JP2006266463A - Oscillating type damper and belt tensioner equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change the damping force without increase in size and production cost of a unit, which is brought about in the case of using an electromagnet, in an oscillating type damper 50 to damp the relative turning of an oscillating piston 51 to a casing 10 in changing the shearing stress applying the magnetic field to the magnetic viscous fluid F in a communicating passage 55a on the magnetic circuit, forming a communicating passage 55 to communicate those both fluid rooms C1, C2 mutually and filling up the magnetic viscosity fluid F into these fluid rooms C1, C2 while demarcating an inner space 10a into two fluid rooms C1, C2 by arranging an oscillating piston 51 in the inner space 10a of the casing 10. <P>SOLUTION: A permanent magnet 60 to apply the magnetic field for the magnetic viscous fluid F in the communicating passage 55 and a displacement means 51a for making displacement of the permanent magnet 60 in interlock with the relative oscillation of the oscillating piston 51 to the magnetic viscous fluid F in the communicating passage 55 are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oscillating damping device that uses a magnetorheological fluid whose viscosity changes according to an applied magnetic field to change the damping force with respect to the relative oscillation between the casing and the oscillating piston. The present invention relates to measures for suppressing the complexity or size of the device.

  For example, in a belt-type auxiliary machine drive device for an automobile engine, a belt tensioner device incorporating a swing type damping device using a magnetorheological fluid in order to suppress flapping of the transmission belt accompanying tension fluctuation while applying tension to the transmission belt As described in Japanese Patent Application Laid-Open No. H10-260707, the one described in Patent Document 1 is known.

  In this case, an oscillating piston composed of a cylindrical element and piston blades is arranged in an internal space of a cylindrical casing to divide the internal space into two fluid chambers, while communicating between the two fluid chambers. A passage is provided, and the two fluid chambers and the communication passage are filled with a magnetorheological liquid (magnetic viscous fluid) as a hydraulic fluid.

  Then, by supplying power to the electromagnet attached to the communication path and applying a magnetic field to the magnetorheological fluid in the communication path, the viscosity of the magnetorheological fluid in the communication path is increased. By increasing the passage resistance of the magnetorheological fluid, the damping force for the relative rotation of the oscillating piston with respect to the casing is increased, while the power supply to the electromagnet is stopped to return the viscosity to the viscosity when no magnetic field is applied, The damping force with respect to the relative rotation of the swing piston is reduced.

As described above, since the damping force with respect to the relative rotation of the swing piston can be changed by the magnetic field with respect to the magnetorheological fluid, the damping force with respect to the rotation of the member that is urged to rotate in the belt pressing direction is applied to the belt tension. It is made to change according to increase / decrease of this, and this is made to absorb the flapping of a transmission belt.
Japanese translation of PCT publication No. 2002-524703 (pages 7-8, FIG. 1 and FIG. 2)

  However, in the above conventional case, a power source for supplying power to the electromagnet is required, and accordingly, the apparatus is not only complicated or enlarged, but also has a drawback that the manufacturing cost increases.

  About this, it is possible to change an electromagnet into a permanent magnet. However, since the strength of the generated magnetic field is constant in the permanent magnet, simply changing the electromagnet to the permanent magnet does not change the strength of the magnetic field applied to the magnetorheological fluid in the communication path. Only a constant damping force can be obtained, which is not suitable as a damping device for the belt tensioner device.

  The present invention has been made in view of such various points, and its main purpose is to be used as a damping device for a belt tensioner device, and the like. The casing is divided into two fluid chambers, the two fluid chambers are communicated with each other by a communication passage, the fluid chamber and the communication passage are filled with a magnetic viscous fluid, and a magnetic field is applied to the magnetic viscous fluid in the communication passage. In the swing type damping device that attenuates the relative swinging of the swinging piston with respect to the shaft, the damping force can be changed without increasing the size or increasing the manufacturing cost.

  In order to achieve the above object, the present invention focuses on the fact that the strength of the magnetic field applied to the magnetorheological fluid in the communication path varies depending on the direction of the permanent magnet and the distance from the permanent magnet. Is displaced with respect to the communication path, thereby changing the strength of the magnetic field applied to the magnetorheological fluid in the communication path, thereby making it possible to change the damping force.

  Specifically, in the present invention, a casing having an internal space having a generally sectoral cross section formed so as to extend radially outward from the axial center side and expand in the circumferential direction, and the internal space of the casing includes the above-mentioned An oscillating piston which is arranged so as to be able to oscillate in two rotational directions around the axis and divides the internal space into two fluid chambers divided in the circumferential direction, and the two fluid chambers communicate with each other At least one of the one or more communication paths, the magnetorheological fluid that fills the two fluid chambers and the communication paths, and changes in viscosity according to the applied magnetic field, and at least one of the one or more communication paths. Magnetic field applying means for applying a magnetic field to the magnetorheological fluid in one communicating path, and applying a magnetic field to the magnetorheological fluid in the at least one communicating path by the magnetic field applying means to shear stress of the magnetorheological fluid Change It assumes oscillating damping apparatus that attenuate the relative rotation of the swing piston relative to the casing by causing.

  The magnetic field application means is a permanent magnet, and the permanent magnet can be displaced relative to the communication path so that the strength of the magnetic field applied to the magnetorheological fluid in the at least one communication path changes. Shall be provided. In addition, displacement means for changing the relative position of the permanent magnet with respect to the at least one communication path in accordance with the relative swing position of the swing piston is provided.

  In the above configuration, the displacement means is provided so as to swing integrally with the swing piston, and the permanent magnet is displaced so that the permanent magnet is displaced according to the relative swing of the swing piston. It can have an engaging part to engage.

  Further, in addition to the above displacement means, the permanent magnet is provided with a holding means for holding the permanent magnet at the predetermined displacement position when the permanent magnet is positioned at the predetermined displacement position. The permanent magnet held at the predetermined displacement position by the holding means can be configured to be displaced to another displacement position different from the predetermined displacement position in accordance with the relative rotation of the swinging portion. In this case, the permanent magnet may be provided with urging means for urging the permanent magnet in a direction in which the permanent magnet is displaced from the other displacement position different from the predetermined displacement position to the predetermined displacement position.

  Furthermore, as a belt tensioner device including the swing type damping device having the above-described configuration, the belt tensioner device has a fixing portion fixed to the fixing side and a pressing portion for pressing the belt, and the pressing portion presses the belt. The swinging portion is supported by the fixed portion so as to be swingable between a direction opposite to the pressing direction, and the swinging portion is attached to the fixing portion toward the belt pressing direction. In the belt tensioner device including the urging means for urging and the attenuating means for attenuating the rotation of the oscillating portion, the attenuating means can be constituted by the oscillating attenuation device. In this case, the casing of the oscillating type damping device is connected to one of the fixed part and the oscillating part, and the oscillating piston of the oscillating type damping apparatus is one of the fixed part and the oscillating part. It will be connected to the other.

  According to the present invention, the oscillating piston is disposed in the internal space of the casing to divide the internal space into two fluid chambers, while forming a communication passage that communicates between the two fluid chambers. A swing type that damps relative swing of the swing piston with respect to the casing by filling the chamber and the communication path with a magnetorheological fluid and applying a magnetic field to the magnetorheological fluid in the communication path to change the viscosity. In the damping device, since the permanent magnet can be displaced relative to the communication path in conjunction with the relative swing of the swing piston, the device becomes complicated and large as in the case of using an electromagnet, and the manufacturing cost is reduced. The damping force can be changed without causing an increase.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show the overall configuration of a belt tensioner device according to an embodiment of the present invention. This belt tensioner device uses a part of the output torque of an automobile engine via a single transmission belt. It is used for applying a predetermined tension to the transmission belt in a belt transmission device having a serpentine layout that is transmitted to the auxiliary machine.

  The belt tensioner device is disposed so as to overlap with the fixed portion 10 fixed to the engine side and the fixed portion 10, and the belt tensioner device swings on the fixed portion 10 in two rotation directions around a predetermined swing axis P. And an oscillating portion 20 supported movably. The swinging part 20 has a tension pulley 30 as a pressing part that presses the transmission belt, and the tension pulley 30 presses the transmission belt between the fixed part 10 and the swinging part 20 ( A torsion coil spring 40 that constantly urges the oscillating portion 20 in the clockwise direction in FIG. 1 and an oscillating damper 50 that attenuates the rotation of the oscillating portion 20 are interposed.

  An annular circumferential groove 11 having a concave cross section that is open toward the swinging portion 20 is provided on the periphery of the fixed portion 10. A shaft hole 12 that penetrates the fixed portion 10 in the axial direction is provided in the axial center portion of the fixed portion 10. Moreover, the fixing | fixed part 10 has the cross-sectional substantially fan-shaped internal space 10a extended toward the radial direction outward from the axial hole 12, and expanded in the circumferential direction. Further, the portion of the fixed portion 10 opposite to the internal space 10a with respect to the shaft hole 12 (each left side in FIGS. 1 and 2) has a substantially fan-shaped cross section that opens toward the swinging portion 20. A recess 13 is provided.

  On the other hand, a shaft member 21 arranged so as to extend along the swing axis P is provided at the shaft center portion of the swing portion 20 so as to swing toward the fixed portion 10 so as to protrude integrally. Yes. The shaft member 21 is fitted and held in the shaft hole 12 of the fixed portion 10 so as to be rotatable about the swing axis P, so that the swing portion 20 can swing about the swing axis P. Is supported by the fixing portion 10. An annular peripheral wall 22 that protrudes toward the fixed portion 10 is provided at the periphery of the swinging portion 20. Moreover, the rocking | swiveling part 20 has the arm 23 provided so that it might protrude toward radial direction outward. A pivot portion 24 is provided at the tip of the arm 23, and the tension pulley 30 is supported by the pivot portion 24 so as to be rotatable about an axis Q parallel to the swing axis P.

  The torsion coil spring 40 includes a cylindrical coil portion 41 and two tangs that protrude outward in the radial direction from both coil ends, although not shown. One coil end portion is accommodated in the circumferential groove 11 of the fixed portion 10, and a tongue extending from the coil end portion is provided in a circumferential direction with respect to the fixed portion 10 at a locking portion (not shown) of the fixed portion 10. It is locked so that it cannot move. The other coil end portion is disposed along the peripheral wall 22 on the inner peripheral side of the peripheral wall 22 of the swinging portion 20, and a tongue extending from the coil end portion is a locking portion of the swinging portion 20 that is not shown. The rocking portion 20 is locked so as not to move in the circumferential direction. The torsion coil spring 40 is wound between the fixed portion 10 and the swinging portion 20 while being wound in the right-handed direction and having a reduced diameter. On the other hand, it is always urged toward the belt pressing direction.

  The oscillating damper 50 is disposed in the internal space 10a of the fixed portion 10 as a casing, and divides the internal space 10a into first and second fluid chambers C1 and C2 divided in the circumferential direction. Has a swinging piston 51. The swinging piston 51 is provided integrally with the shaft portion 52 that is a portion of the shaft member 21 located in the internal space 10a and swings integrally with the shaft portion 52, and is radially outward from the shaft portion 52. It consists of the division part 53 extended toward the direction. Here, it is assumed that the first fluid chamber C1 is positioned on the belt pressing direction side and the second fluid chamber C2 is positioned on the anti-belt pressing direction side.

  The inner wall surface around the swing axis P in the internal space 10a is formed so as to form a clearance having an arcuate cross section projecting toward the recess 13 between the outer peripheral surface of the shaft center portion 52 and the inner wall 10a. It is formed in a cross-sectional arc shape with the moving axis P as the center and a radius slightly larger than the radius of the axial part 52. The gap having an arcuate cross section serves as a communication passage 55 that allows the two fluid chambers C1 and C2 to communicate with each other.

  The two fluid chambers C1 and C2 and the communication path 55 are filled with a magnetorheological fluid F that changes viscosity (shear stress) in accordance with an applied magnetic field. The magnetorheological fluid F passes through the communication path 55 because the volume of the first fluid chamber C1 and the volume of the second fluid chamber C2 increase when the swinging portion 20 rotates in the belt pressing direction. When the first fluid chamber C1 moves to the second fluid chamber C2 while the swinging portion 20 rotates in the anti-belt pressing direction, the volume of the second fluid chamber C2 decreases and the first fluid chamber C1 Since the volume increases, the second fluid chamber C2 moves to the first fluid chamber C1 via the communication path 55.

  Here, the “magnetorheological fluid” is obtained by dispersing and containing magnetic particles having a particle size of 0.5 to 100 μm in a solvent such as hydrocarbon or silicone. The properties are different from those of “magnetic fluid”, which is obtained by dispersing and incorporating magnetic particles having a relatively small particle size of 1 to 100 nm in a solvent, and the fields of application are also different.

  On the other hand, a permanent magnet 60 for applying a magnetic field to the magnetorheological fluid F in the communication passage 55 is disposed in the recess 13 of the fixed portion 10.

  And in this embodiment, the said permanent magnet 60 is provided displaceably with respect to this communication path 55 so that the intensity | strength of the magnetic field applied to the magnetorheological fluid F in the communication path 55 may change, In the above, the position of the permanent magnet 60 with respect to the communication path 55 is changed according to the rotational position of the swing piston 51.

  Specifically, the permanent magnet 60 has a straight rod shape, and both end portions in the length direction are magnetic poles. The permanent magnet 60 is pivotally supported at one end in the length direction (each left end in FIGS. 1 to 3) by a pivot pin 70 erected on the bottom surface of the recess 13 of the fixed portion 10. 70 is arranged on a straight line passing through the oscillation axis P and the substantially center in the circumferential direction of the communication passage 55 in the cross section. Thereby, the permanent magnet 60 is supported so as to be able to swing around the pivot pin 70 in a plane orthogonal to the swing axis P, and the permanent magnet 60 is shown by a one-dot chain line in FIG. , The position where the magnetic pole 61 on the other end in the length direction (the magnetic pole on the right end in each figure; hereinafter referred to as the counter magnetic pole) is closest to the approximate center in the circumferential direction of the communication path 55, that is, the counter magnetic pole 61 and the communication path. When the distance between the magnetic path 55 and the magnetic viscous fluid F in the communication path 55 is at a minimum (maximum applied position M2), the distance in the communication path 55 is It is held at its maximum application position M2 by its own magnetic adsorption force with respect to the magnetic particles in the magnetorheological fluid F. Here, a predetermined displacement position in the present invention is configured by the maximum application position M2, and when the permanent magnet 60 is positioned at the maximum application position M2, the distance between the counter magnetic pole 61 and the communication path 55 is as follows. By disposing the permanent magnet 60 and the communication path 55 so as to be minimized, the holding means in the present invention is configured.

  Further, when the permanent magnet 60 rotates in the direction away from the maximum application position M2 (counterclockwise direction in FIG. 1), the strength of the magnetic field applied to the magnetorheological fluid F in the communication path 55 is accordingly increased. Gradually decreases, and eventually reaches the position indicated by the solid line (non-application position M1) in the figure, the magnetic field strength H becomes H≈0, and the position further rotated in the same direction from that position (no mark) Even when the additional position M0) is reached, the magnetic field strength H remains H≈0 in the range (non-application range M1 to M0) up to the position indicated by the phantom line in FIG. Here, the “other displacement position different from the predetermined displacement position” in the present invention depends on each displacement position within the range between the maximum application position M2 and the non-application position M0 except the maximum application position M2. Is configured.

  Further, an engaging pin 51a as an engaging portion that extends in the axial direction toward the fixing portion 10 is protruded from a portion of the swinging portion 20 corresponding to the concave portion 13 of the fixing portion 10 in the axial direction. . On the other hand, the permanent magnet 60 is provided with a guide groove 60a that engages with the engagement pin 51a in a substantially half swinging range of the entire swinging range of the swinging unit 20. The guide groove 60 a is provided so as to extend in the length direction substantially at the center in the width direction of the permanent magnet 60. The end of the guide groove 60a on the pivot pin 70 side is open to one side in the width direction of the permanent magnet 60 (the lower side in FIG. 1), and the permanent magnet 60 is positioned at the maximum application position M2. Sometimes it is an entry / exit groove 60b that allows the engagement pin 51a to enter and exit the guide groove 60a. In the present embodiment, when the tension of the transmission belt fluctuates up and down across the reference value, the rotation position of the oscillating unit 20 when the transmission belt tension is the reference value is used as the reference of the oscillating unit 20. When the swing portion 20 is positioned at the reference position S1 with the position S1 (the position indicated by the solid line in FIG. 1), the permanent magnet 60 is positioned at the non-application position M1 and the permanent magnet 60 is guided. The engaging pin 51a is set to be positioned at the end of the groove 60a on the side of the pivot pin 70.

  That is, when the swinging portion 20 is positioned at the reference position S1, the permanent magnet 60 is positioned at the non-application position M1, and the swinging portion 20 moves from the reference position S1 to the belt pressing direction (the clockwise direction in FIG. 1). ) To reach the position S0 indicated by a two-dot chain line in FIG. 1, the permanent magnet 60 reaches the non-application position M0. On the other hand, when the swinging portion 20 rotates from the reference position S1 in the anti-belt pressing direction (counterclockwise direction in the figure) and reaches the position S2 indicated by a one-dot chain line in the figure, the permanent magnet 60 is at the maximum application position. At this time, even if the swinging part 20 further rotates in the anti-belt pressing direction from the position S2 and reaches the position S3 indicated by the broken line in the drawing, the permanent magnet 60 remains at the maximum application position M2. Will be held.

  Here, the operation of the swing type damper 50 in the belt tensioner device configured as described above will be described with reference to the characteristic diagram of FIG.

  When the transmission belt tension is at the reference value, the swinging portion 20 of the belt tensioner device is at the reference position S1, and at this time, the permanent magnet 60 is positioned at the non-application position M1. The strength H of the magnetic field applied to the magnetorheological fluid F in the communication path 55 is H≈0. Accordingly, at this time, the damping force with respect to the rotation of the swinging portion 20 is minimal.

  In the above state, when the tension of the transmission belt decreases and the swinging portion 20 rotates from the reference position S1 in the belt pressing direction (clockwise direction in FIG. 1), the engagement pin 51a is While pressing the groove side surface opposite to the entrance / exit groove 60b in the width direction of both groove side surfaces of the guide groove 60a, the guide groove 60a moves from the end on the pivot pin 70 side toward the end on the counter magnetic pole 61 side. Move. Thereby, in the non-application range M1 to M0, the permanent magnet 60 rotates in the direction in which the opposing magnetic pole 61 moves away from the axial center portion 52 of the swing piston 51, so that the damping force with respect to the rotation of the swing portion 20 is minimized. Therefore, when the tension of the transmission belt is lowered, the operation of the belt tensioner device pressing the transmission belt to return the tension to the reference value is performed relatively quickly. Further, since the engaging pin 51a enters the guide groove 60a when it contacts the permanent magnet 60 and restricts the displacement of the permanent magnet 60, the tension fluctuation of the transmission belt is high frequency, and the engaging pin 51a becomes permanent. When the magnet 60 is shockedly contacted, it is possible to avoid a situation in which the permanent magnet 60 is flipped off by the impact and is displaced regardless of the rotational position of the swinging unit 20.

  On the other hand, when the tension of the transmission belt increases from the reference value and the swinging portion 20 rotates from the reference position S1 in the anti-belt pressing direction (counterclockwise direction in FIG. 1), the engaging pin 51a has the guide groove 60a. Contrary to the above case, the groove side surface of the guide groove 60a moves from the opposite magnetic pole 61 side end portion toward the pivot pin 70 side end portion while pressing the groove side surface on the input / output groove 60b side. . Thereby, the permanent magnet 60 is reliably returned from the non-application position M1 to the maximum application position M2, and the strength of the magnetic field applied to the magnetorheological fluid F in the communication path 55 is gradually increased according to this displacement. Therefore, the damping force with respect to the rotation of the rocking portion 20 gradually increases. Therefore, when the tension of the transmission belt increases, the operation of rotating the tension pulley 30 in the anti-belt pressing direction so that the belt tensioner device absorbs the increased belt tension is performed relatively slowly, and the belt The degree of slowness increases according to the amount of increase in tension.

  As described above, when the tension of the transmission belt decreases and the swinging portion 20 of the belt tensioner device rotates in the belt pressing direction, the damping force with respect to the rotation of the swinging portion 20 is small and the tension of the transmission belt is reduced. When the swinging portion 20 of the belt tensioner device rotates and rotates in the anti-belt pressing direction, the damping force with respect to the swinging of the swinging portion 20 gradually increases according to the amount of rotation. The flutter is absorbed smoothly.

  Therefore, according to the present embodiment, the oscillating part 20 is urged to rotate by the urging force of the coil spring 40 by twisting the oscillating part 20 in the direction in which the tension pulley 30 presses the transmission belt with respect to the fixed part 10. 50 by applying a magnetic field to the magnetorheological fluid F in the communication passage 55 at 50 to change the damping force with respect to the rotation of the oscillating piston 51 integrally connected to the oscillating portion 20. In the belt tensioner device that properly maintains the position, the permanent magnet 60 is used, and the permanent magnet 60 is displaced in accordance with the rotational position of the swinging portion 20, so that the inside of the communication path 55 of the swinging damper 50 is maintained. Since the strength of the magnetic field applied to the magnetorheological fluid F can be changed, the structure can be simplified as much as there is no power source or control means compared to the case of using an electromagnet, It, it is possible to suppress an increase in cost due to complication of such structures.

  In the above embodiment, when the swinging portion 20 of the belt tensioner device rotates in the belt pressing direction and then reverses and rotates in the anti-belt pressing direction, the permanent magnet 60 is displaced at the non-application position M0 side. In order to reliably return to the maximum application position M2, the runaway of the permanent magnet 60 is regulated by pressing the groove side surface of the guide groove 60a on the width direction entrance / exit groove 60b side with the engagement pin 51a. As in the modification shown in FIG. 6, the permanent magnet 60 is always moved in the direction in which the permanent magnet 60 is displaced to the maximum application position M <b> 2 by biasing means (such as a tension coil spring, a leaf spring, or a mainspring) such as the compression coil spring 80. It may be energized. In this case, the engagement pin 51a is provided on one side surface (the lower side surface in FIG. 6) in the width direction of the permanent magnet 60 positioned at the maximum application position M2 when the swinging portion 20 is positioned at the reference position S1. The engagement pin 51a presses the permanent magnet 60 at a position where it abuts. The reason why the permanent magnet 60 presses the permanent magnet 60 is the maximum application position M2 in the displacement range between the maximum application position M2 and the non-application position M0. Only when the permanent magnet 60 is displaced in the opposite direction (the direction in which the permanent magnet 60 is displaced from the non-application position M0 to the maximum application position M2) by the compression coil spring 80. The pin 51a fulfills the function of sliding in contact with the side surface of the permanent magnet 60 and regulating its displacement position. However, since the biasing means is interlocked with the swinging portion 20 via the permanent magnet 60 and the engagement pin 51a, the biasing force substantially affects the biasing force of the torsion coil spring 40 of the belt tensioner device. It is necessary to have a slightly weaker force.

  In the above-described embodiment, the damping force is reduced when the transmission belt tension is equal to or less than the reference value. On the other hand, when the transmission belt tension exceeds the reference value, the damping force is increased according to the excess amount. Although gradually increasing, it is possible to set timely how the damping force is changed as required.

  Further, in the above embodiment, the case of the belt tensioner device in which the swing type damping device according to the present invention is incorporated is described. However, the present invention is a swing type damping device in various other devices. Can be used as

It is a top view which shows the state which removed the rocking | swiveling part in the belt tensioner apparatus which concerns on embodiment of this invention. It is a cross-sectional view which shows the whole structure of a belt tensioner apparatus. It is a top view which expands and shows the displacement state of the permanent magnet by the engagement relationship with an engagement pin. It is a characteristic view which shows typically the relationship between the rotation position of a rocking | swiveling part, and damping force. FIG. 3 is a view corresponding to FIG. 2 illustrating an overall configuration of a belt tensioner device according to a modified example of the embodiment. FIG. 6 is an enlarged view corresponding to FIG. 3, showing an enlarged displacement state of the permanent magnet due to the engagement relationship with the engagement pin and the biasing force of the compression coil spring.

Explanation of symbols

10 Fixed part (casing)
20 Oscillating part 30 Tension pulley (pressing part)
40 Torsion coil spring (biasing means)
50 Oscillating damper (Oscillating damping device)
51 oscillating piston 51a engagement pin (engagement part, displacement means)
55 Communication path 60 Permanent magnet 80 Compression coil spring (biasing means)
C1 First fluid chamber (fluid chamber)
C2 Second fluid chamber (fluid chamber)
F Magnetorheological fluid P Oscillation axis (axis)

Claims (5)

A casing having an internal space having a substantially sectoral cross section formed so as to extend radially outward from the axial side and expand in the circumferential direction;
An oscillating piston arranged in the inner space of the casing so as to be oscillatable in two rotation directions around the axis, and dividing the inner space into two fluid chambers divided in the circumferential direction;
One or more communication passages communicating the two fluid chambers with each other;
A magnetorheological fluid that fills the two fluid chambers and the communication path and has a viscosity that changes in response to an applied magnetic field;
A magnetic field applying means for applying a magnetic field to the magnetorheological fluid in at least one of the one or more communication paths;
By applying a magnetic field to the magnetorheological fluid in the at least one communication path by the magnetic field applying means to change the viscosity of the magnetorheological fluid, the relative rotation of the swing piston with respect to the casing is attenuated. An oscillating damping device,
The magnetic field applying means is a permanent magnet,
The permanent magnet is provided so as to be relatively displaceable with respect to the communication path so that the strength of the magnetic field applied to the magnetorheological fluid in the at least one communication path changes.
A swing type damping device comprising a displacement means for changing the position of the permanent magnet with respect to the at least one communication path in accordance with the relative rotational position of the swing piston. The oscillating damping device according to claim 1,
The displacing means is provided with an oscillating piston so as to oscillate integrally, and an engaging portion that engages with the permanent magnet so that the permanent magnet is displaced according to the relative oscillating movement of the oscillating piston. An oscillating attenuation device comprising: The oscillating damping device according to claim 1,
Holding means for holding the permanent magnet at the predetermined displacement position when the permanent magnet is positioned at the predetermined displacement position;
The displacing means is configured to displace the permanent magnet held at the predetermined displacement position by the holding means to another displacement position different from the predetermined displacement position in accordance with the relative rotation of the swinging portion. An oscillating damping device characterized by that. The swing type attenuation device according to claim 3,
A swing type comprising biasing means for biasing the permanent magnet toward a direction in which the permanent magnet is displaced from another displacement position different from the predetermined displacement position to the predetermined displacement position. Damping device. A belt tensioner device comprising the swing type damping device according to claim 1,
A fixed part fixed to the fixed side;
A swing part supported by the fixed part so as to be swingable between a direction in which the pressing part presses the belt and a direction opposite to the pressing direction;
A belt tensioner device comprising: an urging unit that urges the oscillating unit toward the belt pressing direction with respect to the fixing unit; and an attenuating unit that attenuates the rotation of the oscillating unit.
The damping means is constituted by the swing type damping device,
The casing of the swing type damping device is connected to one of the fixed part and the swing part,
The belt tensioner device, wherein the swing piston of the swing type damping device is connected to the other of the fixed portion and the swing portion.

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