JP2005291338A - Damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damper having a simple configuration and capable of adjusting magnitude of damping force by corresponding to a travel position. <P>SOLUTION: A first permanent magnet 51 and a second permanent magnet 52 are provided in an outer peripheral part of a cylinder 2 by changing positions. When a piston 16A is at a neutral position, magnetic field is not applied to an annular clearance 64 (a flow passage 21A). For this reason, viscosity of magnetic fluid 6 passing through the flow passage 21A is constant, and generated damping force is not affected by the first and second permanent magnets 51, 52. When the damper 1A is contracted and magnetic field by the second permanent magnet 52 is applied to the annular clearance 64, viscosity of magnetic fluid 6 flowing in the annular clearance 64 is increased, and generated damping force is increased. Since magnetic fluid 6 passes through the annular clearance 64 directly and damping force is generated, a seal member becomes unnecessary when compared with conventional technology for obtaining damping force by slide resistance for the cylinder of the seal member in a condition in which magnetic fluid is sealed to simplify a structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a damper used in a fully automatic washing machine, a vehicle, a building, and the like, and more particularly, to a damper using a magnetic fluid as a working fluid.

  As an example of a damper using a conventional magnetic fluid, there is a damper shown in Patent Document 1. This damper fits and holds a piston-like member made of a magnetic material in a cylindrical casing made of a magnetic material so as to be slidable in the axial direction thereof, and follows the sliding direction on the outer periphery of the piston-like member. Two upper and lower annular recesses are formed, and two annular electromagnets are housed and fixed in these annular recesses with their same poles facing each other, and the inner peripheral surface of the cylindrical casing and the piston-like member are Between the opposing surface to the outer peripheral surface, a magnetic fluid which is entirely encapsulated by a sealing member and sealed in a capsule shape is interposed in an annular shape.

In this damper, a magnetic flux control device is connected to the coil of the electromagnet, and the magnetic force is changed by adjusting the energization current to the coil to increase the magnetic flux in the intervening region of the electromagnet, piston-like member, and capsule-like magnetic fluid. The density is converged, and the viscosity of the capsule-like magnetic fluid, and consequently the sliding resistance of the piston-like member, is rapidly increased by the high-density magnetic flux.
JP 2003-214480 A

  However, in the above-described prior art, a damping force is obtained by sliding resistance with respect to the piston and / or cylinder generated in a state in which a magnetic fluid is sealed in the sealing member. A load is applied and the seal member is easily damaged. For this reason, it is necessary to make the seal member thicker or to separately provide reinforcing means, which easily causes the apparatus to be complicated.

  This invention is made | formed in view of the said situation, and it aims at providing the damper which can obtain favorable damping force with a simple structure.

The damper according to the first aspect of the present invention includes a cylinder in which a fluid whose viscosity is changed by a magnetic field is sealed, and a magnetic material slidably accommodated in the cylinder so as to define an upper chamber and a lower chamber in the cylinder. A piston composed of a body, a piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, and the piston to allow the fluid to flow between the upper chamber and the lower chamber. It is provided with the provided flow path and the magnet provided in the said cylinder.
According to a second aspect of the present invention, in the damper according to the first aspect, the magnet includes a plurality of magnets arranged in a longitudinal direction of the cylinder.

  According to a third aspect of the present invention, in the damper according to the first aspect, the cylinder has one or a plurality of notches formed in one or a plurality of annular regions defined along the axial direction, and has a magnetic permeability. A cylindrical body made of a low material, and an arcuate body made of a material having a higher magnetic permeability than the cylindrical body fitted into the notch and fixed to the cylindrical body. It is characterized by comprising one or a plurality held by an arcuate body.

  According to a fourth aspect of the present invention, in the damper according to any one of the first to third aspects, the piston forms the flow path between a piston main body connecting the piston rod and the piston main body. And a piston annular portion that slides on the cylinder, and a bridge portion that holds the piston annular portion on the piston body.

  According to a fifth aspect of the present invention, in the damper according to any one of the first to fourth aspects, at least one end side portion of the piston rod is made of a magnetic material, and a magnetic material is provided on a side opposite to the piston rod of the piston. An extension rod made of a body is provided.

  According to a sixth aspect of the present invention, in the damper according to any one of the first to fifth aspects, the magnet is an electromagnet.

  According to the invention described in any one of claims 1 to 6, the amount of magnetic flux applied to the flow path in the face-to-face state with the magnet of the piston and the fluid whose viscosity changes due to the magnetic field flowing through the flow path is changed. Since the damping force changes with this, the damping force can be adjusted according to the displacement of the piston. Since the fluid directly passes through the flow path and generates a damping force, the damping force can be adjusted according to the displacement of the piston with a simple configuration.

According to the second aspect of the present invention, the damping force adjustment range can be widened.
According to the third aspect of the present invention, the direction of the magnetic flux acting on the fluid whose viscosity is changed by the magnetic field can be determined in one direction, thereby efficiently applying the magnetic field to the fluid whose viscosity is changed by the magnetic field. Can do.

  According to the fourth aspect of the present invention, since the flow passage area and hence the damping force can be changed by changing the size of the bridge portion, versatility is enhanced.

According to the fifth aspect of the present invention, the damping force during the expansion / contraction stroke can be balanced.
According to the sixth aspect of the invention, the adjustment range of the damping force is widened.

Hereinafter, the damper concerning a 1st embodiment of the present invention is explained based on Drawing 1 thru / or Drawing 4.
1 to 3, the damper 1 is slidably housed in the cylinder 2 in a liquid-tight and air-tight state so that the cylinder 2 and the inside of the cylinder 2 are defined as first and second chambers 3 and 4. The free piston 5 is provided. A magnetic fluid 6 (fluid whose viscosity changes with a magnetic field) is sealed in the first chamber 3, and a gas is sealed in the second chamber 4, and the second chamber 4 corresponds to the pressure change in the first chamber 3. The free piston 5 moves up and down while the gas in the chamber 4 is compressed and expanded.

  The cylinder 2 closes the bottomed cylindrical body 7 made of a magnetic material (a material that is easily affected by a magnetic field having a high magnetic permeability) and an opening (reference numeral omitted) of the cylindrical body 7, and It is comprised from the cover part 10 for guides which penetrates and guides this.

  An electromagnet 50 is disposed on the outer periphery of the substantially center of the cylindrical body 7 in the longitudinal direction. The electromagnet 50 is fixed to the cylindrical body 7 by C rings 51 and 52. The electromagnet 50 includes a coil 53 and a substantially annular case 54 that houses and holds the coil 53. A drive circuit (not shown) is connected to the coil 53 of the electromagnet 50, and a magnetic force (magnetic flux F) is generated when the coil 53 is supplied with current from the drive circuit.

A piston 16 made of a magnetic material is accommodated in the first chamber 3 so as to be movable in the first chamber 3 so as to define an upper chamber 3a and a lower chamber 3b. The upper chamber 3a and the lower chamber 3b represent the upper and lower portions corresponding to FIG. 1, and do not limit the use of the damper 1. The damper 1 is horizontally or with respect to a horizontal plane. It may be inclined and arranged. One end portion 9a of the piston rod 9 is connected to the piston 16, and the other end portion 9b extends to the outside of the first chamber 3 (cylinder 2).
The piston 16 is fitted to and fixed to one end 9 a of the piston rod 9, and slides on the cylinder 2 to move. The piston 16 is fixed to the piston rod 9 by a nut 32 that engages with a male screw (reference numeral omitted) provided at the tip of the one end 9 a of the piston rod 9.

The piston 16 has an outer diameter smaller than the inner diameter of the cylinder 2 and forms a flow passage 20 (flow passage) by a gap formed between the piston 16 and the magnetic fluid 6 through the flow passage 20. Circulates between the upper chamber 3a and the lower chamber 3b. This flow path corresponds to the flow path provided in the piston of the present invention.
In this damper 1, normally (when no current is supplied to the coil 53, the current value is “0” in FIG. 4), the piston 16 faces the electromagnet 50 via the cylinder 2, that is, It arrange | positions so that it may accommodate in the area | region (arrangement | positioning level area | region 100 of the electromagnet 50) formed inside the annular electromagnet 50. FIG.

  In the damper 1 configured as described above, the movable portion (not shown) connected to the piston rod 9 vibrates with respect to the fixed portion (not shown) connected to the cylinder 2 in a normal state, and the piston rod 9 is pivoted. When a directional force is applied, the piston 16 moves in the vertical direction in FIG. As the piston 16 moves, the magnetic fluid 6 passes through the flow passage 20. At this time, a damping force due to the viscosity of the magnetic fluid 6 is generated. In this embodiment, the magnitude of the damping force is, for example, about 10 N as shown in FIG.

  When a current is supplied to the coil 53, the electromagnet 50 generates a magnetic flux F, and a magnetic field is generated in the vicinity of the flow path 20. For this reason, the viscosity of the magnetic fluid 6 passing through the flow passage 20 changes (becomes larger), and the damping force (extension-side damping force) is larger than that in the normal state (when the current supplied to the coil 53 is “0”). And the contraction side damping force) increase.

  When the current is supplied to the coil 53, as shown in FIG. 2, the piston 16 vibrates slightly in the vicinity of the center of the coil 53 (for example, about ± 2 mm. This roughly corresponds to the magnitude of vibration generated during dehydration in the fully automatic washing machine. ) And the magnetic flux F in the longitudinal direction of the cylinder 2 flowing through the magnetic path 26 flows through the flow passage 20 and the piston 16, but the amount thereof is small. For this reason, the viscosity change (ratio in which the viscosity increases) of the magnetic fluid 6 passing through the flow path 20 is small, and the damping force generated by the vibration (about ± 2 mm) is 10 to 30 N (as shown in FIG. 4). Current 0 to 5 A).

  Further, as shown in FIG. 3, the piston 16 vibrates with a large amplitude (for example, about ± 7 mm, which roughly corresponds to the magnitude of vibration generated at the time of resonance in the fully automatic washing machine), and the piston 16 is driven by the extension operation. Is in a vibration state in which part of the piston 16 exceeds the arrangement level region 100 of the electromagnet 50 (for example, the lower portion 16b of the piston 16 is included in the arrangement level region 100 as shown in FIG. When the vibration state becomes an upper side exceeding 100.), the area of the magnetic path 26 is increased by a part of the piston 16 exceeding the arrangement level region 100 of the electromagnet 50. For this reason, since the amount of magnetic flux passing through the flow passage 20 increases, the viscosity change (ratio of increase in viscosity) of the magnetic fluid 6 passing through the flow passage 20 increases, and the vibration (about ± 7 mm) occurs. The damping force is 10 to 60 N (current 0 to 5 A) as shown in FIG. 4, and the damping force can be further increased as compared with the case where the vibration is small.

As described above, by changing the coil current, vibration with a small amplitude (corresponding to vibration during dehydration in a fully automatic washing machine) is absorbed by reducing the damping force, and vibration with a large amplitude ( For a fully automatic washing machine (corresponding to vibration at resonance), the damping force can be increased to suppress the vibration, and the characteristics required for the washing machine damper can be obtained with certainty.
Further, since the magnetic fluid 6 directly passes through the flow passage 20 and generates a damping force, the above-described conventional technique obtains the damping force by sliding resistance with respect to the piston and / or cylinder generated in a state where the magnetic fluid is sealed in the seal member. Compared to the above, the strength backup for the seal member becomes unnecessary, and the structure can be simplified correspondingly.
Further, since the piston and the cylinder do not slide, deterioration due to sliding is suppressed correspondingly, and durability is improved.

Next, a damper according to a second embodiment of the present invention will be described with reference to FIGS. 5 to 7, the damper 1 </ b> A includes two annular permanent magnets (first and second magnets) arranged in different positions in the longitudinal direction of the cylinder 2 instead of the electromagnet 50 as compared with the damper 1. The main difference is that 51 and 52 are provided, and that a piston 16A is provided instead of the piston 16.
The first and second permanent magnets 51 and 52 are annular and have different magnetic poles on the inner side and the outer side (in this embodiment, the inner side is the S pole and the outer side is the N pole).

The piston 16A includes a rod fitting cylinder portion 61 fitted to the piston rod 9, and a piston small diameter portion and large diameter portions 62, 63 extending radially outward at both ends of the piston fitting cylinder portion and having different diameter dimensions. It is made up of. The piston large diameter portion 63 slides on the cylinder 2. A plurality (four in this embodiment) of flow passages 20A are formed in the piston large diameter portion 63 in the circumferential direction. An annular gap 64 is formed between the piston small-diameter portion 62 and the cylinder 2 and constitutes the flow path 21A together with the flow path 20A.
In the initial state, the damper 1A has the piston 16A disposed at a substantially intermediate position between the first and second permanent magnets 51 and 52 as shown in FIG. 5 (the position where the piston 16A is disposed in this way is neutral for convenience). It is called position.) As the piston 16A reciprocates, the magnetic fluid 6 passes through the flow path 21A and generates a damping force.

In the damper 1A configured as described above, a magnetic field is not applied to the flow path 21A when the piston 16A is in the neutral position. For this reason, the viscosity of the magnetic fluid 6 passing through the flow path 21A is constant, and the generated damping force is not affected by the first and second permanent magnets 51 and 52.
Further, as shown in the left half of FIG. 7, when the damper 1 </ b> A contracts (the piston 16 </ b> A moves downward in FIG. 7) and exceeds a predetermined stroke, the magnetic field generated by the second permanent magnet 52 is generated in the annular gap 64. As a result, the viscosity of the magnetic fluid 6 flowing through the annular gap 64 increases, and the generated damping force changes (increases). Similarly, as shown in the right half of FIG. 7, the damping force also changes (increases) when the damper 1 </ b> A extends beyond a predetermined stroke.

As described above, when the vibration of the piston 16A is displaced near the neutral position, that is, when the amplitude of vibration acting on the piston rod 9 is small, the damping force is reduced to absorb the vibration,
When the piston 16A is displaced beyond a predetermined stroke, that is, when the amplitude of vibration acting on the piston rod 9 is large, the damping force can be increased to suppress the vibration. For this reason, the characteristic requested | required of a washing machine damper can be acquired reliably.
Further, since the magnetic fluid 6 directly passes through the flow path 21A and generates a damping force, the above-described conventional technique obtains the damping force by the sliding resistance with respect to the piston and / or cylinder by the sealing member in which the magnetic fluid is sealed in the sealing member. Compared to the above, the strength backup for the seal member becomes unnecessary, and the structure can be simplified correspondingly.

In the second embodiment, when the damper 1A is contracted, the entire piston 16A is magnetized through the piston large diameter portion 62 before the magnetic field is applied to the annular gap 64 as shown on the left side of FIG. This changes the viscosity of the magnetic fluid 6 passing through, so that the damping force characteristics on the expansion side and the contraction side may be different.
To solve this problem, as shown in FIG. 8, a piston 16B in which a piston sub-small diameter portion 62B is arranged so as to be symmetrical with the piston small-diameter portion 62 with a piston large-diameter portion 63 in between is used instead of the piston 16A. The damper 1B may be configured (third embodiment). In the damper 1B, an annular gap 64B is formed between the piston sub-small diameter portion 62B and the cylinder 2, and the passage 21B is configured by the annular gap 64B, the annular gap 64, and the flow passage 20A.

  According to the third embodiment, since the piston sub-small diameter portion 62B is disposed so as to be symmetrical with the piston small-diameter portion 62 with the piston large-diameter portion 63 in between, the damper 1B operates in a contracting manner even when the damper 1B is extended. Even in this case, an equivalent damping force can be obtained.

Further, as shown in FIG. 9, a piston 16C in which a piston sub-large diameter portion 63C is arranged so as to be symmetrical with the piston large diameter portion 63 with a piston small diameter portion 62 therebetween is used in place of the piston 16A. 1C may be configured (fourth embodiment). In this case, the piston sub-large diameter portion 63C forms the flow passage 20C. In the damper 1C, a channel 21C is constituted by the annular gap 64, the flow passage 20A, and the flow passage 20C.
In the fourth embodiment, similar to the third embodiment, the same damping force can be obtained even when the damper 1C is extended and contracted.

Next, a fifth embodiment of the present invention will be described with reference to FIGS.
10 and 11, the damper 1D has a piston 16D that replaces the piston 16C of FIG. 9, and the piston 16D has a flow passage 20D between the piston main body 65 that connects the piston rod 9 and the piston main body 65. A piston annular portion 66 formed and arranged and slid on the cylinder 2, and a plurality (four in this example) of bridging the piston annular portion 66 and the piston body 65 to hold the piston annular portion 66 on the piston body 65 And a bridge portion 67 made of a nonmagnetic material.

  The damper 1D of the fifth embodiment has a simple configuration as compared to the damper 1C (fourth embodiment), and has the same function as the damper 1C (when the damper 1D operates to expand or contract, Equivalent damping force can be obtained.) Further, by providing the bridge portion 67 made of a non-magnetic material, the magnetic field generated by the first and second permanent magnets 51 and 52 is likely to act on the magnetic fluid 6 in the flow path 20D. Change can be obtained.

Next, a sixth embodiment of the present invention will be described with reference to FIGS.
12 to 14, the damper 1E replaces the cylindrical body 7 with a nonmagnetic material (a material that is not easily affected by a magnetic field having a low magnetic permeability), as compared with the damper 1A (second embodiment) in FIG. A cylindrical body 7E having two notches 72L, 72R, 73L, 73R formed in two upper and lower annular regions 70, 71 defined along the axial direction. Instead of the cylindrical body 7E, and arcuate bodies 74L, 74R, 75L, 75R made of a magnetic material that are fitted into the cutout portions 72L, 72R, 73L, 73R and fixed to the cylindrical body 7E, In place of the annular first and second permanent magnets 51 and 52, a plurality of rod-shaped (two in this example) upper permanent magnets 51E (hereinafter, each of them is appropriately referred to as an upper side). Left and right permanent magnets 51EL and 51ER .) And a plurality of rod-like (in this example, two) lower permanent magnets 52E (hereinafter appropriately referred to as the lower left and right permanent magnets 52EL and 52ER), respectively, and instead of the piston 16. The main difference is that the piston 16E is provided.

The notch 72L and the notch 72R are formed facing the left and right as shown in FIG. 12, and the notch 73L and the notch 73R are also formed facing the left and right as shown in FIG.
The upper left permanent magnet 51EL is suspended from the arcuate body 74L and is held with the north pole facing the arcuate body 74L. The upper right permanent magnet 51ER is suspended from the arcuate body 74R and is held with the south pole facing the arcuate body 74R. The lower left permanent magnet 52EL is suspended from the arcuate body 75L and is held with the north pole facing the arcuate body 75L. The lower right permanent magnet 52ER is suspended from the arcuate body 75R and is held with the south pole facing the arcuate body 75R. By arranging the permanent magnets as described above, for example, as shown in FIG. 13, a magnetic field (magnetic flux F) in a direction (left and right direction in FIG. 13) perpendicular to the longitudinal direction (front and back direction of the paper) of the cylinder 2E is obtained. And a magnetic field acts on the magnetic fluid 6. For example, as shown in FIG. 13, a magnetic field is generated from the lower left permanent magnet 52EL toward the lower right permanent magnet 52ER.

  The piston 16E is fitted to one end portion 9a of the piston rod 9 and fixed to the annular guide member 17E, which slides on the cylinder 2E, and a male screw provided at the tip of the one end portion 9a of the piston rod 9. A piston main body 18E that is screwed into (not shown) and fixed to the piston rod 9. The guide member 17E is made of a nonmagnetic material, and the piston body 18E is made of a magnetic material.

  The outer diameter dimension of the piston body 18E is smaller than the inner diameter dimension of the cylinder 2E, and a gap 19E is formed between the piston body 18E and the cylinder 2E. A plurality of notch-shaped flow passages 20E are formed in the outer peripheral portion of the guide member 17E in the circumferential direction so that the magnetic fluid 6 flows between the upper chamber 3a and the lower chamber 3b through the gap 19E and the flow passage 20E. It has become. A flow path 21E is constituted by the gap 19E and the flow path 20E.

  In the initial state, the damper 1E has an annular portion (nonmagnetic material) including a portion between the upper permanent magnet 51E and the lower permanent magnet 52E in the cylindrical body 7E (hereinafter referred to as a cylindrical intermediate portion) as shown in FIG. It is called 7E1. ], The piston 16E is arranged so that the center P1 of the piston body 18E substantially coincides with the axial center K1 (neutral position of the piston 16E). As the piston 16E reciprocates, the magnetic fluid 6 passes through the flow path 21E and generates a damping force.

  In the damper 1E configured as described above, the movable portion (not shown) connected to the piston rod 9 vibrates with respect to the fixed portion (not shown) connected to the cylinder 2E in the initial state, and the piston rod 9 is pivoted. When receiving a large force in the direction, the piston 16E vibrates, for example, around the cylindrical body intermediate portion 7E1. If the vibration amplitude of the piston 16E is sufficiently large, the piston 16E moves to a portion facing the upper permanent magnet 51E or the lower permanent magnet 52E. With the movement of the piston 16E described above, the arrangement state of the piston 16E (having the piston main body 18E made of a magnetic material) with the cylinder 2E in between with respect to the permanent magnet (the upper permanent magnet 51E or the lower permanent magnet 52E). Changes, and the magnitude of the magnetic field acting on the magnetic fluid 6 changes. For this reason, the viscosity of the magnetic fluid 6 changes, and the magnitude of the damping force acting on the piston 16E changes.

  For example, as shown in FIGS. 12 and 15, the piston body 18 is in the middle of the cylindrical body so that the center P <b> 1 of the piston body 18 </ b> E coincides with the center K <b> 1 of the cylindrical body middle portion 7 </ b> E (position of the horizontal axis 0 in FIG. 15). When facing the portion 7E1, since there is no magnetic path in the vicinity of the piston body 18E, the magnetic flux generated by the permanent magnet (upper permanent magnet 51E or lower permanent magnet 52E) is applied to the piston 16E (piston body 18E). Hardly flows, the magnetic field applied to the magnetic fluid 6 existing in the flow path 21E is small, and the generated damping force is small as shown in the vicinity of the vertical axis T in FIG.

Then, as shown in FIG. 14, the piston 16E moves further from the upper side to the lower side in FIG. 12 (contraction operation), and the piston main body 18E enters the arrangement area of the lower permanent magnet 52E, for example, the center P1 of the piston main body 18E. Is over the upper end G0 of the lower permanent magnet 52E, as shown in FIGS. 12 and 13, the portion between the arcuate bodies 75L and 75R (magnetic material) in the cylindrical body 7E (hereinafter referred to as the lower arcuate shape). Since there is an interbody part) 7E2 (nonmagnetic material), the magnetic flux F generated by the lower left permanent magnet 52EL passes through the arcuate body 75L (magnetic material) almost vertically, and the cylindrical body 7E ( Without being transmitted to the nonmagnetic material (that is, without making a detour), it is transmitted to the arcuate body 75R (magnetic material) via the piston body 18E and flows to the lower right permanent magnet 52ER.
Therefore, when the magnetic field is applied to the flow path 21E, the viscosity of the magnetic fluid 6 existing in the flow path 21E is increased, and the damping force is large as shown in the vicinity of the upper end G0 of the lower permanent magnet 52E in FIG. Become.

Further, the piston 16E moves downward in FIG. 14, and the maximum damping force is generated with the entire surface of the piston main body 18E facing the lower permanent magnet 52E. Thereafter, the piston 16E further moves downward in FIG. As a result, the damping force generated as the area facing the permanent magnet 15 decreases is reduced.
Also, when the piston 16E moves upward in FIG. 12 (in FIG. 15, the piston 16E moves from right to left), the magnitude of the damping force accompanying the movement of the piston 16E is the above-described FIG. It will change almost the same as the case of the downward movement.

  Next, a damper according to a seventh embodiment of the present invention will be described with reference to FIGS. 16 to 18, the damper 1F is provided with first and second permanent magnets 51F and 52F in place of the first and second permanent magnets 51 and 52 as compared with the damper 1A. The second permanent magnets 51F and 52F are annular first and second permanent magnet bodies 51F1 and 52F1 that generate magnetic force and are inserted into the cylindrical body 7, and the outer peripheral portions of the first and second permanent magnet bodies 51F1 and 52F1. The first and second cases 51F2 and 52F2 made of a magnetic material are provided so as to cover the main body, and the piston 16F is provided instead of the piston 16A.

  The piston 16F is a piston made of a nonmagnetic material that is fitted into one end portion 9a of the piston rod 9 and fixed to the piston rod 9 and slides on the cylinder 2, and a non-magnetic material inserted into the one end portion 9a of the piston rod 9. The main body 18F includes a guide member 17F and a nut 32 that fixes the piston main body 18F to the piston rod 9 by screwing with a male screw (reference numeral omitted) formed at the tip of the one end 9a of the piston rod 9.

  The outer diameter of the piston main body 18F is smaller than the inner diameter of the cylinder 2, and a gap 19F is formed between the piston main body 18F and the cylinder 2. A plurality of notch-shaped flow passages 20F are formed in the outer peripheral portion of the guide member 17F in the circumferential direction so that the magnetic fluid 6 flows between the upper chamber 3a and the lower chamber 3b through the gap 19F and the flow passage 20F. It has become. A flow path 21F is constituted by the gap 19F and the flow path 20F.

  In the initial state, the damper 1F has a piston 16F disposed at a substantially intermediate position between the first and second permanent magnets 51F and 52F as shown in FIGS. 16 and 19 (for convenience, the position where the piston 16F is disposed is It is called a neutral position.) As the piston 16F reciprocates, the magnetic fluid 6 passes through the flow path 21F and generates a damping force. When the piston 16F reciprocates in the region including the neutral position, as shown in the neutral position portion of FIG. 19, the generated damping force is small, and the piston 16F has the first, second permanent magnets 51F, As the area approaches 52F and the facing area increases (with the transition from the neutral position to the left and right in FIG. 19), the damping force increases.

The damper 1F configured as described above does not apply a magnetic field to the flow path 21F when the piston 16F is in the neutral position. For this reason, the viscosity of the magnetic fluid 6 passing through the flow path 21F is constant, and the generated damping force is not affected by the first and second permanent magnets 51F and 52F.
When the piston 16F moves downward in FIG. 16 (contraction operation) and approaches the second permanent magnet 52F as shown in FIG. 17, the magnetic field applied to the flow path 21F gradually increases, and the viscosity of the magnetic fluid 6 increases. It gradually increases, and the damping force gradually increases as shown in the left part of FIG. As shown in FIG. 18, when the center of the piston 16F reaches the center position in the axial direction of the second permanent magnet 52F, the magnitude of the magnetic field becomes maximum, and the viscosity and thus the damping force reaches the maximum value as shown in FIG. Will be shown. Even when the piston 16F moves upward (extends) in FIG. 16, the damping force can be changed according to the movement position (displacement) of the piston 16F, as in the case of the contraction operation described above.

  As described above, the timing for increasing the damping force can be easily changed by using permanent magnets having different axial heights for the first and second permanent magnets 51F and 52F, and the degree of design freedom is increased accordingly. be able to. For example, by using a permanent magnet having a large axial height dimension, as shown by the dotted line F1a of the variable F1 in FIG. 19, the timing for increasing the damping force can be advanced, and the axial height can be increased. By using a permanent magnet having a small size, the timing for increasing the damping force can be delayed as indicated by the one-dot chain line F1b of the variable F1 in FIG.

  Further, the maximum value of the damping force can be easily changed by using permanent magnets having different magnetic forces for the first and second permanent magnets 51F and 52F, and the degree of design freedom can be increased accordingly. For example, by using a permanent magnet having a large magnetic force, the maximum value of the damping force can be increased as shown by the alternate long and short dash line F2b of the variable F2 in FIG. By using a small permanent magnet, the maximum value of the damping force can be made smaller than that of the dotted line F2b as shown by the dotted line F2a of the variable F2 in FIG.

  In the damper 1F (seventh embodiment), the magnet is composed of the first and second permanent magnets 51F and 52F. However, the present invention is not limited to this, and a plurality of permanent magnets are connected to the cylinder 2. The position may be shifted in the axial direction. For example, as shown in FIG. 20, a damper 1G that replaces the damper 1F may be configured by providing a third permanent magnet 80G so as to be between the first and second permanent magnets 51F and 52F (first). 8 embodiment). Similar to the first permanent magnet 51F, the third permanent magnet 80G includes a third permanent magnet body 80G1 and a third case 80G2. In this embodiment, the position where the piston 16F faces the third permanent magnet 80G is the neutral position.

In the damper 1G (eighth embodiment), as shown in FIG. 21, a certain amount of damping force can be secured in the region including the neutral position, and the damping force is small in the region including the neutral position of the seventh embodiment. It is possible to reduce the instability (flickering) of the movement of the piston 16 </ b> F that may occur. Furthermore, the damping force can be adjusted at the arrangement position of the third permanent magnet 80G in addition to the arrangement positions of the first and second permanent magnets 51F and 52F, and the damping force adjustment according to the displacement of the piston 16F can be further performed. Highly accurate and can be performed over a wide range.
Further, as with the damper 1F (seventh embodiment), as shown in the variable G1 in FIG. 21, the timing for increasing the damping force can be easily changed by using permanent magnets having different axial heights. . Also, the maximum value of the damping force can be easily changed by using permanent magnets having different magnitudes of magnetic force, as shown in FIG. 21 variable G2, similarly to the damper 1F (seventh embodiment).

  Next, a damper according to a ninth embodiment of the present invention will be described with reference to FIGS. 22 to 25, the damper 1H is provided with first and second permanent magnets 51H and 52H instead of the first and second permanent magnets 51F and 52F as compared with the damper 1F. The second permanent magnets 51H and 52H are separately covered with a case 54H made of a magnetic material, covered with an extension rod 81 made of a magnetic material instead of the nut 32, and replaced with the piston 16F. The main difference is that the piston 16H composed of the guide member 17F and the piston body 18F is constructed.

  The cylindrical body 7H (cylinder 2H) and the piston rod 9H of the damper 1H according to the ninth embodiment are made of a magnetic material. The first and second permanent magnets 51H and 52H have different magnetic poles on the upper and lower sides in FIG. 22, and in this embodiment, the first permanent magnet 51H has the N pole on the upper side in FIG. In the permanent magnet 52H, the upper side in FIG.

The case 54H has an annular upper case space 85 formed between the case upper body 82 and the case intermediate body 83 by overlapping the case upper body 82, the case intermediate body 83, and the case lower body 84, which are each annular. An annular lower case space 86 is formed between the intermediate body 83 and the case lower body 84, and is configured. First and second permanent magnets 51H and 52H are accommodated in the upper and lower case spaces 85 and 86, respectively.
In the damper 1H, a state where the piston main body 18F is disposed between the case intermediate bodies 83 is a neutral position of the piston 16H.

  In the damper 1H configured as described above, as shown in FIG. 23, when the piston 16H slides between the first permanent magnet 51H and the second permanent magnet 52H, the N pole of the first permanent magnet 51H. A part of the magnetic flux F generated from the second permanent magnet 52H and a part of the magnetic flux F generated from the N pole of the second permanent magnet 52H are the cylinder 2H, the magnetic fluid 6, the piston rod 9H, the extension rod 81, and the flow path 20F (flow path 21F). After passing through, go to each S pole. At this time, since the amount of magnetic flux passing through the flow path 20F (flow path 21F) is small, the viscosity of the magnetic fluid 6 flowing through the flow path 20F (flow path 21F) is low as shown in the region including the neutral position in FIG. In the region including the neutral position, the generated damping force is small.

  As shown in FIG. 24, when the piston 16H slides to the position of the second permanent magnet 52H (contraction stroke), the magnetic flux F generated from the N pole of the second permanent magnet 52H is flow path 20F (flow path 21F). Pass through to the south pole. In addition, a part of the magnetic flux F generated from the N pole of the first permanent magnet 51H passes through the cylinder 2H, the magnetic fluid 6, the piston rod 9H, and the piston 16H toward the flow passage 20F (flow passage 21F). Since the amount of magnetic flux at this time is greater than when the piston 16H is in the neutral position (FIG. 23), the viscosity of the magnetic fluid 6 flowing through the flow passage 20F (flow passage 21F) is the left portion (contraction side) of FIG. The damping force generated in the contraction stroke is increased as shown in FIG.

  Further, as shown in FIG. 25, when the piston 16H slides to the position of the first permanent magnet 51H (extension stroke), the magnetic flux F generated from the N pole of the first permanent magnet 51H is changed to the flow path 20F (flow path). 21F) to the south pole. In addition, a part of the magnetic flux F generated from the N pole of the second permanent magnet 52H passes through the cylinder 2H, the magnetic fluid 6, the extension rod 81, and the piston 16H toward the flow passage 20F (flow passage 21F). Here, the amount of magnetic flux becomes the same amount as that during the contraction stroke of FIG. 24 due to the influence of the extension rod 81, so the viscosity of the magnetic fluid 6 flowing through the flow passage 20F (flow passage 21F) is the right side portion (extension side) of FIG. As shown in FIG. 6, the damping force increases in the same manner as in the contraction stroke (the left portion in FIG. 26), and the damping force generated in the expansion stroke increases.

As described above, the extension rod 81 attached to the lower portion of the piston 16H further increases the influence of the magnet (second permanent magnet 52H) on the lower chamber 3b side of the piston 16H on the flow passage 20F (flow passage 21F). As a result, the flow of the magnetic flux F that is biased in the expansion / contraction stroke becomes uniform throughout, and the change in the viscosity of the magnetic fluid 6 passing through the flow path 20F (flow path 21F) also changes to the same extent. As a result, the same damping force can be generated in both the expansion and contraction strokes of the piston 16H, and stable characteristics can be obtained.
Further, since the number of extension rods 81 is increased, the amount of the magnetic fluid 6 sealed in the cylinder 2H can be suppressed, and the cost of the apparatus can be reduced.
Moreover, since there are few sliding parts, durability can be improved.

  The piston rod 9H is made of a magnetic material. However, only the length equivalent to the extension rod 81 on the piston 16H side (one end 9a side) is made of a magnetic material, and the other end 9b side is made of a nonmagnetic material. With this configuration, it is possible to make the damping force characteristics generated at the time of expansion and contraction closer to each other.

In the ninth embodiment, the first and second permanent magnets 51H and 52H are exemplified as different magnetic poles on the upper side and the lower side in FIG. You may make it become a different magnetic pole by the side. For example, as shown in FIG. 27, the first and second permanent magnets 51H and 52H may have N poles on the inner side and S poles on the outer side (tenth embodiment).
In each of the above-described embodiments, the example in which the magnet is attached to the outer peripheral surface of the cylinder has been described. However, the present invention is not limited to this. A part of the cylinder may be a magnet, or a hole may be provided in the cylinder. The magnet may be inserted in such a manner that one end of the magnet is substantially flush with the inner peripheral surface of the cylinder, a lid is provided in the hole, and a magnet is provided in the cylinder chamber.

It is sectional drawing which shows the damper which concerns on 1st Embodiment of this invention. It is a figure which shows typically the flow of the magnetic flux when the displacement amount of the damper of FIG. 1 is small. It is a figure which shows typically the flow of magnetic flux when the displacement amount of the damper of FIG. 1 becomes large to some extent or more. It is a figure which shows the relationship between the electric current of the electromagnet of FIG. 1, and the damping force to generate | occur | produce. It is sectional drawing which shows the damper which concerns on 2nd Embodiment of this invention. It is a top view which shows the piston of FIG. It is a figure for demonstrating the action | operation of the damper of FIG. It is sectional drawing for demonstrating the damper of 3rd Embodiment of this invention. It is sectional drawing for demonstrating the damper of 4th Embodiment of this invention. It is sectional drawing for demonstrating the damper of 5th Embodiment of this invention. It is a top view which shows the piston of FIG. It is sectional drawing for demonstrating the damper of 6th Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is sectional drawing for demonstrating the action | operation in the compression process of the damper of FIG. It is a figure which shows the relationship between the piston displacement of the damper of FIG. 12, and the damping force to generate | occur | produce. It is sectional drawing for demonstrating the damper which concerns on 7th Embodiment of this invention. It is a figure which shows typically the flow of the magnetic flux when the piston of FIG. 16 begins to face a magnet. It is a figure which shows typically the flow of the magnetic flux at the time of the whole surface of the piston of FIG. 16 facing the magnet. It is a figure which shows the relationship between the displacement of the piston of FIG. 16, and the damping force to generate | occur | produce. It is sectional drawing which shows the damper which concerns on 8th Embodiment of this invention. It is a figure which shows the relationship between the displacement of the piston of FIG. 20, and the damping force to generate | occur | produce. It is sectional drawing which shows the damper which concerns on 9th Embodiment of this invention. It is a figure which shows typically the flow of magnetic flux when the piston of FIG. 22 exists in a neutral position. It is a figure which shows typically the flow of the magnetic flux at the time of the contraction stroke of the piston of FIG. It is a figure which shows typically the flow of the magnetic flux at the time of the expansion stroke of the piston of FIG. It is a figure which shows the relationship between the piston displacement of the damper of FIG. 22, and damping force. It is sectional drawing which shows the damper which concerns on 10th Embodiment of this invention.

Explanation of symbols

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H ... damper, 2 ... cylinder, 3a ... upper chamber, 3b ... lower chamber, 6 ... magnetic fluid, 7 ... cylindrical body, 16 ... piston, 20 ... flow path (flow path), 50 ... electromagnet.

Claims (6)

  A cylinder filled with a fluid whose viscosity is changed by a magnetic field, a piston made of a magnetic material slidably housed in the cylinder so as to define the inside of the cylinder in an upper chamber and a lower chamber, and one end of the piston in the piston A piston rod that is connected and has the other end extending to the outside of the cylinder, a flow path provided in the piston to allow the flow of the fluid between the upper chamber and the lower chamber, and provided in the cylinder And a magnet.   The damper according to claim 1, wherein the magnet includes a plurality of magnets arranged in a longitudinal direction of the cylinder. The cylinder has one or a plurality of cutout portions formed in one or a plurality of annular regions defined along the axial direction, and is fitted into the cutout portion and a cylindrical body made of a material having a low magnetic permeability. An arcuate body made of a material having a higher magnetic permeability than the tubular body fixed to the tubular body,
The damper according to claim 1, wherein the magnet includes one or a plurality of magnets held by the arcuate body.   The piston includes a piston main body that connects the piston rod, a piston annular portion that is disposed with the flow path formed between the piston main body and slides on the cylinder, and the piston annular portion is connected to the piston main body. The damper according to any one of claims 1 to 3, further comprising a bridge portion to be held.   5. The piston rod according to claim 1, wherein at least one end portion is made of a magnetic material, and an extension rod made of a magnetic material is provided on the opposite side of the piston to the piston rod. The listed damper. The damper according to any one of claims 1 to 5, wherein the magnet is an electromagnet.

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