JP2007139083A - Rocking type damping device and belt tensioner device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rocking type damping device having reduced manufacturing cost and improved reliability and durability by reducing the number of components and sealing positions. <P>SOLUTION: In the rocking type damping device, section parts 51a, 51a of a rocking piston 51 are arranged in a plurality of internal spaces of casings 12, 16 and each internal space is sectioned into two fluid chambers C1, C2 split in the rocking direction, while a plurality of communication passages 52 are formed between the internal spaces neighboring each other in the rocking direction to communicate both fluid chambers C1, C2 neighboring each other in the rocking direction with each other and magnetic viscose fluid F is filled in the fluid chambers C1, C2 and the communication passage 52. A magnetic field is applied to the magnetic viscose fluid F in each communication passage 52 to change shearing stress so as to change damping force on the relative rocking of the rocking piston 51. Each communication passage 52 is formed by at least part of a gap region out of all gap regions between the rocking piston 51 and each of the casings 12, 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oscillating type damping device that changes a damping force with respect to relative oscillation between a casing and an oscillating piston using a magnetorheological fluid whose shear stress changes in accordance with an applied magnetic field, In particular, the present invention relates to an improvement for fully utilizing a damping force due to a shear stress.

  Generally, as a conventional oscillating type damping device using a magnetorheological fluid, one described in Patent Document 1 is known.

  In this case, an oscillating piston comprising a cylindrical element and a piston blade is arranged in an inner space of a cylindrical casing to divide the inner space into first and second fluid chambers. By arranging a sleeve having an arc-shaped cross section around the element and an insulating layer and providing it integrally with the casing, a communication path composed of a gap having an arc-shaped cross section that connects the fluid chambers between the sleeve and the casing is formed. The first and second fluid chambers and the communication passage are filled with a magnetorheological liquid (magnetic viscous fluid) as a hydraulic fluid.

Then, by applying a magnetic field to the magnetorheological fluid in the communication path, the shear stress of the magnetorheological fluid in the communication path is increased to increase the apparent viscosity, and thereby the magnetorheological fluid in the communication path is increased. By increasing the passage resistance, the relative rotation of the swing piston with respect to the casing is attenuated.
Japanese translation of PCT publication No. 2002-524703 (pages 6-7, FIG. 4)

  However, in the above conventional case, two parts, a sleeve and an insulating layer, and a process of assembling these parts to the casing are required to form a magnetic circuit, and thus the manufacturing cost is increased accordingly. .

  Further, since it is necessary to secure a space for disposing the sleeve and the insulating layer in the casing, it is difficult to make it compact.

  Further, all the gap regions around the swing piston must be sealed, and there is room for improvement in terms of reliability and durability with respect to the damping characteristics.

  The present invention has been made in view of such various points, and its main object is to arrange an oscillating piston in a casing to divide the internal space into two fluid chambers, and to connect the two fluid chambers to each other. Oscillation made to communicate with the passage, and to fill the fluid chamber and the communication path with magnetorheological fluid and to apply a magnetic field to the magnetorheological fluid in the communication path to attenuate the relative oscillation of the oscillation piston with respect to the casing. In the mold damping device, by reviewing the arrangement of the communication passages, the number of parts and seal locations are reduced, thereby contributing to the reduction of manufacturing cost and the improvement of reliability and durability.

  In order to achieve the above object, the present invention pays attention to the gap generated between the swing piston and the casing, and by using at least a part of the gap in the communication path among all the areas of the gap, The number of parts and the number of seals were reduced.

  Specifically, in the oscillating damping device according to the present invention, a casing having a plurality of internal spaces arranged so as to be circumferentially arranged around an axis, and the internal spaces are respectively provided in the internal spaces. It has a plurality of partition portions arranged so as to partition into two fluid chambers divided in the circumferential direction, and is provided so as to be swingable in the first and second rotation directions around the axis. A plurality of communication passages each communicating two fluid chambers adjacent in the circumferential direction between the two internal spaces adjacent to each other in the circumferential direction, the plurality of internal spaces, A magnetic field is applied to the magnetorheological fluid that fills the plurality of communication paths and changes viscosity according to the applied magnetic field, and the magnetorheological fluid in at least one of the plurality of communication paths. And the application means. One or more of the communication passage of the road is assumed to be constituted by at least a portion of the gap area of the total gap area between the rolling piston and the casing.

  In the above configuration, the oscillating piston can be formed in a rotationally symmetric shape about the axis.

  Further, in the case where the swing piston has a shaft portion arranged on the shaft center, each communication path is composed of at least a part of a gap region formed between the shaft portion of the swing piston and the casing. It can be.

  In addition, the magnetic force generator included in the applying means for generating a magnetic force so as to form a magnetic circuit for applying a magnetic field to the magnetorheological fluid in the communication path may be disposed on the casing side, or the oscillating piston You may arrange | position on the axial part. At that time, each communication path is divided into a plurality of application areas and at least one non-application area in the axial direction, and the magnetic force generation unit is a magnetic circuit in which the lines of magnetic force pass only through the plurality of application areas in each communication path. It is preferable that a restricting portion for restricting the passage of the magnetorheological fluid in the non-application area in each communication path is provided in each communication path.

  Furthermore, the oscillating damping device having the above configuration can be used by being incorporated in an arbitrary device such as a belt tensioner device. Specifically, for example, a swing portion that has a pressing portion for pressing the transmission belt and is supported by the fixed portion so as to be swingable in two rotation directions around the swing axis; An urging means that is interposed between the fixed portion and the oscillating portion, and constantly urges the oscillating portion relative to the fixed portion in a rotational direction in which the pressing portion presses the transmission belt; In the case of a belt tensioner device provided with an attenuating means for attenuating the rotation of the oscillating portion, the attenuating means can be selected from the above oscillating attenuation devices. In this case, the casing of the swing type damping device is connected to one of the fixed portion and the swing portion, and the swing piston of the swing type damping device is connected to the fixed portion and the swing portion. It will be connected to the other of them.

  According to the present invention, the plurality of internal spaces of the casing are partitioned into two fluid chambers by the plurality of partition portions having the swing piston, respectively, while the adjacent fluid chambers are adjacent to each other between the adjacent internal spaces. The fluid chamber and the communication passage are filled with a magnetorheological fluid, and a magnetic field is applied to the magnetorheological fluid in at least one of the plurality of communication passages by applying means to change the shear stress. In the oscillating type damping device configured to attenuate the relative oscillation of the oscillating piston with respect to the casing, at least a part of the gap region generated between the oscillating piston and the casing is defined. In the conventional case where a new gap is provided in addition to the gap around the oscillating piston, and the communication path is configured by the gap because it is used as the communication path. Base, it is possible to it is possible to contribute to a reduction in manufacturing cost by reducing the number of parts and parts assembly process, to improve the seal area less to the reliability and durability of around swing piston.

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

(Embodiment 1)
FIG. 1 shows the overall configuration of a belt tensioner device according to Embodiment 1 of the present invention. This belt tensioner device uses a part of output torque of an automobile engine as a plurality of auxiliary torques via one transmission belt. It is used to apply a predetermined tension to a transmission belt in a belt transmission device having a serpentine layout that is transmitted to a machine.

  This belt tensioner device includes a fixed portion 10 fixed to the engine side, and a swinging portion 20 supported by the fixed portion 10 so as to be swingable in two rotation directions around a predetermined swing axis P. It has. A tension pulley 30 for pressing a transmission belt (not shown) is attached to the swinging unit 20. The tension pulley 30 is supported by the swing portion 20 so as to be rotatable about an axis Q parallel to the swing axis P.

  Between the fixed portion 10 and the swinging portion 20, a torsion coil spring 40 that constantly biases the swinging portion 20 with respect to the fixed portion 10 in the rotational direction in which the tension pulley 30 presses the transmission belt is interposed. Has been. In addition, a swing type damper 50 is provided between the fixed unit 10 and the swing unit 20 for attenuating the swing of the swing unit 20 with respect to the fixed unit 10.

  As shown in FIGS. 2 and 3, the fixing portion 10 has a disk-shaped base member 11, and as shown in FIGS. 2 and 3, the fixing portion 10 serves as a lid that covers the opening of the concave portion of the first member. And a second member 16 that bears. Bolt screw holes 11a in which female threads are formed are provided at a plurality of locations on the peripheral edge of the base member 11 so as to penetrate in the axial direction. In addition, a concave groove portion 11b having a rectangular cross section extending in a direction orthogonal to the swing axis P is provided at the center of the surface on the swing portion 20 side (the lower surface in FIG. 1) of the base member 11. Yes. Here, the 1st member 12 and the 2nd member 16 comprise the casing in this invention.

  The peripheral wall portion 13 of the concave portion of the first member 12 has a substantially sectoral cross section in which the portions opposed to each other in the radial direction across the oscillation axis P are expanded in the circumferential direction radially outward from the oscillation axis P side. Is formed. The two fan-shaped portions formed in a sector shape by the peripheral wall portion 13 are connected to each other at the portion of the swing axis P. The peripheral wall 13 in the vicinity of the swing axis P is formed in a circular arc shape with the swing axis P as the center. On the other hand, the radially outer portion of the peripheral wall portion 13 is also formed in a circular arc shape with the oscillation axis P as the center. A shaft hole 12a having a circular cross section that passes through the bottom wall portion 14 in the axial direction is provided at the center of the bottom wall portion 14 of the recess. Further, the first member 12 has an annular mounting portion 15 centering on the swing axis P. The attachment portion 15 forms an opening edge of a recess in the outer peripheral side cross-sectional arc-shaped portion of the peripheral wall portion 13. The outer peripheral part of the attachment part 15 is formed in a bowl shape protruding outward in the radial direction. Bolt insertion holes 12b penetrating the attachment portion 15 in the axial direction are provided at a plurality of locations in the circumferential direction of the flange portion of the attachment portion 15 so as to correspond to the bolt screw holes 11a of the base member 11, respectively. ing.

  The second member 16 has a lid portion 17 that covers the concave portion of the first member 12. Each of the lid portions 17 has a shape in which two portions each having a substantially sector shape are joined to each other at the center portions of the sector shapes. The second member 16 has an annular mounting portion 18 corresponding to the mounting portion 15 of the first member 12. In the second member 16, two openings are formed so as to be aligned in a direction orthogonal to the longitudinal direction of the lid portion 17 and the swing axis P. Each opening has a substantially sector shape that expands in the circumferential direction from the oscillation axis P side toward the radially outer side. A bearing hole 16a having a circular cross section is provided at the center of the surface of the second member 16 on the first member 12 side. Furthermore, the contour shape of the outer peripheral portion of the attachment portion 18 matches the contour shape of the outer peripheral portion of the attachment portion 15 of the first member 12, and the outer peripheral portion is respectively provided at a plurality of circumferential positions in the outer peripheral portion. A bolt insertion hole 16b penetrating in the axial direction is provided so as to correspond to the bolt screwing hole 11a of the base member 11. The shaft portion of the bolt 19 inserted through the bolt insertion hole 12b of the first member 12 and the bolt insertion hole 16b of the second member 16 is screwed into the bolt screwing hole 11a of the base member 11, and thus The first member 12 and the second member 16 are integrally coupled to the base member 11.

  On the other hand, the oscillating portion 20 is fixed to the circular plate-like disc portion 21 whose outer peripheral edge is located radially inward from the outer peripheral edge of the first member 12 of the fixing portion 10, and to the peripheral edge of the disc portion 21. A peripheral wall portion 22 provided so as to protrude toward the side of the portion 10 (upper side in FIG. 1), and an arm portion 23 provided so as to protrude outward in the radial direction from the outer periphery of the disc portion 21. And have. The protruding end of the arm portion 23 is provided with a pivot portion 23a that is parallel to the pivot axis P and extends toward the fixed portion 10, and the tension pulley 30 is provided on the pivot portion 23a. Is pivotally supported around an axis Q parallel to the axis.

  In the central portion of the disk portion 21 of the swinging portion 20, the shaft member 24 arranged so as to extend along the swinging shaft center P is swung integrally so as to protrude toward the fixed portion 10 side. It is attached. The distal end portion of the shaft member 24 is formed in a tapered shape in cross section, and after passing through the shaft hole 12a of the first member 12 of the fixed portion 10, it is inserted into the bearing hole 16a of the second member 16 of the fixed portion 10. I am in attendance. At that time, in the shaft hole 12a of the first member 12, a ball bearing 25 in which a plurality of balls are interposed between the inner ring and the outer ring is press-fitted in the outer ring. The shaft member 24 is connected to the inner ring of the ball bearing 25 in a rotationally integrated manner, so that the shaft member 24 can be pivoted about the pivot axis P in the radial direction so as to be fixed in the radial direction. It is supported by. An annular thrust bearing 26 made of a sliding material that is in sliding contact with the tapered surface of the tip end portion of the shaft member 24 is disposed in the bearing hole 16 a of the second member 16. The shaft member 24 is supported by the fixed portion 10 in the thrust direction so as to be swingable about the swing axis P through the thrust bearing 26. Thus, the swinging portion 20 is supported by the fixed portion 10 via the shaft member 24 so as to be swingable about the swinging axis P.

  Further, in the annular gap space formed between the first member 12 of the fixed portion 10 and the disc portion 21 of the swing portion 20, the tension pulley 30 places the swing portion 20 with respect to the fixed portion 10. A torsion coil spring 40 that is constantly urged toward the rotational direction of pressing the belt is interposed. The coil portion of the torsion coil spring 40 is fitted onto the first member 12 of the fixed portion 10. The tongue on the fixed part 10 side of the coil part is locked so as to be immovable in the circumferential direction by a locking part (not shown) provided in the fixed part 10. The end of the coil portion on the swinging portion 20 side is located on the inner side in the radial direction of the peripheral wall portion 22 on the disk portion 21 of the swinging portion 20, and the tongue on the swinging portion 20 side is located on the swinging portion 20. It is locked so as to be immovable in the circumferential direction by a provided locking portion (not shown). In the illustrated example, the coil portion of the torsion coil spring 40 is left-handed, and the tension pulley 30 urges the swinging portion in the rotational direction from the back side in FIG. 1 toward the near side in FIG. ing. That is, when viewed from the side opposite to the swinging portion in the axial direction, the clockwise direction is the belt pressing direction, and the counterclockwise direction is the anti-belt pressing direction (see FIG. 4).

  In this embodiment, a swinging damper 50 that attenuates the swinging of the swinging unit 20 is provided between the fixed unit 10 and the swinging unit 20.

  Specifically, the swing type damper 50 has the first member 12 and the second member 16 as casings, and each of the swing type dampers 50 extends radially outward from the swing axis P in the casing. Two internal spaces having a substantially sectoral cross section extending in the circumferential direction are formed in a point-symmetric shape with the oscillation axis P as the center.

  In each of the internal spaces, a partition 51a that divides the internal space into a first fluid chamber C1 and a second fluid chamber C2 that are divided in the circumferential direction is disposed. These partition parts 51 a and 51 a are connected to the shaft member 24 in a swinging manner. In the illustrated example, 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. Here, the partition portions 51 a and 51 a and the shaft center portion 51 b which is a portion corresponding to the both internal spaces in the shaft member 24 constitute the swing piston 51.

  Further, the two portions around the swing axis P in the peripheral wall portion 13 of the first member 12 are cross sections each having a radius slightly larger than the radius of the shaft center portion 51b with the swing axis P as the center. It is recessed in the shape of an arc, and is formed so as to form a clearance having an arcuate cross section with the outer peripheral surface of the axial center portion 51b of the swing piston 51. Each of the two gaps has a width dimension in the axial direction that is substantially the same as the axial length of the axial center portion 51b, and the second fluid in the one internal space and the second fluid in the other internal space. The communication passage 52 communicates with the chamber C2 and the communication passage 52 communicates between the second fluid chamber C2 in one internal space and the first fluid chamber C1 in the other internal space.

  In addition, the first fluid chamber C1, the second fluid chamber C2, and the communication path 52 are filled with a magnetorheological fluid F that changes the shear stress in accordance with the applied magnetic field. Further, in the shaft hole 12a of the first member 12, a seal material 27 is disposed to slide and contact the shaft member 24 so that the magnetorheological fluid F does not leak into the external space through the shaft hole 12a. Further, among all the regions of the gap formed between the swing piston 51 and the fixed portion 10, the first clearance is not performed in the gap region other than the gap region located around the axial center portion 51 b of the swing piston 51. In addition, a sealing device (not shown) that suppresses leakage of the magnetorheological fluid F between the second fluid chambers C1 and C2 is provided. Here, the “magnetoviscous fluid” is obtained by dispersing and containing magnetic particles having a particle diameter of 0.5 to 100 μm in a medium such as hydrocarbon or silicone, and the particle diameter is 1 to 100 nm. A “magnetic fluid” in which relatively small magnetic particles are dispersed and contained in a medium is greatly different in dispersion method and damping characteristics, and is also greatly different in application fields.

  On the other hand, an electromagnet 53 that generates a magnetic force for forming a magnetic circuit for applying a magnetic field to the magnetorheological fluid F in each communication path 52 is assembled to the fixed portion 10. The electromagnet 53 includes a substantially U-shaped iron core portion 53a and a coil portion 53b made of a conductive wire wound around the iron core portion 53a (see FIG. 2). The magnetic pole portion is disposed so as to be positioned at a position corresponding to each communication path 52 in the radial direction via the two openings of the second member 16. In addition, each magnetic pole portion formed at the tip of each end portion has a shape that protrudes in a direction approaching each other, and its end surface is substantially the same as the passage width (axial width) of the communication passage 52. It is provided so as to cover the whole.

  The coil part 53b of the electromagnet 53 is connected to a power supply part 56 that supplies current to the coil part 53b. Then, when the power is supplied from the power supply unit 56 and the electromagnet 53 generates a magnetic force, the magnetic lines of force passing through the axial portion 51b of the swing piston 51 in the substantially radial direction pass through the two communication passages 52 and 52 over the entire passage width. Thus, a magnetic circuit penetrating in a substantially radial direction is formed, and a magnetic field is applied to each of the magnetorheological fluids F in each communication path 52 by this magnetic circuit. Here, the electromagnet 53 and the power supply unit 56 constitute application means in the present invention.

  In the present embodiment, the casing of the swing type damper 50 and the swing piston 51 are both provided such that their center of gravity is positioned on the swing axis P.

  Here, in the belt tensioner device, when power supply to the electromagnet 53 is turned ON / OFF, that is, the application of the magnetic field to the magnetorheological fluid F in the communication path 52 of the oscillating damper 50 is turned ON. The relationship between the displacement (rotation amount) and the damping force schematically shown in FIG. 5 (a) is the change in the damping force of the rocking damper 50 that acts on the rocking of the rocking unit 20 when turned off. It demonstrates based on the characteristic view which shows this.

  In FIG. 5, for the horizontal axis indicating the change in displacement, the displacement amount when the swinging portion 20 rotates in the anti-belt pressing direction is “plus”, and the displacement amount when rotating in the belt pressing direction. On the other hand, regarding the vertical axis indicating the change in the damping force, “minus”, the damping force when the swinging portion 20 rotates in the anti-belt pressing direction is “plus”, and the damping force when rotating in the belt pressing direction. The force is shown as “minus” (therefore, its absolute value becomes the damping force when rotating in the belt pressing direction). In addition, arrows in solid lines (thick solid lines and thin solid lines) representing the characteristics indicate the direction of change of the characteristics over time. That is, the characteristics change over time toward the “plus” side of displacement (the right side in the figure) when the swinging portion 20 rotates in the anti-belt pressing direction, while the swinging portion 20 is in the belt pressing direction. , It changes over time toward the “minus” side of the displacement (left side of the figure).

  When the application of the magnetic field is ON, the magnetorheological fluid F in the communication path 52 of the oscillating damper 50 increases its shear stress, and as a result, the apparent viscosity increases. As a result, the passage resistance of the magnetorheological fluid F in the communication path 52 becomes larger than when the application of the magnetic field is OFF, and accordingly, the swing piston 51 is rotated in the rotational direction of the swing piston 51. It receives the pressure of the magnetorheological fluid F in the fluid chambers C1, C2 located on the front side. Specifically, when the swinging part 20 rotates in the belt pressing direction, it receives the pressure of the magnetorheological fluid F in the first fluid chamber C1, while when the swinging part 20 rotates in the anti-belt pressing direction. It receives the pressure of the magnetorheological fluid F in the second fluid chamber C2. Therefore, as indicated by a thin solid line in FIG. 5A, the damping force of the oscillating damper 50 with respect to the oscillation of the oscillating portion 20 when the application of the magnetic field is ON is indicated by a thick solid line in FIG. As compared with the damping force when the application of the magnetic field indicated by is OFF, it becomes larger in any rotation direction.

  Further, as shown in FIG. 4, the belt tensioner device includes a detection sensor 60 as detection means for detecting the swing position of the swing portion 20, and the swing of the swing portion 20 detected by the detection sensor 60. Control means for calculating the rotation direction, rotation speed, rotation angle, and the like of the oscillating unit 20 based on the data on the moving position, and controlling the amount of power supplied from the power source unit 56 to the electromagnet 53 based on the calculation result. As a control unit 61. Specifically, as schematically shown in FIG. 5B, the control unit 61, when the swinging unit 20 rotates in the belt pressing direction, is a swinging damper with respect to the rotation of the swinging unit 20. When the power source 56 is controlled (power OFF) so that the damping force of 50 is reduced, on the other hand, when the swinging portion 20 rotates in the anti-belt pressing direction (counterclockwise direction in the figure), the swinging portion The power supply unit 56 is controlled (power ON) so that the damping force of the oscillating damper 50 with respect to the 20 rotation is increased.

  Next, the operation of the belt tensioner device configured as described above will be described.

  Since the oscillating portion 20 of the belt tensioner device is always urged in the direction in which the tension pulley 30 presses the belt by the urging force of the torsion coil spring 40, basically, the belt tensioner 30 is moved when the belt tension decreases. By rotating in the pressing direction, the belt tension is recovered, and when the belt tension increases, the belt is operated in the anti-belt pressing direction to absorb the increase in the belt tension. That is, it swings according to increase / decrease in belt tension. However, at that time, the swinging portion 20 rotates slightly behind the increase / decrease change in the belt tension. Therefore, simply by operating following the belt tension change, the fluctuation of the belt tension is reversed. There is a risk of doing.

  Therefore, in this belt tensioner device, when the oscillating portion 20 rotates in the belt pressing direction, the damping force of the oscillating damper 50 with respect to the rotation decreases, while the oscillating portion 20 moves in the anti-belt pressing direction. When it rotates, it operates so that the damping force of the swinging damper 50 with respect to the rotation is increased.

  Specifically, the control unit 61 calculates the rotation direction of the swinging unit 20 based on the detection signal of the detection sensor 60, and determines that the swinging unit 20 is rotating in the belt pressing direction. The power supply of the power supply unit 56 to the electromagnet 53 is turned off. As a result, the electromagnet 53 does not generate magnetic force, and no magnetic field is applied to the magnetorheological fluid F in each communication path 52, so that the passage resistance of the magnetorheological fluid F in each communication path 52 is minimized. Therefore, as the swinging part 20 rotates in the belt pressing direction, the swinging piston 51 decreases the volume of each first fluid chamber C1 and rotates the second fluid chamber C2 in a direction that increases the volume. The movement will take place relatively quickly.

  On the other hand, when it is determined that the swinging unit 20 is rotating in the anti-belt pressing direction, the power supply of the power supply unit 56 to the electromagnet 53 is turned ON. As a result, the electromagnet 53 generates a magnetic force and a magnetic field is applied to the magnetorheological fluid F in each communication path 52, so that the shear stress of the magnetorheological fluid F in each communication path 52 increases, and each communication path 52. The passage resistance of the magnetorheological fluid F is maximized. Therefore, as the swinging portion 20 rotates in the anti-belt pressing direction, the swing piston 51 decreases the volume of each second fluid chamber C2 and rotates in the direction that increases the volume of each first fluid chamber C1. The movement will be relatively slow.

  Therefore, according to the present embodiment, in the belt tensioner device in which the swinging portion 20 is rotated and biased by the coil spring 40 in the direction in which the tension pulley 30 presses the belt with respect to the fixed portion 10, In order to dampen the swing of 20, the two compartments of the swing piston 51, which are swingably integrated with the swing portion 20, are respectively provided in the two internal spaces between the first and second members 12, 16. 51a and 51a are arranged to divide each internal space into two fluid chambers C1 and C2 divided in the swing direction, and two fluid chambers C1 and C1 adjacent to each other in the circumferential direction between the two internal spaces. Two communication passages 52, 52 that communicate C2, C2, C1 with each other are formed by a clearance region between the peripheral wall portion 13 of the first member 12 around the axial center portion 51b of the swing piston 51, and fluid C1 and C2 and the communication path 52 are filled with the magnetorheological fluid F, and a magnetic field is applied to the magnetorheological fluid F in each of the communication paths 52 to change the shear stress to swing the first and second members 12 and 16. When using the swing type damper 50 that attenuates the swing of the piston 51, the swing of the entire region of the gap generated between the swing piston 51 and the first and second members 12, 16 is performed. Two gap regions having a relatively small cross-sectional arc shape around the axial portion 51 b of the moving piston 51 are used as the communication passages 52, and a magnetic field is applied to the magnetorheological fluid F in each of the communication passages 52. Since a magnetic circuit for application is formed between the shaft center portion 51b, a gap having a relatively large circumferential dimension is formed in addition to the gap around the swing piston 51, and the communication path is configured by the gap. To do Compared to the conventional case, the number of parts and the part assembling process can be reduced to contribute to the reduction of the manufacturing cost, and the seal between the first and second members 12 and 16 around the swing piston 51 is possible. It is possible to improve the reliability and durability by reducing the area, and moreover, it is possible to easily obtain the damping characteristic that fully utilizes the shear stress characteristic of the magnetorheological fluid F.

  Further, since the center of gravity of the oscillating piston 51 is positioned on the oscillating axis, the behavior of the oscillating piston 51 when the oscillating portion 20 oscillates due to the belt tension change of the transmission belt is balanced and stable. Can be.

  In the above-described embodiment, the communication path 52 is configured by the gap area around the shaft center portion 51b of the swing piston 51. However, the swing piston 51 is located at a position away from the swing shaft P. In the case where the shaft center portion is not provided, the communication path may be configured by a gap region around the shaft center side portion that is a portion close to the swing axis P, and further, the swing path may be configured. Regardless of whether or not the moving piston 51 has the axial center portion 51b, the communication path may be configured by at least some arbitrary gap regions among all the gaps around the swing piston 51.

  In the above embodiment, the gap (gap between the casing) other than the gap (communication path 52) around the axial center portion 51b of the swing piston 51 is made constant. The gap dimension may change according to the rotation direction of the swing piston 51 in at least some of the surrounding gaps. Specifically, as shown in the modified example of FIG. 6, the distal end side portion 51a2 of the partition portion 51a is parallel to the swing axis P with respect to the proximal end portion 51a1 of the partition portion 51a in the axial direction. When the oscillating piston 51 rotates in the belt pressing direction (clockwise direction in the figure), the distal end side portion 51a2 receives the pressure of the magnetorheological fluid F in the first fluid chamber C1. When the swing piston 51 is rotated in the anti-belt pressing direction (counterclockwise direction in the figure), the tip end is turned. The side part 51a2 receives the pressure of the magnetorheological fluid F in the second fluid chamber C2, and can be configured to rotate so that the gap width village method with the casing is reduced and the gap is sealed. . In this case, when the magnetic field is always turned on or always turned off regardless of the rotation direction of the swing piston 51, as shown in FIG. In addition, a constant damping force is always applied regardless of the rotation direction, whereas, as shown in FIG. 5B, an attenuation characteristic that varies greatly depending on the rotation direction can be obtained. Can do.

  Further, in the above embodiment, when the damping characteristic with respect to the swinging of the swinging part 20 is provided with anisotropy (a characteristic in which the damping force varies depending on the rotating direction), the damping force is applied when the belt 20 is rotated in the belt pressing direction. On the other hand, the damping force is increased when rotating in the direction opposite to the belt pressing, but such a damping characteristic can be appropriately set as necessary.

  In the above embodiment, when the swinging portion 20 is rotated in one direction, the damping force is made substantially constant throughout the entire rotation period. The damping force may be changed according to the rotation position.

  In the above embodiment, the electromagnet 53 is used as the magnetic force generating means. However, for example, when a constant magnetic field is always applied, a permanent magnet may be used as the magnetic force generating means.

(Embodiment 2)
FIG. 8 shows an overall configuration of an auto tensioner according to Embodiment 2 of the present invention.

  In the present embodiment, electromagnets 53 as application means are disposed in the two communication paths 52, 52 of the oscillating damper 50.

  Specifically, as shown in FIGS. 9 and 10, each electromagnet 53 is disposed on the outer wall surface of the peripheral wall portion outside the vicinity of the swing axis P in the peripheral wall portion 13 of the first member 12. Has been. The electromagnet 53 is composed of a substantially U-shaped iron core portion 53a and a coil portion 53b made of a conductive wire wound around the iron core portion 53a, and each end portion serving as a magnetic pole faces toward the axis P. It protrudes and the magnetic poles are arranged in a state aligned in the axial direction. At this time, the regions on both ends in the axial direction of the communication passage 52 are each covered with two magnetic poles over substantially the entire axial dimension of the region. A magnetic circuit is formed in which the lines of magnetic force passing through the portion 51b in the substantially axial direction penetrate the respective regions (application regions) on both ends in the axial direction of the communication path 52 in the substantially radial direction. That is, a region sandwiched between these two application regions is a non-application region through which the magnetic lines of force of the magnetic circuit do not pass.

  On the other hand, as shown in an enlarged view in FIG. 11, on the axial center portion 51 b of the swing piston 51, a cylindrical shape as a restricting portion that restricts the passage of the magnetorheological fluid in the non-application area of each communication passage 52. A ring member 55 is provided in an externally fitted state. The ring member 55 is made of a slidable resin material such as PTFE, and is provided so that the outer peripheral surface thereof is in sliding contact with the inner wall surface of the first member 12. That is, each communication path 52 is divided into two application areas by the ring member 55 and restricts the passage of the magnetorheological fluid F in the non-application area. A decrease in damping force due to the passage of the magnetorheological fluid F through a certain non-application region can be suppressed, and the variable range of the damping force can be increased.

Moreover, since the space for accommodating a part of the electromagnet 53 is not necessary for the base member 11 of the fixed portion 10, the concave groove portion 11b (see FIG. 1) as in the first embodiment is not necessary. Therefore, the thickness dimension (axial direction dimension) is reduced accordingly. In addition, since it is the same as that of the case of Embodiment 1 about the structure of the other part including the power supply part of the electromagnet 53, description is abbreviate | omitted. Therefore, according to this embodiment, compared with the case of 1st Embodiment. The damping force of the oscillating damper 50 is constant regardless of the rotational direction of the oscillating portion 20, but the electromagnet 53 can be arranged in the empty space of the first and second members 12, 16, and the shaft Since the accommodation space for the application means is not required on the end face side of the member 24, the base member 11 of the fixing portion 10 can be thinned, and thus the belt tensioner device can be made compact in the axial direction.

  In the above-described embodiment, the electromagnet 53 is arranged for each communication path 52, but a permanent magnet can be arranged instead of the electromagnet 53.

  In the above embodiment, the electromagnet 53 is arranged on the casing side. However, as a modification, as shown in FIG. 12, the electromagnet 53 may be arranged on the shaft portion 51b side of the swing piston 51. Good. The substantially rectangular broken line in the figure schematically shows the magnetic circuit. Such an arrangement of the electromagnet 53 is not limited to the case of the present invention in which the casing has a plurality of internal spaces and the swing piston 51 has a plurality of partition portions 51a, and the reference examples of FIGS. As shown in FIG. 8, the present invention can be applied to the case where the casing has one internal space and the swing piston 51 has one partition portion 51a.

  In the first and second embodiments described above, the fixed portion 10 side is a casing, and the swing piston 51 disposed in the casing is connected to the swing portion 20 in a swinging manner. While the moving part 20 side is a casing, the swinging piston 51 may be coupled to the fixed part 10.

  Furthermore, although Embodiment 1 and Embodiment 2 described above describe the case of the belt tensioner device in which the swinging type damping device according to the present invention is incorporated, the present invention is applicable to various other devices. It can be used as a swing type damping device.

It is a longitudinal section showing the whole belt tensioner device composition concerning Embodiment 1 of the present invention. It is a perspective view which shows the whole structure of the rocking | swiveling damper in a belt tensioner apparatus. It is a perspective view which shows the rocking | fluctuation type damper of the state which removed the 2nd member. It is a block diagram which shows the control system with respect to a rocking | swiveling damper. Contrast each characteristic between the amount of rotation of the oscillating part and the damping force with respect to the oscillating part when the magnetic field is always ON or OFF (a) and when the magnetic field is ON / OFF controlled (b). FIG. FIG. 6 is a transverse cross-sectional view of a main part showing an oscillating piston in a modification of the first embodiment. In the embodiment (a) and the modified example (b), the respective characteristics between the swing amount of the swing when the magnetic field is always ON or OFF and the damping force with respect to the swing of the swing portion are shown in comparison. FIG. 6 is a diagram corresponding to FIG. 5. FIG. 3 is a view corresponding to FIG. 1 illustrating an overall configuration of a belt tensioner device according to a second embodiment of the present invention. FIG. 3 is a view corresponding to FIG. 2 illustrating an overall configuration of a swing type damper in the belt tensioner device. FIG. 4 is a view corresponding to FIG. 3 showing the swing type damper with the second member removed. It is a perspective view which expands and shows the principal part around the communicating path in a rocking | fluctuation type damper. It is sectional drawing which expands and shows the principal part in the modification of Embodiment 2. It is sectional drawing which shows typically the structure of the rocking | swiveling damper as a reference example of a modification. FIG. 13 is an enlarged view of the main part of the reference example, corresponding to FIG. 12.

Explanation of symbols

10 fixed portion 12 first member (casing)
16 Second member (casing)
20 Oscillating part 30 Tension pulley (pressing part)
40 Torsion coil spring (biasing means)
50 Swing type damper (damping means)
51 Oscillating piston 51a Partition part 51b Shaft center part (shaft part)
52 Communication path 53 Electromagnet (Magnetic force generator)
55 Ring member (Regulator)
56 Power supply (applying means)
60 Detection sensor (detection means)
61 Control unit (control means)
C1 First fluid chamber (fluid chamber)
C2 Second fluid chamber (fluid chamber)
F Magnetorheological fluid P Oscillation axis (axis)

Claims (7)

A casing having a plurality of internal spaces arranged in a circumferential direction around an axis;
Each of the internal spaces has a plurality of partition portions arranged so as to partition the internal space into two fluid chambers divided in the circumferential direction, and the first and second two around the axis A swing piston provided so as to be swingable in the rotation direction;
Each comprises at least a part of the entire gap area between the swing piston and the casing, and is adjacent to each other in the circumferential direction between the two internal spaces adjacent to each other in the circumferential direction. A plurality of communication passages each communicating two fluid chambers;
A magnetorheological fluid that fills the plurality of internal spaces and the plurality of communication passages, and changes viscosity according to an applied magnetic field;
An oscillating damping device comprising: an applying means for applying a magnetic field to the magnetorheological fluid in the plurality of communication paths. The oscillating damping device according to claim 1,
The swinging damping device is characterized in that the swinging piston is formed in a rotationally symmetric shape centered on the axis. The oscillating damping device according to claim 1,
The oscillating piston has a shaft portion disposed on the shaft center,
Each of the communication passages includes at least a part of a gap region formed between the shaft portion of the swing piston and the casing. The swing type attenuation device according to claim 3,
The applying means has a magnetic force generator that generates a magnetic force so as to form a magnetic circuit that applies a magnetic field to the magnetorheological fluid in the communication path,
The oscillating damping device according to claim 1, wherein the magnetic force generator is arranged on the casing side. The swing type attenuation device according to claim 3,
The applying means has a magnetic force generator that generates a magnetic force so as to form a magnetic circuit that applies a magnetic field to the magnetorheological fluid in the communication path,
The oscillating type damping device, wherein the magnetic force generating part is disposed on a shaft part of an oscillating piston. The oscillating damping device according to claim 4 or 5,
Each communication path is divided in the axial direction into a plurality of application regions and at least one non-application region,
The magnetic force generator is configured to form a magnetic circuit through which magnetic lines of force pass only through the plurality of application regions in the communication paths.
An oscillating damping device, comprising: a restricting portion that is provided in each of the communication passages and restricts passage of the magnetorheological fluid in the non-application region in the communication passages. A fixed part fixed to a fixed body;
A swing part having a pressing part for pressing the transmission belt and supported by the fixed part so as to be swingable in two rotational directions around the swing axis;
An urging means interposed between the fixed portion and the oscillating portion, and constantly urging the oscillating portion with respect to the fixed portion in a rotational direction in which the pressing portion presses the transmission belt;
A belt tensioner device comprising damping means for damping rotation of the swinging portion,
The damping means is constituted by the swing type damping device according to any one of claims 1, 2, 3, 4, 5, or 6.
The casing of the swing type damping device is connected to one of the fixed part and the swinging 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.

Images