JP2012116437A - Knee bolster for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a knee bolster for vehicles which can reduce mass, while being able to stabilize the load displacement characteristics of an energy absorbing member.SOLUTION: The energy absorbing member 14 which is made of resin and composes the knee bolster for vehicle has an ellipse shape in a cross-sectional shape seen from a metallic bracket 22 side of an instrument panel reinforcement 12 and formed in a cylindrical shape having a bottom and opening at metallic bracket 22 side, and is fixed to the major axis direction both ends side of the ellipse cross section in an opening edge part by the metallic bracket 22. The energy absorbing member 14 disperses stress by dynamically changing the cross-sectional shape, when crushed by the load from the knee P1 of the occupant P by collision etc., of the vehicle. Thereby the load displacement characteristics is stabilized, since the energy absorbing member 14 can be prevented from broken. Also the linear dimension of the metallic bracket 22 can be shortened by lengthening the linear dimension of the energy absorbing member 14.

Description

  The present invention relates to a vehicle knee bolster that restrains an occupant's knee when a vehicle collides.

  In the knee bolster for automobiles shown in Patent Document 1 below, a hard urethane pad (energy absorbing member) supported by an instrument panel reinforcement via a metal bracket is disposed to face an occupant's knee. The This hard urethane pad absorbs the impact energy of the knee by being crushed by a load from the knee of the occupant at the time of a car collision.

JP 2003-31429 A

  However, the rigid urethane pad has a restriction on the length of foaming due to production technology, and is easy to break when crushed (easy to break against a compressive load), so it cannot be formed so long. Therefore, the length of the metal bracket (fixed part) to which the hard urethane pad is fixed cannot be shortened, and there is room for improvement in terms of mass reduction. In addition, since the hard urethane pad is easily cracked with respect to the compressive load as described above, the variation of the load-displacement characteristic may be very large.

  The present invention has been made in consideration of the above facts, and an object of the present invention is to obtain a vehicle knee bolster that can stabilize the load-displacement characteristics of the energy absorbing member and reduce the mass.

  In order to solve the above-described problem, the vehicle knee bolster according to the invention described in claim 1 is disposed in front of a knee portion of an occupant seated on a vehicle seat and is provided on a rigid member on the vehicle body side. A resin-made energy absorbing member whose front end side is fixed to a fixing portion is provided, and the energy absorbing member is formed in a bottomed cylindrical shape having an oval cross-sectional shape viewed from the fixing portion side and having an opening on the fixing portion side. The opening edge portion is fixed to the fixing portion at both ends in the major axis direction of the oval cross section.

  The “oval shape” described in claim 1 includes an oval shape, a rounded oval shape, an oval shape, and the like.

  In the vehicle knee bolster according to the first aspect, the resin-made energy absorbing member is disposed in front of the knee portion of the occupant seated on the vehicle seat. This energy absorbing member has a front end fixed to a fixing portion provided on a rigid member (instrument reinforcement, etc.) on the vehicle body side, and a knee portion of an occupant trying to move inertially forward of the vehicle in the event of a vehicle collision or the like It is crushed by the load from. Thereby, the impact energy of the knee is absorbed.

  Here, the energy absorbing member described above is formed in a bottomed cylindrical shape having an oval cross section viewed from the fixed portion side of the rigid member, and an open cross section at the opening edge. It is being fixed to the fixing | fixed part in the major axis direction both ends.

  For this reason, when the energy absorbing member is crushed, stress concentrates on both ends of the oval cross section in the major axis direction, that is, on both ends having a large curvature in the peripheral wall of the energy absorbing member. As a result, the energy absorbing member is buckled in a bellows shape so that both end sides having a large curvature each form a buckling wave. At this time, in the portion corresponding to the peak of the buckling wave, the energy absorbing member is deformed so that the long diameter of the oval cross section becomes long, and in the portion corresponding to the valley of the buckling wave, the short diameter of the oval cross section. The energy absorbing member is deformed so as to be longer. As described above, since the stress is dispersed by dynamically changing the cross-sectional shape of the energy absorbing member, it is possible to prevent or effectively suppress the energy absorbing member from cracking due to buckling. Thereby, the load-displacement characteristic of an energy absorption member can be stabilized.

  In addition, since the energy absorbing member can be prevented from cracking, the length of the energy absorbing member can be set longer. Thereby, the structure of the said fixing | fixed part can be simplified and the mass of an apparatus can be reduced. That is, for example, when the metal bracket attached to the main body portion (pipe material or the like) of the instrument panel reinforcement is used as the fixed portion, the length of the metal bracket can be shortened. Further, for example, a metal bracket can be omitted by setting a part of the main body of the instrument panel reinforcement as a fixed part and fixing the energy absorbing member directly to the fixed part. This makes it possible to reduce the mass of the device.

  A vehicle knee bolster according to a second aspect of the present invention is the vehicle knee bolster according to the first aspect, wherein the energy absorbing member has a wall thickness at both ends in the major axis direction of the oval cross section in the minor axis direction. It is characterized by being formed thicker than the wall thickness at both ends.

  In the vehicle knee bolster according to claim 2, when the energy absorbing member is crushed, stress is concentrated on both ends in the major axis direction of the oval cross section. Therefore, it is possible to prevent cracks from occurring at both ends in the major axis direction due to excessive stress concentration.

  A vehicle knee bolster according to a third aspect of the present invention is the vehicle knee bolster according to the first or second aspect, wherein the energy absorbing member has an elliptical cross-sectional shape as viewed from the fixed portion side. In addition, the length ratio of the major axis to the minor axis of the elliptical cross section is set to 2: 1.

  In the vehicle knee bolster according to claim 3, the ratio of the length of the major axis (major axis) to the minor axis (minor axis) of the elliptical cross section of the energy absorbing member is set to 2: 1. The mass of the energy absorbing member can be set to a minimum while ensuring the amount of energy absorption required for the energy absorbing member.

  A vehicle knee bolster according to a fourth aspect of the present invention is the vehicle knee bolster according to any one of the first to third aspects, wherein the energy absorbing member has a major axis of the oval cross section. It is characterized by being fixed to the fixed part in a state along the vertical direction.

  In the vehicle knee bolster described in claim 4, the energy absorbing member is disposed in a state where the major axis of the oval cross section is along the vehicle vertical direction. In other words, since the vehicle vertical dimension of the energy absorbing member is set large, the energy absorbing member can be satisfactorily opposed to the knee regardless of variations in the arrangement height of the knee due to the physique difference of the occupant. .

  As described above, in the vehicle knee bolster according to the present invention, the load-displacement characteristic of the energy absorbing member can be stabilized and the mass can be reduced.

1 is a perspective view showing a configuration of a vehicle knee bolster according to a first embodiment of the present invention. It is a disassembled perspective view which shows the partial structure of the vehicle knee bolster which concerns on 1st Embodiment of this invention. It is an expanded sectional view which shows the cut surface along line 3-3 in FIG. It is an expanded sectional view which shows the cut surface along line 4-4 of FIG. (A) is a schematic perspective view for demonstrating the deformation | transformation mode at the time of the energy absorption member which concerns on 1st Embodiment of this invention buckling, (B) is the AA line of (A). It is a schematic sectional drawing for demonstrating the deformation mode of the cross section along A, and (C) is a schematic sectional drawing for demonstrating the deformation mode of the cross section along the BB line of (A). It is. It is a diagram which shows the load-displacement characteristic of an energy absorption member. It is a front view which shows the structure of the energy absorption member which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the partial structure of the knee bolster for vehicles which concerns on 3rd Embodiment of this invention.

<First Embodiment>
Hereinafter, with reference to FIGS. 1-6, the vehicle knee bolster 10 which concerns on 1st Embodiment of this invention is demonstrated. In each figure, the arrow FR indicates the vehicle front direction, the arrow UP indicates the vehicle upward direction, the arrow LH indicates the vehicle left direction, and the arrow RH indicates the vehicle right direction.

  The vehicle knee bolster 10 according to the first embodiment is a device (lower limb restraint device) for restraining both knees of an occupant seated in a driver seat (seat) of a right-hand drive vehicle, which is shown in FIG. As shown, the instrument panel reinforcement 12 and a pair of left and right energy absorbing members 14 are included. The instrument panel reinforcement 12 is disposed inside an instrument panel (not shown) provided at the front of the vehicle interior, and extends in the vehicle width direction to connect the left and right vehicle body panels (in FIG. 1). Only a part of the instrument panel reinforcement 12 is shown).

  The main body 18 of the instrument panel reinforcement 12 is formed of a long metal pipe material. The main body 18 has a thick portion on the driver's seat side that requires strength and a thin portion on the passenger seat side that does not require much strength. A metal column support portion 20 (column bracket) for attaching a steering column is attached to a portion of the main body portion 18 on the driver's seat side. A pair of left and right metal brackets 22 that are fixing portions for fixing the energy absorbing member are disposed on both the left and right sides of the column support portion 20.

  These metal brackets 22 are formed in an open cross-sectional shape (cross-sectional U-shape) by bending a metal plate, and as shown in FIG. 2, an upper wall 22A, a lower wall 22B, and a vertical wall 22C. It has. However, these metal brackets 22 are formed symmetrically and both open to the column support portion 20 side. These metal brackets 22 are formed so that the size in the vertical direction becomes smaller toward the front end side, and the front end portion is welded to the main body portion 18 of the instrument panel reinforcement 12.

  An upper fastening piece 22D extends upward from the rear end of the upper wall 22A of the metal bracket 22, and lower fastening from the rear end of the lower wall 22B of the metal bracket 22 downward. The piece 22E is extended. The energy absorbing member 14 is fastened and fixed to the upper fastening piece 22D and the lower fastening piece 22E.

  The energy absorbing member 14 is formed into a bottomed cylindrical shape by injection molding of a resin material, with the opening 14A facing the metal bracket 22 and the bottom wall 14B facing an instrument panel (not shown). Has been placed. The material of the energy absorbing member 14 is preferably a synthetic resin material that is strong against elongation and has little temperature dependency. For example, a material obtained by adding a plurality of types of rubber to polypropylene is preferable.

  The energy absorbing member 14 has an elliptical cross-sectional shape as viewed from the metal bracket 22 side, and has a tapered shape (substantially conical) in which the peripheral length of the peripheral wall 14C decreases toward the bottom wall 14B side (rear end side). It is formed in a trapezoidal shape. As shown in FIG. 3, the energy absorbing member 14 has a ratio of the length of the major axis d1 (major axis) and the minor axis d2 (minor axis) of the elliptical section to 2: 1. In addition, the energy absorbing member 14 is formed such that the thickness t1 on both ends in the major axis direction of the elliptical cross section is thicker than the thickness t2 on both ends in the minor axis direction.

  The energy absorbing member 14 is arranged in a state where the major axis d1 of the elliptical cross section is along the vehicle vertical direction. An upper fastening portion 14D extends upward from the upper end portion of the opening edge portion of the energy absorbing member 14, and lowers downward from the lower end portion of the opening edge portion of the energy absorbing member 14. The side fastening portion 14E is extended.

  A circular through hole 24 is formed in the upper fastening portion 14D. The screw 28 inserted into the circular through hole 24 is screwed into the screw hole 32 formed in the upper fastening piece 22D of the metal bracket 22, so that the upper fastening portion 14D is fastened and fixed to the upper fastening piece 22D. ing. Similarly, a circular through hole 26 is formed in the lower fastening portion 14E. The screw 30 inserted through the circular through hole 26 is screwed into the screw hole 34 formed in the lower fastening piece 22E of the metal bracket 22, so that the lower fastening portion 14E is engaged with the lower fastening piece 22E. Fastened and fixed.

  That is, the energy absorbing member 14 is fixed to the metal bracket 22 at both ends of the elliptical cross section at the opening edge in the major axis direction, and both ends of the elliptical cross section at the opening edge are at the metal bracket. 22 is not fixed. In other words, only two upper and lower points of the opening edge of the energy absorbing member 14 are fixed to the metal bracket 22 and left and right are free (deformable).

  2 are parting lines formed during the injection molding of the energy absorbing member 14, and are formed at the upper and lower ends of the peripheral wall 14C. These parting lines PL are arranged on both end sides along the major axis d1 of the elliptical cross section of the peripheral wall 14C.

  In the vehicle knee bolster 10 configured as described above, when the occupant P is seated in the driver's seat of the vehicle, the left energy absorbing member 14 is positioned in front of the left knee portion P1 of the occupant P as shown in FIG. The right energy absorbing member 14 is arranged in front of the right knee portion P1 of the occupant P.

  Next, the operation and effect of the first embodiment will be described.

  In the first embodiment, when the occupant P is displaced forward relative to the vehicle body due to inertial force during a frontal collision of the vehicle or the like, both knee portions P1 of the occupant P are attached to the energy absorbing member 14 via an instrument panel (not shown). collide. Thus, the energy absorbing member 14 is crushed by the load from the knee portion P1 of the occupant P while receiving the reaction force from the metal bracket 22 toward the vehicle rear side. At this time, when the energy absorbing member 14 generates a load, the impact energy of the knee portion P1 is absorbed, and the lower limb of the occupant P is restrained.

  Here, the above-described energy absorbing member 14 is formed in a bottomed cylindrical shape having an elliptical cross-sectional shape viewed from the metal bracket 22 side and opened on the metal bracket 22 side, and an elliptical cross-section at the opening edge. Are fixed to the metal bracket 22 at both ends in the major axis direction.

  For this reason, when the energy absorbing member 14 is crushed, stress concentrates on both ends in the major axis direction of the elliptical cross section, that is, on both ends having a large curvature in the peripheral wall 14C (on the upper and lower parting lines PL in this embodiment). . As a result, the energy absorbing member 14 buckles in a bellows shape so that the upper and lower parting line PL sides each form a buckling wave, as indicated by a solid line in FIG.

  At this time, since there is no significant change in the circumferential length of the peripheral wall 14C, the major axis of the elliptical cross section becomes longer at the portion corresponding to the peak of the buckling wave as shown in FIG. The energy absorbing member is deformed. Further, at the portion corresponding to the valley of the buckling wave, as shown in FIG. 5C, the energy absorbing member is deformed so that the minor axis of the elliptical cross section becomes longer. As described above, since the stress is dispersed by dynamically changing the cross-sectional shape of the energy absorbing member, the energy absorbing member 14 can be prevented from cracking due to buckling. Thereby, the load-displacement characteristic of the energy absorption member 14 can be stabilized.

  In FIG. 6, the load-displacement characteristic when the energy absorbing member is not broken is shown by a solid line, and the load-displacement characteristic when the energy absorbing member is broken is shown by a dotted line. As can be seen from FIG. 6, when the energy absorbing member is cracked, a drop in the load occurs (refer to the region marked with E in FIG. 6). Thereby, although the energy absorption amount of an energy absorption member falls significantly, in this embodiment, such a fall of energy absorption amount can be avoided.

  In addition, in the present embodiment, since the energy absorbing member 14 can be prevented from cracking as described above, the length L (see FIG. 4) of the energy absorbing member 14 can be set long. Thereby, since the length dimension of the metal bracket 22 of the instrument panel reinforcement 12 can be significantly shortened, the mass of the apparatus can be reduced.

  Moreover, in this embodiment, the magnitude | size of the load which the energy absorption member 14 generate | occur | produces, and the stroke at the time of the energy absorption member 14 being crushed are freely changed by changing the length dimension, material, and thickness of the energy absorption member 14 suitably. Therefore, there is an advantage that the degree of freedom in design is high.

  Furthermore, in this embodiment, the energy absorbing member 14 is formed such that the thickness t1 on both ends in the major axis direction of the elliptical cross section is thicker than the thickness t2 on both ends in the minor axis direction. For this reason, when the energy absorbing member 14 is crushed, even if stress is concentrated on both ends in the major axis direction of the elliptical cross section, cracks can be prevented from occurring on both ends in the major axis direction due to excessive stress concentration.

  In the present embodiment, the energy absorbing member 14 is set such that the ratio of the lengths of the major axis d1 and the minor axis d2 of the elliptical cross section is 2: 1. Thereby, the mass of the energy absorption member 14 can be set to the minimum while ensuring the energy absorption amount required for the energy absorption member 14 (the mass effect is the highest with respect to the energy absorption amount).

  Furthermore, the energy absorbing member 14 according to the present embodiment is fixed to the metal bracket 22 in a state where the major axis d1 of the elliptical cross section is along the vehicle vertical direction. That is, since the vehicle vertical dimension of the energy absorbing member 14 is set to be large, the energy absorbing member 14 is favorably opposed to the knee portion P1 regardless of variations in the arrangement height of the knee portion P1 due to the physique difference of the occupant P. Can be made. Moreover, since it can avoid that the energy absorption member 14 interferes with a steering column etc., it is suitable also when ensuring the arrangement space of the energy absorption member 14. FIG.

  Next, another embodiment of the present invention will be described. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol as the said 1st Embodiment is provided, and the description is abbreviate | omitted.

<Second Embodiment>
FIG. 7 shows a front view of an energy absorbing member 50 that is a constituent member of a vehicle knee bolster according to the second embodiment of the present invention. The energy absorbing member 50 has basically the same configuration as the energy absorbing member 14 according to the first embodiment. However, in this energy absorbing member 50, the upper fastening portion 14D protrudes toward one side of the elliptical section in the minor axis direction, and the lower fastening portion 14E projects toward the other side of the elliptical section in the minor axis direction. Yes. Thus, by arrange | positioning upper side fastening part 14D and lower side fastening part 14E, the dimension of the energy absorption member 50 along the major axis direction of an elliptical cross section can be set small. Therefore, the molding die of the energy absorbing member 50 can be made small and low cost. In this case, it is necessary to change the arrangement of the upper fastening piece 22D and the lower fastening piece 22E of the metal bracket 22 in accordance with the arrangement of the upper fastening part 14D and the lower fastening part 14E.

<Third Embodiment>
FIG. 8 is a perspective view showing a partial configuration of a vehicle knee bolster according to the third embodiment of the present invention. Although this embodiment has basically the same configuration as the first embodiment, the metal bracket 22 according to the first embodiment is omitted in this embodiment. In this embodiment, the configuration of the energy absorbing member 60 is different from that of the energy absorbing member 14 according to the first embodiment.

  The energy absorbing member 60 is formed in a tapered shape (substantially truncated cone shape) in which the circumferential length of the peripheral wall 14C increases as it goes toward the bottom wall 14B side (rear end side). A front end portion (end portion on the opening 14 </ b> A side) of the energy absorbing member 60 is in contact with a fixing portion 62 provided in the main body portion 18 of the instrument panel reinforcement 12. The upper fastening portion 14D is curved so as to be in close contact with the upper surface of the fixing portion 62, and the screw 28 penetrating the upper fastening portion 14D is screwed into a screw hole (not shown) formed in the upper portion of the fixing portion 62. Yes. Accordingly, the upper fastening portion 14D is fastened and fixed to the fixing portion 62 (a part of the main body portion 18). The lower fastening portion 14E is curved so as to be in close contact with the lower surface of the fixing portion 62, and the screw 30 penetrating the lower fastening portion 14E is inserted into a screw hole (not shown) formed in the lower portion of the fixing portion 62. It is screwed. Accordingly, the lower fastening portion 14E is fastened and fixed to the fixing portion 62 (a part of the main body portion 18).

  As described above, in this embodiment, a part of the main body portion 18 of the instrument panel reinforcement 12 is the fixing portion 62 for fixing the energy absorbing member, and the main body portion 18 directly receives the reaction force of the energy absorbing member 60. It has become. Thereby, since the metal brackets 22 can be omitted, the mass of the apparatus can be greatly reduced.

  In each of the above embodiments, the case where the energy absorbing member 14 is disposed in a state where the major axis d1 of the elliptical cross section is aligned in the vehicle vertical direction has been described. However, the inventions according to claims 1 to 3 include this. However, the energy absorbing member may be arranged in a state in which the major axis d1 of the elliptical cross section is aligned along the left-right direction of the vehicle, or the energy absorbing member is in a state where the major axis d1 of the elliptical cross section is inclined. An arrangement may be adopted.

  Further, in each of the above embodiments, the ratio of the lengths of the major axis d1 and the minor axis d2 of the elliptical cross section of the energy absorbing member 14 is set to 2: 1. This invention is not limited to this, and the setting of the elliptical cross section of the energy absorbing member can be changed as appropriate, and is not limited to the one in which the length ratio is exactly 2: 1.

  Moreover, in each said embodiment, although the thickness t1 of the major axis direction both ends side of the elliptical cross section in the energy absorption member 14 was made thicker than the thickness t2 of the minor axis direction both ends side, it was set as the structure. The invention which concerns is not restricted to this, The setting of the thickness in an energy absorption member can be changed suitably.

  Furthermore, in each said embodiment, it was set as the structure by which the energy absorption member 14 was made into the elliptical cross section seeing from the metal bracket 22 (fixed part) side, However, The invention which concerns on Claim 1 or Claim 2 is not restricted to this Instead, the energy absorbing member may be configured to have an oval cross section or an oval cross section when viewed from the fixed portion side.

  Moreover, in each said embodiment, although the energy absorption member 14 was set as the structure shape | molded by injection molding, the invention which concerns on Claims 1-4 is not restricted to this, The shaping | molding method of the energy absorption member 14 is changed suitably. can do.

  Moreover, in each said embodiment, it was set as the structure by which the fixed part (metal bracket 22 or the fixed part 62) was provided in the instrument panel reinforcement 12, However, The invention which concerns on Claims 1-4 is not restricted to this, For example, you may make it the structure by which the fixing | fixed part was provided in the floor brace which connected the instrument panel reinforcement 12 and the vehicle floor.

  Furthermore, although each said embodiment demonstrated the case where the vehicle knee bolster 10 was applied as an object for the driver's seat of the vehicle of a right steering wheel, it is not restricted to this, The invention which concerns on Claims 1-4 is a vehicle. It can be applied to any of the left and right sheets.

  In addition, the present invention can be implemented with various modifications without departing from the scope of the invention. Further, it goes without saying that the scope of rights of the present invention is not limited to the above embodiments.

10 Vehicle knee bolster 12 Instrument panel reinforcement (rigid member)
14 Energy absorbing member 22 Metal bracket (fixed part)
50 Energy absorbing member 60 Energy absorbing member 62 Fixed part d1 Long diameter d2 Short diameter

Claims (4)

A resin energy absorbing member is provided in front of the knee portion of an occupant seated on a vehicle seat, and a front end side is fixed to a fixing portion provided on a rigid member on a vehicle body side,
The energy absorbing member is formed in a bottomed cylindrical shape having a cross-sectional shape viewed from the fixing portion side and having an opening on the fixing portion side, and the fixing portion is disposed at both ends of the oval cross section in the major axis direction at the opening edge. A knee bolster for vehicles characterized by being fixed to.   2. The vehicle knee bolster according to claim 1, wherein the energy absorbing member is formed such that the wall thickness at both ends in the major axis direction of the oval cross section is thicker than the thickness at both ends in the minor axis direction. .   The energy absorbing member is characterized in that the cross-sectional shape viewed from the fixed portion side is an ellipse, and the ratio of the length of the major axis to the minor axis of the elliptical section is set to 2: 1. The vehicle knee bolster according to claim 1 or 2.   4. The vehicle according to claim 1, wherein the energy absorbing member is fixed to the fixing portion in a state in which a major axis of the oval cross section is along a vehicle vertical direction. Knee bolster.

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