Rotary damper, and combination of rotary damper and link mechanism

Abstract

To provide a rotary damper capable of imparting a resistance torque to a rotor to restrict a rotational speed of the rotor without using viscosity of fluid, and capable of adjusting the resistance torque to an arbitrary value (1), and suppress the rotational speed of the rotor even when a rotational torque acting on the rotor of the rotary damper gradually increases (2).SOLUTION: (1) A pressing piece 68 that locally presses a rotor 10 is disposed in a housing 8, and the pressing piece 68 is movable in a direction toward and away from the rotor 10. (2) A link mechanism 6 is combined with a rotary damper 4, and when an external device rotates, a one-side movable joint P1 that connects a one-side link piece 76 and an intermediate link piece 80 approaches a rotational axis o1 while rotating around an eccentric axis o2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotary damper and a combination of a rotary damper and a link mechanism. [Background technology]

[0002] Rotary dampers that apply a required resistance torque to a rotor to suppress the rotation speed of the rotor are already widely used. For example, rotary dampers are incorporated in a winding mechanism for blinds installed near a window in a room, and suppress the falling speed when a bottom rail connected to the winding mechanism falls freely in the vertical direction. In this case, the rotor of the rotary damper is rotated continuously in one direction. Since the force acting on the bottom rail is constant only due to gravity, the magnitude of the rotation torque applied to the rotor is constant. Rotary dampers are also connected to an external device (rotating member) that can rotate between an open position and a closed position, such as the lid and valve seat of a Western-style toilet or the cover of a copying machine, and may suppress the rotation speed when the device rotates and closes due to gravity from the open position to the closed position. In this case, the rotor of the rotary damper is rotated only within a relatively narrow required angle range, and the magnitude of the rotation torque applied to the rotor changes depending on the rotation angle position of the external device. Rotary dampers used in the latter way are sometimes called swing dampers.

[0003] The mainstream of rotary dampers is the so-called oil damper, which utilizes the viscous resistance of a relatively viscous fluid such as silicon oil sealed inside the housing. However, oil dampers have problems such as the possibility of the sealed fluid leaking to the outside, and the viscous resistance of the fluid being easily affected by temperature, so that performance is likely to vary depending on the operating temperature. In particular, when the operating temperature of the sealed fluid is high, the viscous resistance of the fluid decreases, so if the lid is released while it is slightly open, the lid will rotate to close at a considerable speed without slowing down sufficiently.

[0004] To solve the above problems, the inventor of the present application has devised a rotary damper that uses a spring member without using the viscous resistance of a fluid. This rotary damper was filed by the applicant of the present application prior to the present application and has already been patented (Patent Document 1 below). The rotary damper shown in Patent Document 1 below includes a fixed housing and a rotor that rotates within the housing. The rotor is molded from a required synthetic resin material and has viscoelasticity. Viscoelasticity will be described later. The rotor has a cylindrical mounting wall extending in the axial direction, and a spring member formed by winding a wire in a spiral shape is mounted on the outer circumferential surface of the mounting wall. The spring member is provided with a hook portion, and the hook portion is held by the housing, making the spring member unable to rotate relative to the housing. When the rotor rotates, the hook portion is pushed by the housing, and the rotor slides relative to the spring member.

[0005] Here, the above-mentioned viscoelasticity is, according to the seventh edition of the Kojien dictionary published by Iwanami Shoten Co., Ltd., "one of the mechanical properties of solids and liquids. The phenomenon in which deformation caused by the application of an external force appears as a superposition of time-independent elastic deformation and time-dependent viscous flow." In other words, "having viscoelasticity" means having both elastic and viscous properties. Examples of synthetic resin materials that have viscoelasticity include PPS (polyphenylene sulfide) and PA (polyamide).

[0006] To continue the explanation, since the rotating body has viscoelasticity, the outer peripheral surface of the mounting part is pressed by the wire of the spring member in the region where the wire is present, and elastically concaves radially inward, and elastically restores to its original state in the region where the wire is not present (elastic property). Therefore, the outer peripheral surface of the mounting part of the rotating body is locally pressed by the wire of the spring member. And, since the wire constituting the spring member is wound in a spiral shape, when the rotating body rotates relative to the spring member, any point on the outer peripheral surface of the mounting part intersects with the wire, and the any point moves alternately between the region where the wire is present and the region where it is not present, that is, it is intermittently and repeatedly pressed (elastically deformed) by the wire. Now, when the outer peripheral surface of the mounting part is pressed by the wire and elastically concaves radially inward, both circumferential sides of the concave part become relatively convex. Therefore, when the rotating body rotates relative to the spring member, the wire of the spring member rotates on the outer peripheral surface of the rotating body while relatively pushing the convex located downstream in the rotation direction radially inward. At this time, since the rotating body also has viscous properties, when the wire rotates while pushing the protrusion located downstream in the rotational direction radially inward, the protrusion is compressed downstream in the rotational direction, increasing the pressure on the downstream side in the rotational direction, and generating resistance when the rotating body rotates, i.e., resistance torque. The magnitude of this resistance torque is proportional to the rotational speed of the rotating body (it has speed dependency). This is because the amount of compression increases as the rotational speed of the rotating body increases. This resistance is considered to be similar to wave-making resistance. Therefore, the increase in the rotational speed of the rotating body relative to the spring member is effectively suppressed, and it functions as a rotary damper. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7088993 Summary of the Invention [Problem to be solved by the invention]

[0008] Thus, in the rotary damper shown in the above-mentioned Patent Document 1, (1) the spring member that applies a resistance torque to the rotating body is housed inside the housing, and the spring member cannot be operated from the outside of the housing, so the magnitude of the resistance torque that the spring member acts on the rotating body cannot be adjusted. Therefore, the rotation speed of the rotating body cannot be adjusted arbitrarily. Also, (2) for example, when incorporated in a blind winding mechanism, the falling speed of the bottom rail when it falls freely in the vertical direction can be sufficiently suppressed, but when connected to an external device that swings and closes from the open position to the closed position due to gravity, the swing speed of the external device cannot be sufficiently suppressed. This is because, in the former case, a constant force due to gravity acts on the bottom rail that falls freely in the vertical direction, so the magnitude of the rotation torque acting on the rotating body of the rotary damper is constant, but in the latter case, the rotation torque acting on the rotating body of the rotary damper gradually increases as the external device swings and closes from the open position to the closed position. This will be mentioned further later.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and its first technical object is to provide a new and improved rotary damper that is capable of limiting the rotational speed of a rotor by applying a resistance torque to the rotor without utilizing the viscosity of a fluid, and that is capable of adjusting the resistance torque to an arbitrary magnitude.

[0010] A second technical object of the present invention is to make it possible to suppress the rotational speed of the rotor of the rotary damper even when the rotational torque acting on the rotor gradually increases. [Means for solving the problem]

[0011] As a result of intensive research, the inventors have found that the first technical problem can be solved by providing a pressing piece on the housing that locally presses the rotor, instead of or in addition to mounting a coil spring on the rotor having viscoelasticity, and making the pressing piece movable in a direction toward and away from the rotor. The inventors have also found that the second technical problem can be solved by combining a link mechanism with the rotary damper to reduce the magnitude of the rotational torque acting on the rotor of the rotary damper.

[0012] That is, according to a first aspect of the present invention, there is provided a rotary damper that solves the first technical problem described above, comprising a fixed housing and a rotor that rotates within the housing, a pressing piece for locally pressing the rotating body is disposed on the housing, the pressing piece being movable in a direction approaching and separating from the rotating body, When the rotating body rotates, the pressing piece moves relatively in a circumferential direction around the rotation axis of the rotating body while locally pressing the rotating body, At least a portion of the rotating body that is pressed by the pressing piece has viscoelasticity, thereby providing a rotary damper.

[0013] Preferably, the rotor has a rotating plate arranged perpendicular to the rotation axis, and the pressing piece presses the rotating plate in the axial direction at a position eccentric to the rotation axis. In this case, the housing has a cylindrical support wall penetrating in the axial direction, the axial end face of the support wall faces the rotating plate, the inner peripheral surface of the support wall is formed with a female thread, the pressing piece is arranged inside the support wall, and the outer peripheral surface of the pressing piece is formed with a male thread that screws with the female thread formed on the inner peripheral surface of the support wall. Furthermore, it is preferable that a ball that abuts against the rotating plate and a pressing means that is pressed by the pressing piece to press the ball are further arranged inside the support wall, and the pressing piece presses the rotating plate via the ball. Furthermore, it is preferable that the rotating plate is formed with a shallow groove in an annular shape for guiding the ball. The rotating plate has a cylindrical mounting wall extending in the axial direction, the mounting wall has a central axis common to the rotating shaft, a spring member formed by winding a wire in a spiral shape is mounted on the outer circumferential surface of the mounting wall, the spring member has a hook portion held by the housing, when the rotating body rotates, the hook portion is relatively pressed by the housing in a direction in which the spring member is tightened, the rotating body slides against the spring member, and at least a portion of the outer circumferential surface of the mounting wall where the spring member slides has viscoelasticity. In this case, the housing has an end plate arranged perpendicular to the axial direction, the outer diameter of the rotating plate is larger than the outer diameter of the mounting wall, the spring member is arranged between the bottom surface of the end plate and the rotating plate, the hook portion of the spring member is located close to the rotating plate in the axial direction, and the wire constituting the spring member is wound clockwise from the rotating plate toward the bottom surface of the end plate. Furthermore, the number of turns of the wire forming the spring member is preferably 1. The rotating body may be provided with a one-way clutch and rotate within a required angular range.

[0014] According to a second aspect of the present invention, there is provided a combination that solves the second technical problem, which is a combination of the above-mentioned rotary damper, in which at least the rotating body is provided with a one-way clutch and rotates within a required angle range, and a link mechanism, wherein the link mechanism includes a one-side link piece that is rotatable about an eccentric shaft that is eccentric with respect to the rotation shaft of the rotating body and rotates integrally with an external device, an other-side link piece that is rotatable about the rotation shaft and rotates integrally with the rotating body, and an intermediate link piece that connects the one-side link piece and the other-side link piece, When the external device rotates, a one-side movable joint connecting the one-side link piece and the intermediate link piece approaches the rotation axis while rotating around the eccentric shaft, causing the other-side link piece to rotate. Effect of the Invention

[0015] In the rotary damper according to the first aspect of the present invention, the pressing piece that locally presses the rotor is movable in a direction approaching and moving away from the rotor, and when the rotor rotates, the pressing piece moves relatively in a circumferential direction around the rotation axis of the rotor while locally pressing the rotor, and at least the part of the rotor that is pressed by the pressing piece has viscoelasticity. As the pressing piece moves in a direction approaching and moving away from the rotor, the force with which the pressing piece presses the rotor varies, and the magnitude of the resistance torque due to friction generated between the pressing piece and the rotor and the resistance torque similar to the wave resistance also varies. Therefore, in the rotary damper according to the first aspect of the present invention, it is possible to apply a resistance torque to the rotor without using the viscosity of a fluid, thereby limiting the rotation speed of the rotor, and it is possible to adjust the resistance torque to an arbitrary magnitude.

[0016] In the combination according to the second aspect of the present invention, when the external device rotates, the one-side movable joint connecting the one-side link piece and the intermediate link piece rotates around the eccentric shaft and approaches the rotation axis, causing the other-side link piece to rotate. Since the one-side link piece rotates integrally with the external device, the rotation torque generated by the rotation of the external device is transmitted to the intermediate link piece by the one-side movable joint. Furthermore, since the one-side movable joint approaches the rotation axis, the rotation torque is reduced accordingly and transmitted to the other-side link piece. This is because, as viewed from the other-side link piece, the length of the arm from the rotation axis, which is the center of rotation, that is, the distance to the one-side movable joint, is gradually reduced. Therefore, even if the external device is rotated from the open position to the closed position by gravity and the rotation torque gradually increases, the rotation torque is gradually reduced by the link mechanism, so that even the above-mentioned rotary damper can sufficiently suppress the rotation speed of the external device. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing the configuration of a preferred embodiment of a combination of a rotary damper and a link mechanism configured according to the present invention. [Diagram 2] FIG. 2 is a diagram showing the housing of the rotary damper alone in the combination shown in FIG. 1. [Diagram 3] FIG. 2 is a diagram showing a rotor of the rotary damper alone in the combination shown in FIG. 1. [Figure 4] FIG. 2 is a view showing a spring member of the rotary damper alone in the combination shown in FIG. 1 . [Diagram 5] 2 is a view showing one link piece of the link mechanism in the combination shown in FIG. 1 . FIG. [Figure 6] 2 is a view showing the other link piece of the link mechanism in the combination shown in FIG. 1 alone. FIG. [Figure 7] 7 is a view showing a driven shaft connected to the other side link piece shown in FIG. 6 alone. FIG. [Figure 8] 2 is a view showing a single intermediate link piece of the link mechanism in the combination shown in FIG. 1; FIG. [Figure 9]2 is a cross-sectional view taken along line CC when the external device is turned to close in the combination shown in FIG. 1 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The rotary damper constructed according to the present invention and the combination of the rotary damper and the link mechanism will be described in more detail below with reference to the accompanying drawings. In the following description, the terms "one axial side" and "other axial side" refer to the left side and the right side in the state shown in the cross section B-B in Fig. 1, unless otherwise specified.

[0019] In Fig. 1, a preferred embodiment of a combination of a rotary damper and a link mechanism constructed according to the present invention is indicated by the number 2. The rotary damper is indicated by the number 4, and the link mechanism is indicated by the number 6. This combination 2 is connected to a rotating member X, which is an external device such as the toilet cover and valve seat of a Western-style toilet or the sorter of a copier, and supports it so that it can rotate between an open position and a closed position. Fig. 1 shows the state in which the rotating member X is in the open position, and the rotating member X rotates and closes due to gravity to the closed position shown in Fig. 9(b).

[0020] First, the rotary damper 4 will be described. The rotary damper 4 includes a fixed housing 8 and a rotor 10 that rotates within the housing 8. Referring to FIG. 1 and FIG. 2, the housing 8 made of synthetic resin includes a housing body 12 shown in FIG. 2(a) and a shield 14 shown in FIG. 2(b), and the housing 8 is fixed to a wall or the like by an appropriate fastener (not shown). The housing body 12 is cup-shaped, having a rectangular end plate 16 arranged perpendicular to the axial direction and a square cylindrical outer wall 18 extending from the outer periphery of the end plate to the other axial direction. The end plate 16 is relatively thick, and an accommodation recess 20 is formed on the other axial side of the end plate 16 to accommodate the rotor 10 and a spring member (described later) that is attached to the outer periphery of the end plate. A circular shaft hole 22 is formed in the bottom surface of the accommodation recess 20 and penetrates in the axial direction. A circular recess 24 is further formed in the bottom surface of the accommodation recess 20, and the recess 24 and the shaft hole 22 have a common central axis. The inner peripheral surface of the receiving recess 20 is generally cylindrical, but two arc-shaped pockets 26, the inner diameter of which is increased over a required angular range, are formed on both sides in the diametric direction. Furthermore, an arc-shaped relief groove 28, the inner diameter of which is increased over a required angular range, is also formed in the center between the two pockets 26 as viewed in the circumferential direction. Furthermore, a hook groove 30, the inner diameter of which is locally increased, is also formed between each of the two pockets 26 as viewed in the circumferential direction and the relief groove 28. An arc-shaped step portion 31 extending intermittently in the circumferential direction is formed at the other axial end of the receiving recess 20. The end plate 16 is also formed with a shaft hole 32, the cross section of which is circular and penetrates the axial direction at a position different from the receiving recess 20. An annular step portion 34 facing the other axial side is formed at the axial intermediate portion of the shaft hole 32. A screw hole 36 extending linearly in the axial direction is formed at each corner of the axial end face of the outer circumferential wall 18. The cross-sectional shape of the inner peripheral surface of the outer peripheral wall 18 is not rectangular, but has a required shape as shown in the left diagram of FIG. 2(a).

[0021] The shield 14 includes an end plate 38 having a rectangular shape that is the same as the end plate 16 of the housing body 12 in a plan view. A circular through hole 39 is formed in each corner of the end plate 38, penetrating in the axial direction. The end plate 38 is axially opposed to the end plate 16 of the housing body 12, and the through hole 39 and the screw hole 36 are aligned. In this state, the shield 14 is fastened to the housing body 12 by inserting a fastener such as a bolt (not shown) through the through hole 39 and the screw hole 36. The end plate 38 is formed with two circular shaft holes 40 and 42 penetrating in the axial direction. The two shaft holes 40 and 42 face the shaft holes 22 and 32 formed in the end plate 16, respectively, when the shield 14 is fastened to the housing body 12. The shaft holes 22 and 40 of the housing body 12 and the shield 14, which are opposed to each other in the axial direction, respectively receive both ends of a driven shaft 104 extending along a rotation axis o1 (to be described later) of the rotor 10, and the shaft holes 22 and 40 rotatably support the driven shaft 104. On the other hand, the shaft holes 32 and 42 of the housing body 12 and the shield 14, which are opposed to each other in the axial direction, respectively receive both ends of a drive shaft 84 extending along an eccentric axis o2 (to be described later), and the shaft holes 32 and 42 rotatably support the drive shaft 84. The end plate 38 is further formed with a circular communication hole 43 penetrating in the axial direction, and a cylindrical support wall 44 is formed on one axial side surface of the end plate 38, surrounding the outer periphery of the communication hole 43 and extending in the axial direction. Therefore, the support wall 44 penetrates in the axial direction at a position eccentric to the rotation axis o1. An internal thread 46 is formed on the inner peripheral surface of the support wall 44. The support wall 44 will be described later.

[0022] In the rotary damper of the present invention, at least the portion of the rotor 10 that is pressed by the pressing piece described below has viscoelasticity. In the illustrated embodiment, the entire rotor 10 is made of a required synthetic resin material having viscoelasticity. Examples of such synthetic resin materials include PPS (polyphenylene sulfide) and PA (polyamide). In order to increase the rigidity of the rotor 10 and improve its speed dependency while suppressing costs, it is preferable to appropriately add glass fiber and calcium carbide to the synthetic resin material. Viscoelasticity will be further discussed later.

[0023] Continuing the explanation with reference to FIG. 3 together with FIG. 1, the rotating body 10 has a circular rotating plate 48 arranged perpendicular to the axial direction and a cylindrical mounting wall 50 extending from the rotating plate 48 to one side in the axial direction, and the rotating plate 48 and the mounting wall 50 have a common central axis. As can be understood by referring to the AA cross-sectional view of FIG. 2(a) together with the BB cross-sectional view of FIG. 1, the rotating plate 48 is supported by a step portion 31 formed at the other axial end of the inner peripheral surface of the receiving recess 20 of the housing body 12, and one axial end of the mounting wall 50 is supported by the recessed portion 24 of the housing body 12, and the rotating body 10 rotates around the common central axis as the rotation axis o1. The outer diameter of the rotating plate 48 is larger than the outer diameter of the mounting wall 50, and a circular through hole 52 smaller than the inner diameter of the mounting wall 50 is formed in the center of the rotating plate 48. A ring-shaped shallow groove 53 surrounding the through hole 52 is formed on the other axial side of the rotating plate 48. The center of the shallow groove 53 is common with the rotation axis o1, and the cross section of the shallow groove 53 is arc-shaped. When the housing body 12 and the shield 14 are assembled, one axial end face of the support wall 44 formed on the shield 14 faces the shallow groove 53 in close proximity. On the inner peripheral surface of the mounting wall 50, three locking protrusions 56 are formed at equal angular intervals in the circumferential direction, protruding radially inward and extending linearly in the axial direction. In the illustrated embodiment, a one-way clutch 54 is disposed inside the mounting wall 50. In FIG. 1, the one-way clutch 54 is not hatched for easy understanding. On the outer peripheral surface of the one-way clutch 54, three locking recessed grooves 58 are formed at equal angular intervals in the circumferential direction, extending linearly in the axial direction, and the locking protrusions 56 formed on the inner peripheral surface of the mounting wall 50 are inserted into the locking recessed grooves 58, so that the one-way clutch 54 cannot rotate with respect to the rotor 10. The one-way clutch 54 may be a well-known one, for example, the one described in Japanese Patent No. 3501352, which was filed by the applicant of the present application prior to the present application and has already been granted a patent, and a detailed description thereof will be omitted. A driven shaft 104, which will be described later, is inserted inside the one-way clutch 54, and when the driven shaft 104 rotates clockwise in the AA cross section of Figure 1, the one-way clutch 54 rotates integrally with the driven shaft 104, and when the driven shaft 104 rotates counterclockwise, the one-way clutch 54 rotates idly relative to the driven shaft 104, that is, does not rotate.

[0024] In the illustrated embodiment, a spring member 60 is attached to the outer circumferential surface of the mounting wall 50 of the rotor 10. Referring to FIG. 1 and FIG. 4, the spring member 60 is made of a metal wire having a circular cross section, and includes a wound portion 62 in which the wire is wound in a spiral shape, and a hook portion 64 and a relief hook portion 66 in which the wire extends linearly at both axial ends of the wound portion 62. The wound portion 62 is circular when viewed in the axial direction, and the number of turns of the wire is one. The inner diameter of the wound portion 62 in a free state is smaller than the outer diameter of the mounting wall 50 of the rotor 10, and the spring member 60 is attached to the outer circumferential surface of the mounting wall 50 of the rotor 10 with the wound portion 62 expanded in diameter. The hook portion 64 extends linearly in the normal direction of the wound portion 62, and the relief hook portion 66 extends linearly in the tangential direction of the wound portion 62. When the spring member 60 is accommodated together with the rotating body 10 in the accommodation recess 20 formed in the housing body 12, the spring member 60 is located between the bottom surface of the end plate 16 of the housing body 12 and the rotating flat plate 48 of the rotating body 10, and the outer surface of the wound portion 62 faces the inner peripheral surface of the accommodation recess 20. The hook portion 64 is inserted into one of the two hook grooves 30 formed in the accommodation recess 20, and the escape hook portion 66 is inserted into the escape groove 28 formed in the accommodation recess 20. In the illustrated embodiment, the hook portion 64 is inserted into the hook groove 30 located on the left side in the AA cross-sectional view of FIG. 1, and the hook portion 64 is located on the other axial side, so that the wire constituting the spring member 60 is wound clockwise from the hook portion 64 toward the escape hook portion 66, i.e., toward one axial side. The hook portion 64 is held by the hook groove 30, so that the spring member 60 cannot rotate with respect to the housing 8. After the spring member 60 and the rotating body 10 are accommodated in the accommodation recess 20 of the housing body 12, a lubricant such as grease is filled in the pocket 26. Since such a lubricant is filled in the pocket 26, a relatively large amount of the lubricant can be filled, and so-called grease shortage is prevented as much as possible.

[0025] In the rotary damper of the present invention, a pressing piece 68 for locally pressing the rotor 10 is disposed in the housing 8, and the pressing piece 68 is movable in a direction approaching and receding from the rotor 10. In the illustrated embodiment, the pressing piece 68 is disposed inside the support wall 44 formed in the shield 14, and a male thread 70 that screws into the female thread 46 formed on the inner peripheral surface of the support wall 44 is formed on the outer peripheral surface of the pressing piece 68. As a result, the pressing piece 68 can move in the axial direction relative to the support wall 44 by rotating relative to the support wall 44. Further disposed inside the support wall 44 are a metal ball 72 that abuts against the shallow groove 53 of the rotary plate 48, and a biasing means 74 (compression coil spring) that is pressed by the pressing piece 68 to bias the ball 72, and in the illustrated embodiment, the pressing piece 68 presses the rotary plate 48 via the ball 72. In the illustrated embodiment, the biasing means 74 is a compression coil spring, but any means such as a disc spring may be used as long as it can bias the ball 72. For this reason, when the pressing piece 68 is rotated in one direction relative to the shield 14 and screwed forward in the direction toward the ball 72, the force with which the biasing means 74 biases the ball 72 increases, and the force with which the ball 72 presses the rotating plate 48 of the rotor 10 increases, whereas when the pressing piece 68 is rotated in the other direction and screwed back in the direction away from the ball 72, the force with which the biasing means 74 biases the ball 72 decreases, and the force with which the ball 72 presses the rotating plate 48 of the rotor 10 decreases. That is, in the illustrated embodiment, the pressing piece 68 indirectly presses locally against the outer surface of the rotor 10 via the biasing means 74 and the ball 72, more specifically, locally presses the rotating flat plate 48 in the axial direction at a position eccentric to the rotation axis o1, and the force with which the ball 72 locally presses the rotor 10 can be adjusted by rotating the pressing piece 68 relative to the shield 14. Since the ball 72 is biased by the biasing means 74, the ball 72 is stably pressed against the outer surface of the rotor 10. If desired, the pressing piece 68 may directly press the rotor 10 without the ball 72 and the biasing means 74. In this case, it is preferable that one axial end face of the pressing piece 68 that abuts against the outer surface of the rotor 10 is curved from the viewpoint of preventing wear, etc.Furthermore, if the female thread 46 is formed on the inner peripheral surface of the communication hole 43 of the shield 14, the support wall 44 extending in the axial direction is not necessarily required and may be omitted. In the illustrated embodiment, the pressing piece 68 presses the rotating flat plate 48 in the axial direction toward the end plate 16 of the housing body 12, so that the rotating body 10 is prevented as much as possible from moving to the other axial side relative to the housing body 12 and causing the shield 14 to fall off from the housing body 12.

[0026] The operation of the rotary damper of the present invention will now be described. In the rotary damper of the present invention, when the rotor 10 rotates, the pressing piece 68 moves relatively in the circumferential direction around the rotation axis o1 while locally pressing the rotor 10. In the illustrated embodiment, the pressing piece 68 presses the rotating flat plate 48 in the axial direction via the ball 72, and when the rotor 10 rotates, the ball 72 moves in the circumferential direction around the rotation axis o1 along the shallow groove 53 while pressing the rotating flat plate 48 in the axial direction, that is, is guided by the shallow groove 53. At this time, at least the part of the rotor 10 pressed by the ball 72 (pressing piece 68) (the entire rotor 10 in the illustrated embodiment) has viscoelasticity, so that the rotor 10 is subjected to a resistance torque due to friction with the ball 72 and a resistance torque similar to the wave-making resistance as described above. The latter resistance torque is speed-dependent and increases as the rotation speed of the rotor 10 increases. Therefore, for example, when the rotating body 10 is connected to the bottom rail of a blind and falls freely in the vertical direction, the rotational speed of the rotating body 10 will accelerate under a constant acceleration due to gravity, but as the rotational speed of the rotating body 10 accelerates, the latter resistance torque that the rotating body 10 receives from the pressing piece 68 (ball 72) also increases accordingly, so that the rotational speed of the rotating body 10 is suppressed. Furthermore, in the rotary damper of the present invention, the pressing piece 68 moves closer to the rotating body 10 and in the axial direction, so that the force with which the pressing piece 68 locally presses the rotating body 10 can be adjusted, and therefore the magnitude of the resistance torque can be adjusted, and the falling speed of the bottom rail can be adjusted as desired.

[0027] In the illustrated embodiment, the spring member 60 is attached to the mounting wall 50 of the rotor 10, and this spring member 60 also locally presses the rotor 10 like the pressing piece 68 (ball 72), so that the spring member 60 also has the same effect as the pressing piece 68 (ball 72), and the rotation speed of the rotor 10 can be further suppressed. When the rotation direction of the rotor 10 is such that the hook portion 64 is relatively pressed by the housing 8 in the direction in which the tightening of the spring member 60 is strengthened when the rotor 10 rotates, that is, when the rotation direction is the clockwise direction in the AA cross section of FIG. 1, the hook portion 64 does not bend excessively due to inertia immediately after the rotor 10 starts to rotate. Therefore, the rotor 10 can rotate under the required resistance torque immediately after the start of rotation, that is, without any time delay. At this time, in the illustrated embodiment, since the number of turns of the wire forming the spring member 60 is 1, even if the hook portion 64 is relatively pressed by the housing 8 in a direction in which the spring member 60 is tightened when the rotating body 10 rotates, the rotating body 10 can slide reliably without being locked relative to the spring member 60. Furthermore, in the illustrated embodiment, the spring member 60 is disposed between the bottom surface of the end plate 16 of the housing body 12 and the rotating flat plate 48, the hook portion 64 of the spring member 60 is located close to the rotating flat plate 48 in the axial direction, and the wire forming the spring member 60 is wound clockwise from the rotating flat plate 48 toward the bottom surface of the end plate 16 of the housing body 12 (i.e., toward one axial side). Therefore, when the rotating body 10 rotates relative to the spring member 60 (clockwise rotation in the AA cross section of FIG. 1 as described above), the wound portion 62 of the spring member 60 acts as a screw, and a force that propels the rotating body 10 toward one axial side relative to the spring member 60 acts on the rotating body 10. It is also possible to reverse the winding direction of the wire that constitutes the spring member 60 or to switch the orientation of the spring member 60 so that when the rotating body 10 rotates relative to the spring member 60, a force is exerted on the rotating body 10 to propel it in the other axial direction relative to the spring member 60. However, doing so is not preferable as there is a risk that the rotating body 10 will push the shield 14 and cause it to fall off the housing main body 12.

[0028] Thus, even if the rotating body 10 has viscoelasticity, if the rotary damper 4 is directly connected to the rotating member X without the link mechanism 6, the rotary damper 4 cannot sufficiently suppress the rotation speed of the rotating member X. When the rotating body 10 is connected to the bottom rail of a blind, the bottom rail falls freely in the vertical direction, so a constant rotational torque based on gravity acts on the rotating body 10, but when the rotating body 10 is connected to the rotating member X, the rotating member X rotates due to gravity, so the magnitude of the rotational torque acting on the rotating body 10 changes depending on the rotational angle position of the rotating member. The link mechanism 6 will be explained further below.

[0029] 1, the link mechanism 6 includes a one-side link piece 76, an other-side link piece 78, and an intermediate link piece 80. Referring to FIG. 1 and FIG. 5, the one-side link piece 76 has a main portion 82 in the form of an elongated flat plate. A drive shaft 84 extending in the axial direction is formed on one axial side surface of the main portion 82. The cross-sectional shape of the drive shaft 84 is circular except for one axial end portion, and a ring-shaped step portion 86 facing one axial side is formed in the axial middle portion of the drive shaft 84. A spline connection portion 88 is formed on the outer circumferential surface of one axial end portion of the drive shaft 84. A columnar seat protrusion 90 having a relatively large diameter and a columnar connection protrusion 92 having a relatively small diameter are formed on the other axial side surface of the main portion 82. The seat protrusion 90 has a common central axis with the drive shaft 84, and a columnar support protrusion 94 having a relatively small diameter is further formed in the center of the axial end surface. 5, the drive shaft 84 is inserted into the shaft hole 32 formed in the end plate 16 of the housing body 12 and rotatably supported therein. When the drive shaft 84 is inserted into the shaft hole 32, the spline connection portion 88 is exposed to the outside of the housing 8, and the swivel member X is connected to the spline connection portion 88. The step portion 86 is supported by the step portion 34 formed in the end plate 16 of the housing body 12, and the outer peripheral edge of the base protrusion 90 is supported by the outer peripheral edge of the entrance of the shaft hole 32 formed in the end plate 16 of the housing body 12. Furthermore, when the housing body 12 and the shield 14 are assembled, the support protrusion 94 is inserted into the shaft hole 42 formed in the end plate 38 of the shield 14 and rotatably supported therein. As a result, the one-side link piece 76 rotates integrally with the rotating member X about an eccentric axis o2 that is eccentric with respect to the rotation axis o1 of the rotating body 10.

[0030] 1 and 6, the other-side link piece 78 has a flat main portion 96. The main portion 96 further has a cylindrical connecting protrusion 98 formed on the other axial side surface and a connecting hole portion 100 penetrating in the axial direction. The cross section of the connecting hole portion 100 is generally circular, but six ridges 102 extending linearly in the axial direction are formed on the inner peripheral surface at equal angular intervals in the circumferential direction. The other-side link piece 78 is connected to a driven shaft 104 via the connecting hole portion 100. Continuing the explanation with reference to FIG. 7, the driven shaft 104 is solid and is divided into an intermediate portion 106, a one-side portion 108 located on one axial side of the intermediate portion 106, and an other-side portion 110 located on the other axial side of the intermediate portion 106. The intermediate portion 106 is cylindrical and is inserted into the inside of the rotor 10 as shown in the B-B cross section of FIG. 1. More specifically, the other axial end of the intermediate portion 106 is disposed in the through hole 52 of the rotor 10, and the portion other than the other axial end is disposed inside the one-way clutch 54. The one side portion 108 is cylindrical and has a smaller diameter than the intermediate portion 106, and is inserted into the shaft hole 22 formed in the end plate 16 of the housing body 12 and rotatably supported therein. The other side portion 110 is generally cylindrical and has a smaller diameter than the intermediate portion 106, and six ridges 112 extending linearly in the axial direction are formed at equal angular intervals in the circumferential direction on the outer circumferential surface of the base end portion. As can be understood by referring to the B-B cross-sectional views of FIGS. 6 and 1 as well as FIG. 7, the other side portion 110 is inserted into the connecting hole 100 of the other side link piece 78, and the ridges 112 are engaged with the ridges 102 in the circumferential direction, thereby connecting the driven shaft 104 to the other side link piece 78. The other axial end of the other side portion 110 on which the protrusion 112 is not formed is rotatably supported in a circular shaft hole 40 formed in the end plate 38 of the shield 14. Thus, the other-side link piece 78 can rotate integrally with the rotating body 10 of the rotary damper 4 around the rotation axis o1.

[0031] Explaining with reference to Fig. 1 and Fig. 8, the intermediate link piece 80 is flat and has a circular one-side hole 114 and an other-side hole 116 that penetrate in the axial direction. The connecting protrusion 92 formed on the one-side link piece 76 is gap-fitted into the one-side hole 114, and the connecting protrusion 98 formed on the other-side link piece 78 is gap-fitted into the other-side hole 116. Thus, the one-side link piece 76 and the other-side link piece 78 are connected via the intermediate link piece 80, and these link pieces form a link mechanism. The connecting protrusion 92 and the one-side hole 114 that connect the one-side link piece 76 and the intermediate link piece 80 form one-side movable joint P1, and the connecting protrusion 98 and the other-side hole 116 that connect the other-side link piece 78 and the intermediate link piece 80 form the other-side movable joint P2.

[0032] Next, the operation of the combination 2 will be described with reference to FIG. 9 together with FIG. 1. As described above, FIG. 1 shows the state when the rotating member X is in the open position. In the illustrated embodiment, the rotating member X is in the open position when it is raised at 80 degrees from the horizontal direction (θ=80°, for θ, see FIG. 9(a)). When the rotating member X is in the open position, the side surface of the main portion 82 of the one-side link piece 76 abuts against the inner peripheral surface of the outer peripheral wall 18 of the housing main body 12, preventing the one-side link piece 76 from rotating clockwise around the eccentric shaft o2 in the CC cross section of FIG. 1. This prevents the rotating member X from further rotating open from the open position.

[0033] 9(a) shows the CC section when the rotating member X is rotated from the state shown in FIG. 1, that is, the state in which the rotating member X is in the open position, by gravity, and the rotating member X is tilted 40 degrees (θ=40°) with respect to the horizontal direction. As can be understood by comparing and referring to the CC section of FIG. 1 with FIG. 9(a), when the rotating member X rotates counterclockwise in the figure, the one-side link piece 76, which rotates integrally with the rotating member X via the drive shaft 84, rotates counterclockwise around the eccentric shaft o2. Then, due to the operation of the link mechanism 6, that is, the one-side link piece 76, the other-side link piece 78, and the intermediate link piece 80, the one-side movable joint P1 approaches the rotation axis o1 while rotating counterclockwise around the eccentric shaft o2, and the other-side link piece 78 rotates clockwise around the rotation axis o1. Since the driven shaft 104 is connected to the other-side link piece 78, the driven shaft 104 also rotates clockwise. Here, when the driven shaft 104 rotates clockwise, the one-way clutch 54 connects the driven shaft 104 and the rotating body 10 so that they cannot rotate relative to each other, and so the rotating body 10 rotates clockwise together with the driven shaft 104 (the direction of rotation of the rotating body 10 is shown by an arrow in the AA cross-sectional view of FIG. 1). As a result, the hook portion 64 of the spring member 60 is relatively pressed in the hook groove 30 of the housing 8 in a direction in which the spring member 60 is tightened, and a braking torque acts on the rotating body 10.

[0034] Here, assuming that the mass of the rotating member X is m, the gravitational acceleration is g, and the rotation angle of the rotating member X with respect to the horizontal direction is θ, the component force F that the rotating member X receives in the rotation direction due to gravity when the rotating member X is rotated to close due to gravity is mgcosθ. The component force F gradually increases as the rotation angle θ of the rotating member X becomes smaller, that is, as the rotating member X rotates to close toward the closed position. Since torque is proportional to force, the rotation torque when the rotating member X rotates around the eccentric shaft o2 also gradually increases. The component force F and the rotation torque due to it are maximum at the closed position (θ=0°). Therefore, when the rotating member X is directly connected to the rotary damper 4 without the link mechanism 6, even if the braking torque is applied to the rotating body 10 by the spring member 60, it is not sufficient, and the rotation speed of the rotating body 10, i.e., the rotation speed of the rotating member X, cannot be sufficiently suppressed. However, in the illustrated embodiment, the rotary damper 4 is connected to the rotating member X via the link mechanism 6. Therefore, when the rotating member X rotates, the one-side movable joint P1 connecting the one-side link piece 76 and the intermediate link piece 80 approaches the rotation axis o1 while rotating around the eccentric axis o2, causing the other-side link piece 78 to rotate. Since the one-side link piece 76 rotates integrally with the rotating member X, the rotation torque generated by the rotation of the rotating member X is transmitted to the intermediate link piece 80 by the one-side movable joint P1. Moreover, since the one-side movable joint P1 approaches the rotation axis o1, the above-mentioned rotation torque is reduced accordingly and transmitted to the other-side link piece 78. This is because, as viewed from the other-side link piece 78, the length of the arm from the rotation axis o1, which is the center of rotation, i.e., the distance to the one-side movable joint P1, is gradually reduced. Therefore, even if the rotating member X is rotated from the open position to the closed position by gravity and the rotational torque gradually increases, such rotational torque is gradually reduced by the link mechanism 6, so that even the above-mentioned rotary damper 4 can sufficiently suppress the rotational speed of the rotating member X.

[0035] In the rotary damper of the present invention, when the rotor 10 rotates, the hook portion 64 is relatively pushed by the housing 8 in a direction in which the spring member 60 is tightened, and therefore wear on the outer circumferential surface of the rotor 10 tends to be accelerated and the service life tends to be shorter than when the hook portion 64 is relatively pushed in a direction in which the spring member 60 is tightened (the generated torque is larger, so the comparison of generated torque is the same). However, since the rotor 10 rotates only within a predetermined angle range in which the rotating member X rotates, the number of rotations of the rotor 10 relative to the spring member 60 is reduced compared to when the rotor 10 rotates continuously in one direction. Therefore, when the rotary damper of the present invention is used as in the illustrated embodiment, the service life of the rotary damper 4 itself is unlikely to be an issue.

[0036] When the rotating member X is rotated open from the state shown in Fig. 9(b) to the state shown in Fig. 1, that is, when the rotating member X is rotated open from the closed position to the open position, the rotation is reversed to the above-mentioned rotation closing movement. In other words, since the driven shaft 104 is rotated counterclockwise in Fig. 9(b), the driven shaft 104 rotates freely with respect to the one-way clutch 54 (rotating body 10), and the rotating member X can rotate open without receiving any resistance torque.

[0037] The rotary damper and the combination of the rotary damper and the link mechanism constructed according to the present invention have been described in detail above with reference to the attached drawings. However, the present invention is not limited to the above-mentioned embodiment, and appropriate modifications and changes can be made within the scope of the present invention. In the rotary damper of the present invention, since it is only necessary for the pressing piece to locally press the rotor, the pressing piece is not necessarily limited to pressing the rotating plate in the axial direction, and may press the outer surface of the rotor in the radial direction. In addition, the pressing piece is not limited to moving in the direction approaching and moving away from the rotor by screwing with the housing. For example, if the pressing piece is provided with a plurality of locking means at intervals and the housing is provided with a single locked means, and the position of the pressing piece relative to the housing can be adjusted in stages, the pressing piece can move in the direction approaching and moving away from the rotor. In the illustrated embodiment, the spring member 60 is attached to the outer circumferential surface of the mounting wall 50 of the rotor 10, but it can also be attached to the inner circumferential surface of the mounting wall. In this case, the hook portion of the spring member is held by a shaft-shaped housing inserted inside the rotor, and the one-way clutch is fitted to the outer circumferential surface of the mounting wall. In the illustrated embodiment, the spring member 60 has the hook portion 64 and the escape hook portion 66, but the escape hook portion 66 may be omitted. Also, the hook portion 64 does not necessarily have to extend in the normal direction, and may have any shape as long as it is held by the housing 8. [Explanation of symbols]

[0038] 2: Combination of rotary damper and link mechanism 4: Rotary damper 6: Link mechanism 8: Housing 10: Rotating body 44:Supporting wall 46:Female thread 68: Pressure piece 70: Male screw 72: Ball 74: biasing means

Claims

1. The rotor includes a fixed housing and a rotor that rotates within the housing. a pressing piece for locally pressing the rotating body is disposed on the housing, the pressing piece being movable in a direction approaching and separating from the rotating body, When the rotating body rotates, the pressing piece moves relatively in a circumferential direction around the rotation axis of the rotating body while locally pressing the rotating body, A rotary damper, wherein at least a portion of the rotating body that is pressed by the pressing piece has viscoelasticity.

2. 2. The rotary damper according to claim 1, wherein the rotating body has a rotating plate disposed perpendicular to the rotation axis, and the pressing piece presses the rotating plate in the axial direction at a position eccentric to the rotation axis.

3. 3. The rotary damper according to claim 2, wherein the housing includes a cylindrical support wall penetrating in the axial direction, the axial end face of the support wall faces the rotating plate, an internal thread is formed on the inner surface of the support wall, the pressing piece is disposed inside the support wall, and an external thread is formed on the outer surface of the pressing piece which screws into the internal thread formed on the inner surface of the support wall.

4. 4. The rotary damper according to claim 3, further comprising a ball abutting against the rotating plate and a biasing means for biasing the ball by being pressed by the pressing piece, the pressing piece pressing the rotating plate via the ball.

5. 5. The rotary damper according to claim 4, wherein the rotating plate is formed with an annular shallow groove for guiding the balls.

6. The rotating plate has a cylindrical mounting wall extending in an axial direction, the mounting wall having a common central axis with the rotation shaft, a spring member formed by winding a wire in a spiral shape is attached to an outer circumferential surface of the mounting wall, and the spring member is provided with a hook portion that is held by the housing; When the rotating body rotates, the hook portion is relatively pushed by the housing in a direction in which the fastening of the spring member is strengthened, and the rotating body slides against the spring member, 3. The rotary damper according to claim 2, wherein at least a portion of the outer circumferential surface of the mounting wall, on which the spring member slides, has viscoelasticity.

7. 7. The rotary damper of claim 6, wherein the housing has an end plate arranged perpendicular to the axial direction, the outer diameter of the rotating plate is larger than the outer diameter of the mounting wall, the spring member is arranged between the bottom surface of the end plate and the rotating plate, the hook portion of the spring member is located close to the rotating plate in the axial direction, and the wire constituting the spring member is wound clockwise from the rotating plate toward the bottom surface of the end plate.

8. 7. The rotary damper according to claim 6, wherein the number of turns of the wire forming the spring member is one.

9. 2. The rotary damper according to claim 1, wherein the rotating body is provided with a one-way clutch so as to rotate within a required angular range.

10. A combination of the rotary damper and the link mechanism according to claim 9, the link mechanism includes a one-side link piece that is rotatable about an eccentric shaft that is eccentric with respect to the rotation shaft of the rotating body and rotates integrally with an external device, an other-side link piece that is rotatable about the rotation shaft and rotates integrally with the rotating body, and an intermediate link piece that connects the one-side link piece and the other-side link piece, When the external device rotates, the one-side movable joint connecting the one-side link piece and the intermediate link piece approaches the rotation axis while rotating around the eccentric shaft, causing the other-side link piece to rotate.

Images