Seat structure for vehicle

Details Seat structure for vehicle Seat structure for vehicle

2000-05-16

2003-02-25

Barfield, Anthony D. (Department: 3636)

Chairs and seats

Crash seat

Force-absorbing means incorporated into back

C297S216140

Reexamination Certificate

active

06523892

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a seat structure for a vehicle, which displaces a headrest forward in a rear impact collision.
BACKGROUND OF THE INVENTION
Japanese Patent Laid-Open No. 10-80338 (see
FIGS. 12
to
14
) describes a structure, which receives the passenger load in a rear impact collision by moving backward a shock receiving frame
52
located in front of a seatback frame
51
, moves the lower end portion of a headrest support frame
53
backward upon backward movement of the shock receiving frame
52
, and moves a headrest
55
fixed to the upper end portion of the headrest support frame
53
toward a head
56
of the passenger, since the middle portion of the headrest support frame
53
is axially supported by the seatback frame
51
to be pivotal in the back-and-forth direction.
Japanese Patent Laid-Open No. 7-291005 (see
FIGS. 9
to
11
) describes a structure in which a coupling member
58
, which extends backward upon receiving the passenger load in a rear impact collision, is provided to the coupling portion between a seatback frame
51
that supports a headrest
55
, and a cushion member
57
which is provided to the seatback frame
51
, the headrest support frame
53
pivots about a pivot member
54
when the coupling member
58
extends backward in a rear impact collision, and the headrest
55
moves forward toward a head
56
of a passenger.
When the upper body of the seated passenger is divided into a lower portion (waist) and an upper portion (chest), and the passenger is normally seated, the lower portion of the upper body contacts a seatback, but the upper portion of the upper body is slightly separated from the seatback. Hence, in a rear impact collision, the seatback receives the load from the lower portion of the upper body, and then that from the upper portion of the upper body. In such rear impact collision, the load from the lower portion of the upper body is larger than that from the upper portion of the upper body. That is, in a rear impact collision, the load from the lower portion (waist) of the upper body is quicker and larger than that from the upper portion of the upper body. Ideally, in a rear impact collision, since the headrest must be quickly and stably moved forward and upward toward the head of a passenger, the present invention is premised on that the headrest is moved forward upon receiving the load from the passenger's waist, as described in Japanese Patent Laid-Open Nos. 7-291005 and 10-80338 (
FIGS. 9
to
14
). Under such circumstance, as shown in
FIGS. 9
to
14
, when the headrest support frame
53
is axially supported by the upper frame of the seatback frame
14
, since the spacing between an axial support point
54
of the frame
53
and the shock receiving frame
52
becomes considerably larger than that between the axial support point
54
and headrest
55
, it is difficult to assure a required forward moving amount of the headrest. That is, upon displacing the headrest forward by a required amount in a rear impact collision, since the shock receiving frame requires a large moving amount since it receives the passenger's load, the forward displacement amount of the headrest cannot reach a required level or forward displacement delays. Especially, such problem is conspicuous when the seated passenger is lightweight.
On the other hand, a required forward moving amount of the headrest may be assured by setting the axial support portion of the frame that supports the headrest at substantially the middle position of the seatback in the up-and-down direction, i.e., prolonging the distance from the axial support portion to the headrest. In this structure, since a portion of the frame above the axial support portion is largely displaced forward, the upper portion of the frame may unwantedly push the back of the passenger forward.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above problems, and has as its object to provide a seat structure for a vehicle, which can quickly and stably move a headrest forward by a required amount upon receiving a load from the passenger's waist in a rear impact collision.
The present invention has been made in consideration of the above problems, and has as its another object to provide a seat structure for a vehicle, which can suppress forward dislodging of a load transfer portion while quickly and stably moving a headrest forward by a required amount upon receiving a load from the passenger's waist in a rear impact collision.
In order to solve the aforementioned problems and to achieve the above objects, according to the first invention, since a load transfer portion is axially supported by side surface frames below an upper surface frame, it can receive a load from the passenger's waist and the headrest can be quickly and stably moved forward by a required amount in a rear impact collision.
According to the second invention, since the instantaneous center of rotation (center of rotation) of the load transfer portion is set above the mean load point (input center) of the load acting from the passenger to a pressure receiving portion and load transfer portion, the headrest can be reliably displaced forward by the load acting from the passenger in a rear impact collision.
According to the third invention, the structure further comprises a first guide for moving the pressure receiving portion backward and upward by the load acting on the pressure receiving portion, and a second guide for moving the load transfer portion upward, the first guide is located below the second guide, and the first and second guides respectively axially support the load transfer portion and pressure receiving portion on the side surface frames below the upper surface frame, thus moving the pressure receiving portion by a simple structure. Also, the headrest can be reliably displaced upward and forward by the backward load acting from the passenger in a rear impact collision.
According to the fourth invention, the first and second guides comprise a combination of link members for coupling the side surface frames and pressure receiving portion, and guide holes which are formed in the side surface frames and guide the load transfer portion upward, thus moving the pressure receiving portion by a mechanically simple structure.
Since the first and second guides have different support structures, even when, for example, a seatback frame has been twisted, the headrest can be stably displaced forward and upward in a rear impact collision. Since one of the first and second guides uses the link member having excellent durability and operation stability, and the other uses the guide hole that can be formed in a small space, operation stability and space savings can be maintained at high level.
According to the fifth invention, since the first guide comprises link members for coupling the side surface frames and pressure receiving portion, and the second guide comprises guide holes which are formed in the side surface frames and guide the load transfer portion upward, the pressure receiving portion can be moved by a mechanically simple structure.
In general, a lumber support that protrudes forward to hold the passenger's waist is formed on the lower seatback portion, but no lumber support is formed on the upper seatback portion since it disturbs driving operation of the passenger. That is, a member to be disposed inside the seatback can have only a smaller size in the back-and-forth direction of the vehicle body in the upper seatback portion than that in the lower seatback portion, but a structure that does not require any large space, i.e., a guide hole, is adopted for at least the upper axial support point, thus minimizing the member size in the back-and-forth direction of the vehicle body. On the other hand, a guide hole can also be used as the lower axial support point. However the link member has excellent durability and operation stability, and can stably operate by adopting a support method different from that of the upper axial su

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