Patent Application
20180201171
The present invention relates to a structure or arrangement for mounting a sinuous spring (s) or S-spring (s) to a seat back forming a part of an automotive seat, such that the S-spring (s) is/are secured to a seat back frame of the seat back so as to extend in a transverse direction of the seat back frame.
Conventionally, in this sort of technical field, for example, in Japanese Laid-Open Patent Publications Nos. 2004-148942 and 2004-106647, a seat back frame described therein, which forms a part of a seat back of an automotive seat, includes a pair of left and right side frame portions formed integrally therewith, and a plurality of sinuous springs or S-springs are extended and connected between the left and right side frame portions. The S-springs are arrayed in parallel with one another along a vertical direction of the seat back frame for the purpose of not only supporting a cushion padding thereon, but also giving an elastic cushioning support to a back portion of a seat occupant. A plurality of securing brackets are fixedly disposed by welding to and along each of the left and right side frame portions of the seat back frame, and a distal end of each of the S-springs is inserted and engaged in each of the aforesaid securing brackets, This arrangement facilitates the ease of mounting the S-springs to and along the left and right side frame portions.
Patent-related Document 1:
Japanese Laid-Open Patent Publication No. 2004-148942
Patent-related Document 2:
Japanese Laid-Open Patent Publication No. 2004-106647
However, the above-described conventional structure for mounting the S-springs to the seat back frame has been with the problem that it increases a weight of the seat back frame because of the securing brackets added thereto.
It is a purpose of the present invention to provide an improved spring mounting structure of a seat back, which can realize a light weight of a seat back frame and also can make the seat back frame simplified in structure.
In order to achieve the above-stated purpose, according to the present invention, there is provided a sinuous spring mounting structure in a seat back including a seat back frame forming a part of the seat back, the seat back frame including a first cylindrical portion and a second cylindrical portion, wherein the first and second cylindrical portions are disposed in an opposedly-facing relation with each other, and wherein the sinuous spring mounting structure is adapted for allowing at least one sinuous spring to be mounted to the first and second cylindrical portions so as to be extended therebetween,
the sinuous spring mounting structure being characterized in that:
the at least one sinuous spring has: a first end portion including a curved region; and
a second end portion including a curved region;
the first cylindrical portion of the seat back frame includes a first mounting portion for allowing the first end portion of the at least one sinuous spring to be mounted thereto; and
the second cylindrical portion of the seat back frame includes a second mounting portion for allowing the second end portion of the at least one sinuous spring to be mounted thereto;
and characterized in that the first and second end portions of the at least one sinuous spring are mounted to the first and second mounting portions, respectively, in such a manner that the curved region of the first end portion is contacted on and along an outer circumferential surface of the first cylindrical portion, whereas the curved region of the second end portion is contacted on and along an outer circumferential surface of the second cylindrical portion.
The above-described sinuous spring mounting structure does not require any additional securing arrangement, such as a securing bracket (s), which assists in firm securing of the sinuous spring (s) to the seat back frame, thus realizing a light weight of the seat back frame and also making the seat back frame simplified in structure. Further, the first and second end portions of the sinuous spring are contacted on and along the two circumferential surface areas of the first and second cylindrical portions of the seat back frame, respectively, thereby extremely increasing contact areas of the sinuous spring's first and second end portions for contact with the corresponding two circumferential surface areas of the first and second cylindrical portions of the seat back frame. Therefore, the sinuous springs can be secured to the seat back frame in a stable, hard-to-move manner, which effectively avoids or minimizes friction of the sinuous spring's first end portion against the first cylindrical portion as well as friction of the sinuous spring's second end portion against the second cylindrical portion. This in turn completely or minimally suppresses objectionable noises that may be generated from such frictions.
According to one exemplary embodiment of the present invention, the aforesaid first mounting portion may comprise a first hole portion configured to allow the first end portion of the at least one sinuous spring to be inserted and hookingly engaged therein, and the aforesaid second mounting portion may comprise a second hole portion configured to allow the second end portion of the at least one sinuous spring to be inserted and hookingly engaged therein. In this embodiment, the first end portion of the at least one sinuous spring may be inserted and hookingly secured in the first hole portion, with the curved region of the first end portion being contacted on and along the outer circumferential surface of the first cylindrical portion, and also, the second end portion of the at least one sinuous spring may be inserted and hookingly secured in the second hole portion, with the curved region of the second end portion being contacted on and along the outer circumferential surface of the second cylindrical portion. This embodiment requires no other operation but to simply insert two distal ends of the sinuous spring into the first and second hole portions, respectively, for completion of secure mounting of the sinuous spring to the first and second cylindrical portions.
According to another exemplary embodiment of the invention, the aforesaid first mounting portion may comprise a first truncated-conical hole portion formed in the first cylindrical portion, such first truncated-conical hole portion opening divergent in a direction from an inside to the outer circumferential surface of the first cylindrical portion, and therefore the first truncated-conical hole portion may have a sloped surface that becomes narrow in area in a direction from the outer circumferential surface to the inside of that first cylindrical portion. And, on the other hand, the aforesaid second mounting portion may comprise a second truncated-conical hole portion formed in the second cylindrical portion, such second truncated-conical hole portion opening divergent in a direction from an inside to the outer circumferential surface of the second cylindrical portion, and therefore the second mounting portion may have a sloped surface that becomes narrow in area in a direction from the outer circumferential surface to the inside of that second cylindrical portion. In this embodiment, the first end portion of the at least one sinuous spring may be inserted and hookingly secured in the first truncated-conical hole portion, with the curved region of the first end portion being contacted on and along the outer circumferential surface of the first cylindrical portion, and the second end portion of the at least one sinuous spring be inserted and hookingly secured in the second truncated-conical hole portion, with the curved region of the second end portion being contacted on and along the outer circumferential surface of the second cylindrical portion. The present embodiment therefore allows the two distal ends of the sinuous spring to be slidingly guided on the two sloped surfaces of the first and second truncated-conical hole portions, respectively, and thus smoothly introduced into those particular first and second truncated-conical hole portions, respectively. This does not require much care on the worker's side in inserting and engaging the sinuous spring's two distal ends in those two truncated-conical hole portions, respectively, so that the worker can simply, quickly finish the spring mounting operation.
According to still another embodiment, the aforesaid first mounting portion may comprise a first recessed mounting portion formed in the first cylindrical portion so as to extend in a circumferential direction along the outer circumferential surface of the first cylindrical portion, and the aforesaid second mounting portion may comprise a second recessed mounting portion formed in the second cylindrical portion so as to extend in a circumferential direction along the outer circumferential surface of the second cylindrical portion. In this embodiment, the first end portion as well as the curved region thereof, which are formed in the at least one sinuous spring, may be both hookingly engaged in and along the first recessed mounting portion, and also, the second end portion as well as the curved thereof, which are formed in the at least one sinuous spring, may be both hookingly engaged in and along the second recessed mounting portion. In other words, the present embodiment features a circumferentially extending recess in each of the first and second cylindrical portion, which is defined by each of the first and second recessed mounting portions. This enables a worker to directly see and ascertain a point where the sinuous spring's end portion must be mounted in position. Further, what the worker should do in this respect is an extremely easy, quick action that simply consists of: putting the sinuous spring's first and second end portions in the aforementioned first and second recessed mounting portions, respectively; and then causing those two end portions to slide in and along the two circumferentially extending recesses of the first and second recessed mounting portions, respectively, until completion of hooking engagement of the sinuous spring's two end portions in and along the corresponding first and second recessed mounting portions.
In each of all the foregoing embodiments, the first and second end portions of the at least sinuous spring may each be coated with a resin material. With this resin coating, any frictions of the sinuous spring's first and second end portions against the first and second cylindrical portions may be precluded, thereby completely suppressing objectionable noise that might be generated from such frictions.
According to the present invention, it is possible to realize a light weight of a seat back frame and provide a simplified spring mounting structure.
Referring to the annexed drawings, there are illustrated several preferred embodiments related to a spring mounting structure in a seat back, in accordance with the present invention, in which sinuous springs or S-springs are mounted in the seat back, and each of the embodiments will be described in details hereinafter.
As shown in
The seat cushion SC includes a seat cushion frame 6 provided therein, and the seat back SB includes a seat back frame 7 provided therein. Lower ends of the seat back frame 7 are rotatably connected with two free ends of the seat cushion frame 6, respectively, via hinge portions 8 and 8.
The seat back frame 7 has a pair of left and right cylindrical side frame portions 9L and 9R. Each of the left and right cylindrical frame portions 9L and 9R has a circular cross-section and may be formed from a metallic tubular material, for instance. As shown in
According to a generic concept of the present invention, as seen from
a) Each of the spring elements 10 is commonly formed as a sinuous spring or S-spring which has a first end portion 10a and a second end portion 10b, each being formed in a substantially hooked shape. Those two end portions 10a and 10b are identical to each other in shape and size. Further, the first end portion 10a includes a curved region 10aU shaped to closely contact a predetermined circumferential surface area of the left cylindrical side frame portion 9L in conformity therewith, whereas likewise the second end portion 10b includes a curved region 10bU shaped to closely contact a predetermined circumferential surface area of the right cylindrical side frame portion 9R in conformity therewith.
b) A pair of spring mounting portions are provided to the opposedly-facing left and right cylindrical side frame portions 9L and 9R, respectively, such two spring mounting portions being adapted for allowing the first and second end portions 10a and 10b of each S-spring 10 to be mounted thereto. The left and right cylindrical side frame portions 9L and 9R have a first outwardly-facing lateral region 9La and a second outwardly-facing lateral region 9Ra, respectively. Defined direct in the first outwardly-facing lateral region 9La is a first one of the aforesaid two spring mounting portions, whereas defined direct in the second outwardly-facing lateral region 9Ra is the other second spring mounting portion. Now, in a generic sense, such spring mounting portions shall be referred to as “conceptual spring mounting portions 11 and 11”, as recognizable from reference numerals 11 in
Owing to the quite simplified structure summarized above, in accordance with the gist and technical concept of the present invention, the first and second end portions 10a and 10b of the S-spring 10 can first be contacted on and along the two circumferential surface areas 9Lf and 9Rf, respectively, following which, continuously, the two distal end portions of those first and second end portions can be hookingly mounted to the two spring mounting portions 11 and 11, respectively. With such simple mounting, it is possible to realize rapid, easy operation for not only connecting the S-springs 10 to and between the two cylindrical side frame portions 9L and 9R in position, but also preventing removal of the S-springs 10 therefrom. Further, no additional securing element is required for firm mounting of the S-springs to the cylindrical side frame portions, which therefore simplifies the structure of the seat back and also decreases a weight of the seat back frame 7. Still further, the first and second end portions 10a and 10b of the S-spring 10 are contacted on and along the two circumferential surface areas 9Lf and 9Rf, respectively, in an embracing manner, thereby extremely increasing contact areas of the first and second end portions 10a and 10b for contact with the corresponding two circumferential surface areas 9Lf and 9Rf. In other words, the first and second end portions 10a and 10b are each provided with a greatly increased support area to be supported by the corresponding two cylindrical side frame portions. Thus, when and while a back portion of a seat occupant rests on and contacts the seat back, the S-springs are kept in the state of being pressed and biased toward a rearward side of the seat back frame 7, whereby entire or substantive areas of the first and second end portions 10a and 10b of the S-springs are positively kept in contact with the circumferential surface areas 9Lf and 9Rf, respectively, which completely avoids or minimally reduces dislocation and vibration of the two end portions 10a and 10b in any of left and right directions as well as in any of upward and downward directions. Hence, a stable, hard-to-move attachment of the S-springs to the cylindrical side frame portions is achievable in effect. By those technical reasons, it is possible to avoid or minimize a rattling, keen frictions and objectionable noise, all of which may be caused from contact between the S-spring's first end portion 10a and the left cylindrical side frame portion as well as from contact between the S-spring's second end portion 10b and the right cylindrical side frame portion.
In this connection, it is to be understood that an embodiment shown in
Hereinafter, within the above-noted general gist and technical concept of the present invention, a specific description will be made as to exemplary embodiments of the spring mounting structure in the seat back, with reference to
Reference is first made to
As shown in
In practice, when mounting the aforesaid S-spring 10 to both left and right cylindrical side frame portions 9L and 9R, a worker should first hold both two end portions 10a and 10b of the S-spring 10, then stretch that S-spring 10 long resiliently in the left and right longitudinal directions thereof, and finally insert the two distal ends 10aE and 10bE of the S-spring into the first and second hole portions 11A-1 and 11A-2 of the left and right cylindrical side frame portions 9L and 9R, respectively. With these simple steps, the two distal end portions 10aE and 10bE of the S-spring are hookingly, securely engaged in the first and second hole portions 11A-1 and 11A-2, respectively, while at the same time, the two curved regions 10aU and 10bU are kept in close contact with and along the forwardly-facing circumferential surface areas 9Lf and 9Rf of the left and right cylindrical side frame portions 9L and 9R, respectively. In this regard, it is preferably important that each of the two curved portions 10aU and 10bU should closely contact the corresponding one of the two forwardly-facing circumferential surface areas 9Lf and 9Rf over substantially an overall circumferential length thereof, as shown in
Further, an overall length W1 of the S-spring 10 (a distance between two outermost ends C and C of that spring) should be slightly smaller than an overall width W2 given between the left and right cylindrical side frame portions 9L and 9R. As such, the S-spring 10, upon its being attached to the left and right cylindrical side frame portions 9L and 9R, is stretched outwardly, while causing a resilient contracting force therein, whereby both two distal end portions 10aE and 10bE of the S-spring are resiliently biased toward each other in a direction inwardly of the S-spring. Under such biasing force, the two distal end portions 10aE and 10bE are so firmly engaged in the first and second hole portions 11A-1 and 11A-2, respectively, enough to prevent rattling and wobbling of the two distal end portions themselves on the corresponding left and right cylindrical side frame portions. This also ensures that the two curved regions 10aU and 10bU of the S-spring are maintained in close contact with and along the two forwardly-facing circumferential surface areas 9Lf and 9Rf of the left and right cylindrical side frame portions.
In addition to the above-described arrangement of the S-spring 10, it is to be noted that a center of the first hole portion 11A-1 and a center of the second hole portion 11A-2 are in a coaxial relation with each other, since those two centers are both located on the horizontal line Lh orthogonal to the two vertical central axes Lv respectively of the left and right cylindrical side frames 9L and 9R. Accordingly, the resilient contracting force caused in the S-spring 10 acts in a direction along that horizontal line Lh and is therefore equally distributed to each of the two outermost ends C and C associated respectively with the two curved regions 10aU and 10bU of the S-spring 10. Due to such equal distribution of the resilient contracting force, no toggle action is caused in each of the two curved regions 10aU and 10bU. This arrangement therefore ensures that the resilient contracting force of the S-spring is always concentrated equally to each of the two outermost ends C and C respectively of the two curved regions 10aU and 10bU of the S-spring. In other words, the resilient contracting force works solely for firm engagement of the S-spring with the first and second hole portions 11A-1 and 11A-2, thereby avoiding or minimizing the possibility of irregular force component (s) being derived from the resilient contracting force, which may destabilize the engagement of the S-spring with the two hole portions. Because of these technical effects, the two curved regions 10aU and 10bU are maintained in a stable, hard-to-move condition upon the forwardly-facing circumferential surface areas 9Lf and 9Rf, respectively, and thus positively maintained in close contact therewith. This in effect prevents removal of the two distal ends 10aE and 10bE of the S-spring 10 from the first and second hole portions 11A-1 and 11A-2, respectively.
The above-described stable mounting of the S-spring is also effective for reducing frictions and objectionable noises to a lowest possible degree, even when a vibration is imparted to the S-springs from a seat occupant or a vehicle body. Namely, irrespective of such vibration exerted on the S-spring, the aforementioned arrangement surely minimizes friction of the S-spring's distal end portions 10aE and 10bE against the corresponding first and second hole portions 11A-1 and 11A-2 as well as generation of objectionable noise due to that friction, and also minimizes friction of the S-spring's curved regions 10aU and 10bU against the corresponding two forwardly-facing circumferential surface areas 9Lf and 9Rf as well as generation of objectionable noise due to that friction. Therefore, any uncomfortable touch and uneasiness that might normally occur in these aspects will not be felt by a seat occupant.
In this context, the two distal end portions 10aE and 10bE of the S-spring may optionally be formed rectilinear, instead of the shown shapes thereof, so that they extend straight along the horizontal line Lh when inserted in the first and second hole portions 11A-1 and 11A-2, respectively. Even in that case, such two rectilinear distal end portions can hardly be removed from the first and second hole portions 11A-1 and 11A-2, respectively, thanks to the above-described stable spring mounting wherein substantially an entirety of each of the two curved regions 10aU and 10bU is closely contacted with the corresponding one of the two forwardly-facing circumferential surface areas 9Lf and 9Rf of the cylindrical side frame portions. However, to be safe, each of the first and second distal ends 10aE and 10bE should preferably be bent in the shown manner, such that it is bent and positioned forwardly of the horizontal line Lh, because this bent mode can positively prevent removal of the two distal ends 10aE and 10bE from the corresponding first and second hole portions, with great reliability, in comparison with the suggested rectilinear distal end portions.
In the present invention, with regard to the foregoing first embodiment of S-spring 10, one additional variant mode may be provided, which suggests resin coating to the S-spring. As indicated in
Hence, all like designations given in the present third embodiment correspond to all like designations in the first embodiment, and for the sake of simplicity, any detailed description is omitted for all the elements and parts commonly used between the first and third embodiments. As shown in
The foregoing first and second truncated-conical hole portions 11B-1 and 11B-2 are both situated at a location behind or rearwardly of the horizontal line Lh stated above. As depicted in
As stated above, the present third embodiment illustrates formation of the first and second truncated-conical hole portions 11B-1 and 11B-2 in the left and right cylindrical side frame portions 9L and 9R, respectively, and each of S-springs, identical to the S-spring 10 of the preceding first embodiment, is mounted to the two truncated-conical hole portions 11B-1 and 11B-2 so as to be extended between the two cylindrical side frame portions. Practically, though not shown, a worker may hold the left and right end portions 10a and 10b of the S-spring 10 and stretch the S-spring 10 outwardly along the longitudinal direction thereof, after which, those two end portions 10a and 10b may be inserted by the worker into the first and second hole truncated-conical hole portions 11B-1 and 11B-2, respectively. During this operation, it is appreciated that the two large-diameter openings 22a and 22a, formed respectively in the two truncated-conical hole portions 11B-1 and 11B-2, permit the two distal ends 10aE and 10bE of the S-spring to smoothly, quickly enter the two hole portions 11B-1 and 11B-2, respectively, at one time, and also allow the said two distal ends 10aE and 10bE to be slidingly guided thereon and introduced into the two hollow insides of the two cylindrical side frame portions 9L and 9R, respectively, at one time. This arrangement does not require much care on the worker's side in inserting and engaging the S-spring's two distal ends 10aE and 10bE in the two truncated-conical hole portions 11B-1 and 11B-2, respectively, and therefore the worker can simply, quickly finish the spring engagement. In addition, immediately after that spring engagement, the two curved regions 10aU and 10bU of the S-spring are automatically, positively brought into close contact on and along the two forwardly-facing circumferential surface areas 9Lf and 9Rf of the left and right cylindrical side frame portions 9L and 9R, respectively. This spring mounting structure may be suitably applied to a fully-automated assembly process or a robotic assembling system for production of seats.
In the present embodiment, it is preferably important that each of the two curved regions 10aU and 10bU should closely contact the corresponding one of the two forwardly-facing circumferential surface areas 9Lf and 9Rf over substantially an overall circumferential perimeter of the latter, as seen in
Further, in this third embodiment shown in
In addition to the above-described arrangement of the S-spring 10, with reference to
The above-described stable mounting of the S-spring is also effective for reducing frictions and objectionable noises to a lowest possible degree, even when a vibration is imparted to the S-springs from a seat occupant or a vehicle body. Namely, irrespective of such vibration being exerted on the S-spring, the aforementioned arrangement surely minimizes friction of the S-spring's distal end portions 10aE and 10bE against the corresponding first and second truncated-conical hole portions 11B-1 and 11B-2 as well as generation of objectionable noise due to that friction, and also minimizes friction of the S-spring's curved regions 10aU and 10bU against the corresponding two forwardly-facing circumferential surface areas 9Lf and 9Rf as well as generation of objectionable noise due to that friction. Therefore, any uncomfortable touch and uneasiness that might normally occur in these aspects will not be felt by a seat occupant.
While not shown for this third embodiment, optionally, likewise in
According to this fourth embodiment, reference being made to
More specifically, as shown in
From
According to the above-described structure of this fourth embodiment, the first recessed mounting portion 11C-1, as viewed in cross-section, represents a recess of substantially crescent shape occupying a half circumference range of the left cylindrical side frame portion 9L, whereas likewise, the second recessed mounting portion 11C-2, as viewed in cross-section, represents a recess of substantially crescent shape occupying a half circumference range of the right cylindrical side frame portion 9R. Further, those two crescent recessed mounting portions 11C-1 and 11C-2 are shown to be in a mutually facing relation, with their respective two midway points being both positioned on one and the same horizontal line Lh.
S-spring 10′ employed in this fourth embodiment comprises: a main body portion 10′M; a first hooked end portion 10′a; and a second hooked end portion 10′b. As shown in
Referring to
In the present fourth embodiment, in order to assuredly preclude movement and removal of the S-spring 10′ from the first and second recessed mounting portions 11C-1 and 11C-2 and also to assuredly avoid frictions and noises that might be caused from between the S-spring and the two recessed mounting portions, it is recommended that, as can be seen in
a) A longitudinal central axis of the main body portion 10′M of the S-spring must be coaxial with or nearly coaxial with the horizontal line Lh which is orthogonal to the two vertical central axes Lv respectively of the left and right cylindrical side frame portions 9L and 9R.
b) Each of the two forwardly-facing circumferential surfaces 9Lf and 9Rf of the left and right cylindrical side frame portions 9L and 9R must have a circumferential perimeter equal to an arch of a sector having 45-degree central angle relative to the vertical central axis Lv of the corresponding one of the left and right cylindrical side frame portions. And, each of the two short curved regions 10′aU-1 and 10′bU-1 of the S-spring 10′ must have a perimeter equal to or nearly equal to the above-defined circumferential perimeter of the corresponding one of the forwardly-facing circumferential surfaces 9Lf and 9Rf.
c) Each of the two curved wall surface areas 30 and 30 must be formed to extend in a direction circumferentially of the corresponding one of the left and right cylindrical side frame portions 9L and 9R over an entire outer diameter of circular cross-section of the latter. And, each of the two long curved regions 10′aU-2 and 10′bU-2 of the S-spring 10′ must have a curvature and overall perimeter which are equal to or nearly equal to curvature and overall perimeter of the corresponding one of the two curved wall surface areas 30 and 30.
Inasmuch as all the above-noted requirements are fully met, the present fourth embodiment indeed ensures that the left short and long curved regions 10′aU-1 and 10′aU-2 of the S-spring 10′ are closely contacted and firmly engaged with and along a three-quarters circumferential range of the outer circumferential surface of the left cylindrical side frame portion 9L, such that the left long curved region 10′aU-2, due to its resilient contracting force, makes embracing close contact with an entirety of the curved wall surface area 30 of the first recessed mounting portion 11C-1, while also ensuring that the right short and long curved regions 10′bU-1 and 10′bU-2 of the S-spring 10′ are closely contacted and firmly engaged with and along a three-quarters circumferential range of the outer circumferential surface of the right cylindrical side frame portion 9R, such that the right long curved region 10′bU-2, due to its resilient contracting force, makes embracing close contact with an entirety of the curved wall surface area 30 of the second recessed mounting portion 11C-2. Under such state, both two hooked end portions of the S-spring 10′ are in a sufficient embracing engagement with the left and right cylindrical side frame portions 9L and 9R, respectively, so that the S-spring 10′ is stably supported and retained between the said two cylindrical side frame portions against removal therefrom. In this context, when and while a seat occupant sits on the seat, his or her back portion presses and moves the main body portion 10′M of the S-spring rearwardly, in which case, normally, the S-spring's first and second hooked end portions 10′a and 10′b might be slidingly rotated along the two outer circumferential surfaces of the left and right cylindrical side frame portions 9L and 9R, respectively, and removed therefrom. However, the present embodiment meeting all the above-noted requirements assuredly avoids such sliding rotation and removal of the hooked end portions 10′a and 10′b. This is because the two long curved regions 10′aU-2 and 10′bU-2 of the S-spring 10′ are respectively, positively contacted on and along the two gently curved surfaces (i.e. the two curved wall surface areas 30 and 30) which are smaller in curvature than the two short curved regions 10′aU-1 and 10′bU-1 of the S-spring 10′, with the latter two short curved regions 10′aU-1 and 10′bU-1 being in turn positively contacted on and along the two outer circumferential surfaces of the left and right cylindrical side frame portions 9L and 9R, respectively, and further the two long curved regions 10′a-2 and 10′bU-2 extend along a half circumference range of the corresponding one of the two cylindrical side frame portions 9L and 9R over an entire diameter of a cross-section of the latter. By the virtue of this structure, a rearward load applied from the seat occupant to the S-spring is imparted to each of the two short curved regions 10′aU-1 and 10′bU-1 and transmitted therethrough to each of the two long curved regions 10′a-2 and 10′b-2 along a circumferential direction of the corresponding one of the left and right cylindrical side frame portions, but, the two long curved regions 10′a-2 and 10′b-2, to which the load is being transmitted, are brought to close contact on and along the two curved wall surface area 30 and 30, respectively, because each of those curved wall surface areas 30 and 30 has the small curvature stated above which does not conform to the circumferential direction of the load being transmitted along the circumference of the corresponding one of the two cylindrical side frame portions. Namely, at this point, the initial circumferentially-applied load from the seat occupant's back portion is now transformed into a non-circumferentially applied load or substantially-non-rotational load at each of the S-spring's two long curved regions 10′aU-2 and 10′bU-2, and such substantially-non-rotational load therefore turns nearly unidirectional to each of the two long curved regions 10′aU-2 and 10′bU-2, thus only acting to bias those particular two regions 10′aU-2 and 10′bU-2 into full engagement with the two curved wall surface areas 30 and 30, respectively.
Owing to the above-elaborated effects of the fourth embodiment, substantially an entirety of the first long curved region 10′aU-2 of the S-spring 10′ and substantially an entirety of the second long curved region 10′bU-2 of the same 10′ are closely contacted with and retained in the first and second recessed mounting portions 11C-1 and 11C-2, respectively, against movement, thereby avoiding or minimizing the possibility that both two long curved regions 10′aU-2 and 10′bU-2 will be dislocated from their respective positions in any of upper, lower, left and right directions. In addition, the two short curved regions 10′aU-1 and 10′bU-1 of the S-spring 10′ are firmly maintained in close contact with and along the two forwardly-facing circumferential surface areas 9Lf and 9Rf of the left and right cylindrical side frame portions 9L and 9R, respectively. Hence, irrespective of any vibration being applied to the S-spring from either a seat occupant or a vehicle body, the arrangements thus described completely or minimally inhibit rattling and wobbling of the two hooked end portions 10′a and 10′b of the S-spring 10′, and also avoids or minimizes frictions of the same 10′a and 10′b against the corresponding left and right cylindrical side frame portions 9L and 9R. For that reason, no objectionable noise is generated therefrom, so that a seat occupant may not feel any discomfort.
While not shown, in the present fourth embodiment, such a resin coating as shown in
According to the present invention, it is to be appreciated that all of the foregoing embodiments are commonly effective in: realizing a rapid, easy operation for ensuring that the S-springs 10 or 10′ are extended and retained between the left and right cylindrical side frame portions 9L and 9R against removal therefrom; no necessity of providing additional securing elements to the left and right cylindrical side frame portions for firm mounting of the S-springs thereto; simplifying the mounting structure of the S-springs; and achieving a light weight of the seat back frame 7. Further, it is to be appreciated from the descriptions above that, as one aspect of the invention, each of the first and second end portions 10a and 10b of the S-spring 10 may be closely contacted on and about full or nearly one-seconds circumferential range of the outer circumferential surface of the corresponding one of the left and right cylindrical side frame portions 9L and 9R, and that, as another aspect of the invention, each of the first and second end portions 10′a and 10′b of the S-spring 10′ may be closely contacted on and about full or nearly three-quarters circumferential range of the outer circumferential surface of the corresponding one of the left and right cylindrical side frame portions 9L and 9R. Any of these features ensures a stable, hard-to-move mounting of the S-springs to the left and right cylindrical side frame portions, thereby completely preventing or minimizing the wobbling and frictions of the S-spring's first and second end portions against the left and right cylindrical side frame portions, which in turn attains complete or minimal suppression of objectionable noises that might be generated from the wobbling and frictions.
While having described the present invention thus far, it should be understood that the invention is not limited to all the aforementioned embodiments, but any modification and replacement of pertinent parts and elements may be applied to the invention, without departing from the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-134595 | Jun 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/060603 | 4/3/2015 | WO | 00 |
