CN211995293U - Chair frame - Google Patents

Abstract

The utility model provides a can make seat frame of back frame lightweight and high strength. A seat frame mounted on a vehicle includes a seat cushion frame, a back frame, a connecting device for connecting the seat cushion frame and the back frame, and a seat belt, wherein the back frame includes: a first frame and a second frame made of steel, which are separated from each other in the left-right direction and extend in the up-down direction; an upper frame; a steel lower frame; and a first coupled portion and a second coupled portion fixed to left and right sides of the lower frame, respectively, and coupled to the coupling device, respectively, wherein the first frame is a high-tensile steel frame, the second frame is a steel frame other than the high-tensile steel, and the lower frame is a high-tensile steel frame having a tensile strength greater than that of the high-tensile steel of the first frame.

Description

Chair frame

Technical Field

The present invention relates to a seat frame, and more particularly, to a seat frame that can reduce the weight and increase the strength of a back frame.

Background

A seat frame mounted in a vehicle such as an automobile is connected to a lower end portion of a back frame via a connecting device at a rear end portion of a cushion frame. Among such back frames are back frames as follows: a pull-out portion for pulling out a webbing of a seat belt for restraining an upper body of a seated person forward is provided at an upper portion of 1 side frame extending in the vertical direction (patent document 1). In the technique disclosed in patent document 1, when the webbing is pulled and a strong tensile load is applied to the upper portion of the side frame toward the front through the pull-out portion at the time of a vehicle collision or the like, the side frame is made of a high-tensile steel plate to increase the strength thereof in order to prevent large deformation or breakage of the back frame.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-156212

SUMMERY OF THE UTILITY MODEL

Problem to be solved by the utility model

However, in the above-mentioned patent document 1, since the load (impact) at the time of vehicle collision is received mainly by the side frame provided with the pull-out portion, it is necessary to form the first frame made of high-tensile steel plate thick to ensure the strength of the first frame. However, the first frame is thickened, and the first frame is heavy, which causes a problem that the whole backrest frame is heavy.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a seat frame that can reduce the weight and increase the strength of a back frame.

Means for solving the problems

To achieve the object, a seat frame according to the present invention is a seat frame mounted on a vehicle, comprising: a seat cushion frame; a back frame disposed at a rear end of the seat cushion frame; a connecting device for connecting a rear end of the cushion frame and a lower end of the back frame; and a seat belt, the back frame including: a first frame and a second frame separated from each other in a left-right direction and extending in an up-down direction; an upper frame connecting upper portions of the first frame and the second frame to form an upper edge portion of the back frame; a lower frame connecting lower portions of the first frame and the second frame; and a first coupled portion and a second coupled portion fixed to both left and right sides of the lower frame, respectively, and coupled to the coupling device, respectively, the seatbelt including: a pull-out portion provided on the first frame side of the upper frame with respect to a center in a left-right direction or provided on an upper portion of the first frame; a connecting portion connected to a connected portion that is located at a position apart in a left-right direction from a connecting portion between the first frame and the lower frame and is disposed on a rear end portion side of the seat cushion frame; and a webbing that is mounted on the pull-out portion and the connecting portion, wherein the first frame is a high-tension steel frame, the second frame is a steel frame other than the high-tension steel, and the lower frame is a high-tension steel frame having a tensile strength greater than that of the high-tension steel of the first frame.

Effect of the utility model

According to the seat frame of the first aspect, the pull-out portion is provided on the first frame side of the upper frame with respect to the center in the left-right direction or on the upper portion of the first frame, and the webbing is bridged between the pull-out portion and the connecting portion to restrain the shoulder portion of the seated person. At the time of a vehicle collision (particularly, at the time of a frontal collision) in which such a seat frame is mounted, a load is applied to each part of the back frame that pulls the pull-out portion forward via the webbing and tilts the back frame forward about the vicinity of the first to-be-connected portion and the second to-be-connected portion as a fulcrum. Specifically, a bending load is mainly applied to the first frame, a torsion load or a shear load is mainly applied to the lower frame in which the first coupled portion and the second coupled portion are fixed to both the left and right sides, and a bending load and a torsion load are mainly applied to the second frame coupled to the upper portion of the first frame via the upper frame.

In addition, in a steel material, the bending strength, the torsional strength, and the shear strength are generally determined according to the tensile strength, and the torsional strength and the shear strength of the steel material are smaller than the bending strength of the steel material regardless of the tensile strength of the steel material. Therefore, compared to the case where the second frame to which the bending load and the torsional load are mainly applied is made stronger, the first frame to which the bending load is mainly applied without being substantially applied with the torsional load or the shear load is made stronger, and the strength necessary for preventing deformation or breakage of both the first frame and the second frame connected by the upper frame can be further reduced.

In the frame below, the bending stress generated in the first frame by the fixed end is larger as it approaches the fixed end, and thus the necessary strength of the first frame is higher as it approaches the fixed end. Since the tensile strength of the high-tensile steel forming the first frame is higher than the tensile strength of the steel other than the high-tensile steel forming the second frame, the first frame can be made thin to reduce the weight of the first frame and to sufficiently increase the strength of the first frame.

Since the lower frame is formed of high-tensile steel having a tensile strength greater than that of the first frame, the torsional strength and the shear strength of the lower frame can be sufficiently ensured over the entire length with respect to the bending strength of the first frame when a forward load is applied to the pullout portion, and the lower frame can be reduced in weight.

Further, since the load applied to the pull-out portion in the forward direction can be dispersed and received by the first frame and the lower frame having sufficiently high strength, the necessary strength of the first frame and the lower frame is reduced, and the first frame and the lower frame can be made lightweight by thinning, for example. As a result, the back frame can be made lightweight and high in strength.

According to the seat frame of the second aspect, the following effects are obtained in addition to the effects obtained by the seat frame of the first aspect. The lower frame is provided with: a first lower portion extending from the first frame to a side opposite to the second frame and fixed to the first portion to be connected; and a second lower portion extending from the first frame to a side opposite to the first lower portion and fixed to the second coupling portion. In this case, a larger torsional load and a larger shear load are applied to the lower frame (the first lower portion and the second lower portion) than in the case where the first portion to be connected is provided in the lower portion of the first frame without the first lower portion. Since the tensile strength of the high-tensile steel of the lower frame is greater than that of the high-tensile steel of the first frame, the backrest frame can be sufficiently strengthened and lightened even if the first lower portion is provided.

According to the seat frame of the third aspect, the following effects are obtained in addition to the effects obtained by the seat frame of the first aspect. The backrest frame is provided with a reinforcement member that is overlapped on a coupling portion between the first frame and the lower frame and is coupled with the first frame and the lower frame. Accordingly, when a load is applied to the draw-out portion in the forward direction and the first frame tries to tilt forward about the fulcrum, the stress generated in the coupling portion between the first frame and the lower frame can be reduced by the stress generated in the reinforcing member. As a result, the coupling portion between the first frame and the lower frame can be made high in strength.

According to the seat frame of the fourth aspect, in addition to the effects exhibited by the seat frame of the first aspect, the following effects are exhibited. The back frame includes a reinforcement frame that connects the first connected portion and the first frame above the lower frame on a lower side than a vertical center. This makes it possible to reduce the required strength of each portion in the load transmission path from the first frame to the first portion to be connected, which is located below the connecting portion between the first frame and the reinforcing frame, and therefore, to reduce the weight of the back frame by, for example, reducing the thickness of each portion having a low required strength.

The seat frame according to the fifth aspect provides the following effects in addition to the effects provided by the seat frame according to any one of the first to fourth aspects. Since the connecting member is engaged with the outer peripheral surface of the lower frame and the connecting member is engaged with the first coupled portion or the second coupled portion, it is possible to transmit torque generated in the lower frame in accordance with a load applied to the pull-out portion in the forward direction to the connecting member and to transmit a load corresponding to the torque from the connecting member to the first coupled portion or the second coupled portion. Further, since the connecting member is engaged with the first coupled portion or the second coupled portion at a position spaced apart from the outer peripheral surface of the lower frame in the up-down direction or the front-rear direction, it is possible to reduce the load transmitted from the connecting member to the first coupled portion or the second coupled portion in accordance with the torque of the lower frame. As a result, the transmission path of the load from the lower frame to the first coupling target portion or the second coupling target portion can be strengthened.

According to the seat frame of the sixth aspect, in addition to the effects exhibited by the seat frame of the fifth aspect, the following effects are exhibited. The connecting member includes: a cylinder portion engaged with an outer peripheral surface of the lower frame; and an extension portion that is joined to the first coupled portion or the second coupled portion. The extension is formed in a channel steel shape with two flanges extending from both side edges of the web. The flange extends linearly in a direction away from the cylindrical portion when viewed in the left-right direction. This can improve the strength and rigidity of the extension portion, and can easily disperse the shear stress generated at the joint portion between the extension portion and the first coupled portion or the second coupled portion along the flange, thereby increasing the strength of the joint portion.

Drawings

FIG. 1 is a perspective view of a seat frame according to one embodiment.

Fig. 2 is a rear view of the back frame.

Fig. 3 is a sectional view of the back frame at the line III-III of fig. 2.

Fig. 4 is a cross-sectional view of the back frame at line IV-IV of fig. 2.

Fig. 5 is a sectional view of the back frame at line V-V of fig. 2.

Description of the symbols

1 seat frame

2 seat cushion frame

3 backrest frame

4 tilting means (connecting means)

5 safety belt

5a woven tape

5c pull-out part

5e connecting part

5f connected part

11 first frame

12 second frame

13 upper frame

14 lower frame

14a first lower part

14b second lower part

15 first portion to be joined

16 second coupled part

20 lower reinforcing member (reinforcing member)

21 first connecting part (connecting part)

21a first tube part (tube part)

21b first extension (extension)

22 second connecting part (connecting part)

22a second tube part (tube part)

22b second extension (extension)

23 reinforce the frame.

Detailed Description

Hereinafter, preferred embodiments will be described with reference to the drawings. First, a seat frame 1 according to an embodiment will be described with reference to fig. 1. As shown in fig. 1, the seat frame 1 is a frame used for a left seat and a center seat of three-seat seats of an automobile. The seat frame 1 includes: a seat cushion frame 2; a back frame 3 disposed at a rear end of the seat cushion frame 2; a reclining device (connecting device) 4 that connects the rear end portion of the cushion frame 2 and the lower end portion of the back frame 3; and a harness 5 that restrains an upper body of a seated person seated on the seat.

The seat cushion frame 2 is a steel frame of a seat cushion on which a seated person sits. The seat cushion frame 2 is formed in a substantially square frame shape and attached to a vehicle body (not shown). The cushion is formed by supporting a cushion pad (not shown) made of foamed synthetic resin such as flexible urethane foam having elasticity by the cushion frame 2 and covering the cushion pad with a cover (not shown) made of fabric, synthetic leather, or the like.

The back frame 3 is a frame of a seat back as a back of a seated person. A back pad (not shown) made of foamed synthetic resin such as flexible polyurethane foam having elasticity is supported by the back frame 3, and the back pad is covered with a cover (not shown) made of fabric, synthetic leather, or the like, thereby forming a seat back.

The reclining device 4 is a device that couples the seat cushion frame 2 and the back frame 3 so that the back frame 3 can rotate relative to the seat cushion frame 2 about a rotation shaft (not shown) extending in the left-right direction. The reclining devices 4 are disposed on the left and right sides of the cushion frame 2 and the back frame 3, respectively. The reclining device 4 can adjust the reclining angle of the back frame 3 with respect to the seat cushion frame 2 by a seated person operating a lever or a switch, not shown. On the other hand, when the lever or the switch is not operated by the seated person or the like, the reclining device 4 locks the reclining angle of the back frame 3 with respect to the seat cushion frame 2.

The seat belt 5 is a three-point seat belt that restrains the left and right shoulders of the waist of a seated person seated in the center seat. The seat belt 5 includes: a woven tape 5 a; a retractor 5b attached to the back frame 3; a pull-out portion 5c provided at an upper portion of the back frame 3; a fixed portion 5d disposed at the center in the left-right direction of the rear end portion of the cushion frame 2; a connecting portion (tongue piece) 5e provided slidably with respect to the webbing 5 a; and a connected portion (buckle) 5f disposed on the right side of the rear end portion of the seat cushion frame 2.

One end side of the webbing 5a is wound around the retractor 5b, and the other end of the webbing 5a is fixed to the fixing portion 5 d. The webbing 5a pulled out from the retractor 5b passes through the pull-out portion 5c, and a connecting portion 5e is provided to the webbing 5a pulled out from the pull-out portion 5 c. By connecting the connecting portion 5e to the connected portion 5f, the webbing 5a bridged between the pull-out portion 5c and the connecting portion 5e restrains the shoulder of the seated person, and the webbing 5a bridged between the connecting portion 5e and the fixing portion 5d restrains the waist of the seated person.

The retractor 5b prevents the webbing 5a from being pulled out further in the event of sudden deceleration of the vehicle at the time of vehicle collision or the like. However, the retractor 5b has a function of a force limiter that gradually feeds out the webbing 5a when a tensile load of a predetermined value or more is input to the webbing 5 a.

Further, if the webbing 5a is pulled out from the retractor 5b and the webbing 5a restraining the shoulder of the seated person is pulled at the time of a vehicle collision or the like, a large tensile load is applied to the pull-out portion 5c toward the front. The strength of each part of the back frame 3 and the reclining device 4 is set according to the load so that the back frame 3 does not tilt about the rotation axis of the reclining device 4 or the vicinity of the rotation axis.

Next, the back frame 3 will be further described with reference to fig. 2 to 5 in addition to fig. 1. In fig. 2, the parts of the seat belt 5 are not shown, and in fig. 3, the parts of the back frame 3 visible from the back side of the first frame 11 are not shown. The directions indicated by the arrows U-D, F-B, and L-R in the drawings are the up-down direction, the front-back direction, and the left-right direction of the back frame 3, respectively.

As shown in fig. 1 and 2, the back frame 3 mainly includes: a first frame 11 and a second frame 12 separated from each other in a left-right direction and extending in an up-down direction; an upper frame 13 which connects upper portions of the first frame 11 and the second frame 12 and extends in the left-right direction; a lower frame 14 which connects lower portions of the first frame 11 and the second frame 12 and extends in the left-right direction; and a first coupled portion 15 and a second coupled portion 16 which are respectively disposed on both left and right sides of the lower frame 14 and are coupled to the left and right reclining devices 4, respectively.

In the present specification, when viewed in the left-right direction, a direction parallel to the central axis of the tube portion 12a of the second frame 12, which will be described later, and the rear surface of the first frame 11 is defined as the vertical direction of the back frame 3 (seat frame 1), and a direction orthogonal to the vertical direction is defined as the front-rear direction of the back frame 3. Even if the angle of the back frame 3 with respect to the seat cushion frame 2 is changed, the up-down direction and the front-rear direction of these back frames 3 are not changed.

The first frame 11 is a member disposed at the center of the back frame 3 in the left-right direction, and is provided at a boundary portion between the center seat and the left seat. The first frame 11 is made of high tensile steel (high strength steel). The high tensile steel in the present specification means a steel having a tensile strength of 490MPa or more regardless of alloy components and presence or absence of heat treatment. The first frame 11 in the present embodiment is a quenched and tempered high-tension steel having a tensile strength of about 980MPa, which is subjected to heat treatment such as quenching and tempering, and is formed of a substantially uniform material over the entire length thereof. The quenched and tempered high-tension steel has a high yield ratio and is less susceptible to plastic deformation than non-quenched and tempered high-tension steel subjected to heat treatment without quenching and tempering.

The first frame 11 is formed by bending a steel plate into a square tube shape and welding edges of the steel plate butted on the rear surface side to each other. The welding in the present specification refers to welding in which metals are melted and softened to join, and examples thereof include resistance welding, laser welding, arc welding, friction stir welding, and the like. The cross-sectional shape of the first frame 11 in a square tube shape is a rectangular shape elongated in the front-rear direction. This increases the rigidity of the first frame 11 against a bending load in the front-rear direction.

The second frame 12 is a member disposed on the left side of the back frame 3, and is made of steel having a tensile strength of less than about 490MPa, that is, steel other than high tensile steel. A second coupled portion 16 coupled to the reclining device 4 is provided at a lower portion of the second frame 12 coupled to the lower frame 14. The second frame 12 mainly includes: a tube portion 12a as a steel tube; and a plate portion 12b joined to the cylindrical portion 12a by welding. The upper end of the tube portion 12a is welded to the upper frame 13, and the lower end is welded to the lower frame 14.

The plate portion 12b is a portion formed by bending a steel plate or the like, and has flanges extending inward in the left and right directions (toward the first frame 11) from the front end edge and the rear end edge. The upper end of the plate portion 12b is located apart from the upper end of the tube portion 12a, and covers approximately half of the outer circumferential surface of the tube portion 12 a. In the plate portion 12b, the distance from the tube portion 12a to the distal end edge increases toward the lower end. Since the plate portion 12b is welded to the tube portion 12a to form the second frame 12, the rigidity of the second frame 12 against a bending load in the front-rear direction can be improved.

The upper frame 13 is a steel pipe having a tensile strength of less than about 490 MPa. A fixing member 17 for fixing a headrest (not shown) is attached to the center of the upper frame 13 in the left-right direction. The upper frame 13 on the first frame 11 side of the anchor 17 is provided with a pull-out portion 5 c. The pull-out portion 5c is formed by a part of the upper frame 13 that folds the webbing 5a pulled out upward from the retractor 5b and guides downward and forward, a portion that protrudes upward from both left and right ends of the part of the upper frame 13 to restrict the lateral movement of the webbing 5a, and a portion that connects upper ends of the protruding portion to each other.

In the first frame 11, an upper notch portion 11a is formed by cutting off a corner between an upper end and a rear surface of the first frame 11 along a shape of an outer peripheral surface of the upper frame 13 when viewed in the left-right direction shown in fig. 3. In a state where the upper frame 13 is fitted into the upper cutout portion 11a, the outer peripheral surface of the upper frame 13 is welded to the first frame 11 along the upper cutout portion 11 a. Since the upper portion of the first frame 11 is positioned forward of the upper frame 13 in this manner, when a forward load is applied to the upper frame 13 via the pull-out portion 5c, the load can be easily transmitted from the upper frame 13 to the upper portion of the first frame 11.

As shown in fig. 2 and 3, an L-shaped first upper reinforcing member 18 is superposed on the rear side of the welded portion between the first frame 11 and the upper frame 13. The first upper reinforcing member 18 is formed by bending a steel plate having a tensile strength of less than about 490 MPa. The first upper reinforcing members 18 are welded to the left and right side surfaces of the first frame 11 in the up-down direction, and are welded to the upper and lower sides of the outer peripheral surface of the upper frame 13 in the left-right direction. Thus, when stress is generated at the welded portion between the first frame 11 and the upper frame 13, the stress can be reduced by the stress generated at the first upper reinforcing member 18. As a result, the welded portion (connecting portion) between the first frame 11 and the upper frame 13 can be made high in strength.

As shown in fig. 1 and 2, the outer peripheral surface of the upper frame 13 is welded to the upper end of the second frame 12. A second upper reinforcing member 19 having a T-shape is superposed on the rear side of the welded portion. The second upper reinforcing member 19 is formed by bending a steel plate having a tensile strength of less than about 490 MPa. The second upper reinforcing members 19 are welded to the left and right sides of the outer peripheral surface of the tube portion 12a in the vertical direction, and are welded to the upper and lower sides of the outer peripheral surface of the upper frame 13 in the horizontal direction. Thus, when stress is generated at the welded portion between the second frame 12 and the upper frame 13, the stress can be reduced by the stress generated at the second upper reinforcing member 19. As a result, the welded portion (connecting portion) between the second frame 12 and the upper frame 13 can be made high in strength.

The lower frame 14 is a steel pipe made of high tensile steel. The lower frame 14 in the present embodiment is a quenched and tempered high-tensile steel having a tensile strength of approximately 1470MPa, which is subjected to heat treatment such as quenching and tempering, and is formed of a substantially uniform material over the entire length thereof. That is, the lower frame 14 has a tensile strength larger than that of the material of the first frame 11 over the entire length. The outer diameter of the lower frame 14 is formed larger than the outer diameters of the tube portions 12a of the upper frame 13 and the second frame 12. This increases the rigidity of the lower frame 14.

The lower frame 14 includes: a first lower portion 14a extending from the first frame 11 to the side opposite to the second frame 12 and fixed to the first coupling target portion 15; and a second lower portion 14b extending from the first frame 11 to a side opposite to the first lower portion 14a and fixed to a second coupling portion 16 of the second frame 12. The first lower portion 14a is fixed to the first coupling portion 15 via a first coupling member 21, and the second lower portion 14b is fixed to the second coupling portion 16 via a second coupling member 22.

As viewed in the left-right direction shown in fig. 3, the first frame 11 is formed with a cutout portion 11b formed by cutting out a lower portion of the first frame 11 from the rear surface toward the front along the shape of the outer peripheral surface of the lower frame 14. In a state where the lower frame 14 is fitted into the lower cutout portion 11b, substantially a half of the front side of the outer peripheral surface of the lower frame 14 is welded to the first frame 11 along the lower cutout portion 11 b. In this way, by welding substantially half of the outer peripheral surface of the lower frame 14 to the first frame 11, the length of the welded portion is ensured, and the strength of the welded portion can be ensured.

As shown in fig. 2 and 3, a T-shaped lower reinforcing member 20 is superposed on the rear side of the welded portion between the first frame 11 and the lower frame 14. The lower reinforcing member 20 is formed by bending a steel plate having a tensile strength of less than about 490 MPa. The lower reinforcing member 20 includes: a first portion 20a overlapping the first frame 11; and a second portion 20b overlapping the lower frame 14. The first portion 20a is formed in a channel steel shape (square U shape) by a web overlapping the rear surface of the first frame 11 and a pair of left and right flanges provided on both left and right sides of the web and overlapping both left and right sides of the first frame 11. The front edges of the flanges of the first portion 20a are welded to the left and right side surfaces of the first frame 11 in the vertical direction.

The second portion 20b is integrally formed with the first portion 20 a. The second portion 20b is formed in a semi-cylindrical shape overlapping with a substantially half circumference of the rear side of the lower frame 14. The upper and lower edges of the second portion 20b are welded to the outer peripheral surface of the lower frame 14 along the left-right direction, respectively. When stress is generated at the welded portion between the first frame 11 and the lower frame 14, the stress can be reduced by the stress generated at the lower reinforcing member 20. As a result, the welded portion (connecting portion) between the first frame 11 and the lower frame 14 can be made high in strength.

As shown in fig. 4, the first coupled portion 15 is a portion coupled to the reclining device 4 disposed on the right side of the backrest frame 3. The first coupled portion 15 is formed to extend upward from the rear side with respect to the reclining device 4. The vertical dimension of the first coupled portion 15 is about 1/3 of the vertical dimension of the first frame 11. Both ends of a substantially cylindrical reinforcing frame 23 extending in the left-right direction are joined to the upper end portion of the first coupling target portion 15 and the lower side of the vertical center of the first frame 11 by welding or screwing (see fig. 1).

The first portion to be connected 15 includes: an outer plate portion 15a forming a right side surface on the reclining device 4 side; an outer front flange 15b extending inward (toward the first frame 11) in the left-right direction from the front edge of the outer panel portion 15 a; an outer rear flange 15c extending inward in the left and right direction from the rear edge of the outer panel portion 15 a; an inner plate portion 15d disposed on the left-right direction inner side of the outer plate portion 15 a; an inner front flange 15e extending outward (the reclining device 4 side) from the left and right sides of the front edge of the inner plate portion 15 d; and an inner rear flange 15f projecting outward leftward and rightward from the rear edge of the inner plate portion 15 d.

In the outer plate portion 15a, a portion below the reinforcing frame 23 and above and in front of the lower frame 14 overlaps the inner plate portion 15d as viewed in the left-right direction, and the shape of the overlapping portion is substantially the same. The inner front flange 15e is overlapped with the rear side of the outer front flange 15b substantially without a gap, and the inner rear flange 15f is overlapped with the rear side of the outer rear flange 15c substantially without a gap. The outer front flange 15b and the inner front flange 15e are welded, and the outer rear flange 15c and the inner rear flange 15f are welded.

Thereby, a gap is provided between the outer plate portion 15a and the inner plate portion 15d, and the first coupled portion 15 has a closed cross section from the lower frame 14 toward the reinforcing frame 23. As a result, the strength and rigidity of the first coupling target portion 15 between the lower frame 14 and the reinforcing frame 23 can be improved.

The first connecting member 21 is formed by bending a steel plate having a tensile strength of less than about 490 MPa. The first connection member 21 includes: a substantially semi-cylindrical first tube portion 21a that overlaps substantially half of the front and upper sides of the outer peripheral surface of the first lower portion 14 a; and a first extension portion 21b welded to the inner plate portion 15d of the first coupling target portion 15, and each portion of the first coupling member 21 is integrally molded. Both circumferential edges of the first tube portion 21a are welded to the outer circumferential surface of the first lower portion 14a along the left-right direction.

The first extension portion 21b is formed in a channel steel shape (square U shape) with flanges extending from both side edges of the web. The two flanges of the first extension portion 21b are provided so as to extend linearly from both circumferential edges of the first tube portion 21a in a direction away from the first tube portion 21a (first lower portion 14a) and be parallel to each other, as viewed in the left-right direction. In addition, the web of the first extension 21b is disposed substantially perpendicular to the two flanges. This can improve the strength and rigidity of the first extended portion 21 b.

An end portion of the first extended portion 21b, which is apart from the first tube portion 21a, is brought into contact with the inner plate portion 15d, and an angle between the first extended portion 21b and the inner plate portion 15d is welded. That is, the first connecting member 21 is welded to the first coupling portion 15 at a position away from the outer peripheral surface of the first lower portion 14a in the vertical direction and the front-rear direction.

As shown in fig. 5, the second coupled portion 16 is a portion coupled to the reclining device 4 disposed on the left side of the back frame 3. Reinforcing plates 16a are stacked on the left and right inner sides (the first frame 11 side) of the lower portion of the plate portion 12b of the second frame 12, and inner plate portions 16b are disposed on the left and right inner sides of the reinforcing plates 16 a. The portion of the reinforcing plate 16a below the upper edge is a second connected portion 16 provided in the second frame 12.

The reinforcing plate 16a is a member for improving the strength and rigidity of the second portion to be connected 16 with respect to the upper portion side of the second frame 12, and is joined to the plate portion 12b by welding, screwing, or the like. The inner plate 16b is disposed substantially parallel to the reinforcing plate 16a with a space therebetween. The inner plate portion 16b includes: a first joining portion 16c overlapped and welded to the front surface of the flange of the plate portion 12 b; a second joint portion 16d welded to the outer peripheral surface of the tube portion 12 a; and a third joint portion 16e welded to the reinforcing plate 16 a. This can integrate the members constituting the second portion-to-be-connected 16, and can improve the strength and rigidity of the second portion-to-be-connected 16.

The second connecting member 22 is formed by bending a steel plate having a tensile strength of less than about 490 MPa. The second connection member 22 includes: a substantially semi-cylindrical second tube portion 22a that overlaps a front substantially half circumference of the outer circumferential surface of the second lower portion 14 b; and a second extension portion 22b welded to the inner plate portion 16b of the second coupling-target portion 16, and each portion of the second coupling member 22 is integrally molded. Both circumferential edges of the second tube portion 22a are welded to the outer circumferential surface of the second lower portion 14b in the left-right direction.

The second extension portion 22b is formed in a channel steel shape (square U shape) with flanges extending from both side edges of the web. The two flanges of the second extension portion 22b are provided so as to extend linearly from both circumferential edges of the second tube portion 22a in a direction away from the second tube portion 22a (the second lower portion 14b) and be parallel to each other, as viewed in the left-right direction. In addition, the web of second extension 22b is disposed substantially perpendicular to the two flanges. This can improve the strength and rigidity of the second extension portion 22 b.

An end portion of the second extended portion 22b, which is apart from the second tube portion 22a, is brought into contact with the inner plate portion 16b, and an angle between the second extended portion 22b and the inner plate portion 16b is welded. That is, the second connection member 22 is welded to the second coupling portion 16 at a position distant from the outer peripheral surface of the second lower portion 14b in the front-rear direction.

According to the seat frame 1 as described above, the pull-out portion 5c is provided on the first frame 11 side of the center (anchor 17) in the left-right direction of the upper frame 13, and the webbing 5a bridged over the connecting portion 5e connected to the connected portion 5f and the pull-out portion 5c restrains the shoulder of the seated person. When a load is applied to the pull-out portion 5c via the webbing 5a in a forward direction at the time of a vehicle collision (particularly, a frontal collision) in which such a seat frame 1 is mounted, a bending load, which is mainly applied to the first frame 11 so as to fix the welded portion with the lower frame 14, is applied. In addition, a torsion load or a shear load is mainly applied to the lower frame 14 to which the first coupling part 15 and the second coupling part 16 are fixed on both the left and right sides, and a bending load and a torsion load are mainly applied to the second frame 12 coupled to the upper portion of the first frame 11 via the upper frame 13.

In general, the bending strength, the torsional strength, and the shear strength of a steel material are determined by the tensile strength, and the torsional strength and the shear strength of the steel material are smaller than the bending strength of the steel material regardless of the tensile strength of the steel material. Therefore, compared to the second frame 12 to which the bending load and the torsional load are mainly applied, the first frame 11 to which the bending load is mainly applied without being applied with the torsional load or the shear load can be made stronger, and the strength necessary for preventing deformation or breakage of both the first frame 11 and the second frame 12 coupled by the upper frame 13 can be reduced. Also, the tensile strength of the material of the first frame 11 is greater than that of the material of the second frame 12. Therefore, the first frame 11 can be made sufficiently high in strength, and the first frame 11 can be made thin by an amount corresponding to an increase in the tensile strength of the material, etc., to thereby make the first frame 11 lightweight, and the first frame 11 can be made further lightweight by an amount corresponding to a reduction in the necessary strength for preventing deformation or breakage.

In addition, the tensile strength of the material of the lower frame 14 is greater than that of the material of the first frame 11 over the entire length. Therefore, the torsional strength and the shear strength of the lower frame 14 can be sufficiently ensured over the entire length with respect to the bending strength of the first frame 11 when a forward load is applied to the pullout portion 5c, and the lower frame 14 can be made lightweight.

Further, since the load applied to the pull-out portion 5c in the forward direction can be dispersed and received by the first frame 11 and the lower frame 14 having sufficiently high strength, the necessary strength of the first frame 11 and the lower frame 14 is reduced, and the first frame 11 and the lower frame 14 can be made thin and light in weight. As a result, the back frame 3 can be made lightweight and high in strength.

In particular, in the present embodiment, the first lower portion 14a of the lower frame 14 connects the high-strength first frame 11 and the first coupled portion 15, and the second lower portion 14b of the lower frame 14 connects the high-strength first frame 11 and the second coupled portion 16. Therefore, a larger torsional load and a larger shearing load are applied to the lower frame 14 (the first lower portion 14a and the second lower portion 14b) than in the case where the first coupling portion 15 is provided at the lower portion of the first frame 11 without the first lower portion 14 a. Since the tensile strength of the material of the lower frame 14 is greater than the tensile strength of the material of the first frame 11 over the entire length, the backrest frame 3 can be sufficiently strengthened and lightened even if the first lower portion 14a is provided.

The lower frame 14 is provided over substantially the entire length in the left-right direction of the back frame 3 provided in the seat on which the 2-person can be seated. The lower frame 14 is formed longer than a lower frame provided over substantially the entire length in the left-right direction of the seat on which only 1 person can be seated. By increasing the tensile strength of the material of the lower frame 14, the lower frame 14 can be sufficiently strengthened even if the lower frame 14 is long.

Since the lower reinforcing member 20 is provided at the welded portion between the first frame 11 and the lower frame 14, the stress generated at the welded portion by the load applied to the drawn portion 5c toward the front can be reduced by the stress generated at the lower reinforcing member 20. When a load in the forward direction is applied to the drawn-out portion 5c, a shear load along the circumferential direction of the lower frame 14 is applied to the welded portion between the second portion 20b of the lower reinforcing member 20 and the lower frame 14. Since the second portion 20b is welded to the lower frame 14 in the left-right direction, the shear stress generated at the welded portion between the second portion 20b and the lower frame 14 can be dispersed in the left-right direction, and the welded portion can be made high in strength.

When a load in the forward direction is applied to the drawn-out portion 5c, a shear load is applied in the front-rear direction to the welded portion between the first portion 20a of the lower reinforcing member 20 and the first frame 11. Since the first portion 20a is welded to the first frame 11 in the vertical direction, the shear stress generated at the welded portion between the first portion 20a and the first frame 11 can be dispersed in the vertical direction, and the welded portion can be strengthened. As a result, it is possible to prevent the welded portion between the first frame 11 and the lower frame 14 from being easily broken due to the broken welded portion between the first frame 11 and the lower frame 14, and to strengthen the welded portion between the first frame 11 and the lower frame 14.

The first connecting member 21 is welded to the outer peripheral surface of the first lower portion 14a, and the first connecting member 21 is welded to the first coupled portion 15. Therefore, the torque generated in the first lower portion 14a (the lower frame 14) in accordance with the forward load applied to the pull-out portion 5c can be transmitted to the first connection member 21, and the load corresponding to the torque can be transmitted from the first connection member 21 to the first connection target portion 15. Further, since the first connecting member 21 is welded to the first coupling target portion 15 at a position that is apart from the outer peripheral surface of the first lower portion 14a in the vertical direction and the front-rear direction, the load transmitted from the first connecting member 21 to the first coupling target portion 15 in accordance with the torque of the first lower portion 14a can be reduced. As a result, the load transmission path from the first lower portion 14a to the first portion to be connected 15 can be strengthened.

Similarly, since the second connection member 22 is welded to the outer peripheral surface of the second lower portion 14b and the second connection member 22 is welded to the second coupling-target portion 16 at a position spaced apart from the outer peripheral surface of the second lower portion 14b in the front-rear direction, the transmission path of the load from the second lower portion 14b to the second coupling-target portion 16 can be made high in strength. In addition, although the welded portions between the first connection member 21 and the first connected portion 15 and the first lower portion 14a will be described below, the welded portions between the second connection member 22 and the second connected portion 16 and the second lower portion 14b may be similarly described, and therefore, a part of the description will be omitted.

When torque is transmitted from the first lower portion 14a to the first connection member 21, a shear load is applied to the welded portion between the first lower portion 14a and the first connection member 21 in the circumferential direction of the first lower portion 14 a. Since the first tube portion 21a of the first connection member 21 is welded to the first lower portion 14a in the left-right direction, the shear stress generated in the welded portion between the first tube portion 21a and the first lower portion 14a can be dispersed in the vertical direction, and the welded portion can be made high in strength.

When a load corresponding to the torque generated in the first lower portion 14a is transmitted from the first connection member 21 to the first coupled portion 15, a shear load is applied to the welded portion between the first extension portion 21b of the first connection member 21 and the first coupled portion 15 in the circumferential direction of the first lower portion 14 a. Here, the first extended portion 21b may be formed so as to be in contact with the inner side of the outer front flange 15b or the outer rear flange 15c without providing the inner plate portion 15d in the first coupling portion 15, and the first extended portion 21b may be welded to the outer front flange 15b or the outer rear flange 15 c. However, in this case, the welded portion between the first extended portion 21b and the first coupled portion 15 is easily formed along the circumferential direction of the first lower portion 14a, and there is a possibility that shear stress is easily concentrated on the end portion, the corner portion, or the like of the welded portion.

In contrast, in the present embodiment, the flanges of the first extended portion 21b in the shape of a channel steel linearly extend from both circumferential edges of the first tube portion 21a in a direction away from the first tube portion 21 a. Therefore, the shear stress generated in the welded portion between the first extended portion 21b and the first portion to be connected 15 can be easily dispersed along the flange of the first extended portion 21b, and the welded portion can be made to have high strength.

Further, the first extended portion 21b in the shape of a channel steel may be directly welded to the outer plate portion 15a without providing the inner plate portion 15d in the first coupling portion 15. However, a part of the reclining device 4 may be provided on the inner side (the first frame 11 side) in the left-right direction of the outer plate portion 15a, and the welding position of the first extension portion 21b to the outer plate portion 15a may be restricted. In contrast, in the present embodiment, since the first extension portion 21b is welded to the inner plate portion 15d, the degree of freedom of the welding position of the first extension portion 21b to the first portion to be connected 15 can be increased, and the degree of freedom of the shape of the first extension portion 21b welded to the first portion to be connected 15 can be increased.

Since the upper end portion of the first connected portion 15 and the first frame 11 are connected by the reinforcing frame 23, the necessary strength of each portion on the load transmission path from the first frame 11 to the first connected portion 15 below the connection portion with the reinforcing frame 23 can be reduced. Further, since the upper portion of the second frame 12 and the upper portion of the first frame 11, which are provided with the second connected portion 16 at the lower portion, are connected to the upper frame 13, the necessary strength of each portion on the load transmission path from the first frame 11 to the second connected portion 16 can be reduced. The backrest frame 3 can be made lightweight by thinning the respective portions of the backrest frame 3.

The present invention has been described above based on the embodiments, but it can be easily estimated that the present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the scope of the present invention. The seat frame 1 is not limited to being mounted on an automobile, and may be mounted on a vehicle such as an industrial vehicle, a railway vehicle, a ship, or an airplane. The shapes of the respective portions of the cushion frame 2 and the back frame 3 may be appropriately changed. The tensile strength of the material of the first frame 11 and the lower frame 14 may be appropriately changed.

In the above-described embodiment, the case where the first frame 11 is made of high-tensile steel over the entire length, that is, the case where the tensile strength of the material of the first frame 11 is greater than the tensile strength of the material of the second frame 12 over the entire length, has been described, but the present invention is not necessarily limited thereto. The first frame 11 may be subjected to a partial heat treatment such as induction hardening, liquid carburizing, or gas carburizing to increase the tensile strength of the material of the first frame 11 at least on the lower side of the vertical center to be greater than the tensile strength of the material of the second frame 12. In the following frame 14, the bending stress generated in the first frame 11 by the fixed end is larger as it approaches the fixed end, and thus the necessary strength of the first frame 11 is higher as it approaches the fixed end. As long as the tensile strength of at least the portion having the high required strength is high, the first frame 11 can be sufficiently strengthened and lightened. In addition, since the torsional stress is generated substantially uniformly in the lower frame 14, it is preferable that the tensile strength of the material of the lower frame 14 be substantially the same over the entire length.

In the above embodiment, the case where the pull-out portion 5c is provided in the upper frame 13 has been described, but the present invention is not limited thereto. The first frame 11 may be provided with a pull-out portion 5c at an upper portion thereof.

In the above-described embodiment, the description has been given of the case where the seat frame 1 is a frame used for the left seat and the center seat among the three-seat seats of the automobile, but the present invention is not necessarily limited to this. The seat frame 1 may be turned left and right to serve as a frame for a right seat and a center seat of three-seat seats of an automobile. The seat frame 1 provided in a seat on which two persons can sit is not limited, and the first lower portion 14a may be omitted, and the first connected portion 15 may be provided in the lower portion of the first frame 11 to serve as a seat frame provided in a seat on which only one person can sit. Further, a part of the frame used for the center seat may be connected to the left and right sides of the seat frame from which the first lower portion 14a is omitted.

Further, although the description has been given of the case where the seat belt 5 for restraining the seated person seated in the center seat is provided in the seat frame 1, the connected portion 5f may be provided on the second frame 12 side, and a seat belt for restraining the seated person seated in the left seat or the right seat may be provided in the seat frame. The second frame 12 of the seat frame 1 used for the left seat and the center seat may be a first frame, the first frame 11 may be a second frame, the first portion to be connected 15 may be a second portion to be connected, and the pull-out portion 5c may be provided on the first frame side. The connection target portion 5f is not limited to the case of being attached to the cushion frame 2, and the connection target portion 5f may be attached to a bracket or a vehicle body of the reclining device 4. The retractor 5b and the fixing portion 5d may be attached to the vehicle body.

In the above-described embodiment, the case where both left and right ends of the lower frame 14 are fixed to the first coupling target portion 15 and the second coupling target portion 16, respectively, has been described, but the present invention is not necessarily limited to this. The first coupling target portion 15 and the second coupling target portion 16 may be fixed to the lower frame 14 at positions inward of both the left and right ends.

In the above embodiment, the case where the first frame 11 and the lower frame 14 are welded has been described, but the present invention is not necessarily limited to this. The first frame 11 and the lower frame 14 may be integrally molded, and the tensile strength of the material of the first frame 11 may be made different from the tensile strength of the material of the lower frame 14 by heat treatment. In this case, since stress is likely to concentrate on the coupling portion between the first frame 11 and the lower frame 14, it is preferable to provide the lower reinforcement member 20 to distribute the stress. Further, the first frame 11 and the upper frame 13 may be integrally molded, the upper frame 13 and the second frame 12 may be integrally molded, and the second frame 12 and the lower frame 14 may be integrally molded.

In the above embodiment, the case where the lower reinforcing member 20 is welded to the first frame 11 and the lower frame 14 has been described, but the present invention is not necessarily limited thereto. The lower reinforcing member 20 may be coupled to the first frame 11 and the lower frame 14 by bolts or rivets. Similarly, the first connection member 21 may be joined to the first connected portion 15 and the lower frame 14 by bolts or rivets, or the second connection member 22 may be joined to the second connected portion 16 and the lower frame 14 by bolts or rivets.

Further, the lower frame 14 may be divided into the first lower portion 14a and the second lower portion 14b, and the first lower portion 14a and the second lower portion 14b may be welded to both the left and right sides of the first frame 11, respectively, without being limited to the case where the first frame 11 is welded to the outer peripheral surface of the lower frame 14. Further, the lower frame 14 formed by integrally molding the first lower portion 14a and the second lower portion 14b is welded to the first frame 11, and the manufacturing process of the back frame 3 can be simplified.

In the above-described embodiment, the case where the rear end portion of the seat cushion frame 2 and the lower end portion of the back frame 3 are connected by the reclining device 4 capable of adjusting the reclining angle of the back frame 3 with respect to the seat cushion frame 2 has been described, but the present invention is not necessarily limited thereto. The rear end portion of the seat cushion frame 2 and the lower end portion of the back frame 3 may be coupled by a coupling device that cannot adjust the inclination angle of the back frame 3 with respect to the seat cushion frame 2.

Claims (6)

1. A seat frame mounted on a vehicle, the seat frame characterized by comprising:

a seat cushion frame;

a back frame disposed at a rear end of the seat cushion frame;

a connecting device for connecting a rear end of the cushion frame and a lower end of the back frame; and

a safety belt is arranged on the safety belt,

the backrest frame is provided with:

a first frame and a second frame separated from each other in a left-right direction and extending in an up-down direction;

an upper frame connecting upper portions of the first frame and the second frame to form an upper edge portion of the back frame;

a lower frame connecting lower portions of the first frame and the second frame; and

first and second coupled portions fixed to left and right sides of the lower frame, respectively, and coupled to the coupling devices, respectively,

the safety belt is provided with:

a pull-out portion provided on the first frame side of the upper frame with respect to a center in a left-right direction or provided on an upper portion of the first frame;

a connecting portion connected to a connected portion that is located at a position apart in a left-right direction from a connecting portion between the first frame and the lower frame and is disposed on a rear end portion side of the seat cushion frame; and

a webbing that is provided between the pull-out portion and the connecting portion,

the first frame is a high-tension steel frame,

the second frame is made of steel except high-tension steel,

the lower frame is a high-tension steel frame having a tensile strength greater than that of the high-tension steel of the first frame.

2. The seat frame according to claim 1,

the lower frame is provided with:

a first lower portion that extends from the first frame to a side opposite to the second frame and is fixed to the first portion to be connected; and

and a second lower portion extending from the first frame to a side opposite to the first lower portion and fixed to the second coupling portion.

3. The seat frame according to claim 1,

the back frame is provided with a reinforcing member that is overlapped on a coupling portion between the first frame and the lower frame and is coupled with the first frame and the lower frame.

4. The seat frame according to claim 1,

the backrest frame includes a reinforcement frame that connects the first connected portion and the first frame above the lower frame on a lower side than a center in a vertical direction.

5. The seat frame according to any one of claims 1 to 4,

the backrest frame is provided with a connecting member that is engaged with an outer peripheral surface of the lower frame and is engaged with the first coupled portion or the second coupled portion at a position that is separated from the outer peripheral surface of the lower frame in the up-down direction or the front-rear direction.

6. The seat frame according to claim 5,

the connecting member includes:

a cylinder portion engaged with an outer peripheral surface of the lower frame; and

an extension formed in a channel-shaped steel shape having two flanges protruding from both side edges of the web and engaged with the first coupled portion or the second coupled portion,

the flange extends linearly in a direction away from the cylindrical portion when viewed in the left-right direction.

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