JP2024071731A - Knee Bolster - Google Patents

Abstract

To provide a knee bolster that can handle a wider range of shock magnitudes than conventional ones.
[Solution] The knee bolster 10 of the present disclosure comprises rigid polyurethane foam 40 that compressively breaks when subjected to a pressure from the knee H, and energy absorbing ribs 12 that buckle after the compression and failure of the rigid polyurethane foam 40 progresses, arranged in the direction in which the compression force is received. The rigid polyurethane foam 40 is housed in a container 11 that is divided into first and second container sections 20, 30, and the energy absorbing ribs 12 are integrally formed with the second container section 30.
[Selected figure] Figure 2

Description

This disclosure relates to a knee bolster that supports the knees of an occupant during a vehicle collision and reduces the impact on the knees.

A conventional knee bolster is known that absorbs shock by compressively destroying rigid polyurethane foam (see, for example, Patent Document 1).

JP 2003-327066 A (paragraphs [0017], [0018], FIG. 1, etc.)

However, the magnitude of the impact that the knee bolster receives from the occupant's knees varies greatly depending on, for example, whether a seat belt is fastened or not, and the occupant's seating position. For this reason, there is a demand for the development of a knee bolster that can handle a wider range of impact magnitudes than conventional methods.

The first aspect of the invention made to solve the above problem is a knee bolster that supports the knees of an occupant during a vehicle collision, and is equipped with a rigid polyurethane foam that compresses and breaks when subjected to pressure from the knee, and an energy absorbing rib that buckles after the rigid polyurethane foam compresses and breaks when subjected to the pressure, and is aligned in a first direction, which is the direction in which the pressure is received.

The second aspect of the present invention is a knee bolster according to the first aspect, which has a pair of opposing members that face each other in the first direction with the rigid polyurethane foam therebetween, and stopper portions that are provided on the pair of opposing members and that come close to each other and come into contact with each other as the rigid polyurethane foam compresses and breaks, thereby maintaining the progress of the compressive failure of the rigid polyurethane foam at a constant rate, and in which buckling of the energy absorbing rib begins after the stopper portions come into contact with each other.

The third aspect of the present invention is a knee bolster according to the first or second aspect, in which the container that contains the rigid polyurethane foam is divided in the first direction, and the container sections engage with each other so as to restrict movement in a direction intersecting the first direction, and the fitting between the container sections deepens as the rigid polyurethane foam is compressed and destroyed, and the energy absorbing rib is disposed on the outer surface of the container sections.

The fourth aspect of the present invention is the knee bolster described in the third aspect, in which the pair of container sections have a box-shaped structure with openings on the opposing sides.

The fifth aspect of the present invention is the knee bolster according to the third or fourth aspect, in which the one container section and the energy absorbing rib are integrally molded from resin.

The sixth aspect of the present invention is a knee bolster according to any one of the claims of the third to fifth aspects, in which the energy absorbing rib is in the form of a lattice having a plurality of squares, and a reinforcing rib is provided on the back surface of the surface of one of the container sections that has the energy absorbing rib, the reinforcing rib extending along the diagonal line of the squares of the energy absorbing rib.

The seventh aspect of the present invention is a knee bolster according to any one of the claims of the third to sixth aspects, in which the rib support wall of one of the container sections that is provided with the energy absorbing rib has an elongated shape, the energy absorbing rib is in the form of a lattice having a plurality of square cells, the size of the rib support wall in the short side direction is approximately an integer multiple of the diagonals of the cells, a pair of diagonals of each cell are arranged parallel to the longitudinal direction and the short side direction of the rib support wall, and the diagonals of the cells are arranged to overlap with the center line of the short side direction of the rib support wall.

The eighth aspect of the present invention is a knee bolster according to any one of claims 1 to 6, in which the rigid polyurethane foam has an elongated shape when viewed from the first direction, and the energy absorbing rib has a lattice shape having a plurality of square cells, with a pair of diagonals of each cell being arranged parallel to the longitudinal and lateral directions of the elongated shape.

The knee bolster of the first aspect of the present invention comprises a rigid polyurethane foam and an energy absorbing rib, and when pressure is applied from the occupant's knees, the rigid polyurethane foam is compressed to failure, and then the energy absorbing rib is compressed to failure (buckled). This means that in addition to the range of impact magnitudes that could be handled by conventional knee bolsters, which absorbed impacts from the knees using only rigid polyurethane foam, it can also handle larger impacts, widening the range of impact magnitudes that can be handled compared to conventional knee bolsters.

Here, to prevent the energy absorbing rib from digging into the rigid polyurethane foam, for example, a portion of the rigid polyurethane foam may be impregnated with non-foamed rigid urethane, or a plate member may be provided between the energy absorbing rib and the rigid polyurethane foam.

In addition, as in the second aspect of the present invention, by providing a pair of opposing members that face each other in the first direction with the rigid polyurethane foam between them, and providing stopper sections that come close to each other and come into contact with the opposing members as the rigid polyurethane foam compresses and breaks, and thus maintain the progress of the compressive failure of the rigid polyurethane foam at a constant level, the timing at which the energy absorbing rib starts to buckle and the amount of compressive failure of the rigid polyurethane foam at that time are stable.

According to the knee bolster of the third aspect of the present invention, even if the rigid polyurethane foam is sheared obliquely to the direction of pressure due to the pressure applied, the progress of shearing is suppressed by the mutual engagement of the pair of container halves that contain the rigid polyurethane foam, and compression failure progresses. This stabilizes the amount of compression failure of the rigid polyurethane foam in response to the pressure, and stabilizes the amount of shock absorption.

Here, the pair of container segments may be a box with one end open, and the other container segment may be a lid that closes the opening of the box segment and fits inside the box segment, or may have a box-shaped structure with openings on opposing sides, as in the fourth aspect of the present invention. When both are box-shaped, they may approach each other as the rigid polyurethane foam is compressed and destroyed, and the opening edges of the container segments may come into contact with each other, or the opening edge of one container segment may enter the inside of the other container segment and come into contact with the inner surface of the other container segment. In addition, the pair of container segments may be engaged with each other to "restrict movement in a direction intersecting the first direction," or, for example, multiple protrusions protruding in the first direction from one of the pair of container segments may be inserted into multiple engagement holes on the other container segment to engage as described above.

In addition, one of the container sections and the energy absorbing rib may be integrally molded from resin (fifth aspect of the present invention), or they may be separate bodies.

The energy absorbing rib may be any structure that protrudes in the first direction and buckles under pressure. For example, the cross section may be cruciform, cylindrical, elliptical cylindrical, or honeycomb-shaped, or may be lattice-shaped with multiple squares as in the sixth and seventh aspects of the present invention.

In addition, a reinforcing rib may be provided on the back side of the container section opposite the side on which the energy absorbing rib is provided for reinforcement. For example, as in the sixth aspect of the present invention, the reinforcing rib can be positioned so as to extend along the diagonal of the energy absorbing rib squares, providing a well-balanced reinforcement.

Furthermore, when a grid-like energy absorbing rib having multiple square cells is provided on the elongated rib support wall of the container section, as in the seventh aspect of the present invention, the size of the short side of the rib support wall is approximately an integer multiple of the diagonal of the cells, and a pair of diagonal lines of each cell are arranged parallel to the long and short directions of the rib support wall, and the diagonal lines of the cells are arranged to overlap with the center line of the short side of the rib support wall. This makes it possible to increase the number of intersections between cells surrounded by energy absorbing ribs that are connected to the diagonal lines of the cells while ensuring the required cell size, compared to a configuration in which the length and width of each cell are arranged parallel to the long and short directions of the rib support wall. This prevents the energy absorbing rib from being pushed down without buckling, and stabilizes the timing at which the energy absorbing rib starts to buckle.

FIG. 1 is a cross-sectional view of a portion of a vehicle to which a knee bolster according to a first embodiment is attached; Plan view of knee bolster installed on vehicle Knee bolster cross section A perspective view of the knee bolster from the front Exploded perspective view of knee bolster A perspective view of the knee bolster from the rear side A graph conceptually showing the relationship between the load from the knee and the deformation of the knee bolster. (A) A planar cross-sectional view of a knee bolster, (B) A planar cross-sectional view of the knee bolster when the rigid polyurethane foam is compressed, and (C) A planar cross-sectional view of the knee bolster when the energy absorbing rib is buckled. FIG. 2A is a plan cross-sectional view of a knee bolster according to a second embodiment; and FIG. 2B is a plan cross-sectional view of the knee bolster when the rigid polyurethane foam is compressed. FIG. 13 is an exploded perspective view according to a third embodiment. A perspective view of the knee bolster from the rear side A perspective view of a knee bolster in which rigid polyurethane foam has been crushed by compression FIG. 13 is a perspective view of a knee bolster according to another embodiment, as viewed from the rear side; FIG. 11 is a cross-sectional plan view of a knee bolster according to another embodiment of the present invention;

[First embodiment]
A first embodiment of a knee bolster 10 according to the present disclosure will be described with reference to Figures 1 to 8. As shown in Figures 1 and 2, the knee bolster 10 of this embodiment is attached to a pair of pedestal portions 95 provided on a reinforcement 92 extending in the vehicle width direction behind an instrument panel 91 of a vehicle 90. Each pedestal portion 95 is formed, for example, by fixing a support plate 94 to the tips of a pair of ribs 93 that protrude diagonally downward and rearward from the reinforcement 92. The support plate 94 has, for example, a vertically long rectangular shape and has a mounting surface 94A facing diagonally downward and rearward.

The knee bolsters 10 are attached to the mounting surfaces 94A of a pair of base portions 95 in a stacked manner, and are positioned diagonally above and forward of the knees H of the driver, occupant J. When the vehicle 90 collides and the lower legs of the occupant J rotate forward with the heels as the fulcrum, causing the knees H to move diagonally above and forward and bite into the instrument panel 91, the knee bolsters 10 are pressed against the knees H through the instrument panel 91, causing them to compress and break, mitigating the impact on the knees H.

The direction in which the mounting surface 94A of each pedestal portion 95 faces (i.e., the normal direction of the mounting surface 94A) is set to coincide with the movement direction of the knee H of an occupant J of an expected average build. In the following description of the knee bolster 10, the expected movement direction of the knee H is referred to as the "first direction A1," the side of the knee bolster 10 that is attached to the pedestal portion 95 is referred to as the "rear side," and the opposite side is referred to as the "front side." In addition, the diagonal upward and downward direction perpendicular to the first direction A1 is referred to as the "vertical direction," and the direction perpendicular to the vertical direction and the first direction A1 is referred to as the "horizontal direction."

As shown in FIG. 3, the knee bolster 10 has a rigid polyurethane foam 40 housed in a container 11. As shown in FIG. 4, the container 11 has a generally vertically elongated rectangular shape and is divided into first and second container sections 20, 30 at approximately the center in the first direction A1. The first and second container sections 20, 30 are injection molded products of a resin such as polypropylene, and as shown in FIG. 3, have a box-shaped structure with openings on opposing sides, and have bottom walls 21, 31 and side walls 22, 32 that stand up from the outer edges of the bottom walls 21, 31.

The side wall 32 of the second container section 30 on the rear side is generally perpendicular to the bottom wall 31, while the side wall 22 of the first container section 20 on the front side is inclined relative to the bottom wall 21 so as to expand outward as it moves away from the bottom wall 21. The side wall 32 of the second container section 30 fits inside the side wall 22 of the first container section 20, and rigid polyurethane foam 40 is sandwiched between the bottom walls 21, 31 of the first and second container sections 20, 30, so that the first and second container sections 20, 30 are positioned where only the tips of the side walls 22, 32 fit together.

The rigid polyurethane foam 40 is then pressed against the bottom walls 21, 31 and compressed to failure, and the progression of the compressive failure stops when the tip of the side wall 32 of the second container section 30 abuts against the bottom wall 21 of the first container section 20. That is, in this embodiment, the above-mentioned bottom walls 21, 31 correspond to the "pair of opposing members" in the claims, and the side wall 32 and the bottom wall 21 correspond to the "stopper portion" in the claims.

The first and second container sections 20, 30 have locking projections 23, 33 at their tips on the side walls 22, 32. The locking projections 23, 33 each have a right-angled triangular cross section that extends along the tip edges of the side walls 22, 32 and have a locking surface that is perpendicular to the first direction A1. The locking projection 23 of the first container section 20 protrudes inward from the side wall 22, while the locking projection 33 of the second container section 30 protrudes outward from the side wall 32. The locking surfaces of the locking projections 23, 33 face each other to prevent the first and second container sections 20, 30 from separating.

As shown in FIG. 5, reinforcing ribs 34 are formed on the inner surface of the bottom wall 31 of the second container section 30. The reinforcing ribs 34 are, for example, lattice-shaped and include a vertical rib 34T that extends straight in the vertical direction at the horizontal center of the bottom wall 31, and multiple horizontal ribs 34Y that extend horizontally at multiple positions in the vertical direction of the bottom wall 31. In addition, cylindrical ribs 34E are formed at every other intersection of the vertical ribs 34T and the multiple horizontal ribs 34Y, and a through hole 34F is formed in the center of the cylindrical rib 34E.

In this embodiment, the first and second container sections 20, 30 are prevented from separating by the locking projections 23, 33. However, for example, a member protruding from one side of the side walls 22, 32 of the first and second container sections 20, 30 toward the other may be engaged with a hole formed in the other side to prevent separation of the first and second container sections 20, 30, or the bottom walls 21, 31 of the first and second container sections 20, 30 may be fixed to the rigid polyurethane foam 40 with an adhesive or the like to prevent separation of the first and second container sections 20, 30.

As shown in FIG. 5, the rigid polyurethane foam 40 is a foam-molded product having a substantially rectangular parallelepiped shape. As shown in FIG. 3, approximately half of the back side of the rigid polyurethane foam 40 fits exactly inside the second container section 30, and approximately half of the front side fits inside the first container section 20, and a gap is provided between the side wall 22 of the first container section 20 and the rigid polyurethane foam 40 for the side wall 32 of the second container section 30 to move. As shown in FIG. 5, a groove 40M that receives the reinforcing rib 34 is molded on the back side of the rigid polyurethane foam 40. The side of the rigid polyurethane foam 40 is slightly inclined outward from both ends in the first direction A1 toward the center.

The bottom wall 31 of the second container section 30 corresponds to the "rib support wall" in the claims, and the energy absorbing rib 12 is integrally formed on the outer surface of the bottom wall 31. The energy absorbing rib 12 is perpendicular to the outer surface of the bottom wall 31, and the amount of protrusion from the bottom wall 31 is, for example, 1 to 2 times the thickness of the rigid polyurethane foam 40 in the first direction A1, as shown in Figure 3.

6, the energy absorbing rib 12 includes a plurality of first ribs 13A and a plurality of second ribs 13B that are inclined at an angle of 45 degrees to both the vertical and horizontal directions of the bottom wall 31 and are perpendicular to each other, and a plurality of square cells 14 surrounded on all four sides by the first ribs 13A and the second ribs 13B are arranged in the vertical direction of the bottom wall 31. In detail, the energy absorbing rib 12 is formed so that the length of the diagonal line of the cells 14 is approximately equal to the length of the short side (i.e., the horizontal direction) of the bottom wall 31. The diagonal lines of the cells 14 are arranged so as to overlap with the center line of the short side of the bottom wall 31. With this configuration, compared to a configuration in which the vertical and horizontal sides of each square 14 are arranged parallel to the longitudinal and lateral directions of the bottom wall 31, it is possible to increase the number of intersections between squares 14 surrounded by energy absorbing ribs 12 that are connected diagonally to the bottom wall 31 while maintaining the size of the squares 14. In this embodiment, the length of the longitudinal direction (i.e., the vertical direction) of the bottom wall 31 is, for example, at least two times but less than three times the length of the diagonal of the squares 14, and the shapes of the energy absorbing ribs 12 at both ends of the longitudinal direction of the bottom wall 31 are symmetrical.

The horizontal ribs 34Y (see FIG. 5) of the reinforcing rib 34 are arranged in the longitudinal direction of the bottom wall 31 at a pitch of 1/2 the diagonal of the square 14 of the energy absorbing rib 12, and are arranged so as to overlap the horizontal diagonal of the square 14. Furthermore, the vertical rib 34T of the reinforcing rib 34 is arranged so as to overlap the vertical diagonal of the square 14, as described above, at the center of the horizontal direction of the bottom wall 31. In this manner, in this embodiment, the reinforcing rib 34 is arranged along the diagonal of the square 14 of the energy absorbing rib 12, so that the bottom wall 31 is reinforced in a well-balanced manner. In addition, the aforementioned multiple through holes 34F are arranged in the rib intersection 13C where the first rib 13A and the second rib 13B cross at the center of the horizontal direction of the bottom wall 31 of the energy absorbing rib 12, and the end of the rib intersection 13C on the bottom wall 31 side is cut out to extend the through holes 34F, forming the notch 15. This prevents deformation of the bottom wall 31 due to shrinkage during molding.

As shown in Fig. 4, mounting pieces 17 protrude laterally from the four corners of the front end of the entire energy absorbing rib 12. Then, bolts are passed through through holes 17K that pass through the mounting pieces 17 and are fastened to screw holes (not shown) provided at the four corners of the mounting surface 94A of the base portion 95, thereby fixing the knee bolster 10 to the base portion 95. Note that the mounting pieces 17 are omitted in figures other than Fig. 4.

The energy absorbing rib 12 has a strength such that, when the knee bolster 10 is pressed in the first direction A1, the rigid polyurethane foam 40 is compressed to failure and then the energy absorbing rib 12 is compressed to failure (specifically, buckled). Specifically, the rigid polyurethane foam 40 has a compressive strength of, for example, 3 to 4 kgf/ ^cm2 , and the energy absorbing rib 12 has a buckling strength of, for example, 6 to 7 kgf/ ^cm2 . If the area of the inner surface of the bottom wall 31 of the second container section 30 is the pressing area, a first pressing force approximately equal to the pressing area multiplied by 3 to 4 kgf/ ^cm2 is required to compress the knee bolster 10 from the start to the end of the compressive failure of the rigid polyurethane foam 40, and during that time a first reaction force F1 of the same magnitude as the first pressing force is returned to the pressing side. After the compression and destruction of the rigid polyurethane foam 40 is completed, a second pressing force approximately equal to the pressing area multiplied by 6 to 7 kgf/ ^cm2 is required to compress the knee bolster 10, during which a second reaction force F2 of the same magnitude as the second pressing force is returned to the pressing side.

In addition, FIG. 7 shows a graph of the relationship between the compression amount L of the knee bolster 10 when the knee bolster 10 is pressed and the reaction force F from the knee bolster 10. In the graph, the period when the compression amount L changes from 0 to a corresponds to the elastic deformation of the rigid polyurethane foam 40, the period when it changes from a to b corresponds to the compressive failure of the rigid polyurethane foam 40, the period when it changes from b to c corresponds to the elastic deformation of the energy absorbing rib 12, and the period when it changes from c to d corresponds to the compressive failure of the energy absorbing rib 12.

This concludes the description of the structure of the knee bolster 10 in this embodiment. Next, the action and effect of the knee bolster 10 will be described. When the vehicle 90 collides, for example, the driver, occupant J, moves forward from the driver's seat due to inertial force, and the part of the occupant J above the legs is received by the airbag. Meanwhile, the legs of the occupant J rotate around the heel as a fulcrum, causing the knees H to move diagonally forward and upward, pressing against the instrument panel 91, and as shown in FIG. 8, the knee bolster 10 on the back side of the instrument panel 91 receives the pressing force from the knees H. Then, the knee bolster 10 compresses and breaks, absorbing the kinetic energy due to the inertial force of the occupant J and mitigating the impact on the knees H.

At this time, the kinetic energy due to the inertial force that the knee bolster 10 receives from occupant J varies greatly depending on whether or not occupant J is wearing a seat belt. If occupant J is below the maximum expected weight and wearing a seat belt, the kinetic energy due to the inertial force of occupant J is absorbed by the compressive failure of only the rigid polyurethane foam 40 of the knee bolster 10, and if the seat belt is not worn, the kinetic energy due to the inertial force of occupant J is absorbed by the compressive failure of only the rigid polyurethane foam 40 of the knee bolster 10 and the subsequent compressive failure of the energy absorbing rib 12.

Specifically, when the instrument panel 91 is pushed by the knee H and deformed, it comes into contact with the bottom wall 21 of the first container section 20 of the knee bolster 10, and the first container section 20 moves to deepen its engagement with the second container section 30, and the entire rigid polyurethane foam 40 is pressed in the first direction A1 between the bottom walls 21, 31 of the first and second container sections 20, 30. As a result, the entire rigid polyurethane foam 40 is subjected to a pressing force in the first direction A1 and is compressed and destroyed. At that time, even if the pressing force acts as a shear force inclined with respect to the first direction A1 and the rigid polyurethane foam 40 is sheared, the first and second container sections 20, 30 surround the rigid polyurethane foam 40 from the sides and are engaged (fitted) so that the first and second container sections 20, 30 do not move sideways with each other, so the progress of shearing is suppressed and the compression destruction progresses. This stabilizes the amount of compression failure of the rigid polyurethane foam 40 against the pressure, stabilizes the amount of shock absorption, and stabilizes the reaction force F applied to the knee H from the knee bolster 10. Then, before the entire rigid polyurethane foam 40 is completely compressed and destroyed, as shown in FIG. 8B, the side wall 32 of the second container section 30 abuts against the bottom wall 21 of the first container section 20, and the compression failure of the rigid polyurethane foam 40 ends. The compression failure of the rigid polyurethane foam 40 ends when the side walls 32 and the bottom wall 21 of the first and second container sections 20, 30 abut against each other. This stabilizes the amount of compression failure of the rigid polyurethane foam 40, and also stabilizes the timing at which the energy absorbing rib 12 starts to buckle, as described below.

If the occupant J is wearing a seat belt, the movement of the knee H stops before the compression and destruction of the rigid polyurethane foam 40 is completed. If the occupant J is not wearing a seat belt, the knee H continues to move even after the compression and destruction of the rigid polyurethane foam 40 is completed, and the knee bolster 10 is further pressed, the pressure increases, and the energy absorbing rib 12 begins to compress (specifically, buckle) (see FIG. 8(C)). Here, the energy absorbing rib 12 is arranged so that the number of intersections between the squares 14 surrounded by the energy absorbing ribs 12 connected diagonally to the squares 14 is increased by being inclined with respect to the length and width of the bottom wall 31 of the second container section 30 that supports it, so that the energy absorbing rib 12 is prevented from being pushed down without buckling, and the amount of impact absorption due to the buckling of the energy absorbing rib 12 is stabilized. Even if the occupant J is not wearing a seat belt, the movement of the knee H stops due to the effect of the airbag before the compression and destruction of the energy absorbing rib 12 is completed.

In this manner, the knee bolster 10 of this embodiment includes the rigid polyurethane foam 40 and the energy absorbing rib 12, and when it receives a pressing force from the knee H of the occupant J, the rigid polyurethane foam 40 compresses and breaks, and then the energy absorbing rib 12 compresses and breaks (buckles). This means that in addition to the range of impact magnitude that can be handled by conventional knee bolsters, which absorbed impact from the knee H only with the rigid polyurethane foam 40, it can also handle larger impacts, making the range of impact magnitude that can be handled wider than before. Also, if the knee bolster 10 of this embodiment is set to absorb impacts within the range that can be handled by the conventional knee bolster 10 by compressive failure of only the rigid polyurethane foam 40, it is possible to suppress an increase in the reaction force from the knee bolster 10 to the knee H that accompanies an increase in the range that can be handled.

[Second embodiment]
The knee bolster 10V of this embodiment is shown in Figure 9. In the knee bolster 10V of this embodiment, the first container section 20V is box-shaped with an opening on the side of the second container section 30V, while the second container section 30V is a plate-like lid that closes the opening of the first container section 20V. In addition, the bottom wall 21V of the first container section 20V and the second container section 30V are fixed to the rigid polyurethane foam 40V with, for example, an adhesive.

The rigid polyurethane foam 40V has a plurality of through holes 41 (only one through hole 41 is shown in FIG. 9) formed in the horizontal center thereof, penetrating through a plurality of positions in the vertical direction in the first direction A1. A plurality of cylindrical stopper portions 24A protruding from the bottom wall 21V of the first container section 20V and a plurality of cylindrical stopper portions 24B protruding from the second container section 30V are fitted into both ends of the plurality of through holes 41 in the rigid polyurethane foam 40V. The configuration of the knee bolster 10V of this embodiment other than as described above is the same as that of the knee bolster 10 of the first embodiment.

The configuration of this embodiment achieves the same effects as the first embodiment. In addition, in this embodiment, when the rigid polyurethane foam 40V is compressed and destroyed, the tips of the stopper portions 24A and 24B come into contact with each other, as shown in FIG. 9(B), and the compression and destruction of the rigid polyurethane foam 40V ends.

The locking projection 23 (see FIG. 3) described in the first embodiment may be provided at the tip of the side wall 22V of the first container section 20V to lock onto the outer edge of the second container section 30V.

[Third embodiment]
A knee bolster 10W of the third embodiment is shown in Figures 10 to 12. As shown in Figure 10, the knee bolster 10W of this embodiment includes a front wall 25 and a rear wall 26 that are elongated and generally rectangular and sandwich a rigid polyurethane foam 40W in the first direction A1, and a pair of connecting walls 27 that connect both longitudinal ends of the front wall 25 and the rear wall 26. The pair of connecting walls 27 are also plate-shaped and curved in directions away from each other.

In addition, an enclosure wall 28 is erected on the rear wall 26, protruding toward the front wall 25. The enclosure wall 28 protrudes to a midpoint between the front wall 25 in the first direction A1, and has an open end in a direction intersecting the first direction A1 where the pair of connecting walls 27 are not disposed, thereby housing the rigid polyurethane foam 40W in a state where it is surrounded from three sides.

A cantilever-shaped retaining piece 29 is provided in the longitudinal center of the front wall 25, and its tip is curved toward the rear wall 26. This retaining piece 29 prevents the rigid polyurethane foam 40W from detaching laterally from the surrounding wall 28.

As shown in Fig. 11, the energy absorbing rib 12W includes a plurality of first ribs 13A1 and a plurality of second ribs 13B1 that are inclined at an angle of 45 degrees with respect to both the vertical and horizontal directions of the rear wall 26 and are mutually perpendicular, and a third rib 16 that intersects with the intersection of the first and second ribs 13A1 and 13B1 and extends in both the vertical and horizontal directions of the rear wall 26. In detail, the plurality of first and second ribs 13A1 and 13B1 form square cells 14W, the diagonal length of the cells 14W being slightly smaller than the length in the short direction (i.e., the horizontal direction) of the rear wall 26, and for example, two cells 14W are arranged in the vertical direction of the rear wall 26, and each cell 14W is adjacent to one vertex. The plurality of third ribs 16 extend in the diagonal direction, intersecting three of the vertices of each cell 14W. The shape of the energy absorbing rib 12W is symmetrical with respect to the longitudinal centerline of the rear wall 26. Other than as described above, the configuration of the knee bolster 10W of this embodiment is the same as that of the knee bolster 10 of the first embodiment.

The configuration of this embodiment achieves the same effects as the first embodiment. In addition, in the knee bolster 10W of this embodiment, when the rigid polyurethane foam 40W is compressed, the pair of connecting walls 27 elastically deform, and the front wall 25 moves closer to the rear wall 26, and the front wall 25 abuts against the tip of the surrounding wall 28, completing the compression collapse of the rigid polyurethane foam 40W.

In this embodiment, the front wall 25 and the tip of the surrounding wall 28 correspond to the "stopper portion" in the claims.

[Other embodiments]
(1) In the above embodiment, the squares 14 of the energy absorbing rib 12 were configured so that their diagonals were arranged parallel to the longitudinal and transverse directions of the bottom wall 31 of the second container section 30. However, as in the knee bolster 10X shown in FIG. 13, the vertical and horizontal sides of the squares 14X may be arranged parallel to the vertical and horizontal sides of the bottom walls 21X, 31X of the first container section 20X and the second container section 30X.

(2) In the first embodiment, the rigid polyurethane foam 40 is entirely contained in the container 11. However, a plate member may be provided between the rigid polyurethane foam and the energy absorbing rib to prevent the energy absorbing rib from digging into the rigid polyurethane foam, or the rigid polyurethane foam facing the energy absorbing rib may be impregnated with a non-foamed urethane or the like for reinforcement.

(3) In the first embodiment described above, the progress of compression failure stops when the side wall 32 of the second container section 30 abuts against the bottom wall 21 of the first container section 20 before the entire rigid polyurethane foam 40 is completely compressed and destroyed. However, the compression failure may continue until the rigid polyurethane foam 40 is completely compressed and destroyed.

(4) In the second embodiment, the first and second container sections 20V, 30V are formed with a plurality of cylindrical stopper portions 24A, 24B protruding therefrom, and when the rigid polyurethane foam 40V is compressed to failure, the tips of the stopper portions 24A, 24B come into contact with each other, and the compression failure of the rigid polyurethane foam 40V is terminated. However, as shown in FIG. 14, the knee bolster 10Y may be configured such that a locking claw 24T having a right-angled triangular cross section protrudes outward along the tip edge of the stopper portion 24A1 of the first container section 20Y, while an engagement hole 24K is formed in the circumferential direction near the tip of the stopper portion 24B1 of the second container section 30Y, and when the rigid polyurethane foam 40Y is compressed to failure, the locking claw 24T engages with the engagement hole 24K, and the compression failure of the rigid polyurethane foam 40Y is terminated.

(5) In the first embodiment, the second container section 30 and the energy absorbing rib 12 are integrally formed, but they may be separate.

(6) In the above embodiment, the energy absorbing ribs 12, 12V, 12W are lattice-shaped, but they may have any structure that protrudes in the first direction A1 and buckles when pressed in the first direction A1. For example, they may have a cross-shaped cross section, a cylindrical shape, an elliptical cylindrical shape, a rectangular cylindrical shape, or a honeycomb shape.

(7) In the above embodiment, the rigid polyurethane foams 40, 40V, and 40W are arranged on the front side and the energy absorbing ribs 12, 12V, and 12W are arranged on the back side in the first direction A1, but the arrangement may be reversed.

Note that although specific examples of the technology included in the scope of the claims are disclosed in this specification and drawings, the technology described in the claims is not limited to these specific examples, but includes various modifications and variations of the specific examples, as well as parts of the specific examples taken separately.

10, 10V, 10W, 10X Knee bolster 11, 11V, 11W Container 12, 12V, 12W Energy absorbing rib 14, 14W, 14X Grid 20, 20V, 20X First container section 21, 21V Bottom wall (rib support wall)
26 Lower wall (rib support wall)
22, 22V Side wall 30, 30V, 30X Second container section 31 Bottom wall 32 Side wall 34 Reinforcing rib 40, 40V, 40W Hard polyurethane foam

Claims (8)

A knee bolster that supports the knees of an occupant during a vehicle collision,
The knee bolster includes a rigid polyurethane foam that is compressed and destroyed when subjected to a pressure from the knee, and an energy absorbing rib that buckles after the rigid polyurethane foam is compressed and destroyed by the pressure, the ribs being aligned in a first direction, which is the direction in which the pressure is applied. a pair of opposing members opposed to each other in the first direction with the rigid polyurethane foam therebetween;
stopper portions provided on the pair of opposing members, which come close to each other and come into contact with each other as the rigid polyurethane foam is compressed and destroyed, thereby maintaining the progress of the compression destruction of the rigid polyurethane foam at a constant amount;
2. The knee bolster according to claim 1, wherein buckling of said energy absorbing ribs begins after said stopper portions come into contact with each other. a container for accommodating the rigid polyurethane foam being divided in the first direction, the container being provided with a pair of divided container bodies which engage with each other so as to restrict movement in a direction intersecting the first direction, and whose fitting with each other deepens as the rigid polyurethane foam is compressed and destroyed;
3. The knee bolster according to claim 1, wherein the energy absorbing rib is disposed on an outer surface of the container section. The knee bolster according to claim 3, wherein the pair of container segments have a box-shaped structure with opposing sides open. The knee bolster according to claim 3 or 4, in which the one container section and the energy absorbing rib are integrally molded from resin. The energy absorbing rib is formed in a lattice shape having a plurality of squares,
6. The knee bolster according to claim 3, wherein a reinforcing rib is provided on a surface of the one of the container sections opposite to the surface on which the energy absorbing rib is provided, the reinforcing rib extending along a diagonal line of the squares of the energy absorbing rib. the rib support wall of the one container section that is provided with the energy absorbing rib has an elongated shape,
The energy absorbing rib is in the form of a lattice having a plurality of square cells, and the size of the rib support wall in the short side direction is approximately an integer multiple of a diagonal line of the cell,
7. The knee bolster according to claim 3, wherein a pair of diagonal lines of each of the squares are arranged parallel to the longitudinal direction and the lateral direction of the rib support wall, and the diagonal lines of the squares are arranged to overlap a center line of the rib support wall in the lateral direction. The rigid polyurethane foam has an elongated shape when viewed from the first direction,
7. The knee bolster according to claim 1, wherein the energy absorbing rib is in the form of a lattice having a plurality of square cells, and a pair of diagonals of each of the cells are arranged parallel to the longitudinal direction and the lateral direction of the elongated shape.

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