JP2006057766A - Mr fluid damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MR fluid damper capable of reducing amount of use of MR fluid and simplifying a magnetic field generating device. <P>SOLUTION: This MR fluid damper 10 is constituted by inserting a piston rod 12 into a damper tube 11, providing a first piston 20 and a second piston 30 sliding in the damper tube 11 at two positions in the axial direction of a piston rod 12, and partitioning an MR fluid storage chamber 13 nipped by the first and second pistons 20, 30 of the piston rod 12 to store MR fluid inside the damper tube 11. The magnetic field generating device 40 is provided in a part facing the MR fluid storage chamber 13 of the damper tube 11, the magnetic field generating device 40 partitions the MR fluid storage chamber 13 into two upper and lower chambers 13A, 13B, and a flow passage 14 for MR fluid communicating two upper and lower chambers between the piston rod 12 and it is formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an MR fluid damper.

  As described in Patent Document 1, as an MR fluid damper, a piston rod is inserted into an MR fluid accommodation chamber of a damper tube, and an MR fluid accommodation chamber is partitioned into two upper and lower chambers by a piston provided on the piston rod. Is provided with a magnetic field generator, and the magnetic field generator forms an MR fluid flow path with the inner periphery of the damper tube. The magnetic field generator applies a magnetic field to the MR fluid passing through the MR fluid flow path to generate a damping force.

Also, as described in Patent Document 2, an outer tube is provided around the damper tube in which the piston rod is housed as an MR fluid damper, and the reservoir chamber communicating with the MR fluid housing chamber inside the damper tube is provided as the damper tube and the outer tube. Some are provided between tubes, and a magnetic field generator is provided around the outer tube. The magnetic field generator applies a magnetic field to the MR fluid in the reservoir chamber to generate a damping force.
Special table 2000-514161 Akira Akira 62-151448

  In the MR fluid damper of Patent Document 1, it is necessary to provide a rod volume compensation chamber for the entry / extraction of the piston rod that accompanies expansion / contraction of the piston rod inserted into the damper tube in communication with the MR fluid accommodation chamber of the damper tube. A large amount of expensive MR fluid is required. Moreover, the magnetic field generator is provided on the piston, and the installation structure of the magnetic field generator is complicated.

  In the MR fluid damper of Patent Document 2, the reservoir chamber constitutes a rod volume compensation chamber, but the reservoir chamber communicates with the MR fluid storage chamber, and a large amount of expensive MR fluid is required. In addition, the magnetic field generator is provided around the outer tube, and the coil diameter of the magnetic field generator becomes large.

  An object of the present invention is to reduce the amount of MR fluid used in an MR fluid damper and to simplify the magnetic field generator.

  According to the first aspect of the present invention, the piston rod is inserted into the damper tube, the first and second pistons that slide in the damper tube are provided at two positions in the axial direction of the piston rod, and the piston rod is disposed inside the damper tube. An MR fluid containing chamber is defined between the first and second pistons and contains MR fluid. A magnetic field generator is provided in a portion of the damper tube facing the MR fluid containing chamber. The magnetic field generator moves the MR fluid containing chamber up and down. And a flow path for MR fluid that communicates the upper and lower chambers with the piston rod.

  According to a second aspect of the present invention, in the first aspect of the invention, the damper tube is composed of upper and lower divided tubes, and a magnetic field generator is sandwiched between the upper and lower divided tubes via a sealing material. It is.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the magnetic field generating device further comprises a coil provided in the iron core, and the iron core forms a flow path for MR fluid with the piston rod. It is.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the piston further includes a volume expansion compensation chamber for MR fluid communicating with the MR fluid storage chamber.

  The invention of claim 5 further comprises an outer tube around the damper tube in the invention of any one of claims 1 to 4.

(Claim 1)
(a) In the MR fluid damper, the first and second pistons provided at two positions in the axial direction of the piston rod slide inside the damper tube, and are sandwiched between the first and second pistons inside the damper tube. The MR fluid containing chamber is divided into two upper and lower chambers by a magnetic field generator provided on the damper tube, and the upper and lower chambers communicate with each other between the magnetic field generator and the piston rod. A flow path is formed, and a damping force is generated by applying a magnetic field to the fluid passing through the MR fluid flow path by sliding the piston rod. It is not necessary to provide a rod volume compensation chamber for the piston rod entering / withdrawing from the damper tube, and it is sufficient to seal the MR fluid only in the MR fluid storage chamber of the damper tube, and the amount of MR fluid used can be reduced.

  (b) The magnetic field generator is provided in a portion of the damper tube facing the MR fluid storage chamber, and the installation structure of the magnetic field generator can be simplified and reduced in size.

(Claim 2)
(c) The magnetic field generator can be installed by being sandwiched between the upper and lower divided tubes of the damper tube via a sealing material, and can be easily installed on the portion of the damper tube facing the MR fluid storage chamber.

(Claim 3)
(d) The iron core of the magnetic field generator can form an MR fluid channel with the piston rod, and the MR fluid channel can be easily formed.

(Claim 4)
(e) The volume expansion compensation chamber for MR fluid is sufficient with a small capacity, and the pipe system can be shortened by providing it in the piston, so that the amount of MR fluid used can be reduced. The volume expansion compensation chamber for MR fluid can be integrated with the piston to improve the assemblability.

(Claim 5)
(f) Since the MR fluid damper is constituted by a double tube type in which an outer tube is provided around the damper tube, the proof strength and strength against a lateral force acting on the damper can be improved. A spring seat for a suspension spring provided along with the MR fluid damper can be easily fixed (welded or the like) to the outer tube.

  1 is a cross-sectional view showing an MR fluid damper, FIG. 2 is a cross-sectional view showing an essential part of FIG. 1, FIG. 3 is a cross-sectional view showing a magnetic field generator, and FIG. 4 is a cross-sectional view showing a piston.

  As shown in FIGS. 1 and 2, the MR fluid damper 10 includes first and second pistons in which a piston rod 12 is inserted into a damper tube 11 and slides in the damper tube 11 at two axial positions of the piston rod 12. 20 and 30 are provided, and an MR fluid storage chamber 13 for storing an MR fluid (magnetorheological fluid) sandwiched between the first and second pistons 20 and 30 of the piston rod 12 inside the damper tube 11 is defined.

  Note that the MR fluid is free flowing with a certain viscosity. When exposed to a magnetic field, the liquid instantaneously becomes a solid state, and when the magnetic field disappears, it quickly returns to the liquid state. The change in viscosity of the MR fluid is proportional to the magnitude (magnetic force) of the magnetic field. MR fluids are spherical soft paramagnetic particles such as magnetite, carbonyl iron powder, iron alloys, iron nitride, iron carbide, chrome dioxide, low carbon steel, silicon steel, nickel, cobalt, etc., preferably about 1-6 milokun nominal. It has a diameter and is suspended in a low viscosity liquid such as silicone oil, hydrocarbon oil, paraffin oil, mineral oil, chlorinated and fluorinated fluids, kerosene, glycol, or water.

  The piston rod 12 includes a rod main body 12A located inside the damper tube 11 and a rod protrusion 12B that is coaxially screwed to one end of the rod main body 12A. The rod protrusion 12B is connected to one end of the damper tube 11. Projecting outward from.

  The first piston 20 is sandwiched between the end surface of the rod main body 12A and the stepped portion of the rod protrusion 12B together with the seal presser 21 at one end of the rod main body 12A of the piston rod 12, and is fixed in a liquid-tight manner. The first piston 20 includes a guide bush 22 slidably contacting the damper tube 11 and a fluid seal 23 on the outer periphery, and holds the fluid seal 23 by a seal retainer 21.

  The second piston 30 is sandwiched between the stepped portion of the rod main body 12A and the nut 31 screwed to the rod main body 12A together with the seal presser 32 on the other end side of the rod main body 12A in the piston rod 12 so as to be liquid-tight. Fixed. The second piston 30 includes a guide bush 33 and a fluid seal 34 that are in sliding contact with the damper tube 11 on the outer periphery, and holds the fluid seal 34 with a seal presser 32.

  As shown in FIG. 4, the second piston 30 includes an MR fluid volume expansion compensation chamber 35 that communicates with the MR fluid storage chamber 13. The second piston 30 includes a free piston 36 (O-ring 36A) slidably liquid-tightly on the inner periphery of a cylindrical portion 30A having a guide bush 33 on the outer periphery, and the space close to the rod body 12A of the free piston 36 is volumetric. The expansion compensation chamber 35 is used. The volume expansion compensation chamber 35 communicates with the MR fluid storage chamber 13 through an annular gap formed between the piston 37 and the seal retainer 32 by the hole 37 formed on the proximal end side of the cylindrical portion 30A and the fluid seal 34. To do. Note that a stopper 30B for retaining the free piston 36 is provided at the tip of the cylindrical portion 30A.

  The MR fluid damper 10 is provided with a magnetic field generator 40 at a portion of the damper tube 11 that faces the MR fluid storage chamber 13, in other words, a portion that surrounds the outer periphery of the piston rod 12 (rod body 12 </ b> A). The magnetic field generator 40 divides the MR fluid storage chamber 13 into upper and lower two chambers 13A and 13B, and communicates the upper and lower two chambers 13A and 13B with the outer periphery of the piston rod 12 (rod body 12A). An MR fluid flow path 14 composed of a gap is formed.

  The damper tube 11 is composed of upper and lower divided tubes 11A and 11B, and the magnetic field generator 40 is liquid-tightly sealed between non-magnetic sealing materials 15A and 15B made of aluminum or the like between the upper and lower divided tubes 11A and 11B. Hold it.

  As shown in FIG. 3, the magnetic field generator 40 includes a coil 42 provided on an annular iron core 41, and the iron core 41 forms the MR fluid flow path 14 between the piston rod 12 (rod body 12 </ b> A) and the outer periphery thereof. . The iron core 41 has both end portions along the axial direction as small-diameter portions 41A and 41B, a large outer diameter portion 41C is provided at the central portion along the axial direction, and the inner circumference of the iron core 41 is sandwiched between the small-diameter portions 41A and 41B. A large groove 41D is provided in the middle portion, and the coil 42 is molded with a resin 43 in the large groove 41D. The upper and lower divided tubes 11A and 11B of the damper tube 11 sandwich the large outer diameter portion 41C of the iron core 41 from both sides in the axial direction, and the large diameter portion 16 of the annular sealing materials 15A and 15B is formed on the large outer diameter portion 41C of the iron core 41. The small diameter portion 17 is tightly attached to the outer periphery, and the small diameter portion 17 is liquid-tightly sandwiched between the outer periphery of the small diameter portions 41A and 41B of the iron core 41 and the inner periphery of the divided tubes 11A and 11B. The magnetic field generator 40 faces the outer periphery of the piston rod 12 (rod body 12A) to form the MR fluid flow path 14, and the inner periphery of the small diameter portions 41A and 41B of the iron core 41 and the inner periphery of the resin 43 are flush with each other. To do.

  The MR fluid damper 10 includes an outer tube 50 around the damper tube 11 and forms a double tube. The outer tube 50 is a bottomed cylindrical body, and the lower end portion of the damper tube 11 inserted into the outer tube 50 is seated on the bottom portion of the outer tube 50 via the bottom piece 51. A rod guide 52 and a dust seal 53 (core metal 53A) provided at the upper end portion of the damper tube 11 are inserted into the upper end opening of the outer tube 50, and the damper is placed between the upper end caulking portion 50A and the bottom portion of the outer tube 50. The tube 11 (divided tubes 11A and 11B), the magnetic field generator 40, the bottom piece 51, the rod guide 52, and the dust seal 53 are sandwiched. A cap 54 is attached to the outer periphery of the upper end opening of the outer tube 50, and a bump stopper 55 is attached to the outer surface of the cap 54. A rebound rubber 56 is inserted into the outer periphery of the piston rod 12 (rod protruding portion 12B) inside the damper tube 11 and directly above the first piston 20.

  The MR fluid damper 10 includes a first gas chamber 57A between the first piston 20 and the rod guide 52 inside the damper tube 11, and a second gas chamber 57B between the second piston 30 and the bottom piece 51. An annular gap between the tube 11 and the outer tube 50 is defined as an outer peripheral gas chamber 57C. The first gas chamber 57A communicates with the outer gas chamber 57C through a groove 52A provided in the rod guide 52, and the second gas chamber 57B communicates with the outer gas chamber 57C through a hole 51A and a groove 51B provided in the bottom piece 51. Communicate.

  The MR fluid damper 10 includes an axle side mounting portion at the lower portion of the outer tube 50, and includes a vehicle body side mounting portion at the protruding portion of the piston rod 12. A suspension spring is interposed between the lower spring receiver attached to the outer periphery of the outer tube 50 and the upper spring receiver attached to the piston rod 12. The MR fluid damper 10 absorbs the impact from the road surface by the suspension spring, and the damping force generated due to the flow resistance of the MR fluid that passes through the MR fluid flow path 14 as the piston rod 12 slides up and down. Suppresses the expansion and contraction vibration of the suspension spring.

  That is, in the MR fluid damper 10, when a magnetic field (magnetic field) is generated in the coil 42 by applying a current to the coil 42 of the magnetic field generator 40, the magnetic field passes through the small diameter portion 41 </ b> A of the iron core 41 from one end of the coil 42. The MR fluid passage 14 is jumped over the gap, enters one end of the piston rod 12 (rod body 12A), passes through the piston rod 12, and the other end of the piston rod 12 gaps between the MR fluid passage 14 Is closed, enters the small diameter portion 41B of the iron core 41, and forms a closed magnetic circuit that returns to the other end of the coil 42. The magnitude of the magnetic field exerted by the magnetic field generator 40 on the MR fluid flow path 14 is adjusted by changing the current applied to the coil 42.

  On the other hand, in the extension stroke of the damper 10, when the pistons 20 and 30 of the piston rod 12 slide upward along the inner periphery of the damper tube 11, the MR fluid in the lower chamber 13 </ b> B passes through the MR fluid flow path 14. It flows into the upper chamber 13A. In the compression stroke of the damper 10, when the pistons 20 and 30 of the piston rod 12 slide downward along the inner periphery of the damper tube 11, the MR fluid in the upper chamber 13 </ b> A passes through the MR fluid flow path 14. It flows into the lower chamber 13B.

  In the damper 10, the magnetic field generator 40 adjusts the magnitude of the magnetic field exerted on the flow path 14 when the MR fluid passes through the flow path 14 as described above in the expansion stroke and the compression stroke. The viscosity of the MR fluid passing through the flow path 14 is changed, and as a result, the damping force generated due to the flow resistance of the MR fluid in the flow path 14 can be adjusted.

  In the MR fluid damper 10, since the magnetic field generator 40 is configured as described above, the following operational effects are obtained.

  (a) In the MR fluid damper 10, the first and second pistons 20, 30 provided at two positions in the axial direction of the piston rod 12 are slid inside the damper tube 11, and the first and second pistons 20, 30 are slid inside the damper tube 11. The portion sandwiched between the second pistons 20 and 30 is used as the MR fluid storage chamber 13, and the MR fluid storage chamber 13 is partitioned into two upper and lower chambers 13A and 13B by the magnetic field generator 40 provided in the damper tube 11, and the magnetic field is generated. An MR fluid passage 14 is formed between the device 40 and the piston rod 12 so as to communicate the upper and lower chambers 13A and 13B. A magnetic field is applied to the fluid passing through the MR fluid passage 14 by sliding of the piston rod 12. Giving a damping force. It is not necessary to provide a rod volume compensation chamber for the entry / exit of the piston rod 12 with respect to the damper tube 11, and it is sufficient to seal the MR fluid only in the MR fluid accommodation chamber 13 of the damper tube 11, and the amount of MR fluid used can be reduced. .

  (b) The magnetic field generator 40 is provided in a portion of the damper tube 11 facing the MR fluid storage chamber 13, and the installation structure of the magnetic field generator 40 can be simplified and reduced in size.

  (c) The magnetic field generator 40 can be installed by being sandwiched between the upper and lower divided tubes 11A and 11B of the damper tube 11 via the sealing materials 15A and 15B, and faces the MR fluid storage chamber 13 of the damper tube 11. Can be easily installed on the part.

  (d) The MR fluid channel 14 can be formed between the iron core 41 of the magnetic field generator 40 and the piston rod 12, and the MR fluid channel 14 can be easily formed.

  (e) The volume expansion compensation chamber 35 for MR fluid is sufficient with a small capacity, and the pipe system can be shortened by providing it in the piston 30 and the amount of MR fluid used can be reduced. The volume expansion compensation chamber 35 for MR fluid can be integrated with the piston 30 to improve the assemblability.

  (f) Since the MR fluid damper 10 is configured as a double tube type in which the outer tube 50 is provided around the damper tube 11, it is possible to improve the proof stress and strength against a lateral force acting on the damper 10. A spring seat for the suspension spring provided alongside the MR fluid damper 10 can be easily fixed (welded or the like) to the outer tube.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

FIG. 1 is a cross-sectional view showing an MR fluid damper. FIG. 2 is a cross-sectional view showing a main part of FIG. FIG. 3 is a cross-sectional view showing the magnetic field generator. FIG. 4 is a sectional view showing the piston.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 MR fluid damper 11 Damper tube 11A, 11B Division | segmentation tube 12 Piston rod 13 MR fluid storage chamber 13A, 13B Upper and lower two chambers 14 MR fluid flow path 15A, 15B Seal material 20 First piston 30 Second piston 35 Volume Expansion compensation chamber 40 Magnetic field generator 41 Iron core 42 Coil 50 Outer tube

Claims (5)

Insert the piston rod into the damper tube,
The first and second pistons that slide in the damper tube are provided at two axial positions of the piston rod,
An MR fluid storage chamber for storing the MR fluid sandwiched between the first and second pistons of the piston rod inside the damper tube;
A magnetic field generator is provided at the portion of the damper tube facing the MR fluid storage chamber,
An MR fluid damper in which a magnetic field generator divides an MR fluid containing chamber into two upper and lower chambers and forms a MR fluid flow path communicating with the upper and lower chambers with a piston rod.   The MR fluid damper according to claim 1, wherein the damper tube is composed of upper and lower divided tubes, and a magnetic field generator is sandwiched between the upper and lower divided tubes via a sealing material.   3. The MR fluid damper according to claim 1, wherein the magnetic field generating device is provided with a coil in an iron core, and the iron core forms a flow path for MR fluid with the piston rod.   The MR fluid damper according to any one of claims 1 to 3, wherein the piston includes an MR fluid volume expansion compensation chamber communicating with the MR fluid storage chamber.   The MR fluid damper according to claim 1, further comprising an outer tube around the damper tube.

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