JPH11155679A - Headrest for alleviating whiplash injury - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alleviating a whiplash injury by reducing a deformation quantity of a headrest when a head of a human body is collided with the headrest. SOLUTION: When a hemispherical head model 5 having a weight of 6.8 kg is collided with a predetermined point P on a surface of a cover from a normal line direction of the predetermined point P at a speed of 6.2 km/hr, a movement volume of the predetermined point P, which moves from the time when the head model contacts to the predetermined point P to the time the head model rebounds by repulsive elasticity of the headrest, is less than 40 mm, and a maximum load produced on the headrest is less than 0.7 kN. It is possible to reduce a deformation quantity of the headrest and to alleviate a whiplash injury when the head of the human body is collided with the headrest thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headrest provided on a seat of a vehicle such as an automobile for supporting a human head, and more particularly, to a whiplash absorbing a shock of a human head colliding in a rear-end collision or the like. The present invention relates to a whiplash-reducing headrest that can reduce symptoms.

[0002]

2. Description of the Related Art In recent years, various automobiles have been provided with various impact absorbing devices in order to absorb the impact at the time of a collision and protect the human body from the impact. For example, an airbag is incorporated in a steering wheel or an instrument panel, and an airbag is instantly inflated at the time of a collision, thereby preventing a passenger from colliding with the steering wheel or the instrument panel.

Japanese Patent Application Laid-Open No. 58-53560 proposes a steering wheel provided with a hollow bellows-shaped shock absorber having an air pin hole. According to this proposal, when a shock is applied and the shock absorber is compressed, the shock energy can be absorbed by the air compression resistance while escaping air from the air pin holes. Therefore, impact energy can be absorbed without generating springback (reaction force).

Further, as a shock absorbing structure of a door trim, a technique shown in FIG. 3 is also known. The shock absorbing structure includes a waist shock absorbing member 102 provided in a waist 101 of the door trim 100 and a shoulder shock absorbing member 104 provided in a shoulder 103. Both shock absorbing members 102,104
Are made of urethane foam, each having a mounting surface corresponding to the inner surface shape of the mounting portion, and formed in a block shape.

[0005] This shock absorbing structure is designed to absorb the shock energy by buckling the two shock absorbing members 102 and 104 by the shock energy applied from the side of the door. Further, the headrest of an automobile is formed of a foamed molded body having a core material inside and a surface covered with a skin. Urethane foam is the mainstream as a foam molded article, and in order to prevent wrinkles of the skin body and improve appearance quality,
Alternatively, urethane foam having a rebound resilience of 50% or more is used in order to enhance the use feeling.

[0006]

The factors that affect whiplash include the amount of deformation of the headrest when the headrest collides with the headrest during a rear-end collision, and the rebound of the human head due to the rebound resilience of the headrest. The amount is a major factor. That is, when the amount of deformation of the headrest is large and the amount of rebound is large, the swinging width of the head around the cervical vertebra becomes large at the time of the collision of the human head, and whiplash tends to occur.

[0007] Of these, the deformation amount of the headrest is greatly affected by the thickness of the foam existing between the surface in contact with the human head and the core material. That is, when the thickness of the portion of the foam increases, the amount of deformation also increases. Therefore, when the thickness of the portion is reduced, the amount of deformation can be reduced. However, if the thickness of the foam is reduced, there is a problem that the presence of the core material can be felt during normal use and the use feeling is impaired, and the thickness of the foam in that part needs to be 40 mm or more. Have been. However, in the conventional headrest, the thickness of the headrest at the time of collision increases with this thickness, and it is difficult to reduce whiplash.

Further, if the hardness of the foam is increased, the amount of deformation when the human head collides can be reduced.
However, in this case, there is a problem that the maximum generated load becomes large and the use feeling during normal use is impaired. It is also conceivable to provide a shock absorber having an air pin hole as described in JP-A-58-53560, but the use feeling of the headrest may be impaired, or the appearance may be impaired. This is not effective from the viewpoint of reducing the amount of deformation.

The present invention has been made in view of such circumstances, and reduces the amount of deformation and rebound of a headrest at the time of a collision with a human head while maintaining the same use feeling and appearance quality as before. An object of the present invention is to provide a headrest that can reduce whiplash by doing.

[0010]

The whiplash reducing headrest according to the first aspect of the present invention is characterized in that it has a bag-shaped outer skin, a core member arranged in the outer skin and having a stay, One end of the stay at a position where the stay is engaged with and held by the seat back when the head rest is used so that the distance from the top of the seat back is maximized in a headrest for a vehicle including a core material filled in between. And a predetermined point P on the surface of the epidermis at the portion where the human head abuts
When an impact test is performed in which a hemispherically shaped head model weighing 6.8 kg collides with the predetermined point P at a speed of 6.2 km / hr from the normal direction of the predetermined point P, the head model contacts the predetermined point P A predetermined point P after the headrest is rebounded by the rebound resilience of the headrest
Is less than 40 mm and the maximum load generated on the headrest during the impact test is 0.7 kN or less.

A feature of the whiplash reducing headrest according to claim 2 is that, in the headrest according to claim 1, the core material is made of urethane foam having a rebound resilience of 30% or less. Further, a feature of the whiplash reducing headrest according to the third aspect is that in the headrest according to the second aspect, the core member is made of a bar or a pipe, and has a substantially U-shape.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the whiplash reducing headrest of the present invention, when a hemispherical head model weighing 6.8 kg collides at a speed of 6.2 km / hr with a portion where the human head abuts, The amount of movement of the predetermined point P from contact with the predetermined point P to rebound by the rebound resilience of the headrest is 40 mm or less, and the maximum load generated on the headrest at the time of the collision is
0.7 kN or less. With such a headrest, the amount of deformation of the headrest when the human head collides can be reduced, and whiplash can be reduced.

Here, as the head model, a hemispherical model having a weight of 6.8 kg as shown in FIG. 2 is used. The radius of curvature of the hemisphere is desirably 82.5 mm, and the curved surface of the hemisphere collides with a predetermined point P. The position of the predetermined point P is located on the surface of the skin where the human head comes into contact, and is a straight line formed by intersecting a plane that divides the headrest approximately equally in the vertical direction into two and a plane that divides the headrest into two in the horizontal direction. And the intersection with the epidermis.

Then, a head model is caused to collide with a predetermined point P, which is a portion of the headrest as a sample, which is in contact with the human head, at a speed of 6.2 km / hr from the normal direction of the predetermined point P. At this time, the movement amount of the predetermined point P from when the head model comes into contact with the predetermined point P until the head model is rebounded by the rebound resilience of the headrest is
If the maximum load that occurs on the headrest at the time of the collision is 0.7 kN or less, the whiplash reduction effect is reduced when the headrest of a general shape is attached to the seat and it is assumed that the human head has collided. It will be overwhelming.

Here, when the head model collides, not only the core material of the headrest is deformed, but also the core material is mainly elastically deformed. Therefore, since the movement amount of the head model is the total amount of the deformation amount of the core material and the deformation amount of the core material, the movement amount of the head model may exceed the distance from the predetermined point P to the core material. . If the movement amount of the predetermined point P of the headrest exceeds 40 mm in the above-mentioned impact test, the swing amount of the head becomes large, which is not suitable for whiplash reduction. If the maximum load generated at the time of the collision exceeds 0.7 kN, the possibility of damaging the human head at the time of the collision increases.

The rebound resilience according to claim 2 is JIS-K-6401
It is measured as follows according to the following. (1) Testing machine 460mm from the top of the test piece by magnet or other method
5 specified in JIS-B-1501 (Steel balls for ball bearings)
Use a tester having a mechanism for freely dropping a / 8 average steel ball so as not to rotate. (2) Test method The test piece was placed on a horizontal table of the testing machine, and was 16 mm in diameter and weighed.
A 16.3g steel ball is dropped freely from a distance of 460mm from the top surface of the test piece, and the maximum rebound distance at that time is measured. The test is performed on each of the three specimens, or three of the one specimen.
The measurement is performed three times or more for each part, and the maximum rebound distance is recorded among the respective times. (3) Calculation The rebound resilience R is calculated by the following equation and is represented by an average value of three pieces.

R = 100 × D ₁ / D ₀ [where D ₀ : drop distance 460 (mm), D ₁ : repulsion distance (mm)] By the way, conventionally, if the rebound resilience is not 50% or more, it is favorable. The use feeling was not obtained. However, according to the study of the present inventors, it is inappropriate to evaluate the use feeling at a large acceleration such as free fall of the steel ball, such as the rebound resilience, and it is not appropriate to evaluate the collision at a smaller acceleration. It turned out to be something to be done. It has been clarified that, by appropriately setting the foaming characteristics of the core material, a good use feeling can be obtained even when the rebound resilience is 30% or less.

Therefore, the most significant feature of the invention according to claim 2 is that, in the headrest according to claim 1, the core material is made of urethane foam having a rebound resilience of 30% or less. That is, by using a low rebound resilience core material having a rebound resilience of 30% or less, it is possible to reduce springback while maintaining good use feeling. That is, when a large impact is applied to the headrest according to the first aspect of the invention, the entire core material is elastically deformed by the impact. At this time, since the core material has a rebound resilience of 30% or less, the springback after elastic deformation is small. This reduces whiplash.

When the load is released, the core material is gradually restored to its original shape, so that it can be used again as a headrest. The rebound resilience of the core material is 30%
When the value exceeds, the springback becomes large and it is difficult to reduce whiplash. The core material used for the headrest of the invention according to claim 1 can be formed of, for example, a thermoplastic elastomer, a silicone gel, or the like.
It is desirable that a polyol component having an average molecular weight of 4000 or less be reacted at an NCO index of 60 to 110 to form a foamed urethane foam. By using such urethane foam, it is possible to achieve both good use feeling and springback resistance (a large amount of reduction in springback). It is more desirable to use a polyol component having an average molecular weight of 3000 or less.

In order to form a urethane foam having a rebound resilience of 30% or less, the average molecular weight of the polyol component must be 40%.
It must be less than 00 (preferably less than 3000). As the polyol component, in addition to the main polyol having a relatively high molecular weight serving as a base material of the foam, various polyols such as a relatively high molecular weight auxiliary polyol and a low molecular weight polyol functioning as a crosslinking agent or a chain extender are mixed. The arithmetic average value (average molecular weight) obtained from the number average molecular weight of these polyols and the compounding ratio thereof is set to 4000 or less, whereby the rebound resilience of the obtained urethane foam is set to 30% or less. Can be.

As the isocyanate, TDI, MD
Although various isocyanates such as I and HMDI can be used, the use of TDI is particularly preferable because the resilience of the obtained urethane foam is easily controlled to 30% or less. If the NCO index is less than 60, it becomes difficult to form a urethane foam, and if the NCO index exceeds 110, it becomes difficult to reduce the rebound resilience of the urethane foam to 30% or less. A particularly preferred NCO index range is 70-95.

By the way, a headrest in which the entire core has a shock absorbing property has been proposed, but it is also possible to provide a shock absorbing member only at a necessary portion of the core material. A metal stay is generally fixed to the headrest so as to be detachably fixed to the seat. This stay is connected to a core buried inside the core. As the core material, it is the most inexpensive to use a substantially U-shaped material made of a bar material or a pipe material integrated with the stay.

However, it has conventionally been considered that a substantially U-shaped core material has a small area for receiving a load, so that the amount of deformation of the headrest becomes large, which has an adverse effect on whiplash reduction. For this reason, although expensive, a material having a surface structure serving as a load receiving surface or a substantially M-shaped material made of a rod material or a pipe material is widely used. However, in the headrest according to the second aspect, as described in the third aspect, even if a substantially U-shaped core made of a rod or a pipe is used, the amount of biting into the core at the time of impact is reduced. And the amount of deformation of the headrest can be reduced, so that whiplash can be reduced.
In addition, since the cost of the core material is low, it is preferable in terms of cost.

[0024]

The present invention will be described more specifically with reference to test examples and examples. (1) Test Example <Specimen A> 57 parts by weight of a polyol component having an average molecular weight of 3500 obtained by mixing various polyols, and crude M
43 parts by weight of DI (polymeric 4,4'-diphenylmethane diisocyanate) and 3 parts by weight of water were mixed and freely foamed to form a foam. The NCO index is 95. Cut the obtained foam to a thickness of 30 mm,
Test piece A was obtained.

<Specimen B> 69 parts by weight of a polyol component having an average molecular weight of 3,000 obtained by mixing various polyols, 31 parts by weight of TDI, and 2.9 parts by weight of water are mixed and foamed by free foaming. Was formed. The NCO index is 80. The obtained foam was cut into the same size as the test piece A to obtain a test piece B.

<Specimen C> 58.9 parts by weight of a polyol component having an average molecular weight of 2600 obtained by mixing various polyols, 41.1 parts by weight of a crude MDI (polymeric 4,4′-diphenylmethane diisocyanate) prepolymer,
4 parts by weight of water were mixed and freely foamed to form a foam. The NCO index is 80. The obtained foam was cut into the same size as the test piece A to obtain a test piece C.

<Specimen D> 72 parts by weight of a polyol component having an average molecular weight of 1750 obtained by mixing various polyols, 28 parts by weight of TDI, and 1.0 part by weight of water were mixed and foamed by free foaming. Was formed. NCO index is 110
It is. The obtained foam was cut into the same size as the test piece A to obtain a test piece D.

<Specimen E> 66 parts by weight of a polyol component having an average molecular weight of 4500 obtained by mixing various polyols, 44 parts by weight of a crude MDI (polymeric 4,4′-diphenylmethane diisocyanate) prepolymer, 3 parts by weight of water were mixed and free-foamed to form a foam. The NCO index is 70. The obtained foam was cut into the same size as the test piece A to obtain a test piece E.

<Specimen F> 64.2 parts by weight of a polyol component having an average molecular weight of 5,000 obtained by mixing various polyols, 35.8 parts by weight of a crude MDI (polymeric 4,4′-diphenylmethane diisocyanate) prepolymer,
3 parts by weight of water were mixed and free-foamed to form a foam. The NCO index is 80. The obtained foam was cut into the same size as the test piece A to obtain a test piece F.

<Specimen G> 48.8 parts by weight of a polyol component having an average molecular weight of 2600 obtained by mixing various polyols, 51.2 parts by weight of a crude MDI (polymeric 4,4′-diphenylmethane diisocyanate) prepolymer,
4 parts by weight of water were mixed and freely foamed to form a foam. The NCO index is 120. The obtained foam was cut into the same size as the test piece A to obtain a test piece G.

<Test piece H> 76 parts by weight of a polyol component having an average molecular weight of 1750 obtained by mixing various polyols, 24 parts by weight of TDI, and 1.0 part by weight of water were mixed, and the mixture was foamed by free foaming. Was formed. The NCO index is 90. The obtained foam was cut into the same size as the test piece A to obtain a test piece H.

<Specimen I> 80 parts by weight of a polyol component having an average molecular weight of 1750, obtained by mixing various polyols, 20 parts by weight of TDI, and 1.1 parts by weight of water were mixed and foamed by free foaming. Was formed. The NCO index is 70. The obtained foam was cut into the same size as the test piece A to obtain a test piece I.

<Specimen J> 82 parts by weight of a polyol component having an average molecular weight of 1500 obtained by mixing various polyols, 18 parts by weight of TDI, and 1.1 parts by weight of water were mixed and freely foamed to form a foam. Was formed. The NCO index is 60. The obtained foam was cut into the same size as the test piece A to obtain a test piece J.

<Specimen K> 66 parts by weight of a polyol component having an average molecular weight of 6000 obtained by mixing various polyols, 70% by weight of a crude MDI (polymeric 4,4'-diphenylmethane diisocyanate) prepolymer, and TD
34 parts by weight of an isocyanate mixture consisting of 30% by weight of I and 2.2 parts by weight of water were mixed and freely foamed to form a foam. The NCO index is 95. The obtained foam was cut into the same size as the test piece A to obtain a test piece K.

<Specimen L> 56 parts by weight of a polyol component having an average molecular weight of 6000 obtained by mixing various polyols, 85% by weight of a crude MDI (polymeric 4,4'-diphenylmethane diisocyanate) prepolymer, and TD
44 parts by weight of an isocyanate mixture consisting of 15% by weight of I and 1.8 parts by weight of water were mixed and freely foamed to form a foam. The NCO index is 90. The obtained foam was cut into the same size as the test piece A to obtain a test piece L.

<Test> For the test pieces A to L, the density was measured, and the load required for compressing the test pieces in the thickness direction by 25%, 50% and 75% was measured. The rebound resilience was measured by the method described above. Table 1 shows the results.

[0037]

[Table 1] According to Table 1, the average molecular weight of the polyol is in the range of 2000 to 4000 and the NCO
If the index is in the range of 60 to 110, the rebound resilience
20% to 30%, both good feeling of use and springback resistance. However, even if the average molecular weight of the polyol is in the range of 2000 to 4000 as in Test piece G, if the NCO index exceeds 110, the rebound resilience will be 35.
%, Which indicates that although the use feeling is excellent, the springback resistance is reduced.

When the average molecular weight of the polyol exceeds 4000 as in the test pieces E, F, K, and L, the rebound resilience is 35.
% Or more, indicating that the use feeling is excellent but the springback resistance is reduced. Further, by setting the composition of the raw materials as in the test pieces D, H, I, and J, the rebound resilience can be further reduced. (2) Example and Comparative Example (Example 1) FIG. 1 shows an impact absorbing headrest according to an example of the present invention. This headrest is made of a substantially U-shaped steel bar, and has a core 1 having stays 10 at both ends.
And a bag-shaped skin 3 covering the surface of the core material 2. Core material 2
Is formed entirely of urethane foam having the same composition as the test piece C.

The headrest is formed by disposing a core material 1 in a mold, injecting a urethane foam resin into the mold, and foam-molding to integrate the core material 1 and the core material 2 and then form a separately formed bag. It was produced by coating a skin 3 in the shape of a letter. In this headrest, the core material 1 and the bag-shaped outer skin 3 are arranged in a mold, and a urethane foam resin is injected into the outer skin 3 and foam-molded to be integrally joined to the outer skin 3 and the core material 1. A core material 2 can also be formed.

In the obtained headrest, a stay 10 was fixed to the jig 4 as shown in FIG. That is, the headrest is positioned such that the predetermined point P at which the human head abuts is located above and the normal line of the predetermined point P is vertical, and the horizontal distance L from the predetermined point P to the fixed point of the stay 10 is 183.5 mm. Was fixed to be. The vertical distance from the predetermined point P to the core 1 is 40 mm.

The predetermined point P is an intersection of a straight line formed by intersecting a plane that divides the headrest into two substantially equally in the vertical direction and a plane that divides the headrest into two parts, and the surface of the skin 3. Also, when using the headrest so that the distance from the top of the seat back is the maximum,
The position where the stay 10 is engaged with and held by the seat back is a fixed point. Then, in the state of FIG. 2, the normal from the predetermined point P is vertical.

Then, a head model 5 weighing 6.8 kg from above
Is subjected to an impact test in which the sample is naturally dropped and collides with a predetermined point P. Here, the head model 5 includes a hemispherical portion 50 having a radius of curvature of 82.5 mm, and the spherical surface of the hemispherical portion 50 is naturally dropped downward. Note that a reflector 51 and an accelerometer 52 are attached to the hemisphere 50. An optical distance sensor 6 is provided below the head model 5 so that the distance between the reflecting mirror 51 and the optical distance sensor 6 can be detected.

When the head model 5 collides with the predetermined point P at a collision speed of 6.2 km / hr, the amount of movement of the head model 5 from when the head model 5 comes into contact with the skin 3 to when the head model 5 is rebounded is determined. The measurement was performed by the optical distance sensor 6, and the maximum load generated at the time of the collision was measured by the accelerometer 52. Each measurement was performed twice, the average was calculated, and the results are shown in Table 2. In addition,
Strictly, the amount of movement of the predetermined point P should be measured, but the measurement is often difficult. Therefore, in this embodiment, the movement amount of the head model 5 is measured. When the predetermined point P moves in an arc shape due to the bending of the stay 10 or the like, a slight deviation occurs from the measured value. However, the deviation is actually an error range, and the movement amount of the predetermined point P ≒ the head model The movement amount is 5.

The predetermined point P is set at an offset position shifted by 30 mm in the vertical direction of the headrest (in FIG. 2, the horizontal direction of the paper), and the head model 5 is caused to collide with the predetermined point P. The amount of movement and the maximum generated load were measured. Table 2 shows the results. (Example 2) A headrest similar to that of Example 1 was prepared except that the shape of the core material 1 was substantially M-shaped, and the movement amount and the maximum generated load of the head model 5 were measured in the same manner as in Example 1. did.
Table 2 shows the results.

(Example 3) A headrest similar to that of Example 1 was manufactured except that an iron adjuster having a surface structure serving as a load receiving surface was held at the center of the core material 1.
In the same manner as in Example 1, the movement amount of the head model 5 and the maximum generated load were measured. Table 2 shows the results. (Comparative Example 1) A headrest was manufactured in the same manner as in Example 1 except that the entire core material 2 was formed from the same urethane foam as the test piece L.
And the maximum generated load were measured. Table 2 shows the results.

Comparative Example 2 A headrest was manufactured in the same manner as in Example 2 except that the entire core material 2 was formed from the same urethane foam as the test piece L. And the maximum generated load were measured. Table 2 shows the results. (Comparative Example 3) A headrest was produced in the same manner as in Example 3 except that the entire core material 2 was formed from the same urethane foam as the test piece L.
And the maximum generated load were measured. Table 2 shows the results.

[0047]

[Table 2]

From Table 2, the headrests of Examples 1 to 3 are as follows.
The amount of movement of the head model (that is, the amount of movement of the predetermined point P) is 40 mm
And the maximum generated load is 0.7 kN or less,
Each of the headrests of Comparative Examples 1 to 3 shows a smaller value, and is clearly superior in the whiplash reducing effect. Further, in the headrest of the first embodiment, although a substantially U-shaped core material is used, a higher whiplash reducing effect is obtained as compared with Comparative Example 3 using a conventional surface structure type core material, The cost can be reduced by simplifying the core material.

Also, even when the predetermined point P is shifted to the offset position by 30 mm in the vertical direction, the movement of the head model (that is, the movement of the predetermined point P) is 40 mm or less and the maximum generated load is 0.7 kN or less. This shows that the whiplash reducing effect is excellent.

[0050]

According to the shock absorbing headrest according to the first to third aspects, the core material absorbs the impact applied to the headrest when the vehicle is hit by a rear impact, and the spring back of the core material. Is small, so that whiplash can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a headrest according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a test method in an example.

FIG. 3 is a sectional view of a conventional shock absorbing device.

[Explanation of symbols]

1: core material 2: core material 3: skin 4: jig 5: head model 6: optical distance sensor

Claims (3)

[Claims] 1. A vehicle headrest comprising: a bag-shaped outer skin, a core member having a stay disposed in the outer skin, and a core material filled between the outer skin and the core material. One end of the stay is fixed at a position where the stay is engaged and held with the seat back when the headrest is used so that the distance from the uppermost portion is maximized, and the surface of the epidermis at a portion where the human head abuts When an impact test is performed in which a hemispherical head model having a weight of 6.8 kg collides with the predetermined point P at a speed of 6.2 km / hr from the normal direction of the predetermined point P to the predetermined point P, The amount of movement of the predetermined point P from the time when the part model comes into contact with the predetermined point P until it is rebounded by the rebound resilience of the headrest is 40 mm or less, and the maximum load generated in the headrest during the impact test is 0.7 kN. A whiplash reducing head characterized by the following: Strike. 2. The whiplash reducing headrest according to claim 1, wherein the core material is made of urethane foam having a rebound resilience of 30% or less. 3. The whiplash reducing headrest according to claim 2, wherein the core material is made of a rod material or a pipe material and has a substantially U-shape.