JPH08290754A - Pretensioner device - Google Patents

Abstract

PURPOSE: To eliminate use of any compression spring and reduce the number of component parts by disengaging the lock of a locking coil with a rotary shaft only when an inertial force is applied, and transmitting the torque of the rotary shaft to a webbing takeup shaft through a clutch mechanism. CONSTITUTION: When an automobile makes a collision, etc., to generate an abnormal decelerating condition, an inertia responding sensor 9 hops out in the direction of the inertia to disengage the restraint for a pressure spring 7 by a leg 9a. The pressure spring 7 presses the movable end 4b so that a locking coil 4 spreads on a rotary shaft 2, which is thus rotated in the webbing takeup direction by the pressure of a torsion coil spring. A pin 12 in a retaining groove 11 provided in a minor diametric portion 2B of the rotary shaft 2 protrudes outward with the centrifugal force and is engaged by a detention groove 25 formed in a flange part 24 of the webbing takeup shaft. The torque of the rotary shaft 2 given by a power spring 3 is transmitted to the webbing takeup shaft 22 and a webbing 23 is wound round to generate restraint of the driver/passenger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a pretensioner device for preventing a passenger from moving forward by instantly tightening loose webbing of a seat belt in the event of a vehicle collision.

[0002]

2. Description of the Related Art As a conventional pretensioner device of this type, for example, JP-A-3-114946 and JP-A-4-114946.
There are those disclosed in Japanese Patent No. 50058, Japanese Utility Model Laid-Open No. 4-93248, and the like. Although these conventional pretensioner devices have various structural differences, all of them use a compression coil spring with a large output as a driving source,
The compression coil spring is restrained in a contracted state by a locking means or the like, and in the event of an automobile collision or the like, the compression coil spring in the restrained state is extended and the extension force is used to form a seat belt. The buckle and the webbing are quickly tightened to prevent the occupant's body from moving forward due to the webbing.

[0003]

However, in all of the conventional pretensioner devices, the pretensioner device itself uses the compression coil spring having a large output as a drive source thereof. It goes without saying that the expansion and contraction strokes will inevitably increase in size, but in addition to this, not only a locking means for restraining the compression coil spring in a contracted state, but also a buckle and a buckle are required. Since a large-scale auxiliary mechanism for transmitting the extension force of the compression coil spring to the webbing as its tightening force is further required, the pretensioner device inevitably becomes large in size in any case. Therefore, under the conventional pretensioner device, there are problems that the assembling work becomes difficult and the cost becomes high as the number of parts increases and the device itself becomes large.

[0004]

SUMMARY OF THE INVENTION The present invention was developed to effectively solve the problems of the conventional pretensioner device. The invention according to claim 1 is a webbing retractor for a retractor. A rotary shaft that faces the shaft, a clutch mechanism that connects the rotary shaft to a webbing take-up shaft so that the webbing take-up shaft can be connected and disconnected, and a rotary shaft that is wound around one end of the rotary shaft to wind the webbing in the webbing winding direction. Power spring for forcibly rotating the rotating shaft, a locking coil wound around the other end of the rotating shaft for locking the rotating shaft, and an inertial response operation for releasing the locking state of the locking coil with respect to the rotating shaft. And releasing the locking state of the locking coil with respect to the rotating shaft body by the releasing means only when an inertial force is applied, and rotating force of the rotating shaft body to the clutch mechanism. Adopting a configuration to transmit to the webbing take-up shaft by.

According to a second aspect of the invention, based on the first aspect, a power spring is used as a power spring, and the power spring is wound around a rotating shaft having a small diameter. A structure is adopted in which the clutch mechanism side has an expanded cylindrical end portion, a metal collar is externally fitted to the cylindrical end portion, and the metal collar surface serves as the braking surface of the locking coil.

According to a third aspect of the present invention, on the premise of the second aspect, the rotary shaft body is formed with a fitting groove for fixing the inner end edge of the mainspring spring in the lengthwise direction thereof, and has a cylindrical end whose diameter is expanded. The protrusion is formed at an end opposite to the protrusion, and the fitting groove is continuously opened in the protrusion, while the protrusion is provided on the inner surface of the shaft lid attached to the end where the protrusion is formed. We adopted a configuration that forms a receiving recess that fits and tightens.

According to a fourth aspect of the present invention, on the premise of the third aspect, a configuration is adopted in which an operating concave portion opposite to the receiving concave portion is formed on the outer surface of the shaft cover.

According to a fifth aspect of the present invention, on the premise of the second to fourth aspects, the expanded cylindrical end portion of the rotary shaft body is formed with a holding groove for accommodating the pin member in a retractable manner. A configuration is adopted in which a cylindrical protrusion is provided and a rotary sleeve fixed to the webbing take-up shaft side and having a locking groove formed on the inner peripheral surface is fitted to the outer periphery of the cylindrical protrusion.

According to a sixth aspect of the present invention, based on the first to fifth aspects, the releasing means for releasing the locked state of the locking coil with respect to the rotating shaft body includes a weight portion for inertial response and a locking coil. A structure is adopted which is connected to the movable end and is composed of an arm part that vibrates integrally with the weight part.

According to a seventh aspect of the invention, on the premise of the sixth aspect, when the weight portion vibrates integrally with the arm portion in a direction in which the rocking coil is expanded by inertial force, the weight portion is prevented from returning. A configuration having a blocking means for

According to the eighth aspect of the invention, on the premise of the first to seventh aspects, a structure is provided on the outer periphery of the locking coil, in which a cylindrical body for restricting the diameter expansion amount of the locking coil is provided.

Therefore, under the pretensioner device of the present invention, the clutch mechanism normally disconnects the rotary shaft body from the webbing take-up shaft, so that the webbing is pulled out from the retractor. It is possible to guarantee the proper use of the reel or its winding shaft. Then, once a collision accident or the like occurs and the vehicle is brought into an abnormal deceleration state, the locking state of the locking coil with respect to the rotating shaft body is released by the action of the releasing means that senses the inertial force, and the rotating shaft body is released. Abruptly forcibly rotate in the webbing winding direction by the spring pressure of the power spring.

Then, in conjunction with the abrupt forced rotation of the rotating shaft body, this time, the rotating shaft body and the webbing winding shaft are connected for the first time by the action of the clutch mechanism, and the rotational force of the rotating shaft body is changed. By transmitting to the webbing take-up shaft of the retractor, this allows the loose webbing to be immediately taken up on the webbing take-up shaft to ensure that the tensioned webbing moves the occupant's body forward. It can be prevented.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. The pretensioner device according to the first embodiment, in the event of a car collision,
It was developed as a model that actuates the retractor side of the seat belt, and is characterized by adopting the following configuration.

That is, in the first embodiment, as shown in FIG. 1, the pretensioner case 1 is provided with a rotary shaft body 2 having a diameter difference facing the webbing take-up shaft 22 of the retractor 21. The rotary shaft body 2 and the webbing take-up shaft 22 are rotatably arranged so as to be connectable / disconnectable to each other via a clutch mechanism 10 described later. A power spring for forcibly rotating the rotating shaft body 2 in the winding direction of the webbing 23 is wound on the formed large diameter portion 2A, and on the small diameter portion 2B defined on the other end side of the rotating shaft body 2. The locking coil 4 which can expand the diameter and locks the forced rotation of the rotary shaft body 2 is wound.

As shown in FIG. 2, the former power spring accumulates a spring pressure equal to or greater than the winding amount of the webbing 23 and is wound around the large diameter portion 2A of the rotary shaft body 2. According to the first embodiment, a torsion coil spring 3 is used for this power spring, and the latter locking coil 4 has a coil inner diameter in its free state smaller than that of the small diameter portion 2B of the rotary shaft body 2. Thus, in the winding state of the small diameter portion 2B, by expanding the diameter on the small diameter portion 2B by the set difference and winding it, the repulsive force causes the forced rotation of the rotary shaft body 2 to be twisted. The locking coil 4 is locked against the spring pressure of the torsion coil spring 3, and the locking coil 4 is also formed in the shape of a close contact coil that does not require a stretching stroke.

Further, in the first embodiment, in addition to this structure, as shown in FIGS. 3 and 4, the fixed end portion 4a of the locking coil 4 is provided on the upper side of the case 1. The movable end 4b is fixed to the stopper 5 which is attached to the case 1
While facing the pair of stopper members 6 provided on the lower side in a free state, the compression coil-shaped pressing spring 7 is guided to the side where the movable end 4b of the locking coil 4 of the stopper member 6 does not exist. A structure is adopted in which the leg 9a of the pop-out type inertial response sensor 9 is detachably interposed between the pressing spring 7 and each of the stopper members 6 by being mounted so as to be expandable and contractable via a rod 8.

Therefore, in a normal state, the pressure spring 7 is constrained in a contracted state by the interposition of the leg portion 9a of the inertial response sensor 9, but the inertial response sensor 9 receives inertia when the vehicle crashes or the like. When a force is applied, the inertial response sensor 9 then pops out in the inertial direction along with the leg 9a to release the restraint state with respect to the pressing spring 7, and at the same time, the pressing spring 7 immediately expands and the locking coil is released. Since the movable end portion 4b of 4 is pressed in the radial direction, the locking coil 4 itself expands in diameter, and the locked state with respect to the rotary shaft body 2 can be automatically released.

The clutch mechanism 10 for connecting and disconnecting the rotary shaft body 2 and the webbing take-up shaft 22 is, as shown in FIG.
A cylindrical flange portion 24 into which the end of the small diameter portion 2B of the rotary shaft body 2 is fitted is integrally formed on the opposite side of the webbing take-up shaft 22, and the inner peripheral surface of the flange portion 24 has a serrated engagement. Stop groove 2
While forming 5 continuously, a concave holding groove 11 is formed in the small diameter portion 2B of the rotary shaft body 2, and the pin member 12 is retractably housed in the holding groove 11.

Therefore, in a normal state, the pin member 12 is sunk in the holding groove 11 of the small diameter portion 2B to disconnect the rotary shaft body 2 from the webbing take-up shaft 22.
However, when the rotary shaft body 2 is twisted and forced to rotate by the spring pressure of the coil spring 3, the pin member 12 is subjected to centrifugal force. The flange portion 24 is projected outward from the holding groove 11.
The rotation shaft body 2 and the webbing take-up shaft 22 can be connected to each other by locking the rotation shaft body 2 in the locking groove 25.

Therefore, under an automobile equipped with the pretensioner device having such a structure, the connection between the rotary shaft body 2 and the webbing take-up shaft 22 is normally disconnected by the action of the clutch mechanism 10 described above. Therefore, the webbing 23 can be guaranteed to be properly used by being pulled out from the retractor 21 or being wound around the winding shaft 22.

Then, once a collision accident occurs,
When the vehicle is in an abnormal deceleration state, as shown in FIG. 6, the inertial response sensor 9 jumps out in the inertial direction by this inertial force and releases the restrained state of the pressing spring 7 by its own leg portion 9a. As shown in FIG. 7, the extended pressing spring 7 causes the movable end portion 4 b of the locking coil 4 to move.
Since the locking coil 4 is forcibly expanded on the rotary shaft body 2 by pressing, the locking coil 4 is
The locked state with respect to the rotating shaft body 2 is immediately released, and the rotating shaft body 2 is forcibly and rapidly rotated in the winding direction of the webbing 23 by the accumulated spring pressure of the torsion coil spring 3 which is a power spring.

Then, due to the rapid rotation of the rotary shaft body 2, this time, as shown in FIG.
The pin member 12 in the holding groove 11 formed on the outer peripheral surface of the flange portion 24 of the webbing take-up shaft 22 protrudes outward by centrifugal force.
Since the rotational force of the rotary shaft body 2 is transmitted to the webbing take-up shaft 22 of the retractor 21 by being locked in the lock groove 25 formed in the webbing 23, the loose webbing 23 is wound by the webbing winder. It is possible to reliably prevent the occupant's body from moving forward due to the tensioned webbing 23 being immediately wound around the take-up shaft 22.

Next, the pretensioner device according to the second embodiment will be described. Also in the second embodiment, the rotary shaft body 2 is basically used as in the first embodiment. The power spring forcibly rotating in the winding direction of the webbing 23, the locking coil 4 for locking the forcible rotation of the rotary shaft body 2, and the lock state of the locking coil 4 with respect to the rotary shaft body 2 are released by using the inertial response operation. Release means, rotating shaft body 2 and webbing winding shaft 22
A clutch mechanism 10 for connecting and disconnecting
The feature is that the following configuration is adopted.

First, in the second embodiment, as shown in FIG.
As shown in FIG. 10, a power spring is used as a power spring, and a mainspring spring 31 whose diameter can be made as small as possible and whose rising motion is quick is used.
Is fixed to the small-diameter rotating shaft body 2 side and the outer end edge 31b is fixed to the case 1 side through the slit 1a, whereby a spring pressure equal to or more than the winding amount of the webbing 23 can be accumulated.

To explain this in detail, the small-diameter rotary shaft body 2 is made of synthetic resin, and as shown in FIG.
The inner end edge 3 of the mainspring spring 31 extends in the lengthwise direction.
While forming a fitting groove 32 for fixing 1a, one end facing the webbing take-up shaft 22 is formed as an enlarged hexagonal cylindrical end portion 33 with a collar 34, and a pin is formed in the hexagonal cylindrical end portion 33. A columnar protrusion 35 having a holding groove 11 for accommodating the member 12 retractably is integrally provided, and a protrusion 36 having a cross shape is integrally formed at the other end, and the protrusion 36 is fitted into the protrusion 36. The groove 32 is configured to be continuously opened. The inner peripheral surface of the hexagonal tubular end portion 33 has a regular arc shape.

Further, with respect to the inner side surface of the shaft lid 37 attached to the other end side where the protruding portion 36 is formed, the protruding portion 3
6 is formed with a slightly smaller cross-shaped receiving recess 38 into which the receiving recess 38 can be fitted, and a plurality of operating recesses 39 are formed on the outer surface of the coaxial lid 37 in the opposite direction to the receiving recess 38. Shall be formed.

Therefore, the inner end edge 31a of the mainspring 31 is fitted and fixed in the fitting groove 32 of the rotary shaft body 2, and the projection 36 on the other end side is tightly fitted in the receiving recess 38 of the shaft lid 37. When fitted, the receiving groove 38 is pressed to forcibly tighten the fitting groove 32 that opens to the side of the protrusion 36.
The inner end edge 31a of the mainspring 31 is securely held between the collar 34 of the hexagonal tubular end 33 and the shaft lid 37, and
After fixing the outer end edge 31b of the mainspring 31 to the case 1 side with the case lid 1b via a stopper, a tool tip (not shown) is inserted into the operation recess 39, and the shaft lid 37 is attached. When the mainspring spring 31 is rotated in a predetermined direction, it is possible to easily accumulate a spring pressure equal to or more than the winding amount of the webbing 23.

Further, under the second embodiment, as shown in the drawing, a metal collar 40 having a hexagonal inner peripheral side is externally fitted to the hexagonal cylindrical end portion 33 of the rotary shaft body 2, Since the locking coil 4 is wound around the metal collar 40 and the peripheral surface of the metal collar 40 serves as the braking surface of the locking coil 4, the hexagonal tubular end portion 33 is obviously reinforced. However, when the rotary shaft body 2 and the webbing take-up shaft 22 are connected, the pin member 12 held in the holding groove 11 of the columnar protrusion 35 has the hexagonal tubular end portion 3.
There is no need to worry about breaking through 3 and jumping outside. It should be noted that the thickness of the metal collar 40 may be thick enough to reach the holding groove 11, but in this case, the holding groove portion formed on the side of the columnar projection 35 and the holding portion formed on the side of the metal collar 40. Since the groove portion is required to have high accuracy, it can be said that it is preferable to form the holding groove 11 only on the side of the columnar projection 35 in order to smoothly ensure that the pin member 12 appears and disappears.

In addition to this, with respect to the outer periphery of the cylindrical projection 35 of the hexagonal tubular end portion 33, the resin is fixed to the webbing winding shaft 22 side and the engaging groove 25 is continuously formed on the inner peripheral surface thereof. The rotary sleeve 41 of FIG. 1 is rotatably fitted, and the rotary sleeve 41 and the columnar projection 35 holding the pin member 12 in the holding groove 11 make it possible to use the same clutch mechanism 1 as in the first embodiment.
Configures 0.

Further, regarding the releasing means for releasing the locked state of the locking coil 4 with respect to the rotary shaft body 2, in the second embodiment, instead of the above-mentioned pop-out type inertial response sensor 9, a pendulum type is used. Inertial response sensor 42
Shall be used. The inertial response sensor 42 is
As shown in FIG. 11 and FIG. 12, it is attached to the outside of the case 1 via a bracket 43, and a weight portion 42a made of iron or the like, and a crank-shaped arm portion 42b that vibrates integrally with the weight portion 42a. And a connecting portion 42c connected to the movable end portion 4b of the locking coil 4 in the case 1.
It consists of and.

Therefore, when an inertial force is applied to the weight portion 42a and the arm portion 42b vibrates integrally with the weight portion 42a in a predetermined direction due to a collision accident of an automobile or the like, the arm portion 4a.
Due to the vibration of 2b, the movable end 4b of the locking coil 4 is pressed in the radial direction, so that the locking coil 4 itself expands in diameter, and as in the first embodiment,
Although the locked state with respect to the rotary shaft body 2 is automatically released, the arm portion 42b may vibrate in the opposite direction together with the weight portion 42a before the webbing 23 is completely wound up. , A means to prevent the return shall be attached.

Specifically, as shown in FIG. 14A, the weight portion 42a is placed at a predetermined position on the vibration locus of the weight portion 42a in a state where the operation on the webbing take-up shaft 22 side is not hindered. 42
By disposing the magnet 44 for magnetically attaching a through the bracket 43 and magnetically attaching the weight portion 42a to the magnet 44 when the weight portion 42a vibrates integrally with the arm portion 42b, An elastic claw that prevents the weight portion 42a from returning, or forms a receiving portion 45 on the back surface side of the weight portion 42a and locks the receiving portion 45 on the bracket 43 side, as shown in B of FIG. 46, and when the weight portion 42a vibrates integrally with the arm portion 42b, the elastic claw 46
It is conceivable that the return of the weight portion 42a is prevented by locking the tip end of the weight portion to the receiving portion 45 of the weight portion 42a, but the present invention is not limited to this.

However, in the former case, as shown in FIG. 15, when the weight 42a passes through the balance point θA from the hanging point 0, the arm 42 by the magnet 44 is passed.
The torque (Tmag) for rotating b is set so as to rapidly increase with respect to the rotation torque (Tspr) of the arm portion 42b necessary for expanding the diameter of the locking coil 4,
For example, even if the rotational torque due to the inertial force is instantly reduced, it is preferable to set the weight portion 42a to be surely magnetically attached to the magnet 44 and effectively prevent the return. In the figure, θO indicates the point where the weight portion 42a is magnetically attached to the magnet 44.

Therefore, even under an automobile equipped with the pretensioner device having such a structure, the clutch mechanism 10 normally keeps the connection between the small-diameter rotary shaft 2 and the webbing take-up shaft 22. Since it has been cut off, the webbing 23 is pulled out of the retractor or the winding shaft 22 thereof.
It can be guaranteed to be used properly.

Then, once a collision accident occurs,
When the vehicle is in an abnormal deceleration state, the pendulum type inertial response sensor 42 vibrates in a predetermined direction and the weight portion 42a is magnetically attached to the magnet 44 as shown in A of FIG. As shown in B, the receiving portion 4 of the weight portion 42a
Since the return of the weight portion 42a is prevented by locking the tip end of the elastic claw 46 to 5 while the locking coil 4 itself is expanded on the metal collar 40, this allows the locking coil 4 to move. The locked state with respect to the rotary shaft body 2 is immediately released, and the rotary shaft body 2 is suddenly and forcibly rotated in the winding direction of the webbing 23 by the accumulated spring pressure of the power spring 31 which is a power spring.

Then, although not specifically shown, the hexagonal tubular end portion 33 is then provided in the same manner as in the first embodiment.
The pin member 12 housed in the holding groove 11 of the cylindrical projection 35 existing inside the boss protrudes outward due to centrifugal force, and is inserted into the locking groove 25 formed in the rotary sleeve 41 on the webbing winding shaft 22 side. Since the locking force is transmitted to the webbing winding shaft 22 of the retractor, the rotational force of the rotating shaft body 2 is transmitted to the loosening webbing 23.
Will be immediately rolled up.

When the apparatus is to be reset, the weight 42a is removed from the magnet 44 or the elastic claw 46, and the main spring 31 may be wound up by using the operation recess 39 of the shaft lid 37. Compared with the first embodiment, the resetting work becomes very easy. Further, in the second embodiment, the pendulum type inertial response sensor 42 is adopted, so that it is possible to reduce the number of parts by omitting the pressing spring 7 and the like required under the first embodiment. Needless to say, since the pressing force can be directly applied to the movable end portion 4b of the locking coil 4, it is possible to obtain further quickness and reliability as compared with the pop-out type.

Finally, the pretensioner device according to the third embodiment will be described. In the third embodiment, the pretensioner device partially follows the above-described first and second embodiments as they are. However, the description of the specific premise structure will be omitted, and only the characteristic part will be described.

The locking coil 4 is expanded indirectly or directly by using the pop-out inertial response sensor 9 in the first embodiment or the pendulum inertial response sensor 42 in the second embodiment. In case of diameter
In any case, the diameter of the locking coil 4 is gradually increased from the movable end portion 4b side to the fixed end portion 4a side. In this case, the first winding connected to the movable end portion 4b is greatly expanded. While expanding the diameter, gradually expand the expanding force to
Since it has to be transmitted to the winding ...
In releasing the locked state of the rotary shaft body 2, there is a dislike for lack of quickness in its operation, and since a considerable pressing load is required to greatly expand the diameter of the first winding,
The inertial response sensor side will also increase in size accordingly.
Therefore, in the third embodiment, the cylindrical body 47 shown in FIG. 16 is provided on the outer circumference of the locking coil 4 to improve the above problems.

More specifically, the cylindrical body 47 is an integrally molded product of synthetic resin, the inner diameter of which is set to be slightly larger than the outer diameter of the locking coil 4, and the movable end portion 4b of the locking coil 4 is fitted therein. It has a deep groove 48 with 49 and a shallow notch 50 for avoiding interference with the fixed end 4 a of the locking coil 4. And this cylindrical body 47 is
As shown in FIG. 17, a pair of guide members 51 provided inside the case 1 rotatably support the locking coil 4 concentrically.

Under such a state, when a pressing force F is applied to the cover 49 of the cylindrical body 47 from the pressing spring 7 or the inertial response sensor 42 used together with the inertial response sensor 9, the cylindrical body 47 causes the guide members 51 to move. While rotating in the same direction while sliding on the circular arc-shaped guide surface 51a, the movable end portion 4b of the locking coil 4 is also rotated in the same direction by the same distance and expanded in diameter. Since only a small gap is defined between the coils 4, the first winding of the locking coil 4 immediately comes into pressure contact with the inner peripheral surface of the cylindrical body 47, and further expansion is restricted. Then
This diameter expansion phenomenon of the first winding is sequentially transmitted to the fixed end 4a side through the following second and third windings, and the diameter expansion of the entire circumference of the locking coil 4 is promptly promoted. The locked state of the body 2 can be released more quickly.

Moreover, for example, when the locking coil 4 is pressed against the inner peripheral surface of the cylindrical body 47 under linear pressure, the cylindrical body 47 itself rotates together with the movable end portion 4b of the locking coil 4, The cylindrical body 47 itself is the guide member 51.
Since it is allowed to slide on the arc-shaped guide surface 51a in a state where the surface pressure is applied, the friction between the two 47 and 51 can be reduced, and the pressing load on the movable end 4b side of the locking coil 4 can be reduced. Therefore, even if the pressing load applied from the inertial response sensor side is strengthened and the first winding of the locking coil 4 is not greatly expanded in diameter, the first winding of the locking coil 4 is expanded slightly in diameter with a small pressing load. This has the advantage that the diameter expansion of the entire circumference can be completed.

[0044]

As described above, according to the present invention, the power spring as the drive source and the rocking coil thereof are wound around the rotary shaft side without using the compression coil spring requiring the expansion and contraction stroke as the drive source. Since it is only applied on the rotary shaft body, it is possible to greatly reduce the number of parts and greatly contribute to downsizing of the pretensioner device itself. In addition, the fact that the number of parts can be reduced makes it possible not only to secure the reliability of the operation but also to contribute to the simplification of the assembly work and the cost reduction of the apparatus.

In addition to this, in particular under claim 2,
The diameter of the rotary shaft can be reduced and the operating speed can be expected to be improved. Under claim 3, it can be expected that the inner end edge of the main spring is firmly fixed and held to the rotary shaft, and under claim 4. After assembling the pretensioner device, it can be expected that the mainspring spring can be easily rolled up to accumulate the required spring pressure. Under the claim 5, even if the clutch mechanism side is damaged due to high speed rotation, There is no need for the member to break through the tubular end portion where the metal collar is fitted and to jump out to the outside.

Further, according to the sixth aspect, needless to say, since the releasing means can be simplified, the cost can be reduced, but since the movable end of the locking coil can be directly expanded in diameter, its reliability is improved. Further, according to claim 7, it can be ensured that the locking coil itself is in a state where the diameter of the locking coil is surely expanded, and under claim 8, further speeding up of the diameter expansion of the entire circumference of the locking coil and locking can be achieved. A reduction in the pressing load on the movable end of the coil can be expected.

[Brief description of drawings]

FIG. 1 is a sectional view showing a pretensioner device according to a first embodiment of the present invention together with a seat belt retractor.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG. 3;

5 is a cross-sectional view taken along the line DD of FIG.

FIG. 6 is a cross-sectional view showing a state where the inertial response sensor has popped out.

FIG. 7 is a cross-sectional view showing a state in which the locking coil has an expanded diameter.

FIG. 8 is a cross-sectional view showing a state where a rotary shaft body and a webbing take-up shaft are connected.

FIG. 9 is a cross-sectional view showing a pretensioner device according to a second embodiment together with a seat belt retractor.

10 is a sectional view taken along line EE of FIG. 9.

11 is a sectional view taken along line FF of FIG. 9.

12 is a cross-sectional view taken along line GG of FIG.

FIG. 13 is an exploded perspective view showing a rotary shaft body and related components used under the second embodiment.

FIG. 14 (A) is an explanatory view of a main part showing a state in which the weight portion is magnetically attached to the magnet to prevent its return, and FIG. 14 (B) shows that the elastic claw is locked to the receiving portion of the weight portion. It is an important part explanatory view showing the state where return was blocked.

FIG. 15 is a diagram showing a relationship between a torque for rotating the arm portion by magnetic force and a rotation torque for the arm portion necessary for expanding the diameter of the locking coil.

FIG. 16 is a perspective view showing a cylindrical body used under the pretensioner device according to the third embodiment.

FIG. 17 is a cross-sectional view of essential parts showing a state where a cylindrical body is provided on the outer periphery of the locking coil.

FIG. 18 is a cross-sectional view of essential parts showing a state where the diameter expansion of the locking coil is restricted.

[Explanation of symbols]

 1 Pretensioner case 2 Rotating shaft body 2A Large diameter part of rotating shaft body 2B Small diameter part of rotating shaft body 3 Torsional coil spring (power spring) 4 Locking coil 4a Locking coil fixed end 4b Rocking coil movable end 6 Stopper member 7 Pressing spring 9 Pop-out type inertial response sensor 10 Clutch mechanism 11 Holding groove 12 Pin member 21 Retractor 22 Webbing take-up shaft 23 Webbing 24 Flange portion 25 Locking groove 31 Spring spring (power spring) 31a Of spring spring End edge 31b Outer edge of spring spring 32 Fitting groove 33 Hexagonal tubular end portion 34 Tsuba 35 Cylindrical protrusion 36 Cross-shaped protrusion 37 Shaft lid 38 Cross-shaped receiving recess 39 Operation recess 40 Metal collar 41 Rotating sleeve 42 Pendulum type Inertial response sensor 42a Weight section 42b Arm part 42c Connecting part 43 Bracket 44 Magnet 45 Receiving part 46 Elastic claw 47 Cylindrical body 48 Deep groove 49 Cover 50 Notch part 51 Guide member 51a Arc guide surface

Claims (8)

[Claims] 1. A rotary shaft member that faces a webbing take-up shaft of a retractor, a clutch mechanism that connects the rotary shaft member to the webbing take-up shaft so that the rotary shaft member can be connected to and disconnected from the rotary shaft member, and the rotary shaft member is wound around one end portion side. The power spring forcibly rotating the rotary shaft in the webbing winding direction, the locking coil wound around the other end of the rotary shaft to lock the rotary shaft, and the rotation of the locking coil. It is provided with a releasing means utilizing inertial response operation for releasing the locked state to the shaft body, and only when an inertial force is applied, the locking state of the locking coil to the rotating shaft body is released by the releasing means to rotate the rotating shaft body. A pretensioner device characterized in that the force is transmitted to the webbing take-up shaft via the clutch mechanism. 2. A power spring is used as a power spring, and the main spring is wound around a small-diameter rotary shaft body, while the small-diameter rotary shaft body has a cylindrical end portion whose diameter is expanded toward the clutch mechanism side. The pretensioner device according to claim 1, wherein a metal collar is externally fitted to the cylindrical end portion, and the metal collar surface serves as a braking surface of the locking coil. 3. The rotary shaft body is formed with a fitting groove for fixing an inner end edge of the mainspring spring in a length direction thereof, and a protruding portion is formed at an end opposite to the expanded diameter cylindrical end. While the fitting groove is continuously opened in the protrusion, a receiving recess for fitting and tightening the protrusion is formed on the inner side surface of the shaft lid attached to the end where the protrusion is formed. The pretensioner device according to claim 2. 4. The pretensioner device according to claim 3, wherein an operation recess opposite to the receiving recess is formed on the outer surface of the shaft cover. 5. The expanded cylindrical end portion of the rotating shaft body is provided with a columnar projection having a holding groove for accommodating a pin member therein so that the pin member can be retracted and retracted, and the webbing take-up shaft side is provided on the outer periphery of the columnar projection. The pretensioner device according to any one of claims 2 to 4, wherein a rotary sleeve that is fixed and has a locking groove formed on its inner peripheral surface is fitted. 6. The unlocking means for unlocking the locking state of the locking coil with respect to the rotating shaft body is a weight portion for inertial response, and an arm portion connected to the movable end portion of the locking coil and vibrating integrally with the weight portion. The pretensioner device according to any one of claims 1 to 5, which comprises: 7. The weight unit has a blocking means for blocking the return of the weight unit when the weight unit vibrates integrally with the arm unit in a direction to expand the diameter of the locking coil by inertial force. The described pretensioner device. 8. The pretensioner device according to any one of claims 1 to 7, wherein a cylindrical body for restricting a diameter expansion amount of the locking coil is provided on an outer circumference of the locking coil.