JP3547546B2 - Seat belt retractor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seat belt retractor in which a pawl or a lock piece is engaged with a ratchet wheel fixed to one end of a webbing take-up shaft to lock a webbing withdrawal, and in particular, a pawl or lock piece and a ratchet wheel. The present invention relates to a seat belt retractor capable of securely engaging a pawl or a lock piece with a ratchet wheel to prevent rotation of the ratchet wheel even when a large load is applied when the ratchet wheel is engaged.
[0002]
[Prior art]
As a seat belt retractor, for example, a retractor described in Japanese Utility Model Laid-Open No. 61-134461 is known.
This is a frame having a U-shaped cross section, a webbing take-up shaft rotatably supported on both side plates of the frame, and a pair of ratchet wheels fixed to both ends of the take-up shaft inside the both side plates. And a pawl having a pair of pawls that are swingably supported on the both side plates and engage with the respective ratchet wheels, and the pair of pawls of the pawl engage with the pair of ratchet wheels to form the ratchet wheel. This prevents rotation and locks the webbing drawer.
[0003]
By the way, in recent years, a ratchet wheel has been fixed to only one end of the winding shaft, the other end is inserted from the outside of the side plate of the U-shaped frame, and the winding shaft is attached to the frame. A seat belt retractor with a suitable structure is employed.
In this structure, the load on the ratchet wheel applied to the pawl cannot be absorbed by both side plates of the frame, as shown in Japanese Utility Model Application Laid-Open No. 61-134461. All must be absorbed by the side plates. Therefore, in particular, the pawl portion of the pawl may be damaged or deformed.
[0004]
In addition, a device described in Japanese Utility Model Laid-Open No. 59-79153 has been proposed.
This includes a webbing take-up shaft rotatably supported on both side plates of a U-shaped frame, a ratchet wheel fixed to the end of the take-up shaft outside one side plate, and the one side plate. A lock plate attached to the pin supported on the outside of the side plate, and a tie plate attached to the take-up shaft and the pin outside the ratchet wheel and the lock piece to connect the take-up shaft and the pin. is there.
The lock piece and the ratchet wheel are engaged to prevent rotation of the winding shaft, and the tie plate bridged between the winding shaft and the pin does not deform the pin due to a load applied to the lock piece. Has been reinforced.
[0005]
[Problems to be solved by the invention]
According to Japanese Utility Model Laid-Open Publication No. 59-79153, the tie plate connected to the take-up shaft is bridged to the outer end of the pin to which the lock piece is attached, which increases the cost. Has the disadvantage that the size of the device becomes excessive and the device itself becomes large.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a seat belt retractor which prevents deformation of a pawl engaged with a ratchet wheel, simplifies the structure, reduces the cost and does not increase the size of the device itself. It is intended for. The invention according to claim 2 provides a seat belt retractor that has a simple structure, prevents deformation of the pin when the lock piece and the ratchet wheel are engaged, and is low in cost and does not increase the size of the device itself. It is intended.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 of the present invention comprises a frame having a pair of side plates, a rotatably supported by both side plates of the frame, and a rotation in a direction in which the webbing is wound. A pawl including a biased take-up shaft, a ratchet wheel fixed to one end of the take-up shaft, and a pawl having a flat plate shape and both end portions rotatably supported by both side plates and engaging with the ratchet wheel in an emergency. The side plate protrudes to the side of the engagement surface between the ratchet wheel and the pawl portion of the pawl, and forms an overhanging portion that comes into contact with the back surface of the pawl pawl portion when the ratchet wheel and the pawl pawl portion engage. It is characterized by doing.
According to a second aspect of the present invention, there is provided a frame having a pair of side plates, a winding shaft rotatably supported on both side plates of the frame and rotationally biased in a direction of winding the webbing, and a winding shaft. A ratchet wheel fixed to one end of the frame, and a lock piece rotatably mounted on a pin fixed to the frame and rotatably engaged with the ratchet wheel, and the side plate has an engagement surface side between the ratchet wheel and the lock piece. And a projection that comes into contact with the lock piece when the ratchet wheel and the lock piece engage with each other.
[0008]
Here, the overhang portion is formed so as to protrude from the side plate to the side of the engagement surface between the ratchet wheel and the pawl portion or the lock piece of the pawl (in other words, to approximately the same plane as the ratchet wheel).
For example, the overhanging portion may be formed by bending the side plate outward, or may be formed by bending the side plate outward so that the tip end faces the ratchet wheel. Alternatively, the side plate may be formed by bending outwardly to a ratchet wheel outer surface into a U-shaped cross section.
When the pawl claw or lock piece engages with the ratchet wheel in an emergency, the overhang absorbs the load of the ratchet wheel applied to the pawl claw or lock piece in substantially the same plane as the ratchet wheel. To prevent the pawl claw or the lock piece from being damaged or deformed.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially cutaway front view of a retractor according to the present invention, FIG. 2 is a sectional side view of a main part of the retractor, FIG. 3 is an exploded perspective view of the retractor, FIG. 4 is a front view of a frame, and FIGS. And FIG. 7 is a cross-sectional view of a main part showing a supporting relationship between a frame side plate and a lock piece.
[0010]
Reference numeral 11 denotes a frame having a U-shaped cross section. The frame 11 is formed by bending and extending side plates 13 and 14 from both side edges of a back plate 12 for fixing so as to face each other.
Reference numeral 15 denotes a protector that is fitted to the upper end of the back plate 12 to cover the upper end of the back plate 12 and prevent the webbing 16 from being damaged.
Reference numeral 17 denotes a lock pin for fixing an end of the webbing 16 to a winding shaft 21 described later.
[0011]
Support holes 18 and 19 are formed at lower ends of both side plates 13 and 14 to rotatably support a pawl 38 described later.
The side plate 14 in the vicinity of the support hole 19 protrudes to the side of the engagement surface between the ratchet wheel 23 and the pawl portion 39 of the pawl 38 (in other words, to approximately the same plane as the ratchet wheel 23). At the time of engagement, an overhanging portion 20 is formed which comes into contact with the back surface of the claw portion 39 of the pawl 38.
[0012]
The projecting portion 20 absorbs the load of the ratchet wheel 23 applied to the pawl portion 39 of the pawl 38 in substantially the same plane as the ratchet wheel 23 when the pawl portion 39 of the pawl 38 is engaged with the ratchet wheel 23 in an emergency, The pawl 39 of the pawl 38 is prevented from being damaged or deformed.
As shown in FIGS. 4 and 5, the overhang may be formed as an overhang 20a formed by bending the side plate 14 near the support hole 19 outward.
Further, as shown in FIG. 6, the side plate 14 near the support hole 19 may be formed by bending outward, and the projecting portion 20 b may be configured so that the tip end faces the ratchet wheel 23.
[0013]
A winding shaft 21 for winding the webbing 16 is rotatably supported at the center of both side plates 13 and 14 of the frame 11.
Outside the side plate 13, a mainspring spring unit 22 connected to one end of the winding shaft 21 for urging the winding shaft 21 to rotate in the webbing winding direction is provided.
A ratchet wheel 23 is fixed to the base end of the take-up shaft 21 protruding outside the side plate 14. The ratchet wheel 23 rotates integrally with the winding shaft 21.
[0014]
At an end of the winding shaft 21 outside the ratchet wheel 23, a plate 28 described later is pivotally supported. Further, between the plate 28 and the ratchet wheel 23, a lock plate 24 that can rotate coaxially with the winding shaft 21 is supported by a cylindrical portion 29 that extends from the plate 28. The lock plate 24 is provided on its inner peripheral surface with the same number of internal teeth 25 as the number of teeth of the ratchet wheel 23.
A guide piece 26 is formed on a part of the outer peripheral edge of the lock plate 24 so as to extend in parallel with the side plate 14. The guide piece 26 is provided with a guide hole 27. The guide hole 27 is configured to be curved in a direction away from the winding shaft 21.
[0015]
The plate 28 is a rotation shaft of the lock plate 24 and rotates integrally with the winding shaft 21. On the plate 28, pins 30 are erected.
Reference numeral 32 denotes a lock arm which is swingably supported between the projections 31 provided on the plate 28 by the pins 30. The lock arm 32 is urged by a coil spring 35 interposed between the plate 28 and the lock arm 32 so that the claw 33 of the lock arm 32 does not engage with the internal teeth 25.
[0016]
A metal inertia member 36 is rotatably mounted coaxially with the winding shaft 21 outside the plate 28.
The inertia member 36 has a hole 37 into which the tip of the pin 34 of the lock arm 32 is fitted. When the rotation of the inertia member 36 is delayed from the rotation of the plate 28, the inertia member 36 acts to engage the claw 33 of the lock arm 32 with the internal teeth 25.
[0017]
The pawl 38 has a flat plate shape, and both ends of the pawl 38 are rotatably supported by support holes 18 and 19 provided in both side plates 13 and 14 of the frame 11.
A pawl portion 39 that engages with the ratchet wheel 23 in an emergency is formed at the distal end of the pawl 38 protruding outside the side plate 14.
Reference numeral 40 denotes a pawl lever fitted on the tip of the pawl 38 outside the claw portion 39.
[0018]
Reference numeral 41 denotes a support pin erected at the tip of the pawl lever 40, which is inserted into the guide hole 27 provided in the lock plate 24. The support pin 41 slides in the guide hole 27 by the rotation of the lock plate 24, and acts so that the pawl portion 39 of the pawl 38 engages with the ratchet wheel 23.
A spring 42 is interposed between the base end of the pawl lever 40 and the lock plate 24, and the pawl 38 is urged by the spring 42 in a direction that does not engage the ratchet wheel 23.
[0019]
A rivet 43 is inserted into the winding shaft 21, the plate 28, the inertia member 36 and the like.
Reference numeral 44 denotes a cover attached to the side plate 14, and various members such as the ratchet wheel 23 located outside the side plate 14 are covered with the cover 44.
[0020]
Next, an engagement mechanism between the pawl portion 39 of the pawl 38 and the ratchet wheel 23 will be described.
When an abnormal impact such as an automobile collision is received, a sharp pulling force is generated in the webbing 16 restraining the occupant, and the winding shaft 21 rotates in the pulling-out direction (counterclockwise in FIG. 2).
The inertia member 36 also rotates in the pulling-out direction along with the rotation of the winding shaft 21, but a rotation speed difference is generated between the inertia member 36 and the winding shaft 21, and the inertia member 36 relatively rotates with respect to the winding shaft 21. The relationship is such that it rotates clockwise in FIG. The rotation of the inertia member 36 in the relative winding direction causes the pin 34 of the lock arm 32 connected by the hole 37 of the inertia member 36 to rotate the lock arm 32, and the lock arm 32 resists the coil spring 35. As a result, the pawl 33 is engaged with the internal teeth 25 of the lock plate 24 in the same direction as the inertia member 36.
[0021]
Next, since the lock plate 24 is connected to the winding shaft 21 via the lock arm 32 (plate 28), the rotation of the winding shaft 21 is transmitted to the lock plate 24, and the lock plate 24 is It rotates in the pull-out direction (counterclockwise in FIG. 2) in opposition.
When the lock plate 24 rotates, the support pin 41 slides in the guide hole 27, the pawl 38 rotates (clockwise in FIG. 2), and the claw portion 39 engages with the ratchet wheel 23.
Thus, the rotation of the winding shaft 21 in the webbing withdrawing direction is prevented.
[0022]
When the pawl portion 39 of the pawl 38 is engaged with the ratchet wheel 23, the load of the ratchet wheel 23 is applied to the pawl portion 39 of the pawl 38.
The ratchet wheel 23 projects to the side of the engaging surface between the pawl portion 39 of the pawl 38 and contacts the rear surface of the pawl portion 39 of the pawl 38 when the ratchet wheel 23 and the pawl portion 39 of the pawl 38 engage. In addition, since the pawl portion 39 of the pawl 38 abuts on the overhang formed on the side plate 14, the load is absorbed by the overhang, so that the pawl 39 of the pawl 38 is not damaged or deformed.
Therefore, the pawl portion 39 of the pawl 38 is engaged with the ratchet wheel 23 without being damaged or deformed, so that the rotation of the winding shaft 21 in the webbing withdrawing direction can be reliably prevented in an emergency.
[0023]
In the above embodiment, the use of the pawl has been described, but a lock piece may be used instead of the pawl.
For example, the one shown in FIG. 7 has a locking piece 46 rotatably attached to a pin 45 fixed to the side plate 14 of the frame 11. The lock piece 46 is configured to be located outside the side plate 14.
Then, the side plate 14 in the vicinity of the pin 45 is bent outward in a U-shaped cross section to the outside surface of the ratchet wheel 23 to form the overhang portion 20c.
In this embodiment, when the lock piece 46 and the ratchet wheel 23 are engaged with each other, the load of the ratchet wheel 23 applied to the lock piece 46 comes into contact with the protrusion 20 c formed on the side plate 14 because the lock piece 46 abuts. The pin 45 is not deformed due to the absorption by the overhang portion 20c.
Therefore, also in this embodiment, the lock piece 46 is securely engaged with the ratchet wheel 23, and the rotation of the winding shaft 21 can be reliably prevented in an emergency.
[0024]
In the above-described embodiment, a device in which the vehicle body detection mechanism is omitted has been described. However, the present invention is not limited to this, and the vehicle body detection mechanism is attached to the side plate 14, and the acceleration applied to the vehicle body by the vehicle body detection mechanism Alternatively, it is needless to say that a configuration for detecting an action such as an abnormal inclination of the vehicle body may be employed.
[0025]
【The invention's effect】
As described above, according to the first aspect of the present invention, the projecting portion that abuts on the back surface of the pawl claw portion when the ratchet wheel and the pawl claw portion engage with each other is formed on the side plate of the frame. The structure of the pawl is simple, and the apparatus itself does not become large at low cost.
According to the second aspect of the present invention, it is only necessary to form an overhang on the side plate of the frame, and there is no need to provide a reinforcing member such as a tie plate. The size can be reduced and the cost can be reduced.
Further, since the projecting portion is merely formed on the side plate of the frame, a reinforcing effect can be obtained regardless of the shape of the lock piece.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view of a retractor according to the present invention.
FIG. 2 is a side sectional view of a main part of the retractor.
FIG. 3 is an exploded perspective view of the retractor.
FIG. 4 is a front view of the frame.
FIG. 5 is a sectional view of a main part showing a supporting relationship between a frame side plate and a pawl portion of a pawl.
FIG. 6 is a cross-sectional view of a main part of another embodiment showing a support relationship between a frame side plate and a pawl portion of a pawl.
FIG. 7 is a sectional view of a main part showing a support relationship between a frame side plate and a lock piece.
[Explanation of symbols]
11 Frame 13, 14 Side plate 16 Webbing 20a, 20b, 20c Overhang 21 Take-up shaft 23 Ratchet wheel 38 Paul 39 Paul pawl 45 Pin 46 Lock piece

Claims (2)

A frame having a pair of side plates, a winding shaft rotatably supported on both side plates of the frame and urged to rotate in a direction of winding the webbing, and a ratchet wheel fixed to one end of the winding shaft. A pawl having a flat plate shape and both ends rotatably supported by the both side plates and having a pawl portion which engages with the ratchet wheel in an emergency. A seat belt retractor characterized in that an overhanging portion is formed which comes into contact with the back surface of the pawl pawl when the ratchet wheel engages with the pawl pawl. A frame having a pair of side plates, a winding shaft rotatably supported on both side plates of the frame and urged to rotate in a direction of winding the webbing, and a ratchet wheel fixed to one end of the winding shaft. A lock piece rotatably attached to a pin fixed to the frame and engaging with the ratchet wheel in an emergency, protruding from the side plate to an engagement surface side between the ratchet wheel and the lock piece, and a ratchet wheel and the lock piece. A retractor for a seat belt, wherein an overhanging portion is formed which comes into contact with the lock piece when engaged with the seat belt.

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