JP2008208885A - Viscous variable fluid damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve safety of a damper using viscous variable fluid. <P>SOLUTION: In the damper using viscous variable fluid, an orifice 18 for generating resistance variable effects is provided on a viscous fluid passage 12 communicating with a piston head side chamber 9. Permanent magnets 16 and coils 17 are provided in a magnetic material 13 having the orifice 18 for generating resistance variable effects. Polarities of magnetic force generated by the coils 17 vary with respect to the permanent magnets 16. Thus, since the magnetic field strength with respect to the viscous variable fluid is maximized when no electric current is carried to the coils 17, a fail-safe function is exhibited. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a shock absorber using a variable viscosity fluid that is applied to a railway vehicle coupler, an aircraft landing device, a shock absorber when an elevator is dropped, and the like.

  In general, the shock absorber applied in the technical field must have the ability to absorb collision energy so as to reduce the deceleration generated in the collision object as much as possible. Most of this type of shock absorber has a variable area orifice by sliding the cylinder and piston, and the resistance force is a combination of the resistance force due to dynamic pressure and the resistance force due to the restoring spring, or due to the dynamic pressure. The resistance variable stroke was determined by assuming the mass / velocity of the collision object, and determining the variable area orifice under these conditions, and providing the resistance stroke characteristics according to the collision conditions.

  In recent years, even in the case of a shock absorber using an MR fluid (or a magnetorheological fluid) whose viscosity changes due to a change in magnetic force due to an increase or decrease in current as a working fluid, the viscous resistance force when no magnetic force is applied. Is proportional to the temperature-dependent MR fluid viscosity coefficient, and therefore changes with temperature.

  On the other hand, since the resistance force due to dynamic pressure is not affected by temperature change, in order to minimize the effect of temperature change in the shock absorber using a variable viscosity fluid, a structure that generates resistance force due to dynamic pressure is incorporated, It is important to reduce as much as possible the ratio of the viscous resistance force when there is no electric field or no magnetic field in the total resistance force.

From such a viewpoint, the applicant previously proposed the invention shown in Patent Document 1. That is, a cylinder and a piston are inserted into the cylinder, the piston has a piston rod, and the cylinder is provided with a plurality of orifice holes in the peripheral wall at intervals in the longitudinal direction. An orifice having a variable area is formed by the plurality of orifice holes and the piston. Then, a passage for the variable viscosity fluid is formed on the outer periphery of the cylinder in which the variable viscosity fluid flows in the longitudinal direction, and an orifice for generating a variable resistance effect due to the viscosity of the variable viscosity fluid flowing in the passage is provided. One of the paths of the viscosity variable fluid communicates with the plurality of orifice holes, and the other communicates with a chamber pressurized with a pressurized gas.
JP 2005-54847 A

  However, in Patent Document 1, the variable viscosity fluid is added with a dynamic pressure resistance generating device in order to reduce the influence of temperature, but in addition to that, the variable viscosity depends on the current value applied to the coil. The strength of the magnetic field is also changed. For this reason, in the event of an emergency, if the energization of the coil is interrupted, the magnetic field is lost and the viscosity is extremely reduced, which may cause a disadvantage that the desired buffer effect cannot be obtained.

  Accordingly, the present invention provides a variable viscosity fluid shock absorber incorporating a fail safe mechanism in which the resistance value of the variable viscosity fluid is prevented from decreasing even if the current is interrupted by the coil and the shock absorber continues its action. Is to provide.

The variable viscosity fluid shock absorber according to the present invention has a cylinder and a piston inserted into the cylinder. The piston is provided with a piston rod, and the variable viscosity fluid is stored in a piston head side chamber composed of the cylinder and the piston. And a passage of variable viscosity fluid connected to the piston head side chamber and a chamber pressurized with gas, and the variable resistance fluid generating orifice is provided in the passage of the variable viscosity fluid,
The orifice for generating a resistance effect is that a permanent magnet and a coil are arranged in parallel with a magnetic material, and the coil has a different polarity of the magnetic force generated with respect to the permanent magnet. .

  As a result, the variable viscosity fluid in the piston head side chamber passes through the variable area orifice composed of a large number of orifice holes, and further flows in the passage of the variable viscosity fluid. First, when the variable viscosity fluid passes through the variable area orifice, a resistance force due to dynamic pressure is generated, and when the variable viscosity fluid passes through the passage of the variable viscosity fluid, it is obtained from the magnetic field strength generated compared to the current value applied to the coil. Due to the viscosity, a resistance force that is the sum of the viscous resistance force generated in the resistance variable effect generating orifice and the resistance force of the restoring spring (pressurized gas) is generated.

  Then, this time the variable resistance effect generating orifice is constructed by arranging a permanent magnet and a coil in parallel on the magnetic material, and the polarity of the magnetic force generated in this coil is made different from that of the permanent magnet. It is possible to obtain a characteristic that the viscous resistance force is maximum when no current is supplied and the viscous resistance force decreases as the current supplied to the coil increases. Therefore, even if the current to the coil is interrupted, the applied magnetic field is maximized, the viscous resistance generated in the resistance variable effect generating orifice is maximized, and the safety of the shock absorber can be improved.

  As the variable viscosity fluid, MR (magnetoviscous fluid) whose viscosity is changed by the magnetic field intensity changed by the current value is used. Further, the variable resistance effect generating orifice is constituted by a gap between the magnetic material and a portion constituting a path of the variable viscosity fluid.

  As described above, according to the present invention, the variable resistance fluid generating orifice is provided in the passage of the variable viscosity fluid, and the permanent magnet and the coil are arranged in parallel with the magnetic material in the variable resistance effect generating orifice. In addition, since the coil has a different polarity of the magnetic force with respect to the permanent magnet, the strength of the magnetic field is controlled by the change in the current value to the coil, and as the current value increases, the resistance variable effect The resistance value of the variable viscosity fluid passing through the generating orifice can be gradually reduced.

  That is, even if no current is supplied to the coil due to an accident or the like, the variable resistance effect generating orifice has the maximum magnetic field generated therein and the maximum viscosity resistance of the variable viscosity fluid. Therefore, even in the event of a shortage, a sufficient impact reduction function can be obtained and a fail-safe mechanism can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  In FIG. 1, a shock absorber 1 of the present invention is shown. In the shock absorber 1, a cylinder 2 is arranged in a vertical direction, a piston 4 is slidably inserted therein, and a piston rod 5 is inserted into the piston 4. It is fixed and protrudes from the cylinder 2 to the outside.

  The cylinder 2 is composed of two members 2a and 2b which are divided into upper and lower parts, and a plurality of orifice holes 6 are formed in the peripheral wall of the lower member 2b with appropriate intervals in the longitudinal direction. A large number of orifice holes 6 and the piston 4 constitute an area variable orifice 7. The relationship between the piston 4 and the large number of orifices 6 is configured so that the rear end of the piston is not exceeded even when the piston 4 is pushed in most to minimize the volume of the piston head side chamber 9.

  This variable area orifice is set so that the deceleration approaches the theoretical minimum, assuming the lightest object collision.

  The viscosity variable fluid passage 12 includes an intermediate cylinder 13 made of a magnetic material provided on the outer periphery of the cylinder 2 and a case 14 made of the same magnetic material disposed on the outer side thereof. The other is in communication with the pressurized chamber 22 described below. The intermediate cylinder 13 constituting the passage 12 has a plurality of concave portions 15a and convex portions 15b continuously formed in the vertical direction by alternately changing the outer dimension thereof.

  A permanent magnet 16 is disposed in the recess 15 a, and a coil 17 is disposed outside the permanent magnet 16. The relationship between the permanent magnet 16 and the coil 17 is that the upper part of the permanent magnet 16 is N and the lower part is S. The magnetism generated by energization of the coil 17 is the reverse direction, that is, the upper part is S, and the upper part is S. N.

  Further, the convex portion 15b is formed with a large number of gaps having a squeezing action with the case 14. The size of this gap can be obtained from experimental results. This gap serves as an orifice 18 for a variable resistance effect generator using a variable viscosity fluid.

  The chamber 22 is formed by a case 14 and a lid 21 above the cylinder 2, and a pressurized gas is placed inside the chamber 22, and the pressurized gas acts to apply pressure to the viscosity variable fluid (MR fluid). The cylinder 2 communicates with the piston rod chamber 23 through an upper communication hole 23 formed in the cylinder 2. That is, the pressurized gas has a restoring spring action that moves the piston 4 upward.

  The variable viscosity fluid flowing in the variable viscosity fluid passage 15 can change its viscosity with the strength of the generated magnetic field by passing an electric current through the coil 17, and is, for example, an MR fluid. That is, a large resistance force is generated when passing through the resistance variable effect generating orifice 18 in the passage 12. This resistance force has a relationship that decreases in inverse proportion to an increase in current value.

  This characteristic is shown as a characteristic diagram shown in FIG. 2. When a current (direct current) is applied to the coil 17, an S pole is generated above and an N pole is generated below. The intensity of the generated magnetic field is proportional to the applied current.

  Unlike the polarity of the permanent magnet 16, the polarity of the magnetic force generated from the coil 17 is reversed. Therefore, the magnetic force of the coil 17 acts in the direction of decreasing the strength of the magnetic force (magnetic field) of the permanent magnet 16. That is, the current value of the coil 17 and the resistance force are in an inversely proportional relationship as indicated by the characteristic line. As is apparent from this characteristic line, when the magnetic force from the coil 17 is lost, only the strength of the magnetic field is obtained from the permanent magnet 16, and the maximum resistance force is obtained. That is, even if the supply of electricity is cut off due to a shortage, a resistance can be obtained and a fail-safe function can be obtained.

  The current applied to the coil 17 is output from a control circuit 26 provided outside, and the output is controlled by the input from the input device 27. The input signal is the mass from the mass detector. Although not shown, a buffered object is connected to the tip of the piston rod 5.

It is sectional drawing which shows the Example of this invention. It is a resistance force characteristic line generated in the orifice for generating the current value and the resistance variable effect.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Buffer 2 Cylinder 4 Piston 5 Piston rod 7 Area variable orifice 9 Piston head side chamber 12 Viscosity variable fluid passage 13 Intermediate cylinder 14 Case 15a Recess 15b Protrusion 17 Coil 18 Resistance variable effect generating orifice 26 Control circuit 27 Input device

Claims (3)

The piston has a piston inserted into the cylinder, and the piston is provided with a piston rod. Viscous variable fluid is stored in a piston head side chamber composed of the cylinder and the piston, and is added to the piston head side chamber by gas. It has a passage of variable viscosity fluid connected to the pressurized chamber, this variable viscosity fluid passage is equipped with an orifice for variable resistance effect generation,
The resistance variable effect generating orifice has a permanent magnet and a coil arranged in parallel to a magnetic material, and the coil has a different polarity of the magnetic force generated with respect to the permanent magnet. Shock absorber.   2. The variable viscosity fluid buffer according to claim 1, wherein an MR (magnetorheological fluid) whose viscosity is changed by a magnetic field intensity which is changed by an electric current value is used as the variable viscosity fluid.   2. The variable viscosity fluid shock absorber according to claim 1, wherein the variable resistance effect generating orifice is configured by a gap between the magnetic material and a portion constituting a path of the variable viscosity fluid.

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