WO2018180674A1 - Friction damper - Google Patents

Abstract

Provided is a friction damper configured so as to enable frictional force to be easily adjusted. This friction damper (1) is provided with a cylinder (10), a rod (20), and friction members (30). The cylinder (10) is tube-shaped. The rod (20) is axially movable in a reciprocating manner, and a part of the rod (20) is contained in the cylinder (10). A plurality of grooves (recesses)(23) are formed in the outer peripheral surface of the rod (20). The friction members (30) are arranged in the plurality of grooves (23) and are in contact in a slidable manner with the inner peripheral surface of the cylinder (10).

Description

Friction damper

The present invention relates to a friction damper.

Patent Document 1 discloses a conventional friction damper. This friction damper includes a cylinder and a sliding ring as a friction member. The cylinder is formed in a cylindrical shape. The friction member slides in the cylinder and generates a required friction force. That is, the friction damper generates a frictional force by sliding between the cylinder and the friction member.

JP 2000-317194 A

In the case of the friction damper of Patent Document 1, since a friction force is generated between the cylinder and the friction member, it is necessary to finish the sliding surface with a strict dimensional accuracy in order to generate a desired friction force. However, there is a fear that a large difference may occur in the frictional force caused by the difference in the dimensions of the sliding surface.

The present invention has been made in view of the above-described conventional situation, and an object to be solved is to provide a friction damper capable of easily adjusting the frictional force.

The friction damper of the present invention includes a cylinder, a rod, a plurality of recesses, and a friction member. The cylinder is formed in a cylindrical shape. The rod is reciprocally movable in the axial direction, and a part thereof is accommodated in the cylinder. The plurality of recesses are formed on one of the inner peripheral surface of the cylinder and the outer peripheral surface of the rod. The friction member is disposed in at least one of the plurality of recesses and slidably contacts the other of the inner peripheral surface of the cylinder and the outer peripheral surface of the rod.

In the friction damper of the present invention, the friction member may be an O-ring. The recess is a groove formed in an annular shape in the circumferential direction of the inner peripheral surface of the cylinder or the outer peripheral surface of the rod, and an O-ring can be fitted therein.

FIG. 3 is a side sectional view schematically showing the friction damper of the first embodiment. FIG. 5 is a side cross-sectional view schematically showing a friction damper according to a second embodiment.

Embodiments 1 and 2 embodying the friction damper of the present invention will be described with reference to the drawings. In the following embodiment, a friction damper used in a caster such as a wheelchair, a baby buggy, or a transport cart is exemplified. For example, the friction damper is incorporated in a mechanism portion such as a link mechanism provided between a caster mounting bracket and a wheel, so that a road surface with unevenness or steps such as a Braille block (block) is provided. It is possible to damp vibrations during travel and reduce impact.

<Embodiment 1>
The friction damper 1 of Embodiment 1 is provided with the cylinder 10, the rod 20, and the friction member 30 as shown in FIG. In addition, the friction damper 1 includes a rod side joint portion 40, an elastic member 50, and a cover member 60.

The cylinder 10 is formed in a cylindrical shape. The cylinder 10 is made of resin. The cylinder 10 has an insertion part 11 and a cylinder side joint part 12. The insertion portion 11 is provided on the one end portion 10A side of the cylinder 10 and the rod 20 is inserted therethrough. The inner peripheral surface on the other end 10B side of the cylinder 10 is formed to have a diameter larger than the inner diameter of the inner peripheral surface on the end 10A side. Thereby, a stepped step portion 10 </ b> C is formed on the inner peripheral surface of the cylinder 10. The stepped portion 10C receives an enlarged diameter portion 22 of the rod 20 described later.

Further, the outer peripheral surface 10D on the end portion 10B side of the cylinder 10 is formed with a larger diameter than the outer peripheral surface 10E on the end portion 10A side. By forming the outer peripheral surface 10 </ b> D on the side of the end 10 </ b> B in such a manner as described above, a stepped step portion 10 </ b> F is formed on the outer peripheral surface of the cylinder 10. The step portion 10F receives one end of an elastic member 50 described later.

The cylinder side joint portion 12 is provided on the end portion 10B side of the cylinder 10 adjacent to the insertion portion 11. The cylinder side joint part 12 is a part which becomes a connection part with other members when the friction damper 1 is incorporated in the mechanism part together with the rod side joint part 40. The cylinder side joint portion 12 is formed with a through hole 12A through which a pin or the like can be inserted.

The rod 20 can reciprocate in the axial direction. A part of the rod 20 is housed in the cylinder 10. The rod 20 is made of resin. The rod 20 is formed in a cylindrical shape. The rod 20 has an outer diameter slightly smaller than the inner diameter of the insertion portion 11 of the cylinder 10. The rod 20 has a reduced diameter portion 21 formed at one end portion 20A and an expanded diameter portion 22 formed at the other end portion 20B. The rod 20 is inserted into the cylinder 10 from the end 10 </ b> B side of the cylinder 10, and is arranged with the end 20 </ b> A side protruding from the end 10 </ b> A of the cylinder 10. The reduced diameter portion 21 is inserted into the rod side joint portion 40. The enlarged diameter portion 22 contacts the stepped portion 10 </ b> C of the cylinder 10. The enlarged diameter portion 22 functions as a retaining member that prevents the rod 20 from slipping out from the end portion 10 </ b> A side of the cylinder 10.

A groove portion (illustrated as a recess according to the present invention) 23 is formed on the outer peripheral surface in the axial direction of the rod 20. The groove 23 is formed in an annular shape in the circumferential direction of the outer peripheral surface of the rod 20. A plurality of grooves (six in FIG. 1) are formed. Each groove portion 23 is provided side by side in the axial direction of the rod 20.

The friction member 30 is disposed in each of the plurality of groove portions 23 formed in the rod 20. The friction member 30 is slidably in contact with the inner peripheral surface of the insertion portion 11 of the cylinder 10. In the present embodiment, the friction member 30 employs an O-ring made of nitrile-butadiene rubber (NBR).

The friction member 30 generates a frictional force by a relative movement between the cylinder 10 and the rod 20 to generate a damping force. In the case of the present embodiment, the friction member 30 moves relative to the cylinder 10 together with the rod 20 as the rod 20 moves relative to the cylinder 10 in the axial direction. A frictional force is generated between That is, in the friction damper 1 of the first embodiment, the friction surfaces are the outer peripheral surface (outer surface) of the friction member 30 and the inner peripheral surface of the cylinder 10. The frictional force generated by sliding between these friction surfaces acts as a damping force that suppresses the axial movement of the rod 20. In the present embodiment, a polyphenylene sulfide (PPS) resin, which is a material having excellent slidability, is used for the cylinder 10 that is one of the friction surfaces.

The rod side joint part 40 is a connecting part with other members together with the cylinder side joint part 12. The rod side joint portion 40 is made of resin. The rod side joint portion 40 is formed with a through hole 40A through which a pin or the like can be inserted. The rod side joint part 40 is formed in a bottomed cylindrical shape having a bottom part 41 formed in a disc shape and a cylindrical part 42 formed in a cylindrical shape extending in the axial direction from the periphery of the bottom part 41. A through hole 41 </ b> A is formed in the radial center of the bottom 41. The reduced diameter portion 21 of the rod 20 is inserted through the through hole 41A. A push nut 43 is attached to the distal end portion of the reduced diameter portion 21 from the cylindrical portion 42 side. Thereby, the rod side joint part 40 and the rod 20 are being fixed. The rod side joint portion 40 moves relative to the cylinder 10 together with the rod 20 when the cylinder 10 and the rod 20 move relative to each other. Further, a stepped portion 41 </ b> B having a step shape is formed on the peripheral portion of the bottom portion 41. The step portion 41 </ b> B receives one end of the elastic member 50.

The elastic member 50 is disposed on the outer periphery of the cylinder 10. Specifically, the elastic member 50 employs a cylindrical urethane foam, and is disposed on the outer periphery of the cylinder 10 in such a manner that the cylinder 10 is inserted into the inner periphery from the end portion 10A side. One end of the elastic member 50 abuts on a stepped portion 10F provided on the outer periphery of the cylinder 10, and the other end contacts a stepped portion 41B formed on the periphery of the bottom 41 of the rod side joint portion 40. Touching. Thereby, the elastic member 50 gives an elastic force in the direction (left-right direction in FIG. 1) in which the protruding length from the cylinder 10 on the end 20A side of the rod 20 becomes longer. In other words, the elastic member 50 applies an elastic force in the direction in which the friction damper 1 is extended.

The cover member 60 is formed in the cylindrical shape which consists of resin, and is arrange | positioned so that the outer peripheral surface of the elastic member 50 may be covered. The cover member 60 is inserted from the rod side joint portion 40 toward the cylinder 10 side. The cover member 60 is fixed to the bottom 41 of the rod side joint 40 by press fitting. Therefore, when the cylinder 10 and the rod 20 move relative to each other, they move relative to the cylinder 10 together with the rod 20.

Next, the effect of the friction damper 1 according to the first embodiment will be described.
When the friction damper 1 is contracted by receiving an external force, or when the external force is removed and the elastic member 50 is expanded by the elastic force of the elastic member 50, the friction member 30 fitted in the groove portion 23 of the rod 20 causes the inner peripheral surface of the cylinder 10 to be stretched. A sliding force is generated by sliding. When this frictional force acts against expansion and contraction, it acts as a damping force that attenuates the contraction or expansion motion.

When adjusting the damping force of the friction damper 1, the number of friction members 30 arranged in the groove 23 is adjusted. That is, when the friction damper 1 is assembled, the number of friction members 30 arranged in the groove portion 23 formed in the rod 20 is adjusted so that a desired damping force is obtained. As a result, the magnitude of the frictional force generated at the time of expansion / contraction changes and the damping force is adjusted.

As described above, the friction damper 1 of the first embodiment includes the cylinder 10, the rod 20, and the friction member 30. The cylinder 10 is formed in a cylindrical shape. The rod 20 is reciprocally movable in the axial direction, and a part thereof is accommodated in the cylinder 10. On the outer peripheral surface of the rod 20, groove portions 23 as a plurality of concave portions are formed. The friction member 30 is disposed in the plurality of groove portions 23 and slidably contacts the inner peripheral surface of the cylinder 10.

With such a configuration, the friction damper 1 has a plurality of groove portions 23 formed on the outer peripheral surface of the rod 20, and the friction damper 1 is brought into contact with the sliding surface by changing the number of friction members 30 arranged in the groove portions 23. The area and the contact pressure can be easily changed.

Therefore, the friction damper 1 can easily adjust the friction force.

Also, the friction damper 1 employs an O-ring as the friction member 30. And the groove part 23 is cyclically | annularly formed in the circumferential direction of the outer peripheral surface of the rod 20, and the O-ring as the friction member 30 is fitted. As described above, since the O-ring that is a standard product and excellent in dimensional accuracy is adopted as the friction member, variations in the contact area with the sliding surface and the contact pressure are suppressed, and a desired damping force is easily generated. be able to. Further, by adopting the O-ring, it is possible to reduce the cost (cost down) as compared with the case where the friction member is separately designed and manufactured.

Further, in the friction damper 1, main parts such as the cylinder 10, the rod 20, the rod side joint portion 40, the elastic member 50, and the cover member 60 are formed of resin. For this reason, it can form more easily compared with the case where these components are formed with a metal. As a result, the manufacturing cost of the friction damper 1 can be reduced.

<Embodiment 2>
Next, Embodiment 2 will be described with reference to FIG.
The friction damper 201 of the second embodiment shown in FIG. 2 is different from the friction damper 1 of the first embodiment in terms of the arrangement of the friction members. In other parts, parts having substantially the same configurations and functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted.

As shown in FIG. 2, the friction damper 201 according to the second embodiment includes a cylinder 210 and a rod 220. A groove portion 213 as a concave portion is formed on the inner peripheral surface of the insertion portion 211 of the cylinder 210. The groove portion 213 is formed in an annular shape in the circumferential direction of the inner peripheral surface of the cylinder 210. A plurality of grooves (213 in FIG. 2) are formed. Each groove part 213 is provided along with the axial direction of the cylinder 210. As described above, the groove 213 is formed on the inner peripheral surface of the cylinder 210.

Unlike the first embodiment, the rod 220 is not formed with a groove (concave portion). The friction member 30 disposed in each groove portion 213 of the cylinder 210 is slidably in contact with the outer peripheral surface of the rod 220. In the case of this embodiment, the friction member 30 moves relative to the rod 220 together with the cylinder 210 when the rod 220 moves relative to the cylinder 10 in the axial direction. A frictional force is generated between That is, in the friction damper 1 of the second embodiment, the friction surfaces are the inner peripheral surface (outer surface) of the friction member 30 and the outer peripheral surface of the rod 220. In the present embodiment, the rod 220 serving as one of the friction surfaces is made of PPS resin. On the other hand, the cylinder 210 is formed of another general resin material for mechanical structure.

When the friction damper 201 receives an external force and contracts, or when the external force is removed and the elastic member 50 expands due to the elastic force of the elastic member 50, the friction member 30 fitted in the groove 213 of the cylinder 210 slides on the outer peripheral surface of the rod 220. To generate frictional force. When this frictional force acts against expansion and contraction, it acts as a damping force that attenuates the contraction or expansion motion.

When adjusting the damping force of the friction damper 201, the number of the friction members 30 arranged in the groove portion 213 is adjusted as in the first embodiment. That is, when the friction damper 201 is assembled, the number of friction members 30 arranged in the groove portion 213 formed in the cylinder 210 is adjusted so that a desired damping force is obtained. As a result, the magnitude of the frictional force generated at the time of expansion / contraction changes and the damping force is adjusted.

Also in this case, the same effects as the friction damper 1 of the first embodiment can be obtained, and the frictional force can be easily adjusted.

The present invention is not limited to Embodiments 1 and 2 described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the first and second embodiments, the O-ring made of nitrile rubber is exemplified as the friction member, but this is not essential. The friction member may be a standard product other than an O-ring, or may be separately designed and manufactured. Further, the shape and material of the friction member are not limited to this. The shape of the friction member may be a spherical shape, an arc shape, a polygonal shape such as a rectangular parallelepiped, or the like. Further, as the material of the friction member, other than the nitrile rubber such as urethane rubber, an elastomer may be adopted.
(2) In Embodiments 1 and 2, the groove portion formed in an annular shape as the concave portion is illustrated, but this is not essential. The shape of the recess can be a bottomed hole, an arc-shaped groove, or the like.
(3) In the first and second embodiments, the form in which the main members of the friction damper are formed of the resin is illustrated. However, a part or all of the parts may be formed of other materials such as metal. Moreover, when adopting resin, it is not limited to a specific resin material.
(4) In the first and second embodiments, the cylinder and the rod having a surface that slides on the friction member to form the friction surface are exemplified by the PPS resin, but this is not essential. A resin material similar to that of other members may be employed for the member having the friction surface, or a material of another material such as a metal material may be employed.
(5) In Embodiments 1 and 2, the form in which cylindrical foamed urethane is employed as the elastic member is illustrated, but the form of the elastic member is not particularly limited. The elastic member may be other types of elastic members such as other elastomers having elasticity other than urethane foam and metal coil springs. In the present invention, the elastic member is not an essential configuration.

1, 201 ... Friction damper, 10, 210 ... Cylinder, 10A, 10B ... End of cylinder, 10C ... Cylinder inner peripheral step, 10D, 10E ... Cylinder outer peripheral surface, 10F ... Cylinder outer peripheral step, 211 ... Insertion part, 12 ... Cylinder side joint part, 12A ... Through-hole, 20 ... Rod, 20A, 20B ... End part of rod, 21 ... Reduced diameter part, 22 ... Expanded part, 23, 213 ... Groove part, 30 ... Friction member, 40 ... rod side joint part, 40A ... through hole, 41 ... bottom part, 41A ... through hole, 41B ... step part, 42 ... cylindrical part, 43 ... push nut, 50 ... elastic member, 60 ... cover member

Claims (2)

A cylindrical cylinder;
A rod reciprocally movable in the axial direction, a part of which is housed in the cylinder;
A plurality of recesses formed on one of the inner peripheral surface of the cylinder and the outer peripheral surface of the rod;
A friction member disposed in at least one of the plurality of recesses and slidably contacting the other of the inner peripheral surface of the cylinder and the outer peripheral surface of the rod;
A friction damper characterized by comprising: The friction member is an O-ring;
2. The friction damper according to claim 1, wherein the recess is a groove formed in an annular shape in the circumferential direction of the inner peripheral surface of the cylinder or the outer peripheral surface of the rod, and the O-ring is fitted therein.

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