 is engaged with the engagement jaw 264, the rotational force is not transmitted to the pole holder 250, 240 and the pole holder 250 can be slipped to prevent the hook 262 from being broken and at the same time the pawl holder 250 is rotated in the opposite direction and the cam protrusion 252 is disengaged from the cam groove 224, So that the fixing of the member 220 can be prevented from being released.

It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or scope of the invention as defined in the appended claims. It is obvious to them. Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and the present invention is not limited to the above description, but may be modified within the scope of the appended claims and equivalents thereof.

20; Spool 24: cam hole
25: Torsion bar 100: Pretensioner
110: housing 120: rack gear
130: Feed pipe 140: Gas generator
160: Ball member 170: Pinion gear
180: Trigger 190: Rocker
200: overshoot mitigation module 220: pole member
222: gear teeth 224: cam groove
230: spool hole 232: inner gear
240: Rod coupler 244: Rotary groove
250: Pole holder 252: Cam protrusion
254: rotation projection 260: reverse rotation prevention part
262: hook 264:

Claims (6)

A frame having a spool hole formed on the other side opposite to the side where the pretensioner is positioned and having an inner gear formed around an inner circumferential surface of the spool hole;
A spool rotatably provided in the frame so that the webbing is wound or unwound, and a cam hole is formed on the other side;
A torsion bar provided on the inside of the spool and rotated together with the spool by sharing a rotation axis of the spool;
An overshoot mitigation module provided on the other side of the spool, wherein the pretensioner fixes one side of the torsion bar and then rotates together with the spool to rotate the other side of the torsion bar;
/ RTI >
Wherein the overshoot mitigation module comprises:
A gear tooth formed on the other side surface of the spool and movably received in a pawl chamber forming a space open toward the outside of the spool, the gear teeth meshing with the internal gear of the spool hole on a surface facing the outside of the spool, A pawl member protruding selectively outwardly of the spool and engaging with the inner gear to restrict rotation of the spool;
A rod coupler engaged with the other end of the torsion bar and transmitting the rotational force of the torsion bar to the spool;
A pawl holder provided on the other side of the rod coupler and rotatable in accordance with rotation of the rod coupler and having a cam protrusion penetrating the cam hole of the spool and restricting the projection of the pawl in accordance with rotation;
A reverse rotation front portion for preventing reverse rotation of the pole holder;
Wherein the pawl member is prevented from being separated from the pawl member. The method according to claim 1,
The pole chamber is formed to communicate with the cam hole,
Wherein the pawl member has a cam groove in which the cam protrusion is received at a position communicating with the cam hole,
And the pawl member is prevented from being released from the pawl member in which the projection of the pawl member is limited as the cam protrusion is received in the cam groove by rotation of the pawl holder. The method according to claim 1,
The reverse-
A hook formed around the pole holder;
A hook that is formed at a position corresponding to the periphery of the pole holder on the other side of the spool and is configured to limit the rotation of the pole holder by hooking the hook;
Wherein the pawl member is detached from the pawl member. The method of claim 3,
Wherein the hook and the engagement jaw do not restrict rotation when the pawl holder rotates forward and restrict rotation when the pawl holder rotates in the reverse direction, Tractor. The method according to claim 1,
A protrusion protruding from a surface of the pole holder in contact with the rod coupler is formed,
And a pawl member formed on a surface of the rod coupler in contact with the rotation protrusion and having a rotation groove for receiving the rotation protrusion is prevented from being released. 6. The method of claim 5,
So that a space is formed between the rotation projection and the rotation groove in the rotation direction thereof,
Wherein the rotation groove prevents the pawl member, which is formed to have a wider width than the rotation protrusion, from being released.

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