JP5252148B2 - Pre-tensioner mechanism for seat belt - Google Patents

Description

  The present invention relates to a rack and pinion type pretensioner mechanism mounted on a seat belt retractor.

  Generally, a seat belt retractor is provided with a pretensioner mechanism that removes looseness of a seat belt in the event of a vehicle emergency due to a collision or the like.

  FIG. 4 shows a schematic configuration of a seat belt retractor including a rack and pinion type pretensioner mechanism described in Patent Document 1.

  The seat belt retractor includes a frame 100 that is fixed to a vehicle. A spindle 102 is rotatably supported on the frame 100, and a seat belt 105 is wound around the spindle 102. The seat belt retractor includes a rack and pinion type pretensioner mechanism 110.

  The pretensioner mechanism 110 includes a pinion 112 coupled so as to rotate integrally with the spindle 102, a cylinder 118 disposed in the vicinity of the pinion 112 by being fixed to the frame 100, and a movably accommodated in the cylinder 118. At the same time, from the front end side to the base end side, a rod portion 122 having a rack gear 124 that can be engaged with the pinion 112 is formed on one side surface, and the base end side is slidably fitted to the inner wall of the cylinder 118. The piston member 126 is introduced into the rack member 120 having a disc-shaped piston portion 126 and the cylinder chamber 132 defined under the piston portion 126 in the cylinder 118 in the event of a vehicle emergency. Is moved in the direction of arrow A by the gas pressure, the rack gear 124 and the pinion 112 are meshed, The spindle 102 and a gas pressure generating means for rotating the direction of the arrow B of winding the seat belt 105 (reference numeral 140 shown in FIG. 1).

  Further, an O-ring 128 that seals a gap between the piston portion 126 and the inner wall of the cylinder 118 is attached to the lower side of the piston portion 126. Further, the piston portion 126 has a small diameter that allows the gas pressure in the cylinder chamber 132 to escape. The gas vent hole 130 is provided. The vent hole 130 is for smoothly operating a force limiter mechanism (not shown) that restricts the load on the occupant by the seat belt to a certain amount or less in an emergency of the vehicle.

  The force limiter mechanism includes, for example, an energy absorbing member, and allows the spindle 102 to rotate in the seat belt withdrawing direction when the energy absorbing member is deformed by a passenger's load on the seat belt in an emergency of the vehicle. is there. By operating the force limiter mechanism after the pretensioner mechanism 110, the load on the occupant by the seat belt 105 in the event of an emergency of the vehicle can be limited to a certain amount or less.

By the way, when the force limiter mechanism is activated and the spindle 102 is about to rotate in the seat belt withdrawing direction (the arrow D direction in the figure), the pinion 112 and the rack member 120 are engaged with each other. A force in the downward direction (the direction of arrow C in the figure) acts. However, if the gas pressure at the time of generating the pretensioner function remains in the cylinder chamber 132, it becomes a resistance, and the spindle 102 is smoothly rotated in the seat belt withdrawing direction (arrow D direction). Disappear. For this reason, this problem is solved by providing the gas vent hole 130 to release the gas pressure to the outside.
Japanese Patent Laid-Open No. 2002-67878

  Incidentally, since the slider 134 for temporarily closing is attached to the gas vent hole 130 as shown in FIG. 4, the gas vent hole 130 has to be processed from two directions, the axial direction and the radial direction.

  Further, as shown in FIG. 5, the other rack member 120 may be provided so as to penetrate the piston portion 126 in the axial direction at a position where the gas vent hole 150 avoids the rod portion 122 from the viewpoint of workability. Conceivable.

  However, in this case, since the gas vent hole 150 is disposed at a position avoiding the rod portion 122 so as to penetrate the piston portion 126, the gas vent hole 150 is located in the vicinity of the peripheral edge of the disk-shaped piston portion 126. However, since there is an O-ring attachment portion at the peripheral portion of the piston portion 126, there is a limit to approaching the edge. For this reason, in order to escape the gas vent hole 150 from the thick rod portion 122 in order to form a rack having a strength sufficient to withstand a heavy load due to gas pressure, the rod portion 122 is moved to one side, A large unbalanced load is generated in the rod portion 122 that receives the pushing force from the piston portion 126, and the rod portion 122 is easily bent.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to place the gas vent hole as close as possible to the center side of the rack member in a state where the rod portion is arranged at an appropriate position of the rack member. It is possible to provide a pretensioner mechanism capable of improving workability.

The above-mentioned subject concerning the present invention is attained by the following composition.
(1) a pinion that rotates integrally with a spindle that winds up the seat belt;
A cylinder disposed in the vicinity of the pinion;
A rod portion in which a rack gear that is movably accommodated in the cylinder and that can mesh with the pinion is formed on one side surface from the distal end side toward the proximal end side, and the inner wall of the cylinder on the proximal end side A rack member having a disc-like piston portion slidably fitted to
By introducing gas pressure into the cylinder (for example, the cylinder chamber in the present embodiment), the piston portion is moved by the gas pressure, the rack gear and the pinion are engaged, and the spindle winds up the seat belt. Gas pressure generating means for rotating in the direction;
With a pretensioner mechanism for seatbelts comprising
On the other side surface different from the side surface of the rod portion where the rack gear is formed, a groove portion extending to the piston portion is formed,
In the piston portion of the rack member, a gas vent hole for venting the gas pressure in the cylinder (for example, the cylinder chamber in the present embodiment) penetrates in the thickness direction of the piston portion and opens into the groove portion. A pretensioner mechanism for a seat belt, which is formed as described above.

  According to the seat belt pretensioner mechanism of the present invention, since the groove portion extending to the piston portion is formed on the other side surface different from the side surface of the rod portion on which the rack gear is formed, the gas penetrating in the thickness direction of the piston portion is formed. A punch hole can be formed to open into the groove. Thereby, in the state which has arrange | positioned the rod part in the suitable position of a rack member, a gas vent hole can be arrange | positioned as close as possible to the center side of a rack member. Accordingly, the rack member can be moved straight by the force acting on the piston portion, the rod portion is not bent, and the sliding resistance of the piston portion is not increased by the uneven load, and a simple piercing process or the like can be performed. Drilling can be employed, and workability can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a seat belt pretensioner mechanism of the invention will be described in detail with reference to the drawings. Since the present invention relates to the rack member of the pretensioner mechanism, the other components of the pretensioner mechanism are denoted by the same or equivalent reference numerals as those shown in FIG. To do.

  FIG. 1 is a side view showing a pretensioner mechanism of the present embodiment, FIG. 2 is a view showing a configuration of a rack member, (a) is a side view, and (b) is a view taken along the arrow Ib in (a). (C) is an Ic arrow directional view of (a), and FIG. 3 is a perspective view which shows the state of the processed product after the forge process before processing a rack gear.

  The rack member 10 is movably accommodated in a cylinder 118 and has a rod portion 12 formed with a rack gear 14 that can mesh with a pinion 112 on one side surface from the distal end side toward the proximal end side, and a proximal end On the side, a disc-shaped piston portion 26 slidably fitted to the inner wall of the cylinder 118 is provided. The diameter of the piston portion 26 is smaller than the maximum cross-sectional dimension of the rod portion 12, and the lower half portion 17 of the piston portion 16 is formed to have a small diameter so that the O-ring 128 can be fitted.

  In addition, a V-groove portion 18 extending from the distal end side to the proximal-side piston portion 16 is formed on a side surface different from the side surface of the rod portion 12 where the rack gear 14 is formed. It is formed in a substantially U shape. Further, the piston portion 16 of the rack member 10 is formed with a gas vent hole 30 for releasing the gas pressure in the cylinder chamber 132 so as to penetrate in the thickness direction of the piston portion 16 and open into the V groove portion 18. ing.

  When manufacturing the rack member 10 configured as described above, as shown in FIG. 3, first, an outer shape having the rod portion 12, the V groove portion 18, and the piston portion 16 is manufactured by pressure forging. In addition, the gas vent hole 30 is formed by piercing, and the rack gear 14 is cut into a predetermined range S on the distal end side of the rod portion 12.

As described above, when the rod portion 12 having the V groove portion 18 on one side surface is formed in a substantially U-shaped cross section, and the piston portion 16 is penetrated so as to open in the V groove portion 18, the gas vent hole 30 is formed. The position of the gas vent hole 30 can be arranged from the vicinity of the outer periphery of the piston portion 16 to the vicinity of the center. Further, the rod portion 12 can be arranged at a position near the center of the piston portion 16 while avoiding the gas vent hole 30. Accordingly, the rack member 10 can be moved straight due to the force acting on the piston portion 16, and the rod portion 12 is not bent, and the sliding resistance of the piston portion 16 with respect to the cylinder 118 is not increased by the uneven load. Simple drilling such as piercing can be employed to improve workability.
Moreover, by forming the V-groove portion 18, the weight can be reduced without reducing the bending rigidity of the rack member 10, and the operability of the rack member 10 can be improved.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimensions, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.
For example, the shape of the groove portion of the present invention is not limited to a V shape, and is arbitrary such as a U shape, but is preferably a shape that can be processed by pressure forging.
Further, the position of the groove portion may be another side surface different from the one side surface on which the rack gear is formed, but in the case of a substantially rectangular shape as in the present embodiment, the side surface intersecting with the one side surface from the viewpoint of strength. It is preferable that
Further, the groove portion may be formed in the lower half portion 17 of the piston portion 16, and a plurality of gas vent holes 30 may be formed in the groove portion.

It is a side view of the pretensioner mechanism of the embodiment of the present invention. It is a figure which shows the structure of the rack member employ | adopted for (a), a side view, (b) is an Ib arrow directional view of (a), (c) is an Ic arrow directional view of (a). It is a perspective view which shows the state of the rack member after the forge process before processing the said rack gear. It is a figure which shows schematic structure of the seatbelt retractor provided with the conventional rack and pinion type pretensioner mechanism. It is the bottom view seen from the end surface by the side of a piston part which shows the example in the case of forming the gas vent hole which penetrated the piston part in the rack member employ | adopted for the pretensioner mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rack member 12 Rod part 14 Rack gear 16 Piston part 18 V groove part 30 Gas vent hole 105 Seat belt 102 Spindle 112 Pinion 118 Cylinder

Claims (1)

A pinion that rotates together with the spindle that winds up the seat belt;
A cylinder disposed in the vicinity of the pinion;
A rod portion in which a rack gear that is movably accommodated in the cylinder and that can mesh with the pinion is formed on one side surface from the distal end side toward the proximal end side, and the inner wall of the cylinder on the proximal end side A rack member having a disc-like piston portion slidably fitted to
A gas pressure generating means for introducing a gas pressure into the cylinder to move the piston portion by the gas pressure so as to mesh the rack gear and the pinion and to rotate the spindle in the direction of winding the seat belt;
A pretensioner mechanism for a seat belt comprising:
On the other side surface different from the side surface of the rod portion where the rack gear is formed, a groove portion extending to the piston portion is formed,
In the piston portion of the rack member, a gas vent hole for venting the gas pressure in the cylinder is formed so as to penetrate in the thickness direction of the piston portion and open into the groove portion. Pretensioner mechanism for seat belt.

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