Angle adjuster for legless chair

Abstract

[Problem] The present invention provides a rotary torque variable-type angle adjuster for a legless chair, the angle adjuster having a first arm and a second arm which are attached on a seat part side and a back part side, respectively, of the legless chair and which swing and rotate around a mutual pivot point. [Solution] This rotary torque variable-type angle adjuster for legless chair has an initial motion mechanism in which one of the first arm and the second arm of the angle adjuster is equipped with a protruding part while the other of the first arm and the second arm has a recessed part or a hole. The protruding part and the recessed part or the hole of the initial motion mechanism are aligned by the position of the protruding part overlapping with the position of the recessed part or the hole when the first arm and the second arm reach a mutual opening limit position and by the protruding part being received in the recessed part or the hole. When the first arm and the second arm swing in a closing direction from the mutual opening limit position, the first arm and the second arm are elastically deformed in the thickness direction by the rotational torque caused by the swinging, and thus the protruding part is removed from the recessed part or the hole.

Description

Angle adjustment device for seat chair

[0001] The present invention relates to an angle adjuster for a legless chair that can vary the rocking and rotation torque so that the legless chair will not bend even when rocked or subjected to a small force, even when it is in the open limit position such as flat during transportation or storage.

[0002] The seatback is designed to adjust the angle of inclination of the backrest by folding or unfolding the seat and backrest with a pivot gear. Conventionally, the angle of inclination of this seatback has been adjusted using an angle adjuster that pivots a first arm (first member) and a second arm (second member) that are connected to the seat and backrest, respectively (see, for example, Patent Documents 1 and 2).

[0003] With such an angle adjustment device, in order to adjust to the angle desired by the user, the seat and backrest can be opened approximately 180 degrees and then freely swung and rotated in the folding direction (closing direction) from a flat or similar state, while the swinging in the opening direction is locked, and when the seat and backrest are folded to the closing limit state where they are close to each other, the lock in the opening direction is released and the device can be opened again until it becomes flat or similar.

[0004] Conventional chairs equipped with the angle adjuster described above were developed with the primary focus on allowing the seat and backrest to swivel and rotate smoothly when folding or unlocking the seat, but no attention was paid to the rotational torque required during the swivel and rotation. As a result, conventional angle adjusters were designed to be folded and opened with a light force.

[0005] However, in the case of angle adjustment devices that can be folded and opened with a light force, they often become bent and locked in the folded state during storage or transportation, and each time this happens, it is necessary to first open the seat and backrest to the limit of opening, such as flat, before storing or transporting the device, which is inconvenient.In addition, a structure that can be folded and opened with a light force, in addition to the above-mentioned problem of ease of use during storage and transportation, cannot be denied as being one of the factors that makes users feel that the device looks cheap.

[0006] For this reason, the inventors proposed a new idea at the time: to apply a certain rotational torque when swinging and rotating to prevent accidental bending and opening, thereby improving workability when storing and transporting and giving the chair a luxurious feel. Specifically, by caulking the pivot shaft from both sides in the thickness direction and applying pressure in the thickness direction, a structure is provided in which a certain degree of rotational torque is always applied, and rotation is restricted when the backrest and seat are at the limit of opening, such as when flat, or when swinging and rotating, so that the chair does not easily bend.

[0007] On the other hand, in a structure in which the pivot shaft is simply crimped from both sides in the thickness direction to apply rotational torque, it was found that after a user repeatedly rotates the pivot shaft in a swinging motion several hundred times, the crimping gradually loosens and the rotation restriction no longer functions, leaving durability as an issue. Based on this, the inventors proposed a structure in which crimping is performed with a disc spring inserted in the thickness direction. With this structure, even when the pivot shaft is repeatedly rotated in a swinging motion by applying pressure in the thickness direction using the elastic force of the disc spring, the pressure in the thickness direction continues to be applied as long as the elastic force and restoring force of the disc spring are in effect, thereby resolving the durability issue (see Patent Document 4).

[0008] On the other hand, even with the structure of inserting and caulking the disc springs, it is only possible to apply pressure to the extent that each disc spring can act, and the force acting in the thickness direction by the disc springs is difficult to adjust, making it impossible to maintain a steady pressure during oscillating rotation, which can lead to problems such as malfunction. Furthermore, adding disc springs increases the number of parts in the angle adjustment tool as a whole, which increases the parts cost and cycle cost.

[0009] Utility Model Publication No. 59-20118 Publication of Patent No. 3766669 Publication of Patent No. 6981697 Publication of Patent No. 5091363 Publication of Patent No. 5555341

[0010] The present invention was created to solve the above problems, and aims to provide an angle adjustment device for a chair that, during the initial operation when starting to rock and rotate from a flat or other open limit position, applies a rotational torque that is not easily bent by the load or impact of transport or storage work, and that is durable enough to always apply a rotational torque of just the right strength during rocking rotation regardless of the number of times it is used, giving the user a sense of luxury.

[0011] The present invention provides an angle adjuster (1) for a legless chair, in which a first arm (10) attached to the seat side of the legless chair and a second arm (20) attached to the back side are swung and rotated about their respective pivotal connections (see, for example, the rotation receiving portions 12, 12' and the rotation portion 22), wherein the first arm (10) and the second arm (20) are capable of swung and rotated in the closing direction at their respective pivotal connections (see, for example, the rotation receiving portions 12, 12' and the rotation portion 22), and have a locking mechanism in which the swung rotation in the opening direction is locked when they swung and rotate from their respective open limits to their respective closed limits, and the lock on the swung rotation in the opening direction is released when the swung rotation in the closing direction reaches the closed limit, and thereafter, when the swung rotation in the opening direction reaches the open limit, the swung rotation in the opening direction is locked again, and further, one of the first arm and the second arm has a protrusion, The convex portion, when its top comes into contact with the opposing second arm (20) or first arm (10), elastically deforms the first arm (10) and the second arm (20) in the thickness direction, and an elastic restoring force in the thickness direction due to the elastic deformation acts, causing a rotational torque to act during the swinging rotation from the open limit to the closed limit.

[0012] The legless chair angle adjuster (1) of the present invention, like conventional legless chair angle adjusters, has a locking mechanism that, after folding the seat and backrest of the legless chair to their closed limit, releases the lock and allows them to swing freely in the open direction, and once the open limit is reached, locks the open direction again, adjusting and positioning the closed angle to the angle of the backrest desired by the user. Regarding the "open limit" mentioned here, when this legless chair angle adjuster (1) is used with a normal legless chair, the open limit is when the backrest is roughly flat (approximately 180°) relative to the seat. However, when used with a high legless chair, which has recently become popular for elderly people and those receiving care, the open limit of the swing rotation angle of the backrest relative to the seat may be set just before the backrest is roughly flat to prevent the legless chair from tipping backward.

[0013] In this case, the present invention employs a structure that constantly applies a constant rotational torque during rocking rotation from the open limit where the seat and backrest are approximately flat to the folding closed limit position, or when the lock is released and rocking rotation is being performed from the closed limit to the open limit. The configuration of this chair angle adjuster (1) can also be used in an angle adjuster such as that in Patent Document 5, which restricts rocking rotation in the open direction by pulling back slightly in the closing direction on the way from the closed limit to the open limit.

[0014] Furthermore, this legless chair angle adjuster is attached to the pivotal connection (see, for example, the pivoting support parts 12, 12' and the pivoting part 22) between the first arm (10) attached to the seat side and the second arm (20) attached to the back side. However, in addition to legless chairs in which the back and seat pivot relative to each other, there are also multi-jointed legless chairs in which the back and seat can pivot to allow for fine angle adjustments. This legless chair angle adjuster can also be used for the pivotal connection between the seat "side" and back "side" of each joint in such multi-jointed legless chairs. Furthermore, the term "legless chair" as used in this specification is defined in a broad sense to include all chairs in which the back can pivot relative to the seat up to the limit of its opening, where it is approximately flat, in addition to the legless chair shown in Figure 2, such as so-called high legless chairs with low legs below the seat.

[0015] Specifically, a convex portion (protrusion (28)) is provided on one of the first arm (10) and the second arm (20) that protrudes toward the opposing second arm or the first arm (in the thickness direction). The top of this convex portion (protrusion (28)) abuts against the opposing arm, causing the two arms to elastically deform and widen the gap between them as they swing and rotate. Therefore, the first arm and the second arm constantly and stably sandwich each other with an elastic restoring force, which constantly applies a rotational torque that is neither too strong nor too weak. Furthermore, the convex portion (protrusion (28)) can be manufactured using a simple process such as press working. This allows for stable application of the desired rotational torque without the need for additional components during normal angle adjustment, and provides an angle adjustment tool that is highly durable and gives the user a luxurious feel.

[0016] Furthermore, the angle adjuster for a legless chair (1) has an initial movement mechanism that has the convex portion (protrusion (28)) on one of the first arm (10) and the second arm (20) and a concave portion or hole (receiving hole (15)) on the other, and the convex portion (protrusion (28)) and the concave portion or hole (receiving hole (15)) in the initial movement mechanism are such that when the first arm (10) and the second arm (20) reach their respective open limit positions, the position of the convex portion (protrusion (28)) coincides with the position of the concave portion or hole (receiving hole (15)). and the protrusion (protrusion (28)) is positioned by being received in the recess or hole (receiving hole (15)), and when the first arm (10) and the second arm (20) start to swing in the closing direction from the open limit position, the first arm (10) and the second arm (20) are elastically deformed in the thickness direction by the rotational torque caused by the swing, and the protrusion (protrusion (28)) comes off the recess or hole (receiving hole (15)), thereby starting to swing in the closing direction.

[0017] As described above, the angle adjustment device (1) has a convex portion (protrusion (28)) on one of the first arm (10) and the second arm (20), and the convex portion (protrusion (28)) rotates and swings while widening the gap between the two arms through elastic deformation, thereby continuously applying an appropriate rotational torque during the swinging rotation. However, a preferred angle adjustment device (1) has a recess or hole (receiving hole (15)) at a position opposite the convex portion (protrusion (28)) at the open limit when the backrest and seat are approximately flat, and has an initial movement mechanism that receives the convex portion (protrusion (28)) into this recess or hole (receiving hole (15)) to position it.

[0018] Specifically, with this initial movement mechanism, the convex portion (protrusion (28)) is firmly received and positioned in the recess or hole (receiving hole (15)) at the open limit, preventing it from easily bending from a substantially flat state (the open limit state) during transportation or storage. At the same time, when a user wants to fold it, the convex portion (protrusion (28)) needs to be released from the state in which it is received in the recess or hole (receiving hole (15)). When swinging and rotating it to release it (initial movement), a large rotational torque is applied so that the top of the convex portion (protrusion (28)) overcomes the recess or hole (receiving hole (15)), causing elastic deformation. Therefore, while a large rotational torque is required to ensure firm positioning and prevent bending during transportation or storage at the open limit, this provides a significant advantage in that it provides a variable rotational torque structure that can stably apply a moderate rotational torque during normal angle adjustment without the need for any additional parts, while maintaining sufficient durability for repeated use.

[0019] Furthermore, it is preferable that the convex portion (protrusion (28)) provided on one of the first arm (10) and the second arm (20) in the initial movement mechanism has a guide groove (85) that receives the convex portion (protrusion (28)) on a trajectory where the convex portion (protrusion (28)) abuts against the other of the first arm (10) and the second arm (20) while supplying lubricating oil when the convex portion (protrusion (28)) swings from the open limit received in the recess or hole (receiving hole (15)) provided on the other of the first arm (10) and the second arm (20) to the closed limit, leaving the recess or hole (receiving hole (15)).

[0020] In the angle-adjustable fitting 1 for a legless chair as described above, a guide groove (85) is provided on the trajectory of the protrusion (protrusion (28)) in the swing direction, which receives the protrusion (protrusion (28)) and guides it while supplying lubricating oil. With this configuration, when the protrusion (protrusion (28)) is initially moved from a state in which it is received in the recess or hole (receiving hole (15)) at the closed limit position to a state in which it is received in the recess or hole (receiving hole (15)), a large rotational torque acts, and then the force in the thickness direction is reduced as the protrusion (protrusion (28)) is received in the guide groove (85), and together with the accumulation of lubricating oil in the guide groove (85), the rotational torque during swing is significantly reduced. Therefore, while maintaining the above-mentioned function of applying rotational torque when initially swinging from the open limit in the closing direction, the rotational torque is released during the swinging motion to the closing limit after the initial movement, making the swing easier and improving the angle adjustment performance.Furthermore, wear on the metal surface on the path where the convex portion (protrusion (28)) comes into contact during swinging is reduced, thereby improving the durability of this angle adjustment fitting for a recliner (1).

[0021] Furthermore, it is preferable that the convex portion (protrusion (28)) has a hemispherical or dome shape that protrudes in the thickness direction, and that the concave portion or hole (receiving hole (15)) has an outer diameter that is the same as or larger than the outer diameter of the bottom of the convex portion (protrusion (28)).

[0022] The convex portion (protrusion (28)) disposed on either the first arm (10) or the second arm (20) can be securely received (fitted) into each other and securely position (lock) the first arm and the second arm at the open limit by making the convex portion (protrusion (28)) hemispherical or dome-shaped and making the outer diameter of its base the same as or larger than that of the recess or hole (receiving hole (15)). Note that in order to smoothly lock at the open limit position and taking into consideration processing accuracy, the recess or hole (receiving hole (15)) can be made slightly larger than the bottom of the convex portion (protrusion (28)) to provide so-called play.

[0023] At the same time, as described above, when releasing the lock between the convex portion (protrusion (28)) and the recessed portion or hole (receiving hole (15)), the convex portion (protrusion (28)) needs to climb over the recessed portion or hole (receiving hole (15)) and elastically deform the first arm (10) and the second arm (20) in the thickness direction to escape. Therefore, if the convex portion (protrusion (28)) is made hemispherical or dome-shaped, the force in the swinging rotation direction can be divided into a force that spreads in the thickness direction (a force in the height direction of the convex portion) and a force that causes the convex portion (protrusion (28)) to penetrate (a force in the circumferential direction of the convex portion) without a sudden change, and the first arm (10) and the second arm (20) can be elastically deformed smoothly to allow the convex portion (protrusion (28)) to escape into the recessed portion or hole (receiving hole (15)).

[0024] Furthermore, in this angle adjusting device (1), the pivotal connection portions of the first arm (10) and the second arm (20) are each composed of a pair of plate-shaped rotating members (rotation receiving portions 12, 12', rotating portion 22) arranged in parallel with a gap in the thickness direction, one pair of plate-shaped rotating members (rotation receiving portions 12, 12') is inserted into the gap between the other pair of plate-shaped rotating members (rotation receiving portions 12, 12') and are stacked opposite each other in the thickness direction so as to be pivotally rotatable relative to each other, the convex portions (protrusions (28)) that protrude in the thickness direction are arranged on both sides of the other or one pair of plate-shaped rotating members (rotation portions 22 or rotation receiving portions 12, 12'), and the concave portions or holes (receiving holes (15)) that receive the convex portions (protrusions (28)) in the thickness direction are arranged on both sides of the one or other pair of plate-shaped rotating members (rotation receiving portions 12, 12' or rotation receiving portions 12, 12'), It is preferable that, during inelastic deformation, the distance in the thickness direction between the tops of the respective convex portions (protrusions (28)) is greater than the distance between the rotating members facing the tops of the respective convex portions (protrusions (28)).

[0025] With this angle adjuster (1) configuration, a pair of parallel plate-shaped rotating members (see, for example, the rotation receiving portion 12 and the rotating portion 22) are inserted into the gap between them and pivotally connected as shown in Figures 3 to 7 below, and a convex portion (protrusion (28)) is provided on "both sides" of each of the pair of rotating members. This reduces the overall thickness of the pivotal connection, while equalizing the force in the thickness direction, eliminating twisting, allowing for smooth swinging and rotation while also ensuring strength.

[0026] Furthermore, when not elastically deformed, the distance (W2+2r) between the tops of the convex portions (protrusions (28)) on both sides is greater than the distance (W1) between the rotating members that they abut, and when the convex portions (protrusions (28)) overcome the recesses or holes (receiving holes (15)) to escape, they always do so by elastic deformation, making it possible to configure a variable rotational torque angle adjustment device that can change the rotational torque in stages by elastic force at a stage where it is locked at the open limit, an initial movement stage where it starts to close from the open limit, and an operating stage where it swings and rotates to adjust the angle.

[0027] Furthermore, it is preferable that the angle adjustment tool be subjected to a hardening treatment that allows elastic deformation at the position of the second arm (20) or the first arm (10) where the convex portion (protrusion (28)) abuts during swing rotation.

[0028] In the preferred example (1) of the angle adjuster for a seat chair, the portion (the trajectory of the protrusion) that the protrusion (protrusion (28)) contacts is subjected to a hardening process that allows elastic deformation. This hardening process prevents the protrusion (protrusion (28)) from scraping the arm even with repeated swinging and rotation, even if the material of the arm that the protrusion (protrusion (28)) contacts is a standard, inexpensive iron-based material. A stable elastic restoring force acts in the thickness direction, allowing a constant rotational torque to be applied stably and continuously, improving durability. In other words, simply pressing a general-purpose, inexpensive iron-based material and hardening it allows the rotational torque to be continuously applied, making for inexpensive and easy manufacturing.

[0029] The angle adjuster for a chair according to the present invention applies a constant, stable rotational torque during normal rocking rotation, giving it high durability and a luxurious feel, and at the same time, when it is at its open limit, such as flat, it will not bend easily under the load or impact of transport or storage work, and is rigid enough that it will not bend unless the user applies a certain amount of rotational torque.

[0030] This figure shows a perspective view of a frame that is disposed within the cushion of a seat chair to support the seat chair and adjust the inclination angle of the backrest relative to the seat. This figure shows a perspective view of the frame of Figure 1, indicated by dotted lines, disposed inside the cushion and with the angle adjusted. This figure shows a perspective view of the open limit of one embodiment of the angle adjustment device of the present invention. This figure shows an exploded assembly view of the angle adjustment device of Figure 3. (a) is a front view of the angle adjustment device of Figure 3 as seen from the thickness direction of the second arm, (b) is a top view, (c) is a bottom view, and (d) is a left side view. This figure shows a perspective view of the angle adjustment device of the present invention at the open limit, swung and rotated in the closing direction. This figure shows the operation states of the floating rust in the angle adjustment device of the present invention shown in Figures 3 to 6 as it moves from the open limit to the closed limit. This figure, following Figure 7, shows the operation states of the floating rust in the angle adjustment device of the present invention shown in Figures 3 to 6 as it moves from the open limit to the closed limit. The first arm has a guide groove, and (a) is a perspective view thereof, (b) is a side view seen from line S-S in (c), and (c) is a front view seen from the axial direction (thickness direction).

[0031] First, let us explain the function of a legless chair whose angle is adjusted using the legless chair angle adjuster 1 of the present invention. Figure 1 shows a perspective view of a frame that is disposed within the legless chair cushion 300 to support the legless chair and adjust the angle of inclination of the backrest relative to the seat. Figure 2 shows a perspective view of the frame shown in Figure 1, indicated by the dotted line, disposed within the cushion 300 and with the angle adjusted.

[0032] The frames 100, 200 of the legless chair are constructed by connecting tubular members. The cushion 300 forms an integrated member in which the backrest cushion and the seat cushion are connected at a bent portion 330. The backrest frame 100 is disposed within the backrest cushion 310, and the seat frame 200 is disposed within the seat cushion 320, and both frames 100, 200 are connected within the bent portion 330 by the legless chair angle adjuster 1 of the present invention so that the angle can be adjusted.

[0033] The backrest frame 100 and the seat frame 200 each comprise a pair of side frames 101, 201 that extend parallel to one another and support the user's body axis, and upper frames 102, 202 that support the upper parts of the side frames 101, 201 laterally, which are connected at corners 103, 203. Furthermore, the side frames 101, 201 are reinforced laterally by connecting frames 104, 204 that extend laterally at their intermediate positions. The side frames 101, 201 are connected at their respective ends to a legless chair angle adjuster 1, which can be swung from a flat position (open limit) as shown in Figure 1 to a closed position to adjust the angle as shown in Figure 2.

[0034] In the above-mentioned angle adjustment device for a chair 1, the backrest frame 100 and the seat frame 200 are connected and the two can be swung and rotated, but the angle adjustment device for a chair of the present invention is not limited to this and can also be used for so-called multi-stage movable chairs in which the seat frame is connected to the knee frame, thigh frame, buttock frame, etc. with the angle adjustment device, and the backrest frame is connected to the waist frame, upper back frame, head frame, etc. with the angle adjustment device.

[0035] Next, the angle adjuster for a seat chair 1 of the present invention will be specifically described with reference to FIGS.

[0036] Figure 3 is a perspective view of an angle adjusting device for a chair 1 (hereinafter also referred to as "angle adjusting device 1" or "this angle adjusting device 1"), which is one embodiment of the angle adjusting device for a chair of the present invention, and Figure 4 shows an exploded assembly view of this angle adjusting device 1. Figure 5 shows (a) a front view of this angle adjusting device 1 as seen from the thickness direction of the second arm 20, (b) a top view, (c) a bottom view, and (d) a left side view. Also, Figure 6 shows a perspective view of this angle adjusting device 1 at the open limit shown in Figure 3, when swung and rotated in the closing direction.

[0037] As shown in Figures 3 to 6, the angle adjustment device 1 of the present invention is generally composed of a first arm 10, a second arm 20, a floating wedge 30, a spring member 40, a bottom casing 60, an upper casing 50, and a main support shaft 70.

[0038] The first arm 10 is composed of an attachment portion 11 into which a side frame 201 of the seat frame 200 shown in Figures 1 and 2 is inserted and connected, and a rotation bearing portion 12 continuous with the attachment portion 11. The rotation bearing portion 12 has a pair of side walls 13, 14 that face each other in the thickness direction. The pair of side walls 13, 14 are each provided with a bearing hole 16 near the center, at positions that face each other on the same axis, and have an inner diameter that allows the shaft portion 70a of the main support shaft 70 (described later) to be inserted so as to be pivotally rotatable about the bearing hole.

[0039] The pair of side wall portions 13, 14 each have a receiving hole 15 formed in front of the bearing hole 16 (on the second arm 20 side) at a position where they can see each other on the same axis. The receiving hole 15 is provided in a position where it can receive a protrusion 28 of the gear plate portions 23, 24 of the second arm 20, which will be described later, when the first arm 10 and the second arm 20 are connected at the open limit of approximately 180° as shown in Figure 4, which will be described in detail later. The receiving hole 15 may be a through hole or a recessed portion as long as it can receive (fit) the protrusion 28 of the gear plate portions 23, 24 of the second arm 20, and the size of the receiving hole 15 may be large enough to fit the protrusion 28, or may be large enough to provide some play in the swinging and rotational direction (see arrows A and B) when the protrusion 28 is received.

[0040] Furthermore, each of the pair of side walls 13, 14 has a through wedge-shaped window 17 formed at a position where it can be seen behind (on the mounting portion 11 side of) the bearing hole 16 so that a floating wedge 30 (described later) can be inserted in the thickness direction and sandwiched therebetween. The wedge-shaped window 17 has a counterbore 18 that is recessed in the thickness direction of the side walls 13, 14 to form a bottom edge surface, and forms an opening that penetrates with the counterbore 18 as its edge.

[0041] Next, the second arm 20 is composed of an attachment portion 21 into which the side frame 101 of the chair back frame 100 shown in Figures 1 and 2 is inserted and connected, and a rotating portion 22 continuous with the attachment portion 21. The rotating portion 22 has a pair of substantially circular gear plates 23, 24 facing each other at an insertable distance on the inner side in the thickness direction of the side wall portions 13, 14 of the rotation receiving portion 12 of the first arm 10. The pair of gear plates 23, 24 are each arranged near the center at positions that face each other and are coaxial with each other, with a shaft hole 25 having an inner diameter that allows the shaft portion 70a of the main support shaft 70 (described later) to be inserted therein for pivotal rotation. Furthermore, on the outer peripheral surface of each of the gear plates 23, 24, a gear portion 26 having a gear groove and a circular arc surface portion 27 that is radially longer than the gear portion 26 are formed so as to be continuous from the first arm 10 side.

[0042] Although the first arm 10 and the second arm 20 of the angle adjustment device 1 described above are manufactured by pressing a single metal plate, this is not necessarily limited to this. For example, the first arm 10 and the second arm 20 may each be manufactured by pressing two separate metal plates and joining the metal plates together. Furthermore, the mounting portions 11 and 21 that connect to the side frames 101 and 201 are not limited to a cylindrical shape and may be, for example, a square tube shape, a rectangular pillar shape, or a plate shape.

[0043] As shown in Fig. 5(e), the pair of gear plate portions 23, 24 are provided with projections 28 that protrude on both sides in the thickness direction and are coaxial with each other in front of the shaft hole 25 (on the first arm 10 side). These projections 28 are provided at positions where they can be received in the receiving holes 15 of the side wall portions 12, 13 of the rotation receiving portion 12 of the first arm 10 when the first arm 10 and the second arm 20 swing to the open limit of approximately 180° as shown in Fig. 4. The inner thickness direction length w1 (see Fig. 4) of the pair of side wall portions 13, 14 of the first arm 10 is greater than the outer thickness direction length w2 (see Fig. 5(c)) of the pair of gear plate portions 23, 24 of the second arm 20 (w1>w2), and is smaller than the thickness direction length w2+2r (see Fig. 5(c)) obtained by adding the height r of the tops of the projections 28 on both sides to the inner thickness direction length w1 (see Fig. 4).

[0044] Therefore, when a pair of gear plate portions 23, 24 are interposed between a pair of side wall portions 13, 14 and the protrusions 28 are not received in the receiving holes 15, the tops of the protrusions 28 of the gear plate portion 24 abut against the side wall portions 13, 14, respectively, causing the side wall portions 13, 14 to elastically deform and expand the thickness-wise length w1 (w1 = w2 + 2r), and this elastic restoring force constantly applies a constant rotational torque to the swinging rotation of the second arm 20 relative to the first arm 10 during the swinging rotation.

[0045] On the other hand, when the first arm 10 and the second arm 20 swing to their open limit and the protrusion 28 is received in the receiving hole 15, they are released from the action of their respective thicknesswise elastic forces, and the side walls 13, 14 return to their original thicknesswise length w1 (w1 > w2 + 2r), positioning them at the open limit. To swing them back in the closing direction from this state, the top of the protrusion 28 of the second arm 20 must overcome the receiving hole 15 of the first arm 10, elastically deforming and expanding the side walls 13, 14 again (w1 = w2 + 2r), and a large initial rotational torque must be applied until the chair overcomes the hole. This initial large rotational torque prevents the chair from easily bending when open, during transport or storage. However, if the protrusion 28 is made cylindrical or has a shape with a sudden change in inclination, it will be difficult for it to overcome the receiving hole 15 or an excessively large initial rotation torque will be required, so the protrusion 28 is made hemispherical or dome-shaped as shown in Figures 3(c) and (e), etc.

[0046] Although the first arm 10 and the second arm 20 of the angle adjustment device 1 described above are manufactured by pressing a single metal plate, this is not necessarily limited to this. For example, the first arm 10 and the second arm 20 may each be manufactured by pressing two separate metal plates and joining the metal plates together. Furthermore, the mounting portions 11 and 21 that connect to the side frames 101 and 201 are not limited to a cylindrical shape and may be, for example, a square tube shape, a rectangular pillar shape, or a plate shape.

[0047] Furthermore, in this angle adjustment device 10, the protrusion 28 is provided on the second arm 20 so that it protrudes outward on both sides in the thickness direction, and the receiving hole 15 is provided on the first arm 10, but there are also cases where the protrusion 28 is provided on the first arm 10 so that it protrudes outward on both sides in the thickness direction, and the receiving hole 15 is provided on the second arm 20.

[0048] Furthermore, the angle adjustment device 1 may also include a guide groove 85 that guides the protrusion 28 from the open limit to the closed limit. Figure 9 shows a first arm 10' having the guide groove 85, with (a) a perspective view, (b) a side view taken along line S-S in (c), and (c) a front view taken along the axial direction (thickness direction). As shown in Figure 9(b), the guide groove 85 is formed by extruding the guide groove 85 from the inner wall side toward the outer wall side of each of the side wall portions 13', 14' by press working, forming a recess 85a with a substantially semicircular cross section on the inner wall side and a protrusion 85b on the outer wall side by extrusion. The guide groove 85 is formed along a contact locus (arc-shaped locus) on the side wall portions 13', 14' as the protrusion 28 swings from the open limit, where the protrusion 28 is received in the receiving hole 15, to the closed limit, where the protrusion 28 overcomes the receiving hole 15.

[0049] Furthermore, lubricating oil is stored in the recess 85a of the guide groove 85. This guide groove 85 and the lubricating oil stored therein reduces the force in the thickness direction after the protrusion 28 has climbed over the receiving hole 15 from a state in which it is received in the receiving hole 15, significantly reducing the rotational torque during oscillation, making oscillation easier, and also reducing surface wear on the side wall portions 13', 14' on the path where the protrusion 28 abuts.

[0050] Next, the floating wedge 30 has, on its inner side (the second arm 20 side), a tooth surface 31 with a gear groove that meshes with the gear portion 26 from the front end to the rear end (from the top end to the bottom end in FIG. 3), and an oscillating slope portion 32 that slopes (including steps) at its rear edge to the rear end, and on its outer side (the first arm 10 side), an abutment surface 33 that slopes while gradually widening in width from the front end to the rear end. The operation of the floating wedge 30 will be described later.

[0051] The spring member 40 is sandwiched between the inner side of the side wall portions 13, 14 of the rotation receiving portion 12 in the thickness direction, and elastically biases the floating wedge 30 in a direction pressing it against the gear portion 26 of the rotation portion 22 of the second arm 20. This spring member 40 is formed by enclosing steel wire in a substantially rectangular shape, and both upper and lower ends are fixed by the bottom casing 60 and the upper casing 50 described below, with the vertical center portion abutting against the central region of the abutment surface 33 of the floating wedge 30. The spring member 40 elastically biases the floating wedge 30 against the gear portion 26. Note that the spring member 40 may be formed of a leaf spring.

[0052] 3, the upper casing 50 is a thin resin plate member that is attached from above with the pivot receiving portion 12, the pivoting portion 22, and the floating wedge 30 assembled thereto to prevent foreign matter from entering the area around the floating wedge 30 from above or through the wedge-shaped window portion 17 and to prevent the floating wedge 30 from falling out of the wedge-shaped window portion 17. The upper casing 50 is provided with a pair of side covers 51 that have an area that covers the wedge-shaped window portion 17 when placed from above with a distance between them that allows the pivot receiving portion 12 of the first arm 10 to be sandwiched from both sides in the thickness direction, and a plate-like mounting portion 52 that extends forward (toward the second arm 20) from the side covers 51. The mounting portions 52 are each arranged near the center at a position where they can see each other on the same axis, with shaft holes 53, and have an inner diameter that allows the shaft portion 70a of the main support shaft 70 (described later) to be inserted therein.

[0053] The pair of side covers 51 have their upper edges and rear upper edges connected by plate-shaped top covers 54 and trailing edge covers 55, respectively, to prevent the floating wedge 30 from floating up and foreign matter from entering the area around it. A gap 56 is defined between the top cover 54 and the trailing edge cover 55 in the thickness direction, and when the spring member 40 is attached, its upper end is inserted into the gap 56 and is fixed by being sandwiched between the top cover 54 and the trailing edge cover 55.

[0054] 3, the bottom casing 60 is a thin resin plate member that is attached from below with the pivotal support 12, pivotal portion 22, and floating wedge 30 assembled to protect the lower portion and prevent foreign matter from entering from below. The bottom casing 60 is composed of a plate-shaped bottom cover 60a that covers the lower portion of the floating wedge 30, side covers 60b that stand along both edges of the bottom cover 60a and protrude from the front end of the bottom cover 60a to sandwich the entire lower area of ​​the pivotal support 12 of the first arm 10 from both sides in the thickness direction, and a male portion 60c that is inserted into two receiving holes (not shown) provided in the bottom of the pivotal support 12 of the first arm 10 and snapped into place. When the spring member 40 is attached, the bottom end of the bottom casing 60 is supported by the bottom cover 60a.

[0055] The main support shaft 70 forms a swinging rotation axis (pivot) at the pivotal connection between the first arm 10 and the second arm 20, and has a shaft portion 70a and a flange portion 70b that is integrally connected to the shaft portion 70a and has an expanded diameter. The shaft portion 70a has an outer diameter that is the same as or smaller than the inner diameters of the bearing hole 16 of the rotation receiving portion 12 of the first arm 1, the shaft hole 25 of the rotating portion 22 of the second arm 20, and the shaft hole 53 of the upper casing 50, and is inserted into these bearing holes 16, shaft holes 25, and shaft holes 53, which are positioned so as to face each other, using the flange portion 70b as a stopper. After insertion, the tip of the shaft portion 70a is crimped to form the swinging rotation axis (pivot) of the first arm 10 and the second arm 20.

[0056] This angle adjustment device 1 combines the first arm 10, second arm 20, floating wedge 30, spring member 40, upper casing 50, bottom casing 6, and main support shaft 70 as described above, and adjusts the angle of the second arm 20 by swinging and rotating relative to the first arm 10 from the open limit (position in Figure 4) to the closed limit.

[0057] Next, the operation of the floating wedge 30 employed in the angle adjusting tool 1 shown in FIGS. 3 to 6 will be described.

[0058] The relationship between the rotation of the gear portion 26 and the operation of the floating wedge 30 will now be described. First, Figure 7(a) shows the state of the open limit position of Figure 3, in which the floating wedge 30 meshes with the gear portion 26 and abuts against the wedge-shaped window portion 17 (spring member 40, not shown), and the second arm 20 does not swing any further in the opening direction (clockwise in Figure 8 (opposite direction of arrow B in Figures 3 and 7(a))). When the second arm 20 is swung counterclockwise from this state (in the direction of arrow B in Figure 3), as shown in Figure 7(b), the abutment surface 33 of the floating wedge 30 that meshes with the tooth surface 26 moves away from the upper edge surface 17a of the wedge-shaped window portion 17, creating a small gap d. When the second arm 20 further swings and rotates counterclockwise (in the direction of arrow B in FIG. 3), as shown in FIG. 7(c), the guide slope portion (notch) 32 of the floating wedge 30 comes into contact with the stepped portion 17b of the wedge-shaped window portion 17, and the gap d causes the tooth surface 31 of the floating wedge 30 to separate from the tooth surface of the gear portion 26, allowing the tooth surface 31 of the floating wedge 30 to ride over the tooth surface of the gear portion 26 with a clicking sound.

[0059] The guide slope portion 32 of the floating wedge 30 is formed on the rear edge portion (lower edge portion in FIG. 3 ) of the tooth surface 31 of the floating wedge 30, and the stepped portion 17b is formed so that the swing slope portion 32 can abut against the inner edge surface 17c on the second arm 20 side of the wedge-shaped window portion (movement space) 17. Therefore, the tooth surface 31 of the floating wedge 30 meshes with the gear portion 26, and the abutment surface 33 abuts against the outer edge surface 17d, and the wedge action of the floating wedge 30 sandwiched between the gear portion 26 and the upper edge portion 17a allows the second arm 20 to swing freely in one direction relative to the first arm 10 and restricts swinging in the other direction. In other words, the first arm 101 and the second arm 20 can be maintained at any bending angle (inclination angle).

[0060] 7(c) , when the second arm 20 is further swung to its limit beyond a predetermined angle relative to the first arm 10 as shown in FIG. 8(a), the arcuate surface 27 at one end of the gear portion 26 comes into contact with and presses against the front edge (upper edge) of the floating rust 30. Then, as shown in FIG. 8(b), when the second arm 20 is further swung from the closed limit swing state (maximum folded state), the guide slope portion 32 of the floating rust 30 pushed back by the arcuate surface 27 climbs over the stepped portion 17b and is accommodated in the retraction space 17e at the bottom of the movement space of the floating rust 30, disengaging the tooth surface 31 of the floating rust 30 from the gear portion 26, and the floating rust 30 becomes separated from the gear portion 26.

[0061] In this way, the second arm 20 becomes free relative to the first arm 10 and can again swing and rotate in the open direction (clockwise (the opposite direction of arrow B in FIG. 3)), and can be returned to the open limit position. Then, when the second arm 20 is deployed and swung to the open limit of approximately 180° relative to the first arm 10, the arc surface portion 29 pushes out the floating wedge 30 housed in the retraction space 17e, as shown in FIG. 8(c), so that the tooth surface 31a and the gear portion 26 are again in mesh, and the second arm 20 can be returned to the state shown in FIG. 7(a).

[0062] The above describes an embodiment of the variable rotational torque angle adjuster for a chair of the present invention with reference to Figures 1 to 8, but it will be understood by those skilled in the art that the present invention is not limited to this and that other modifications and improvements can be made without departing from the spirit and teachings of the claims and the specification.

[0063] DESCRIPTION OF SYMBOLS 1 Variable rotational torque angle adjuster for seat chair 10 First arm 11 Mounting portion 12 Rotation receiving portion (pivot connection portion) 13 Side wall portion 14 Side wall portion 15 Receiving hole (recess or hole) 16 Bearing hole 17 Wedge-shaped window portion 17a Upper edge portion 17b Step portion 17c Inner edge surface 17d Outer edge surface 17e Retraction space 18 Counterbore portion 20 Second arm 21 Mounting portion 22 Rotation portion (pivot connection portion) 23 Gear plate portion 24 Gear plate portion 25 Shaft hole 26 Gear portion 27 Arc surface portion 28 Protrusion (convex portion) 29 Arc surface portion 30 Floating wedge 31 Tooth surface 32 Guide gradient portion 33 Contact surface 40 Spring member 50 Upper casing 51 Side cover 52 Mounting portion 53 Shaft hole 54 Top cover 55 Rear edge cover 56 Gap 60 Bottom casing 60a Bottom cover 60b Side cover 60c Male portion 70 Main support shaft 70a Shaft portion 70b Flange portion 80 Reinforcement cover 81 Rear cover 82 Top cover 83 Front cover 84 Hole 100 Backrest frame 101 Side frame 102 Upper frame 103 Corner frame 104 Connecting portion frame 200 Seat frame 201 Side frame 202 Upper frame 203 Corner frame 204 Connecting portion frame 300 Cushion 310 Backrest cushion portion 320 Seat cushion portion 330 Bending portion

Claims

1. An angle adjustment device for a chair, in which a first arm attached to the seat side of the chair and a second arm attached to the back side swing and rotate around each other's pivot connection part, wherein the first arm and the second arm are capable of swinging and rotating in the closing direction at each other's pivot connection part, and have a locking mechanism whereby the swinging rotation in the opening direction is locked when they swing and rotate from the opening limit to the closing limit, the lock on the swinging rotation in the opening direction is released when the swinging rotation in the closing direction reaches the closing limit, and thereafter, when the swinging rotation in the opening direction reaches the opening limit, the swinging rotation in the opening direction is locked again, and further wherein one of the first arm and the second arm has a convex part, the top of which abuts against the opposing second arm and the first arm, elastically deforming the first arm and the second arm in the thickness direction, and an elastic restoring force in the thickness direction due to the elastic deformation acts, and a rotational torque acts during the swinging rotation from the opening limit to the closing limit.

2. The angle adjustment device for a chair as described in claim 1, characterized in that it has an initial movement mechanism having a convex portion on one of the first arm and the second arm and a concave portion or hole on the other, and the convex portion and the concave portion or hole in the initial movement mechanism are positioned by the position of the convex portion overlapping the position of the concave portion or hole and the convex portion being received in the concave portion or hole when the first arm and the second arm reach their respective open limit positions, and when the first arm and the second arm start to swing from their respective open limit positions in the closing direction, the first arm and the second arm elastically deform in the thickness direction due to the rotational torque caused by the swing, causing the convex portion to come out of the concave portion or hole, thereby commencing the swing in the closing direction.

3. The angle adjustment device for a chair as described in claim 2, wherein the convex portion provided on one of the first arm and the second arm in the initial movement mechanism has a guide groove that receives the convex portion on a trajectory where the convex portion abuts against the other of the first arm and the second arm while supplying lubricating oil when the convex portion swings from the open limit received in the recess or hole provided on the other of the first arm and the second arm to the closed limit after leaving the recess or hole.

4. The angle adjustment device for a chair described in any one of claims 1 to 3, characterized in that the convex portion has a hemispherical or dome shape that protrudes in the thickness direction, and the concave portion or hole is the same as or larger than the outer diameter of the base of the convex portion.

5. The angle adjustment device for a chair described in any one of claims 2 to 4, characterized in that the pivot connection parts of the first arm and the second arm are each composed of a pair of plate-shaped rotating members arranged in parallel with a gap in the thickness direction, one pair of plate-shaped rotating members is inserted into the gap between the other pair of plate-shaped rotating members and they are stacked opposite each other in the thickness direction so as to be freely pivotable around each other, the convex portion that protrudes in the thickness direction is arranged on both sides of the other or one pair of plate-shaped rotating members, and the concave portion or hole that receives the convex portion in the thickness direction is arranged on both sides of the one or the other pair of plate-shaped rotating members, and during inelastic deformation, the distance in the thickness direction between the tops of each of the convex portions is greater than the distance between the rotating members facing the tops of the convex portions.

6. The angle adjustment device for a chair described in any one of claims 1 to 5, characterized in that the position of the second arm or the first arm where the protrusion comes into contact during rocking and rotation is subjected to a hardening process that allows elastic deformation.

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