JP6141634B2 - Chair - Google Patents

Description

  The present invention relates to a chair provided with a synchro tilt mechanism (synchronous tilt mechanism) that interlocks a seat with a backward tilting action of a backrest.

  With respect to the synchro tilt mechanism, conventionally, a structure has been adopted in which the height and angle of the seat are changed in accordance with the degree of backward tilting of the backrest in order to improve the sitting comfort and reduce the uncomfortable feeling when the backrest tilts backward. In general, a back frame that supports the backrest has a substantially L shape in a side view, a front end of the back frame extends below the seat, and a left and right rotation shaft is provided at the front end portion. Many structures have been adopted in which the back frame tilts backward as the back frame rotates backward. According to this structure, the backrest moves backward so as to sink backward. Since it is necessary to make the seat follow this, the seat also tilts backward while moving backward (Patent Documents 1, 2, etc.).

JP 2009-165661 A JP 2006-181101 A

  By the way, in the normal synchro tilt mechanism described above, all of the reaction force for returning the back tilted backrest to the standing state while the person is sitting depends on the rear tilt force generating mechanism arranged below the seat. Therefore, a large spring (a spring having a large spring constant) is used in the backward tilt force generation mechanism. The magnitude of the reaction force to return the backrest depends on the weight of the seated person and the preference of the seated person, and a reaction force adjusting mechanism for that is essential, but in the normal synchro tilt mechanism described above, as the reaction force adjusting mechanism In general, a structure is adopted in which the spring receiver of the spring is moved by a screw feed mechanism to change the amount of compression of the spring. The reaction force adjustment mechanism with this structure allows a large adjustment range (the amount of change in the compression amount of the spring), but it is necessary to turn the handle of the screw feed mechanism many times with a human hand, and as the spring is compressed. There was a problem that the rotation of the handle became heavier and a considerable amount of labor was required for the adjustment work.

  Then, this invention is made | formed in view of this situation, and makes it a subject to provide the chair which can adjust easily the strength of the reaction force for returning the back leaning back to an upright state. .

A chair according to the present invention includes a synchro tilt mechanism that interlocks a seat with a back tilting action of a backrest, and a rear tilt force generation mechanism that generates a reaction force for returning the backrest that has been tilted back to a standing state. The synchro tilt mechanism is a mechanism that raises the seat in conjunction with the backrest tilting backward, and the backward tilt reaction force generation mechanism is a means for generating the reaction force. comprising an elastic member, the reaction force strength reactive force adjusting mechanism capable of adjusting a, wherein the reaction force adjusting mechanism, wherein the alterable cylindrical cam the amount of compression of the elastic body, rotating the said cylindrical cam The first cam portion rotatable about an axis, the second cam portion arranged coaxially with the first cam portion, and the first cam portion, A guide shaft that integrates the second cam portion while allowing relative displacement in the axial direction. The cam portion has a bottomed cylindrical shape, the operation portion projects from the bottom portion along the central axis, and the annular end portion on the second cam portion side gradually moves along the circumferential direction in the axial direction. The second cam portion is a bottomed cylindrical shape, the bottom portion abuts against the elastic body, and the annular end portion on the first cam portion side is in the axial direction. An inclined cam surface whose position gradually changes along the circumferential direction, and the guide shaft includes a hollow portion of the first cam portion and a hollow portion of the second cam portion in a state where the cam surfaces face each other. The cylindrical cam has a length in the axial direction of the cylindrical cam as the first cam portion rotates relative to the second cam portion relative to the second cam portion by rotating the operation portion. Is variable, whereby the amount of compression of the elastic body can be changed .

  According to the chair of the present invention, when the seat occupant switches from the backward tilted posture to the standing posture by adopting the synchro tilt mechanism in which the seat rises in conjunction with the backrest tilting backward, the seat is seated. The seat is lowered by the weight of the person, and the backrest tends to stand up as the seat moves downward. Therefore, the weight of the seated person can be converted into the standing reaction force of the backrest. Therefore, unlike the conventional rear tilt force generation mechanism that must cover all of the weight of the seated person and the preference of the seated person, the sync tilt mechanism also has the function of generating the rear tilt force. Can be shared.

  Therefore, the burden on the rearward tilt force generating mechanism is reduced, and the rearward tilt force generating mechanism can be reduced in size as compared with the conventional rearward tilt force generating mechanism.

  Moreover, the rearward tilt force generation mechanism only needs to be able to adjust the “seat preference”, and the adjustment range is smaller than the conventional rearward force generation mechanism that requires considerable labor for adjustment. Therefore, the strength of the reaction force can be easily adjusted.

  Here, as one aspect of the chair according to the present invention, the synchro tilt mechanism adopts a configuration that lifts at least a part of the seat in conjunction with the back tilt of the backrest, thereby lifting the seated person's body. can do.

  According to this configuration, when the seat occupant changes from the backward tilted posture to the standing posture, the seat moves down due to the weight of the seat occupant, and the backrest tends to stand up as the seat moves downward. An effect can be produced.

  As described above, according to the chair of the present invention, the strength of the reaction force for returning the back tilted backrest to the standing state can be easily adjusted.

The perspective view of the chair concerning one embodiment of the present invention is shown. The left side view which disassembled the upholstery of the chair is shown. The exploded perspective view which omitted some composition of the chair is shown. The base part of the same chair and the perspective view of a part of back support arm are shown. The disassembled perspective view of a part of the base and a back support arm is shown. The exploded perspective view which omitted some composition of the base is shown. The left view of the base and seat is shown. The bottom view which abbreviate | omitted one part structure of the base is shown. The front view of the base is shown. (A) is a left side view of an essential part of a rear reaction force generation mechanism with a reaction force adjustment mechanism incorporated in the base, and (b) is an enlarged side view of a rotating cam of the reaction force adjustment mechanism. . It is an action explanatory view of reaction force adjustment using the reaction force adjustment mechanism, (a) is a state where the spring is most extended, (b) is a state where the spring is compressed more than (a), (c ) Indicates a state in which the spring is most compressed. FIG. 8 is an operation explanatory diagram corresponding to FIG. 7 regarding the synchro tilt mechanism of the chair. The schematic of the reaction force adjustment mechanism which concerns on other embodiment is shown. The schematic diagram of the rotating cam of the reaction force adjustment mechanism which concerns on another embodiment is shown. Furthermore, the schematic diagram of the rotating cam of the reaction force adjustment mechanism which concerns on another embodiment is shown. The schematic diagram of another embodiment of a synchro tilt mechanism is shown. In this embodiment, the backrest is tilted backward.

  Hereinafter, an office swivel chair which is an embodiment of a chair according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the chair includes a leg 1, a base 3 attached to the leg 1, a seat receiver 5 disposed on the base 3, and a seat supported by the seat receiver 5. 7, a backrest support 9 that is pivotally attached to the base 3, a backrest 11 that is supported by the backrest support 9, and a seat 7 that is attached to the backrest 11 in a backward tilting motion. A synchro tilt mechanism 13 to be interlocked and an armrest 15 attached to the backrest support 9 are provided.

  As shown in FIGS. 1 to 3, the leg 1 includes a leg base 17 and a leg support 19 provided at the center of the leg base 17. The leg base 17 is formed by projecting a plurality of leg blades 23 radially from a hub 21 provided at the center. A caster 25 is provided at the tip of each leg blade 23. The leg support 19 is a gas spring type, and elastically expands and contracts in the vertical direction so that it can be locked at a desired position. The leg column 19 includes a gas spring body 27 fitted to the hub 21 of the leg base 17 and a rod 29 protruding from the upper end of the gas spring body 27. At the upper end of the rod 29, an operation button 31 for unlocking is provided protruding. The base 3 is attached to the upper end of the rod 29. The unlocking operation button 31 is operated by a lifting operation lever 295 provided on an armrest 15 described later.

  As shown in FIGS. 4 to 6, the base 3 includes a main frame 33 attached to the rod 29 of the leg support 19, a front link shaft 35 attached to the main frame 33, and a support shaft 37 as a rear link shaft. And. The front link shaft 35 is for supporting the front end portion of the seat receiver 5 via the front link 39. The support shaft 37 supports the backrest support 9 so as to be rotatable at a position in front of the leg support 19 and supports the intermediate portion of the seat receiver 5 via the rear link 41.

  The main frame 33 includes a boss portion 43 fitted to the upper end portion of the rod 29 of the leg column 19, a rear frame member 45 having a semicircular shape in plan view surrounding the upper end side of the boss portion 43, and the rear frame member. A pair of side frame members 47, 47 extending forward from the left and right front ends of 45, and a front frame member 49 that joins the front end portions of these side frame members 47, 47 and has a flat surface at the front end. I have. The boss portion 43, the rear frame member 45, the side frame members 47 and 47, and the front frame member 49 are integrally molded by aluminum die casting or the like. A bearing portion 51 that supports the front link shaft 35 is integrally provided on the upper surface portion of the front frame member 49, and the support shaft 37 is supported near the boundary between the rear frame member 45 and the side frame member 47. A bearing portion 53 is integrally provided. In addition, the height from the floor surface of the shaft center of the two bearing portions 51 and 53 is different, and the front bearing portion 51 is set at a higher position than the rear bearing portion 53.

  As shown in FIGS. 7 and 8, the main frame 33 incorporates a rearward reaction force generation mechanism 55 for biasing the backrest 11 forward, that is, for returning the backrest 11 tilted rearward to a standing state. It is.

  The rear tilting force generating mechanism 55 is installed between a pair of torque transmission brackets 57, 57 having a base end portion supported by the support shaft 37 and the distal ends of the left and right torque transmission brackets 57, 57. A movable shaft 59, a spring 63 that elastically urges the movable shaft 59 provided on the main frame 33 as a scaffold, and an elastic urging force (reaction force) (strength) of the spring 63. A reaction force adjusting mechanism 79 for adjusting is provided.

  The spring 63 is a compression coil spring having a spring constant of, for example, 10 kg / mm and a length of, for example, 90 mm. A front mount 65 is attached to the front end portion of the spring 63, and a rear mount 67 is attached to the rear end portion of the spring 63. The front mount 65 is made of metal, has an outer diameter slightly smaller than the inner diameter of the spring 63, and is inserted into the spring 63 from the front end side of the spring 63, and extends along the axis from the insert section 69. And a guide shaft 71 provided so as to protrude. The above-described spring receiver 61 is integrally provided at the front end of the insert portion 69 as a header portion of the front mount 65 and as a pressing member, and comes into contact with the front end surface of the spring 63. The rear mount 67 is made of resin, has an outer diameter slightly smaller than the inner diameter of the spring 63, and is inserted into the spring 63 from the rear end side of the spring 63, and at the rear end of the insert section 73. The header portion 75 is provided integrally and abuts against the rear end surface of the spring 63 and is engaged with a movable shaft 59 provided between the tip portions of the torque transmission brackets 57 and 57.

  The spring 63 is incorporated in the main frame 33 by fixing the spring receiver 61 as the header portion of the front mount 65 to the main frame 33 and fixing the header portion 75 of the rear mount 67 to the movable shaft 59. Since the spring 63 has already been compressed to some extent (about 4 mm in this embodiment) in this state, a reaction force due to the compression force of the spring 63 acts on the front and rear mounts 65 and 67. Since the front mount 65 is fixed to the main frame 33, the front end of the spring 63 is a fixed end, but the rear mount 67 is a torque transmission bracket 57, 57 that is allowed to rotate in a certain angle range. The rear end of the spring 63 is a free end that is allowed to move within a certain range. Therefore, the spring 63 always urges the movable shaft 59 backward, that is, urges the backrest 11 forward. When the backrest 11 tilts backward, the movable shaft 59 moves forward with the rotation of the torque transmission brackets 57, 57, and the spring 63 is compressed via the rear mount 67. Increases, and the force to return the tilted backrest 11 to the upright state increases.

  The rear mount 67 is formed with an insertion hole 77 along the axis, and the guide shaft 71 of the front mount 65 is inserted into the insertion hole 77. The guide shaft 71 is slidable and non-rotatable in the axial direction with respect to the insertion hole 77. The front mount 65 and the rear mount 67 are integrated while allowing relative displacement in the axial direction by inserting the guide shaft 71 into the insertion hole 77, and impart linearity to the spring 63.

  As shown in FIGS. 7 to 10, the reaction force adjusting mechanism 79 is used to change the overall length of the spring 63 (when the backrest 11 is not tilted backward) in a stepwise manner. A rotating cam 81 that contacts (abuts) the spring receiver 61 and an operation lever 83 as an operation unit that rotates the rotating cam 81.

  The rotating cam 81 is disposed in a rotating cam housing portion 85 formed on the front frame member 49 of the main frame 33 of the base portion 3. The rotating cam housing portion 85 is formed by cutting out the front frame member 49, and is opened toward the front surface of the spring receiver 61 by penetrating the front frame member 49 forward and backward. The rotating cam 81 is disposed in the rotating cam accommodating portion 85, and the lever shaft 89 of the operation lever 83 that passes through the front frame member 49 is inserted therethrough and integrated with the lever shaft 89. It can be rotated.

  The rotating cam 81 is formed on the circumferential surface 95 centered on the axis W and has a plurality of cam surfaces 100 to 102 capable of compressing the reaction force stepwise, and the protrusion amount (separation amount) from the axis W is the smallest. A stopper portion 93 that is formed between the cam surface 100 and the largest cam surface 102 and prevents further rotation of the rotary cam 81 is provided. Specifically, as shown in FIG. 10 (b), the rotating cam 81 protrudes in a direction away from the axis W and a main body portion 91 formed with a plurality of cam surfaces 100 to 102 centering on the axis W. And a convex portion 93 as a stopper portion. The convex portion 93 is formed in the cam surface non-formation region 99 excluding the cam surface formation region 97 within a predetermined angle range with the axis W as the center on the peripheral surface 95 of the main body 91. A first cam surface 100, a second cam surface 101, and a third cam surface 102 are formed in the cam surface formation region 97 along the direction around the axis W. The distance between the first cam surface 100 and the axis W (rotation center) is T1, the distance between the second cam surface 101 and the axis W (rotation center) is T2, and the distance between the third cam surface 102 and the axis W (rotation center) is When the distance is T3, the relationship is T1 <T2 <T3. Since the circumferential surface 95 of the rotating cam 81 is in contact with the front surface of the spring receiver 61, the cam surfaces 100 to 102 are sequentially brought into contact with the front surface of the spring receiver 61 when a seated person rotates the rotating cam 81. It has become.

  The rotating cam 81 is disposed on the axis of the spring 63, that is, at the center position of the spring 63 as viewed from the axial direction of the spring 63. Therefore, the axis W (rotation center) of the rotating cam 81 is also on the axis of the spring 63. Is arranged. Further, each of the cam surfaces 100 to 102 has a diameter extending from the axis W (rotation center) except for an edge portion for obtaining continuity with the peripheral surface 95 other than the cam surfaces 100 to 102 in the cam surface forming region 97. It is a plane orthogonal to the direction or a plane equal thereto.

  The spring receiver 61 is arranged in an internal space of a bracket 86 attached to the front frame member 49, and guide pieces 62, 62 projecting from the left and right of the spring receiver 61 are respectively vertical wall portions of the bracket 86. By being slidably inserted into a slide groove 88 formed in 87, the spring receiver 61 can slide in the length range of the slide groove 88 along the axial direction of the spring 63. When the spring receiver 61 moves in the direction approaching the rear mount 67, the spring 63 is compressed. On the other hand, when the spring receiver 61 moves away from the rear mount 67, the spring 63 expands. A groove 66 corresponding to the width of the rotating cam 81 is formed on the front surface of the spring receiver 61, and a part of the outer peripheral portion of the rotating cam 81 enters the groove 66. Therefore, when the rotating cam 81 rotates in one direction, one end surface of the convex portion 93 finally hits one end edge of the groove 66 to prevent further rotation, and when rotating in the opposite direction, the rotating cam 81 finally rotates. As the other end face of the convex portion 93 of the cam 81 hits the other edge of the groove 66 and the further rotation is prevented, the convex portion 93 keeps the rotating cam 81 from rotating in one direction or the opposite direction. Functions as a stopper to prevent.

  According to the reaction force adjusting mechanism 79 described above, the lever shaft 89 is rotated by holding the handle 90 of the operation lever 83 and the first cam surface 100 of the rotating cam 81 contacts the spring receiver 61 as shown in FIG. In other words, the state in which the spring receiver 61 is farthest from the rear end of the spring 63, that is, the state in which the spring 63 is extended the most, in other words, the state in which the compression amount of the spring 63 is the smallest (first state: FIG. 11 (a)) and the state where the second cam surface 101 of the rotating cam 81 is in contact with the spring receiver 61, that is, the state where the spring receiver 61 is closer to the rear end of the spring 63 than the first state, The state in which the spring 63 is compressed more than in one state (second state: see FIG. 11B), and the state in which the third cam surface 102 of the rotating cam 81 is in contact with the spring receiver 61, that is, in the second state. The spring receiver 61 is further A state of approaching the rear end of 63, that is, a state where the spring 63 is further compressed than the second state, in other words, a state where the compression amount of the spring 63 is the largest (third state: see FIG. 11C). ) And can be switched to. Since the reaction force of the spring 63 increases as the compression amount increases, the reaction force increases in the second state than in the first state and in the third state than in the second state.

  4 to 6, reference numeral 64 denotes a lifting / lowering unlocking arm for pressing the unlocking operation button 31 provided on the rod 29 of the leg column 19, and reference numeral 297 denotes an armrest 15. This is an elevating wire for transmitting the operating force of the elevating operation lever 295 provided to the elevating lock release arm 64. When the wire 297 is pulled by operating the operation lever 295, the base end boss portion 66 fitted on the support shaft 37 rotates, and is provided integrally on the opposite side of the wire 297 across the base end boss portion 66. The unlocking arm 64 is rotated downward.

  A front link 39 is rotatably attached to each front bearing portion 51 of the base portion 3 via a front link shaft 35. That is, as shown in FIGS. 4 to 6, the base 3 includes a pair of opposing flat surfaces 105, 105 that are perpendicular to the left and right in the axial direction, and each front link 39 can be used to perform the original function of the chair. A plane corresponding portion 107 located between the flat surfaces 105, 105 in the hour rotation range and located outside the planes 105, 105 in the insertion / removal rotation range in which the front link 39 can be inserted into and removed from the base 3; The plane corresponding portion 107 is rotatably supported by the base portion 3 via the front link shaft 35 while being positioned between the planes 105 and 105.

  The base 3 is provided with a link arm accommodating portion 109 that opens forward and upward at positions adjacent to each other in the axial direction of the front bearing portion 51. The link arm accommodating portion 109 is formed between a pair of planes 105 and 105 orthogonal to the front link shaft 35. The front link 39 has a shaft hole 113 that holds the front connecting shaft 111 at the upper end portion, and has a boss portion 115 that is externally mounted on the front link shaft 35 at the base end portion. A link arm 117 is provided. The plane corresponding portion 107 described above is a portion corresponding to the link arm accommodating portion 109 of the link arm 117.

  In the rotation range in use, the plane corresponding portion 107 of the link arm 117 is located between the opposing planes 105 and 105 of the link arm housing portion 109. Therefore, the front link 39 is prohibited from coming off from the front link shaft 35 and the front connection shaft 111. On the other hand, in the rotation range at the time of insertion / removal, the plane corresponding portion 107 of the link arm 117 is located outside between the opposed planes 105, 105 of the link arm housing portion 109. Therefore, the front link 39 can be detached from the front link shaft 35 and the front connection shaft 111. In the assembled state, the left and right front links 39, 39 are set so that they cannot rotate to the rotation range during insertion / removal. At the time of assembly, the left and right front links 39, 39 are laid back and passed from the left and right to the front connecting shaft 111 passed through the front link mounting portion 121 of the seat 5 and the front bearing portions 51, 51 of the main frame 33. The front link shaft 35 is fitted. In this state, the front link 39 is tilted forward, and the link arm 117 of the front link 39 is fitted between the opposed planes 105, 105 of the link arm housing portion 109. Thereafter, the rear connecting shafts 123 are fitted into the left and right rear link mounting portions 127 and 127 located substantially in the middle of the seat receiver 5, respectively, and the back support arm 151 of the backrest support body 9 to be described later is attached from the left and right. It becomes a state. As described above, the seat receiver 5 is supported by the base 3 via the front link 39 and the rear link 41.

  The base 3 is covered with an upper cover 65 and a lower cover 67 as shown in FIGS. The upper cover 65 covers the base 3 from the upper surface side. The lower cover 67 covers the base 3 from the lower surface side. The upper cover 65 and the lower cover 67 are arranged so that the opening end edges 73 and 75 face each other. That is, in the opening edges 73 and 75, a groove, specifically, one of the upper cover 65 and the lower cover 67 has a fitting recess exposed to the outside, and the other has a fitting recess exposed to the inside. L-shaped grooves that can be fitted to each other are formed.

  The upper cover 65 and the lower cover 67 conceal the reaction force adjusting mechanism 79 from the outside, and the operation lever 83 is disposed outward from the upper cover 65 and the lower cover 67. The upper cover 65 and the lower cover are inserted through the lever shaft 89 of the rotating cam 81, the front link shaft 35, the support shaft 37, and the like. 67. The upper and lower covers 65, 67 are joined to each other so that the respective insertion portions of the upper cover 65 and the corresponding insertion portions of the lower cover 67 are matched so that the respective shafts are inserted. A hole is formed. For this reason, the upper cover 65 and the lower cover 67 can be easily assembled or disassembled.

  As shown in FIG. 2, the seat 5 has a form that can be referred to as an outer shell, and is integrally formed of synthetic resin. On the lower surface of the seat 5, as described above, a front link mounting portion 121 for mounting the rotating end 119 of the front link 39 via the front connecting shaft 111 at a position from the front end portion, and a substantially center in the front-rear direction A rear link attaching portion 127 is provided at a position and for attaching the rotation end 125 of the rear link 41 via the rear connecting shaft 123. The front link mounting portion 121 and the rear link mounting portion 127 are provided integrally with the seat receiver 5.

  As shown in FIG. 3, the seat 7 includes an inner shell (not shown) attached to the upper surface of the seat receiver 5, a cushion 131 disposed on the inner shell, and a tension stretched on the outer surface of the cushion 131. The ground 133 is provided. The inner shell is integrally formed of synthetic resin. The cushion 131 is made of foamed urethane or the like. On the upper surface of the cushion 131, there are provided uneven portions arranged in one direction, in this embodiment, a plurality of grooves 145 arranged in the front-rear direction. The upholstery 133 has a bag shape that covers the cushion 131 and the periphery of the inner shell. A visual feature portion is formed in the upholstery 133 in association with the groove 145 formed in the cushion 131. In the present embodiment, the visual feature portion is a line 149 obtained by embossing the tension fabric 133. In the present embodiment, a plurality of the filaments 149 are present so as to be arranged in the front-rear direction, and are present at a position overlapping the groove 145 of the cushion 131 from above when the tension fabric 133 is placed on the cushion 131 from above. ing.

  2 to 5, the backrest support 9 includes left and right back support arms 151 and 151 extending rearward and upward from the base 3, and upper end portions 169 of the left and right back support arms 151 and 151. , 169 and the left and right back support brackets 155 that are integrally extended from the base end of the torque transmission bracket 57 toward the rear upper side and are attached to the inner side surface of the base end portion of the back support arm 151. , 155 and a lower connecting member 157 for connecting the rear ends of the left and right back support brackets 155, 155.

  The left and right back support arms 151 and 151 are made of a resin that is rotatably supported by the base portion 3, and is continuous from the front and rear direction extending portion 159 extending in the front and rear direction and the rear end of the front and rear direction extending portion 159. And an upright portion 161 extending upward. The front-rear direction extending portion 159 and the upright portion 161 have a generally U-shape when viewed from the side. Each back support arm 151 has a shaft mounting portion 167 for fitting from the outside to the base end portion thereof, that is, the front end portion 163 of the longitudinally extending portion 159, to the end portion 165 of the support shaft 37 provided in the base portion 3. I have. Each back support arm 151 is provided with an arm protrusion 171 for attaching the upper connecting member 153 to the tip, that is, the upper end 169 of the standing part 161.

  As shown in FIGS. 4 and 5, the shaft mounting portion 167 includes a shaft hole 173 that is opened only inward so as to fit the end portion 165 of the support shaft 37. Specifically, the end 165 of the support shaft 37 is fitted in the shaft hole 173 via the bush 175 so as to be relatively rotatable. The bush 175 is inserted from the inner surface side of the back support bracket 155 before the support shaft 37 is mounted, and the support shaft 37 is fitted on the inner periphery of the bush 175 so as to be relatively rotatable. The flange portion 177 of the bush 175 is located between the back support bracket 155 and the main frame 33. A shaft mounting portion 167 is fitted on the outer periphery of the bush 175, and the end portion 165 of the support shaft 37 is covered by the shaft mounting portion 167. The shaft hole 173 has a tapered shape with a large diameter on the opening end side, and the support shaft 37 has a cylindrical shape. The bush 175 has a shape that fills the space between the inner peripheral surface of the shaft hole 173 and the outer peripheral surface of the shaft 37. That is, the outer peripheral surface of the bush 175 has a tapered shape, and the inner peripheral surface has a cylindrical shape having the same cross-sectional shape in each part.

  A rear link 41 is integrally provided on the outer periphery of the shaft mounting portion 167. A cover member 181 that covers the half half 179 of the lower connecting member 157 is integrally provided on the inner surface of each back support arm 151 in the vicinity of the shaft mounting portion 167. The cover member 181 is provided with a screw insertion hole 183, and screws (not shown) inserted into the screw insertion hole 183 are screwed into screw holes 185 provided in the lower connecting member 157, thereby supporting the left and right back supports. The arms 151 and 151 are attached to the lower connecting member 157.

  In this state, the left and right back support arms 151 and 151 are coupled to each other via the lower connecting member 157, so that the shaft mounting portion 167 does not come out of the support shaft 37. That is, the left and right back support brackets 155 and 155 whose rear ends are connected by the lower connecting member 157 are supported by the base 3 via the support shaft 37, and both end portions of the support shaft 37 that protrude outward from the back support bracket 155. Since the left and right back support arms 151 and 151 rotating together with the back support brackets 155 and 155 are supported on the 165, the left and right back support arms 151 and 151 are attached from the left and right outside of the back support brackets 155 and 155. The support shaft 37, the back support brackets 155 and 155, and the lower connecting member 157 can be covered with the left and right cover members 181 and 181. The ends 189 and 189 of the left and right cover members 181 and 181 are in close contact with each other in the assembled state.

  As shown in FIG. 3, the arm protruding portion 171 is for attaching an end portion of the upper connecting member 153, and includes a plurality of screw insertion holes 191 and 191, and nuts having screw holes continuous to the screw insertion holes 191. (Not shown).

  The upper connecting member 153 is made of a metal having a channel shape and is installed between the arm projecting portions 171 and 171 of the left and right back support arms 151 and 151 and then screwed to the nut of each arm projecting portion 171 ( (Not shown) is attached to each back support arm 151. That is, the upper connecting member 153 has a shape that opens to the rear, and is fitted between the upper ends 169 and 169 of the back support arms 151 and 151 by being fitted to the arm projecting portion 171 from the front side.

  As shown in FIGS. 4 and 5, the back support bracket 155 is made of metal, is integrally formed with the torque transmission bracket 57, and is rotatably supported by the main frame 33 via the support shaft 37.

  As shown in FIG. 3, the lower connecting member 157 is made of metal, and both ends thereof are welded to the rear ends of the left and right back support brackets 155 and 155. The lower connecting member 157 has a skeletal function of the back support arms 151 and 151 made of synthetic resin in cooperation with the left and right back support brackets 155 and 155. Further, the lower connecting member 157 receives a load in the backward tilt direction acting on the backrest 11 through the left and right back support arms 151 and 151, and tilts the load back through the left and right back support brackets 155 and 155. It also has a function of transmitting to the torque transmission bracket 57 of the force generation mechanism 55.

  1-3, the backrest 11 is made of a resin having a slit-like opening 203 that is curved at the top 201 until it becomes substantially horizontal and extends in the vertical direction for elastic deformation promotion. A back shell 205, a back support member 209 that supports a tip edge 207 positioned rearward of the top portion 201 of the back shell 205, and a tension fabric 206 stretched on the surface side of the back shell 205. The back shell 205 is supported so that the front left and right edges are supported by the front surfaces of the upright portions 161 of the left and right back support arms 151, extend upward to form a backrest surface, and are separated from the backrest surface rearward. Folded 180 degrees to form a top portion 201, having a rear end edge at a position extending rearward and lower than the top portion 201, the rear end edge being made of a resin supported by a backrest support 9, and an upper region A plurality of belt-like members 213 extending in the vertical direction are arranged on the left and right sides, and a slit-like opening 203 is formed between the belt-like members 213 and 213. The back support member 209 has a plate shape that is disposed so as to face the back surface of the back shell 205 so as to form a left and right space 245. The back shell 205 is supported by the back support 9, and the belt-like members arranged on the left and right act independently to control deflection in the front-rear direction due to the weight of the seated person. A plurality of ribs 253 extending in the vertical direction are formed on the back support member 209 so as to be arranged in the left and right directions, and rigidly support the flexible back shell 205. The upholstery 206 is mainly composed of a cloth material having air permeability and translucency, and has a substantially rectangular shape with a size capable of covering and covering almost the entire area of the back shell 205.

  As shown in FIG. 12, the synchro tilt mechanism 13 is a weight sensing type in which the seat 7 is moved upward while being tilted in accordance with the backward tilting motion of the backrest 11. In other words, the synchro tilt mechanism 13 is a weight sensing type that raises the position of the center of gravity of the seated person (lifts the body of the seated person) in accordance with the backward tilting action of the backrest 11. The synchro tilt mechanism 13 has a base 3 that holds the front link shaft 35 on the front side and a support shaft 37 on the rear side, and a lower end that can rotate to the base (front end) 3 via the front link shaft 35. By integrating the supported front link 39 and the lower end portion with the shaft mounting portion 167 of the back support arm 151 supported by the support shaft 37, the rotation center is made equal to the rotation center of the back support arm 151 in a side view. The rear link 41 and the front link mounting portion 121 are connected to the rotating end 119 of the front link 39 via the front connecting shaft 111, and the rear link mounting portion 127 is connected to the rotating end of the rear link 41 via the rear connecting shaft 123. The seat receiver 5 connected to the main body 125 is mainly configured.

  Specifically, the synchro tilt mechanism 13 supports the seat receiver 5 that supports the seat 7 on the base portion 3 by the front link 39 and the rear link 41 that are inclined in the same front direction, and is supported by the base portion 3. In accordance with the backward tilting action of the back support arm 151, the front link 39 and the rear link 41 are rotated in the standing direction to lift the seat 5 upward, and the backrest is 11, the front portion of the seat 7, that is, the front portion 7a1 of the seat surface 7a is lifted more than the rear portion 7a2 of the seat surface 7a. In the normal backrest and the seat synchro tilt mechanism, the seat is tilted only in the downward direction in accordance with the backward tilting motion of the backrest, but the weight sensing type synchro tilt mechanism 13 is different from the normal synchro tilt mechanism. As shown by a two-dot chain line in FIG. 12, the seat 7 is lifted against the load of the seated person while tilting the seat 7 in accordance with the backward tilting motion of the backrest 11.

  Here, the dimension γ1 in which the front part 7a1 of the seat surface 7a is lifted by the backward tilting operation of the backrest 11 is larger than the dimension γ2 in which the rear part 7a2 of the seat surface 7a is lifted. More specifically, when the backrest 11 is not tilted backward, the front link 39 has a greater forward inclination than the rear link 41. In other words, the inclination angle α of the front link 39 with respect to the horizontal line is smaller than the inclination angle β of the rear link 41 with respect to the horizontal line when the backrest 11 is not tilted backward. The center of rotation of the front link 39 relative to the base 3 is higher than the center of rotation of the rear link 41 relative to the base 3. In other words, the axial center of the front link shaft 35 is higher than the axial center of the support shaft 37 by a distance h. The effective length dimension of the front link 39, that is, the distance L1 between the front link shaft 35 and the front connecting shaft 111, and the effective length dimension of the rear link 41, that is, the support shaft 37 and the rear connecting shaft which are the rear link shaft The distance L2 between the axes with respect to 123 is substantially the same distance. Further, the back support arm 151 is pivotally supported by a portion of the base 3 that is in front of the leg column 19. In other words, the shaft mounting portion 167 of the back support arm 151 is supported by the support shaft 37 positioned in front of the leg column 19 in a side view.

  The point that the forward tilting degree of the front link 39 is larger than the forward tilting degree of the rear link 41 is intended to lift the front side of the seat 7 relatively larger than the rear side during the rearward tilting. By making the degree of forward inclination of the link 39 and the rear link 41 greatly different from each other, it is possible to increase the lift of the seat 7 at the time of the backward inclination. In other words, the front link 39 often has an operation of lifting the front portion of the seat 7 (the front portion 7a1 of the seating surface 7a) upward, and the rear link 41 is centered on the operation of moving the seat 7 rearward. As a result, the seat surface 7a lifts the front portion 7a1 much, while the rear portion 7a2 of the seat surface 7a moves backward, and moves backward so as to follow the backrest 11 tilting backward. As a result, the relative positional relationship between the rear end portion of the seat 7 and the lower end portion of the backrest 11 is effectively suppressed by tilting the seat surface 7a relatively rearward.

  The point that the rotational center positions of the front link 39 and the rear link 41 are different in the vertical direction is mainly for the purpose of adjusting the level of the seat 7 when standing upright. In combination with the difference in the degree of forward tilt, the posture of the seat 7 when the backrest 11 stands and the posture of the seat 7 when the backrest 11 is tilted backward are both set to an optimum state. By making the effective length dimension L1 of the front link 39 and the effective length dimension L2 of the rear link 41 substantially the same, the setting can be made more appropriate. However, of course, the effective length dimension L1 of the front link 39 may be different from the effective length dimension L2 of the rear link 41. From the setting of the arrangement of the front link 39 in the base 3 and the connection position to the seat 5 and the like. For example, the dimension L1 may be slightly longer than the dimension L2.

  In general, in a chair in which the back support arm is pivotally supported on the front side of the leg column at the base, the backrest tends to sink downward when the backrest is tilted. When using a normal weight-sensing synchro tilt mechanism that sometimes lifts the entire seat up on average, there is a great sense of incongruity, more specifically, against the seated person's expectations, As a result of the entire seat including the part being lifted up, there is a sense of incongruity caused by the simultaneous movement of the backrest sinking motion and the seat lifting motion opposite to the sinking motion in the vicinity of the seated person's waist. According to the weight sensing type synchro tilt mechanism according to the present embodiment, the uncomfortable feeling is alleviated. That is, although the weight sensing type synchro tilt mechanism of the present embodiment is of the weight sensing type, the rear side of the seat 7 does not lift up greatly even when the backrest 11 is tilted backward, so that it is difficult to give a great sense of incongruity. .

  The rear link 41 rotates together with the back support arm 151 and the torque transmission bracket 57 around the support shaft 37 that is the rotation center of the back support arm 151. Thereby, not only the interlocking operation of the seat 7 accompanying the back tilting operation of the backrest 11 but also the accurate positioning of the seat 7 by the base 3 via the rear link 41 is realized. Further, the rotation range of the backrest 11 is set to 20 degrees, and the angle formed by the seat surface 7a in the state where the backrest 11 is tilted back to the maximum is 4 degrees later than when the backrest 11 stands. It comes to tilt. That is, the back tilt of the backrest 11 by the front link 39 is larger than the dimension γ2 in which the rear portion 7a2 of the seat surface 7a is lifted mainly due to the lifting of the substantially central portion of the seat 5 when the backrest 11 is tilted backward by the rear link 41 As a result of increasing the lifting dimension γ1 of the front portion 7a1 of the seating surface 7a at the time, the angle of the seating surface 7a when the backrest 11 is maximum tilted backward is tilted 4 degrees from when the backrest 11 stands. Yes. In addition, since the rear link 41 is connected to the substantially central portion in the front-rear direction of the seat receiver 5, the front receiver 5 can be lifted together with the front and rear links 39, 41 when the backrest 11 is tilted backward. Since the link 39 lifts the seat receiver 5 more than the rear link 41, the rear end portion of the seat receiver 5 can be relatively lowered from the front end portion, and when the front end portion of the seat receiver 5 rises. The height position of the rear end portion of the seat 5 is hardly changed between when the backrest 11 stands and when it tilts backward.

  As shown in FIGS. 1 to 3, the armrest 15 is arranged on the elbow support portion 287 and an elbow support portion 287 that integrally protrudes forward from the front surface of the upper end of the back support arm 151 of the backrest support 9. The elbow rest 289 is provided.

  The elbow support part 287 has a bottomed boat shape opened upward. A penetrating window (not shown) is formed in the bottom of the front end portion of the right elbow support portion 287 as viewed from the seated person in the one elbow support portion 287, and downward through the window. The operation lever 295 is protruded. The operation lever 295 is for operating the operation button 31 for unlocking the leg support 19. The operation lever 295 and the operation button 31 are connected by a wire 297, and the operation force applied to the operation lever 295 is transmitted to the operation button 31 by the wire 297, so that the operation of the operation button 31, and consequently the leg column 19 can be switched between lock / unlock. The proximal end portion of the operation lever 295 and one end portion of the wire 297 connected to the operation lever 295 are accommodated in the elbow support portion 287.

  The elbow rest 289 is detachable from the elbow support 287. Thereby, arbitrary things can be selected and used out of several types of elbow pads 289, ... which can be attached to the common elbow support part 287. FIG.

  As described above, in the chair according to the present embodiment, when the backrest 11 is tilted backward, the front part 7a1 of the seating surface 7a is lifted up a lot. Compared with the synchro tilt mechanism, a change in relative positional relationship with the lower end of the backrest 11 is suppressed. Thereby, the seated person can effectively suppress the change in posture caused by the back tilt of the backrest 11. Further, with this configuration, the seat 7 can be provided such that the surface direction toward the backrest 11 in the seating surface 7a always intersects with a certain portion of the lower end portion of the backrest 11 in a side view. As a result, when the backrest 11 stands and tilts backward, it is possible to suppress the occurrence of a positional shift in the vertical direction in the virtual portion of the backrest 11 located on the rearward extension line of the seating surface 7a. In addition, the weight sensing type synchro tilt mechanism according to the present embodiment, even if it is a weight sensing type, as in the prior art, in particular, two close proximity of lowering the lower end of the backrest and raising the rear end of the seat. It is not an aspect in which the part feels the opposite direction for the skeleton of the human body, and the rear end portion of the seat 7 is tilted backward so that the relative positional relationship with the lower end portion of the backrest 11 is as much as possible. The structure which raises a front part (front part 7a1 of the seat surface 7a) relatively rather than the intermediate part of the seat 7 is applied so that it may not be changed. As a result, when the backrest 11 tilts backward, a portion that rises with the weight of the seated person is created, and the center of gravity of the upper body when the backrest 11 tilts backward is lowered, and the center of gravity of the lower body when the seat 7 rises It is linked to the rise of As a result, it is possible to compensate for the difference in the backward tilting force necessary for the backrest 11 due to the difference in the weight of the seated person using the weight of the seated person without a sense of incongruity. That is, the chair according to the present embodiment can smoothly continue the desk work smoothly without causing a sense of incongruity even if the work at the time of standing and backward tilting of the backrest 11 is frequently switched. .

  In addition, the chair according to the present embodiment employs the weight sensing type synchro tilt mechanism 13 so that when the seat occupant switches from the tilted posture to the standing posture, the seat 7 moves down due to the weight of the seat occupant, Since the backrest 11 tends to stand as the seat 7 moves downward, the weight of the seated person can be converted into the standing reaction force of the backrest 11. Therefore, unlike the conventional backward tilt force generation mechanism that must cover all of the weight of the seated person and the preference of the seated person, the synchro tilt mechanism 13 has an action of generating the backward tilt force. Can also be shared. Therefore, the burden on the rearward reaction force generation mechanism 55 is reduced, and a smaller spring 63 is required compared to the conventional rearward reaction force generation mechanism, and the rearward reaction force generation mechanism 55 itself can be reduced in size. it can. In addition, the backward tilting force generation mechanism 55 only needs to be able to adjust mainly the “seater preference”, and the adjustment range (spring) is larger than that of the conventional backward tilting force generation mechanism that requires considerable labor for adjustment. 63), the reaction force adjustment work can be easily performed.

  In addition, since the conventional backward reaction force generation mechanism must cover all of the weight of the seated person and the preference of the seated person, as described above, a large spring (a spring having a large spring constant) is used. Therefore, the adjustment range (amount of change in the compression amount of the spring) is large, and the required compression force of the spring corresponding to the adjustment range is large. However, the chair according to this embodiment is mainly “sitting As described above, a small spring (a spring having a small spring constant) 63 is used, so that the adjustment range (the amount of change in the compression amount of the spring 63) is small. Thus, the necessary compression force of the spring 63 corresponding to the adjustment range becomes small. Therefore, also from such a viewpoint, the backward tilting force generating mechanism 55 can be reduced in size, and the reaction force adjusting mechanism 79 can be reduced in size.

  In addition, the chair according to the present embodiment includes a rotary cam 81 having a peripheral surface 95 with a different distance from the rotation center and capable of changing the compression amount of the spring 63 as a main component of the reaction force adjusting mechanism 79. . As a result, when the rotational angular displacement of the rotary cam 81 occurs, the distance from the rotation center of the rotary cam 81 to the peripheral surface 95 changes, and the compression amount of the spring 63 changes. As described above, since the adjustment range (the amount of change in the compression amount of the spring 63) of the backward tilting force generation mechanism 55 is small, the amount of change that makes the circumferential surface 95 of the rotating cam 81 different in distance from the rotation center. Thus, the strength of the reaction force in the backward tilt reaction force generating mechanism 55 can be adjusted appropriately.

  Moreover, the axis W (rotation center) of the rotating cam 81 is disposed on the axis of the spring 63, and each of the cam surfaces 100 to 102 formed on the peripheral surface 95 of the rotating cam 81 is separated from the axis W (rotation center). It is a surface orthogonal to the extending radial direction or a surface equal thereto. Therefore, each of the cam surfaces 100 to 102 is in a state orthogonal to or substantially orthogonal to the axis of the spring 63, that is, the center line of the elastic biasing force of the spring 63. Therefore, the rotating cam 81 is not inadvertently rotated by the elastic biasing force of the spring 63, and the stationary state of the rotating cam 81 can be suitably maintained until the rotating cam 81 is rotated. Therefore, there is no need to provide, for example, an anti-rotation latch mechanism for preventing the rotating cam 81 from being inadvertently rotated by being pushed from the spring 63, and it can be configured with a simple structure with a small number of parts. The force adjusting mechanism 79 can be further reduced in size.

  In addition, the chair which concerns on this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the reaction force adjusting mechanism 79 is provided in front of the rearward tilt reaction force generating mechanism 55, and the position of the front end in the axial direction of the spring 63 is displaced in the axial direction of the spring 63. Adjust the strength of the reaction force. However, the present invention is not limited to this. The reaction force adjusting mechanism 79 may adjust the strength of the reaction force of the spring 63 by displacing the position of the rear end in the axial direction of the spring 63 in the axial direction of the spring 63.

  In the above embodiment, each of the cam surfaces 100 to 102 is a surface orthogonal to or equal to the axis of the spring 63. However, the present invention is not limited to this. Whereas the contact portions of the spring receiver 61 with the cam surfaces 100 to 102 are flat, the cam surfaces 100 to 102 may be convex arcuate surfaces, or alternatively, the cam surfaces 100 to 102 of the spring receiver 61 However, the cam surfaces 100 to 102 may be convex arcuate surfaces. In any case, each of the cam surfaces 100 to 102 is in a state orthogonal to or substantially orthogonal to the axis of the spring 63, that is, the center line of the elastic biasing force of the spring 63. Therefore, the rotating cam 81 is not inadvertently rotated by the elastic biasing force of the spring 63, and the stationary state of the rotating cam 81 can be suitably maintained until the rotating cam 81 is rotated.

  Alternatively, as shown in FIG. 13, a concave portion 98 is provided on any or all of the cam surfaces 100 to 102, and a convex portion 61 a is provided at a contact portion of the spring receiver 61 with the cam surfaces 100 to 102. And the convex portion 61a may engage with the concave and convex portions to positively restrict the rotating cam 81 from rotating carelessly. Incidentally, the spring receiver 61 can be displaced in a direction away from the rotary cam 81 when the spring 63 is compressed. Therefore, when the operation lever 83 is turned, the engagement between the concave portion 98 and the convex portion 61a is released, and the rotary cam 81 can be rotated. In addition, while a recessed part and a convex part are provided in reverse, a recessed part is formed in the contact part with the cam surfaces 100-102 of the spring receiver 61, and a convex part is formed in any or all of the cam surfaces 100-102. It may be provided.

  Moreover, in the said embodiment, reaction force adjustment can be performed in three steps by providing the three cam surfaces 100-102. However, the present invention is not limited to this. There may be two cam surfaces, or four or more cam surfaces.

  Further, in the above embodiment, the cam surfaces 100 to 102 are formed at positions separated from each other in the circumferential direction in the cam surface forming region 97 of the peripheral surface 95 of the main body 91 of the rotating cam 81. However, the present invention is not limited to this. The cam surfaces 100 to 102 may be formed to be connected to each other.

  Moreover, in the said embodiment, reaction force adjustment can be performed in steps by providing the some cam surfaces 100-102. However, the present invention is not limited to this. For example, the cam surface forming region 97 of the peripheral surface 95 of the main body 91 of the rotating cam 81 is formed so that the distance from the rotation center gradually changes, and a continuous cam surface in which the distance from the rotation center gradually changes can be obtained. If provided, the reaction force can be adjusted steplessly. In this case, the cam surface is not orthogonal to or substantially orthogonal to the axis of the spring 63, that is, the center line of the elastic biasing force of the spring 63, and the rotating cam 81 is inadvertently caused by the elastic biasing force of the spring 63. It can rotate. Accordingly, it is preferable to provide, for example, an anti-rotation latch mechanism for preventing the rotating cam 81 from being pushed by the spring 63 and rotating carelessly.

  In the above-described embodiment, the rotating cam 81 is rotated in the cam surface forming region 97 excluding the cam surface non-forming region 99 on the peripheral surface 95 of the main body 91 of the rotating cam 81. However, the present invention is not limited to this. For example, the rotary cam 81 may be rotated in an angle range smaller than this, or conversely, the cam surface non-formation region 99 is narrowed, that is, the convex portion 93 in the circumferential direction of the rotary cam 81. The rotation cam 81 may be rotated in an angle range larger than the cam surface formation region 97.

  Further, in the above-described embodiment, the convex portion 93 as a stopper portion that contacts the base portion 3 (the main frame 33 (the front frame member 49) thereof) and restricts the rotation of the rotary cam 81 is the main body portion 91 of the rotary cam 81. It protrudes in a direction away from the axis W at a position adjacent to the cam surfaces 100, 102 on the peripheral surface 95. However, the present invention is not limited to this. The convex part 93 as the stopper part may protrude in the direction along the axis W as shown in FIG. In this case, a structure in which the rotation of the rotary cam 81 is restricted by the protrusion 93 coming into contact with a part of the main frame 33 (for example, the front frame member 49) can be adopted.

  In the above embodiment, the disk-shaped rotating cam 81 is used. However, the present invention is not limited to this. The rotating cam includes a cylindrical cam (a cam surface is formed so as to be pushed in the direction in which the rotating shaft of the rotating cam extends) and an eccentric plate-shaped rotating cam (the plate-shaped peripheral surface is the cam surface, The direction in which the rotating shaft extends and the direction of pushing on the cam surface are orthogonal to each other), and the form of the rotating cam is not particularly limited.

  What is shown in FIG. 15 is one form of a cylindrical cam. The cylindrical cam is a cam whose axial length can be changed by a rotating operation. Specifically, the cylindrical cam includes a first cam portion 81A that can rotate around an axis, and a second cam portion 81B that is disposed coaxially with the first cam portion 81A. The first cam portion 81A is a bottomed cylindrical body, and a shaft body 89A protrudes from the bottom along the central axis, and a handle 90A is attached to an end portion of the shaft body 89A. An annular end of the first cam portion 81A on the second cam portion 81B side is an inclined cam surface 81Aa whose position in the axial direction gradually changes along the circumferential direction. The cam surface 81Aa has a transition point (step) where the position closest to the second cam portion 81B and the position farthest from the second cam portion 81B are adjacent in the circumferential direction. The second cam portion 81 </ b> B is also a bottomed cylindrical body, and a guide shaft 71 </ b> A protrudes from the bottom along the central axis, and the guide shaft 71 </ b> A is inserted into the insertion hole 77 of the rear mount 67. On the outer peripheral surface of the distal end portion of the guide shaft 71A, a plurality of elongated ridges 71Aa are formed side by side in the circumferential direction (so-called vertical knurls), while an insertion hole 77 of the rear mount 67 is formed on the guide shaft. The guide shaft 71A is slidable and non-rotatable in the axial direction with respect to the insertion hole 77. The annular end portion of the second cam portion 81B on the first cam portion 81A side is an inclined cam surface 81Ba whose position in the axial direction gradually changes along the circumferential direction. The cam surface 81Ba also has a transition point (step portion) where a position closest to the first cam portion 81A and a position farthest from the first cam portion 81A are adjacent in the circumferential direction. By inserting a guide shaft 81C having the same diameter or substantially the same diameter across the hollow portion of the first cam portion 81A and the hollow portion of the second cam portion 81B, the first cam portion 81A and the second cam portion 81B Are integrated while allowing relative displacement in the axial direction. The first cam portion 81A is rotatably mounted, for example, via a bracket 81D so that the handle 90A projects forward from the base portion 3 (the main frame 33 (the front frame member 49)). Therefore, if the handle 90A is turned, the position of the cam surface 81Aa of the first cam portion 81A that is farthest from the second cam portion 81B and the position of the cam surface 81Ba of the second cam portion 81B that is closest to the first cam portion 81A And the position where the axial length of the cylindrical cam is minimized (see FIG. 15B), the position closest to the second cam portion 81B of the cam surface 81Aa of the first cam portion 81A, and the second cam Between the position of the cam surface 81Ba of the portion 81B that is closest to the first cam portion 81A and the axial length of the cylindrical cam is maximized (see FIG. 15C). The axial length is variable. If the operation lever 83 is located on the left and right outside of the seat 7 as in the above embodiment, the operation lever 83 may accidentally turn when hitting an obstacle when the chair is moved. If the handle 90 </ b> A is provided in front of the main frame 33, the handle 90 </ b> A is hidden under the front portion of the seat 7, so there is no possibility of such a case. In addition, the cross-sectional shape of the tip portion of the guide shaft 71A for making the rotation impossible with respect to the insertion hole 77 is the same for the guide shaft 71 of the above embodiment, but it may be a square shape or an elliptical shape, In short, the guide shafts 71A and 71 need only be non-circular because they cannot rotate.

  In the above embodiment, the spring 63 is an elastic body as a means for generating a reaction force in the backward tilt reaction force generation mechanism. However, the elastic body as means for generating the reaction force may be other than the spring.

  In the above embodiment, the bracket 86 is provided to support the spring receiver 61 while defining the moving direction of the spring receiver 61. However, the present invention is not limited to this. A structure may be provided in which the spring receiver 61 is slidably supported on the main frame 33 (the front frame member 49) of the base 3.

  In the above embodiment, the synchro tilt mechanism 13 that interlocks the seat 7 with the back tilting motion of the backrest 11 is tilted forward in the standing state of the backrest 11, and the back tilting motion of the backrest 11 is performed. A so-called front / rear link system (a four-link system of the base 3, the front link 39, the rear link 41, and the seat 5) using the front link 39 and the rear link 41 to be erected is employed. However, the present invention is not limited to this. As a weight-sensing synchro tilt mechanism that raises the center of gravity position of the seat occupant in accordance with the back tilting operation of the backrest, for example, a front slide system described in JP-A-2008-212622 may be used. .

  Specifically, as shown in FIGS. 16 and 17, the front slide method is the same as the front and rear link method in that the rear link 41 is used for the rear portion of the seat 5, but the front link 39 is not used. Further, the front portion of the seat receiver 5 is engaged with the base portion 3 so as to be slidable upward or rearward and obliquely upward. In other words, the front slide system includes a first rotation axis X for connecting the backrest support 9 to the base 3 so as to be able to tilt backward, a front side of the first rotation axis X and the same height as the first rotation axis X. A second rotational axis Y that is displaced from above or above the first rotational axis X and that connects the seat 5 to the base 3 so as to be swingable in the vertical direction, and the first rotational axis X and the second rotational axis. Y is displaced above the line L connecting the first rotation axis X and the second rotation axis Y, and the backrest support 9 and the seat 5 are connected so as to be swingable in the vertical direction. A third rotating shaft Z that rises in conjunction with the backward tilt of the back support 9 and a slide mechanism 39A that guides the second rotating shaft Y obliquely upward and rearward in conjunction with the rising of the third rotating shaft Z. This is a synchro tilt mechanism provided.

  In addition, the weight sensing type synchro tilt mechanism is a pivoting system in which the front part of the seat is raised and the rear part of the seat is lowered, more specifically, the rising amount of the front part of the seat is larger than the lowering amount of the rear part of the seat. It may be a rotating method.

  DESCRIPTION OF SYMBOLS 1 ... Leg, 3 ... Base, 5 ... Seat rest, 7 ... Seat, 9 ... Backrest support, 11 ... Backrest, 13 ... Synchro tilt mechanism, 15 ... Armrest, 33 ... Main frame, 35 ... Front link shaft, 37 ... Support shaft, 39 ... Front link, 41 ... Rear link, 45 ... Rear frame member, 47 ... Side frame member, 49 ... Front frame member, 51 ... Bearing portion, 53 ... Bearing portion, 55 ... Rear tilting force generation Mechanism: 57 ... Bracket for torque transmission, 59 ... Movable shaft, 61 ... Spring receiver, 62 ... Guide piece, 63 ... Spring (elastic body), 65 ... Front mount, 66 ... Groove, 67 ... Rear mount, 69 ... Insert part , 71 ... Guide shaft, 73 ... Insert part, 75 ... Header part, 77 ... Insertion hole, 79 ... Reaction force adjusting mechanism, 81 ... Rotating cam, 83 ... Operation lever, 85 ... Rotating cam housing part, 86 ... Bracket, 87 ... Vertical wall, 88 ... Sly Groove, 89 ... lever shaft, 90 ... handle, 91 ... main body, 93 ... convex part, 95 ... circumferential surface, 97 ... cam surface forming region, 99 ... cam surface non-forming region, 100 ... first cam surface, T1 ... Distance: 101 ... Second cam surface, T2: Distance, 102 ... Third cam surface, T3 ... Distance, 111 ... Front connecting shaft, W ... Axis, 121 ... Front link mounting portion, 123 ... Rear connecting shaft, 127 ... Back Link mounting part

Claims (2)

A chair provided with a synchro tilt mechanism that interlocks the seat with the back tilting action of the backrest, and a back tilt force generation mechanism that generates a reaction force for returning the backrest tilted back to the standing state,
The synchro tilt mechanism is a mechanism in which the seat rises in conjunction with the backrest tilting backward,
The rear傾反force generating mechanism, wherein comprises an elastic member serving as means for generating a reaction force, the reaction force strength reactive force adjusting mechanism capable of adjusting the, the,
The reaction force adjustment mechanism includes a cylindrical cam capable of changing a compression amount of the elastic body, and an operation unit for rotating the cylindrical cam.
The cylindrical cam includes a first cam portion rotatable about an axis, a second cam portion disposed coaxially with the first cam portion, and the first cam portion and the second cam portion relative to each other in the axial direction. A guide shaft that is integrated while allowing displacement,
The first cam portion has a bottomed cylindrical shape, the operation portion protrudes along the central axis from the bottom portion, and the annular end portion on the second cam portion side is positioned in the circumferential direction in the axial direction. An inclined cam surface that gradually changes along
The second cam portion has a bottomed cylindrical shape, the bottom portion abuts on the elastic body, and the annular end portion on the first cam portion side changes gradually in the axial direction along the circumferential direction. An inclined cam surface,
The guide shaft is inserted across the hollow portion of the first cam portion and the hollow portion of the second cam portion in a state where the cam surfaces are opposed to each other,
In the cylindrical cam, the first cam portion is rotated relative to the second cam portion relative to the second cam portion by rotating the operation portion, whereby the axial length of the cylindrical cam is variable. The chair can change the amount of compression of the elastic body . The chair according to claim 1, wherein the synchro tilt mechanism is a mechanism that raises at least a part of the seat in conjunction with the backward tilt of the backrest, thereby lifting the body of the seated person.

Images