JP2013167313A - Magnetic viscous fluid damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic viscous fluid damper, in which types of pistons can be reduced among products with different specifications.SOLUTION: A magnetic viscous fluid damper 1 includes a bypass flow passage 7 that is open to a piston 10 and communicates two fluid chambers 3, 4 in parallel to a main flow passage 6. The bypass flow passage 7 includes: a plurality of bypass holes 31 to 33, each of which is formed to be open to a piston core 20 (a first piston member) and has a different flow passage resistance to be imparted to a magnetic viscous fluid; and bypass openings 86, 96 which are formed to be open to plates 80, 90 (second piston members) and open at least one of the plurality of bypass holes 31 to 33 by the assembly positions of the plates 80, 90.

Description

  The present invention relates to a magnetorheological fluid shock absorber that generates a damping force by a magnetorheological fluid.

  As a magnetorheological fluid shock absorber mounted on a vehicle, there is one in which a magnetorheological fluid whose apparent viscosity changes due to the action of a magnetic field is sealed, and a fixed restrictor through which the magnetorheological fluid passes is formed in a piston (for example, Patent Documents) 1).

US Pat. No. 6,260,675

  However, in such a conventional magnetorheological fluid shock absorber, the opening diameter of the fixed throttle must be changed according to the damping characteristics required for the product. There is a problem that the number of types of pistons needs to be increased.

  The present invention has been made in view of the above problems, and an object thereof is to provide a magnetorheological fluid shock absorber capable of reducing the types of pistons among products having different specifications.

  The present invention relates to a magnetorheological fluid shock absorber that generates a damping force by a magnetorheological fluid, a cylinder in which the magnetorheological fluid is enclosed, a piston that is slidably disposed in the cylinder, and a partition formed by the piston. Two fluid chambers, a main channel that opens to the piston and communicates the two fluid chambers, and a bypass channel that opens to the piston and communicates the two fluid chambers in parallel with the main channel. The piston includes a first piston member and a second piston member assembled to each other, and the bypass channel is formed by opening the first piston member, and a plurality of bypass holes having different channel resistances applied to the magnetorheological fluid. A bypass opening formed in the second piston member and opening at least one of the plurality of bypass holes depending on the assembly position of the second piston member. Is the fact characterized.

  In the present invention, when assembling the magnetorheological fluid shock absorber, a bypass hole communicating two fluid chambers is arbitrarily selected by changing the assembly position of the first and second piston members. As a result, the magnetorheological fluid shock absorber is provided with a bypass flow path corresponding to the required damping characteristics, so that it is possible to share the piston among products with different specifications. Can be reduced.

It is sectional drawing of the magnetorheological fluid shock absorber which shows embodiment of this invention. (A) is a top view of a piston core, (B) is sectional drawing which follows the AOA line of (A). (A) is a top view of a plate, (B) is sectional drawing which follows the BOB line of (A).

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

  FIG. 1 is a cross-sectional view showing a piston portion of a magnetorheological fluid shock absorber (hereinafter simply referred to as “buffer 1”). The shock absorber 1 is interposed between a vehicle body and an axle of a vehicle such as an automobile, and generates a damping force that suppresses vibration of the vehicle body by an expansion / contraction operation.

  The shock absorber 1 includes a cylindrical cylinder 9 in which a magnetorheological fluid is sealed, and a piston 10 that is slidably disposed in the cylinder 9 and divides the cylinder 9 into two fluid chambers 3 and 4. Prepare.

  One end of a rod 60 is connected to the piston core 20 of the piston 10. The other end of the rod 60 extends to the outside of the cylinder 9. The other end of the rod 60 is connected to one of the vehicle body and the axle, and the cylinder 9 is connected to the other. Thereby, the shock absorber 1 is expanded and contracted by the relative movement of the rod 60 and the cylinder 9 as the axle moves with respect to the vehicle body.

  A gas chamber (not shown) in which gas is sealed is defined in the cylinder 9 via a free piston (not shown), and the volume change in the cylinder 9 due to the entry and withdrawal of the rod 60 is caused by this gas chamber. Compensated.

  The piston 10 includes a piston core 20 to which a rod 60 is coupled, a cylindrical flux ring 50 disposed at a predetermined interval on the outer periphery of the piston core 20, and a plate 80 that supports the flux ring 50 on the piston core 20. 90 and nuts 88 and 98 for fastening the plates 80 and 90 to the piston core 20, respectively.

  The piston core 20 has cylindrical boss portions 25 and 26 projecting from both ends thereof, and male screws 37 and 38 are formed on the outer circumferences of the boss portions 25 and 26. A screw hole 29 is opened in the end surface of one boss portion 25, and the tip of the rod 60 is screwed into and connected to the screw hole 29.

  The plates 80 and 90 are annular members that engage with both ends of the piston core 20 and the flux ring 50.

  The nuts 88 and 98 are screwed into the male screws 37 and 38, respectively. The plates 80 and 90 are sandwiched between the nuts 88 and 98 and the end surfaces 23 and 24 of the piston core 20.

  Both ends of the flux ring 50 are supported by the piston core 20 via plates 80 and 90. At both ends of the flux ring 50, annular annular protrusions 54 and 55 that engage with the plates 80 and 90 are formed, respectively.

  The annular plate 90 has an inner peripheral surface 94 that fits to the outer periphery of the boss portion 26, and planar end surfaces 91 and 92. One end surface 91 abuts on the end surface 24 of the piston core 20. A nut 98 abuts on the other end surface 92.

  An annular groove 93 is formed on the end surface 91 of the plate 90. The annular protrusion 55 of the flux ring 50 is fitted into the annular groove 93.

  The plate 80 has the same shape as the plate 90 described above, and an inner peripheral surface 84, end surfaces 81 and 82, and an annular groove 83 are formed. The annular convex portion 54 of the flux ring 50 is fitted into the annular groove 83 of the plate 80.

  The shock absorber 1 includes a main flow path 6 that opens to the piston 10 and communicates the two fluid chambers 3 and 4 as a damping force generating element.

  A cylindrical gap 16 is defined between the outer peripheral surface 22 of the piston core 20 and the inner peripheral surface 51 of the flux ring 50. The piston core 20 and the flux ring 50 are arranged concentrically with respect to the center line O of the piston 10. The gap 16 has a constant opening width in the radial direction of the piston 10.

  The plates 80 and 90 are formed with a plurality of main openings 85 and 95 that open to face the gap 16. The main openings 85 and 95 are formed in an arc shape extending on the same circumference as the gap 16 and communicate with the gap 16.

  The main flow path 6 is constituted by the gap 16 and the main openings 85 and 95 and communicates with the fluid chambers 3 and 4 on both sides of the piston 10.

  The shock absorber 1 includes an electromagnetic coil 70 that generates a magnetic field (magnetic field) inside the main flow path 6. The electromagnetic coil 70 generates a magnetic field when a current flows.

  An annular recess 21 is formed on the outer periphery of the piston core 20, and an electromagnetic coil 70 is accommodated in the recess 21. The electromagnetic coil 70 is wound around the outer periphery of the piston core 20 and is provided facing the gap 16 of the main flow path 6.

  A lead wire 71 extending from the electromagnetic coil 70 is provided inside the piston core 20 and the rod 60. The lead wire 71 is inserted through the recess 28 formed in the piston core 20 and is inserted through the hollow portion 61 of the rod 60 and is connected to a controller (not shown). The electromagnetic coil 70 is surrounded by a mold resin body (not shown). Mold resin bodies (not shown) are also formed between the electromagnetic coil 70 and the recess 21, between the lead wire 71 and the recess 28 (see FIG. 2), and the hollow portion 61.

  The magnet wire constituting the electromagnetic coil 70 has one end connected to the piston core 20 and the other end connected to the lead wire 71. The drive current output from the controller is guided to the electromagnetic coil 70 through the lead wire 71, and after flowing through the electromagnetic coil 70, is guided to the controller through the piston core 20, the rod 60, and a vehicle body (not shown).

  The piston core 20 and the flux ring 50 are each formed of a magnetic material. On the other hand, the plates 80 and 90 are made of a nonmagnetic material. Thereby, the piston core 20 and the flux ring 50 constitute a magnetic circuit that guides the magnetic flux of the electromagnetic coil 70, and gives a magnetic field to the magnetorheological fluid flowing through the main flow path 6.

  A magnetorheological fluid is a fluid in which fine particles having ferromagnetism are dispersed in a liquid such as oil, and the apparent viscosity changes depending on the strength of the magnetic field.

  When the piston 10 slides in the cylinder 9, the magnetorheological fluid flows through the main flow path 6 as indicated by an arrow in FIG. 1 and moves between the fluid chambers 3 and 4 on both sides of the piston 10. At this time, when a current is passed through the electromagnetic coil 70, a magnetic field acts on the magnetorheological fluid flowing through the main flow path 6, and the viscosity of the magnetorheological fluid changes. The shock absorber 1 generates a damping force corresponding to the magnitude of the viscous resistance of the magnetorheological fluid flowing through the main flow path 6.

  As the magnetic field strength of the electromagnetic coil 70 increases, the viscosity of the magnetorheological fluid increases and the damping force generated by the shock absorber 1 also increases. The damping force generated by the shock absorber 1 is adjusted by changing the energization amount of the electromagnetic coil 70 and changing the strength of the magnetic field acting on the magnetorheological fluid flowing through the main flow path 6.

  The shock absorber 1 includes, as a damping force generating element, a bypass flow path 7 that opens to the piston 10 and communicates with the fluid chambers 3 and 4 on both sides of the piston 10 in parallel with the main flow path 6.

  In the shock absorber 1, when the piston 10 moves in the cylinder 9, the magnetorheological fluid flows through the bypass channel 7 as shown by an arrow in FIG. A damping force is generated by the flow path resistance.

  Since the electromagnetic coil 70 is provided on the outer periphery of the piston core 20 made of a magnetic material and the bypass flow path 7 is defined by bypass holes 31 to 33 (see FIG. 2) that penetrate the piston core 20 described later, The magnetorheological fluid flowing through the flow path 7 is not easily affected by the magnetic field generated by the electromagnetic coil 70.

  In the shock absorber 1, bypass holes 31 to 33 of the bypass flow path 7 are set according to the attenuation characteristics required for the product. As a result, in the shock absorber 1, pressure fluctuations in the fluid chambers 3 and 4 are alleviated by the flow path resistance of the bypass flow path 7, and impacts, noises, and the like due to sudden pressure fluctuations are prevented.

  Hereinafter, a specific configuration of the bypass channel 7 will be described.

  The bypass channel 7 is formed by opening to the piston core 20 (first piston member) and has a plurality of bypass holes 31 to 33 having different channel resistances (channel cross-sectional areas) applied to the magnetorheological fluid, a plate 80, The bypass opening portions 86 and 96 are formed to open to the 90 (second piston member) and open at least one of the plurality of bypass holes 31 to 33 depending on the assembly position of the plates 80 and 90.

  Hereinafter, FIG. 2 will be described. 2A is a plan view of the piston core 20, and FIG. 2B is a cross-sectional view taken along line A-O-A in FIG. As shown in this figure, the piston core 20 provided as the first piston member is formed with three sets of bypass holes 31, 32, 33 having different opening diameters. Each bypass hole 31, 32, 33 is formed as a through hole extending substantially parallel to the center line O of the piston 10 and penetrates the piston core 20.

  The number of bypass holes is not limited to three, and may be increased or decreased depending on the number of corresponding products.

  Two bypass holes 31, 32, and 33 having the same opening diameter are formed, and these are arranged symmetrically with respect to the center line O.

  Each bypass hole 31, 32, 33 is arranged on a circle S concentric with the center line O of the piston 10.

  Hereinafter, FIG. 3 will be described. 3A is a plan view of the plate 90, and FIG. 3B is a cross-sectional view taken along line B-O-B in FIG. As shown, a pair of bypass openings 86 and 96 are formed in the plates 80 and 90 provided as the second piston members, respectively. The bypass openings 86 and 96 are formed in a circular hole shape, and have an opening diameter larger than the opening diameter of each bypass hole 31, 32, and 33.

  Two bypass openings 86 and 96 having the same opening diameter are formed, arranged symmetrically with respect to the center line O, and arranged on the concentric circle S with the center line O of the piston 10.

  Thus, when the piston core 20 is assembled, the plates 80 and 90 are rotated with respect to the piston core 20 to change the assembly position of the plates 80 and 90, so that the bypass openings 86 and 96 are connected to the bypass holes 31, 32 and 33. By communicating with either of these, the bypass flow path 7 is opened.

  When the piston 10 is assembled, the plates 80 and 90 are rotatably fitted to the bosses 25 and 26 of the piston core 20 and the plates 80 and 90 are attached to the piston core 20 before the nuts 88 and 98 are tightened. In contrast, it is easy to change the assembly position of the plates 80 and 90 by rotating the plates 80 and 90, and the concentricity of the plates 80 and 90 with respect to the piston core 20 is ensured. After the assembly positions of the plates 80 and 90 are thus determined, the nuts 88 and 98 are tightened, whereby the plates 80 and 90 are fixed to the piston core 20.

  In the state after assembly shown in FIG. 1, each bypass hole 31 communicates with the bypass openings 86 and 96 to constitute the bypass flow path 7, and the other bypass holes 32 and 33 are blocked by the plates 80 and 90. Has been. In this case, when the piston 10 slides in the cylinder 9 during the operation of the shock absorber 1, the magnetic viscous fluid flows through each bypass hole 31, and each bypass hole 31 provides a flow path that imparts to the magnetic viscous fluid flow. A damping force is generated by the resistance.

  Thus, when the piston core 20 is assembled, any of the bypass holes 31, 32, 33 is arbitrarily opened to set the flow resistance of the bypass flow path 7 according to the damping characteristic required for the product.

  According to the present embodiment, when the shock absorber 1 is assembled, the two fluid chambers 3, 4 are moved by changing the assembly position of the first piston member (piston core 20) and the second piston member (plates 80, 90). The bypass holes 31 to 33 communicating with each other are arbitrarily selected. Thereby, the shock absorber 1 can obtain the flow path resistance of the bypass flow path 7 according to the required attenuation characteristics. Thereby, it becomes possible to share the piston 10 among products with different specifications, and the types of the piston 10 can be reduced.

  The bypass openings formed in the plates 80 and 90 are not limited to the hole shape, and a plurality of the bypass holes 31, 32, and 33 are formed as a shape in which a part of the plates 80 and 90 are cut out. It is good also as a structure which opens a group.

  Further, the plates 80 and 90 may be provided as the first piston member, and the piston core 20 may be provided as the second piston member. In this case, a plurality of sets of orifices having different opening diameters are formed in the plates 80 and 90 as bypass holes constituting the bypass flow path. As a bypass opening constituting the bypass flow path, a set of through holes for opening any of the orifices is formed in the piston core 20. Thereby, at the time of assembling the piston, by adjusting the assembly position of the plates 80, 90 and the piston core 20, the opening orifice is selected, and the flow resistance of the bypass flow path is arbitrarily set.

  In the present embodiment, a piston core 20 made of a magnetic material around which the electromagnetic coil 70 is wound is provided as the first piston member, and the bypass holes 31 to 33 are formed as through holes penetrating the piston core 20. As a result, the magnetorheological fluid flowing through the bypass channel 7 becomes less susceptible to the magnetic field generated by the electromagnetic coil 70, and the fluid chambers 3, 4 are affected by the channel resistance of the bypass channel 7 regardless of the strength of the magnetic field. Pressure fluctuation is alleviated.

  In the present embodiment, plates 80 and 90 that are pressed against the end surfaces 23 and 24 of the piston core 20 are provided as the second piston member, and the piston core 20 has a boss portion 25 to which the plates 80 and 90 are rotatably fitted, 26, and the plates 80 and 90 are rotated with respect to the piston core 20 to change the assembly position of the plates 80 and 90. Thereby, the concentricity of the plates 80 and 90 with respect to the piston core 20 is ensured when the piston 10 is assembled, and the alignment of the bypass openings 86 and 96 formed in the plates 80 and 90 and the respective bypass holes 31, 32 and 33 is performed. Is performed with high accuracy.

  In this embodiment, the bypass flow path 7 is opened by changing the assembly position of the two plates 80 and 90. However, the present invention is not limited to this, and the bypass flow path is changed by changing the assembly position of one plate. 7 may be configured to be opened.

  In the present embodiment, a flux ring 50 in which the main flow path 6 is defined is provided between the outer peripheral surface 22 of the piston core 20 and the plates 80 and 90 are configured to support the flux ring 50 with respect to the piston core 20. . Accordingly, the plates 80 and 90 can both support the flux ring 50 and switch the flow resistance of the bypass flow path 7 when the piston 10 is assembled, and the structure of the shock absorber 1 can be simplified.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Magnetorheological fluid buffer 3, 4 Fluid chamber 6 Main flow path 7 Bypass flow path 9 Cylinder 10 Piston 20 Piston core (1st piston member)
22 Outer peripheral surface 25, 26 Boss part 31-33 Bypass hole 50 Flux ring 70 Electromagnetic coil 80, 90 Plate (second piston member)
86, 96 Bypass opening

Claims (4)

A magnetorheological fluid shock absorber that generates a damping force by a magnetorheological fluid,
A cylinder in which the magnetorheological fluid is sealed;
A piston slidably disposed in the cylinder;
Two fluid chambers defined by the piston;
A main flow path that opens to the piston and communicates two fluid chambers;
A bypass channel that opens to the piston and communicates the two fluid chambers in parallel with the main channel, and
The piston includes a first piston member and a second piston member assembled together,
The bypass flow path is formed to open to the first piston member and has a plurality of bypass holes with different flow path resistances applied to the magnetorheological fluid, and is formed to open to the second piston member. And a bypass opening for opening at least one of the plurality of bypass holes according to the assembly position of the magnetic viscous fluid shock absorber. An electromagnetic coil for generating a magnetic field;
A piston core around which the electromagnetic coil is wound as the first piston member;
The magnetorheological fluid shock absorber according to claim 1, wherein the plurality of bypass holes are formed as through holes penetrating the piston core. A plate that is pressed against the end face of the piston core as the second piston member;
The piston core has a boss part into which the plate is rotatably fitted,
The magnetorheological fluid shock absorber according to claim 2, wherein the plate is rotated with respect to the piston core to change the assembly position of the plate. A flux ring having an inner peripheral surface that defines the main flow path between the outer peripheral surface of the piston core,
The magnetorheological fluid shock absorber according to claim 3, wherein the plate supports the flux ring on the piston core.

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