Chairs and seats – Bottom or back – Cushioned
Reexamination Certificate
2002-12-04
2004-11-16
Cranmer, Laurie K. (Department: 3636)
Chairs and seats
Bottom or back
Cushioned
C297S452270, C297S452560, C297S452130
Reexamination Certificate
active
06817674
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seat structure, more in detail, to a seat structure suitable for transportation machines such as a plane, a train, a ship, a fork lift, and an automobile, or for various chairs used in the inside or the outside of a building.
2. Description of the Related Art
Polyurethane foam or a structure composed of a combination of a polyurethane foam and a metal spring are usually used as a cushioning material used for a seat for a plane, a train, a ship, and an automobile. Among spring characteristics and damping characteristics which polyurethane foam possesses, usually former spring characteristics are thought as important in design in consideration of vibration absorption property and displacement amount.
However, there is an individual difference in a shape of the haunches and a shape of a skeletal structure (shape of the letter S) of the back of a human body, fitness of a seat cushion portion or a seat back portion of a seat is not sufficient for the human body, and there arises deviation in the manner of contact of the human body to the seat cushion portion and the seat back portion of a seat. Therefore, there is a room to improve in point of a body pressure dispersion property. Further, in the above described vehicle seat, it is always required to absorb more efficiently an impact energy caused by collision.
On the other hand, the present inventors have proposed various seat structures for transportation machines in which three-dimensional net member is used as a cushioning material. Especially, a three-dimensional net member shows cushioning characteristic (spring characteristics and damping characteristics) equal to that of polyurethane foam and excellent in air permeability because it can be used as a tension field by providing it as a tension structure member through suspension onto a frame though it is a thin type. When this three-dimensional net member is used as a cushioning material, in order to function the damping characteristics sufficiently due to deformation of the three-dimensional net member, it is provided with almost no tension between the side frames at the time of no load so that the elongation thereof is set to be 5% or less in a static seating state.
However, there is a demand for a seat structure having a narrow seat width, for instance, only about 380 mm to about 400 mm in the seat width. When the three-dimensional net member is provided loosely without almost no rate of elongation on a seat having such a narrow width, since the acromion, the scapula, the haunches and the pelvis come close to the frame of the seat side portion due to thinness of the three dimensional net member, a feeling of something foreign coming from these portions is apt to be felt when a person is seated.
In order to solve the above disadvantage, it is conceivable to make sinking-in small when a person is seated by putting up the three-dimensional net member with predetermined tension. However, when taking this means, a feeling of stroke on seating is disappeared, and hard feeling of seating with no fitness is felt by a seated person and when back-and-forth vibration is inputted, slipping of the backside is apt to occur. Further, there remains a problem in vibration absorption characteristics when a large excitation force such as vibration having a large amplitude is inputted because a spring constant becomes high on seating.
SUMMARY OF THE INVENTION
The present invention is achieved in view of the above problems, and the object of the present invention is to provide a seat structure in which rebound of a human body can be suppressed with a small reaction force due to large damping ratio and the impact force inputted into a human body is relaxed by damping the impact force on large deformation such as input of impact force, in particular, by forming a predetermined tension field at least one of a seat cushioning member and a back cushioning member to make a structure in which damping characteristics are thought more important than spring characteristics, and on the other hand, vibration relief property is not lost against input with a small excitation force due to the spring characteristics by making the effect of the damping characteristics small. In addition to this, when a three-dimensional net member is used as a cushioning member, a feeling of something foreign in the frame to a human body is more reduced and a feeling of stroke can be increased in comparison with a seat structure using a conventional three-dimensional net member.
In order to solve the above-described problems, in claim
1
of the present invention, provided is a seat structure comprising a cushion structure having a seat cushioning member for a seat cushion and a back cushioning member for a seat back, wherein the seat cushioning member and the back cushioning member are provided as a tension structure having a tension field formed from an elastic member, and
at least one of the seat cushioning member and back cushioning member is structured to vary the tension in the tangential direction by changing the strain energy in accordance with the magnitude of an excitation force to be an input, and different damping characteristics are exhibited according to the magnitude of the excitation force to be an input in such a manner that the damping characteristics function at a small damping ratio for an input of a small excitation force, and the damping characteristics function at a large damping ratio for an input of a large excitation force.
In claim
2
of the present invention, provided is the seat structure according to claim
1
, wherein the cushioning structure forms a vibration system in which an arbitrary portion of the seat cushioning member positioned more front than the vicinity of the boundary of the seat cushion portion and the seat back portion and/or an arbitrary portion of the back cushioning member positioned upper than the vicinity of the boundary portion serves as an free end by putting an extendable direction on the plane surface of the cushioning structure along the back-and-forth direction of the seat cushion portion and along the vertical direction of the seat back portion respectively, and by holding the vicinity of the boundary portion of the seat cushion portion and the seat back portion; and
wherein in at least one of the seat cushioning member and back cushioning member in which the vibration system is formed, tension in the tangential direction is varied by changing the strain energy of the tension structure formed from an elastic member in accordance with the excitation force to be an input, and at least the other of the seat cushioning member and back cushioning member includes a portion exhibiting relatively high spring characteristics in the normal line direction of the tension structure, and has a structure in which an excitation force inputted from the normal line direction to the cushioning member is scatterable into an excitation force in the tangential direction by a combined function of these different characteristics.
In claim
3
of the present invention, provided is the seat structure according to claim
1
, wherein any of the seat cushioning member and the back cushioning member which can exhibit damping characteristics different in damping ratio according to the magnitude of the excitation force to be an input is formed of a three-dimensional net member made by connecting a pair of ground knitted fabrics disposed apart from each other with a connecting fiber; and
wherein the cushioning member is put up at a rate of elongation of 30% or less between side frames provided in the seat cushion portion or in the seat back portion at the time of no load, and is arranged to be in a camber shape provided with a top portion bulging upward in the case of the seat cushion portion and forward in the case of the seat back portion within an area of contact with a human body.
In claim
4
of the present invention, provided is the seat structure according to claim
1
, wherein both of the seat cushioning m
Chizuka Kazuyoshi
Fujita Etsunori
Kawasaki Seiji
Kikusui Miho
Kojima Shigeyuki
Cranmer Laurie K.
Delta Tooling Co., Ltd.
Steinberg & Raskin, P.C.
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