JPWO2018180363A1 - Cylinder device - Google Patents

Abstract

Each flow path 20 through which the electrorheological fluid 2 in the inner cylinder electrode 3 flows by the movement of the piston rod 9 from the upstream side to the downstream side in the axial direction is provided between the inner cylinder electrode 3 and the outer cylinder electrode 18. Have been. Further, an introduction section 21 for introducing the electrorheological fluid 2 from the inner cylinder electrode 3 toward each flow path 20 is provided. In addition, the electric field intensity applied to the electrorheological fluid 2 in the introduction section 21 of each flow path 20 is smaller than the electric field strength after passing through the introduction section 21 in the vicinity of the introduction section 21 of each flow path 20. Is provided with a spacer 22 as an electric field strength lowering member made of an insulator or a high resistance material.

Description

  The present invention relates to a cylinder device suitably used for buffering vibration of a vehicle such as an automobile or a railway vehicle.

  Generally, in a vehicle such as an automobile, a cylinder device represented by a hydraulic shock absorber is provided between a vehicle body (on a spring) side and each wheel (under a spring) side. Here, in Patent Document 1, in a damper (buffer) using an electrorheological fluid, an electrorheological fluid whose properties change due to an electric field flows in a flow path between the inner cylinder electrode and the outer cylinder electrode. The structure to perform is disclosed.

International Publication No. 2014/135183

  By the way, in the cylinder device disclosed in Patent Document 1, an electrorheological fluid that maintains high fluidity in the inner cylinder electrode because there is no influence by the electric field is in a state where the viscosity is greatly increased by the action of the electric field. It is rapidly introduced into the flow path having poor fluidity. For this reason, there is a problem that due to the difference in fluidity, the flow velocity locally increases near the boundary between the inner cylinder electrode and the flow path, causing cavitation, and the flow of the electrorheological fluid is disturbed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to obtain a stable damping force by smoothly flowing an electrorheological fluid near the boundary between the inner cylinder electrode and the flow path. It is an object of the present invention to provide a cylinder device that can perform the above.

  One embodiment of the present invention is a cylinder device in which an electrorheological fluid whose fluid properties are changed by an electric field is sealed and a rod is inserted therein, and an inner cylinder electrode serving as electrodes having different potentials, and the inner cylinder An outer cylinder electrode provided outside the electrode, and is formed between the inner cylinder electrode and the outer cylinder electrode, and the electrorheological fluid flows by movement of the rod from one end side to the other end side in the axial direction. And an introduction part for introducing the electrorheological fluid into the flow path, and the electric field strength applied to the electrorheological fluid in the introduction part of the flow path is determined by the introduction part. An electric field strength reducing member made of an insulator or a high resistance material is provided in the vicinity of the introduction portion of the flow path so as to be smaller than the electric field strength after passing.

  According to the cylinder device according to an embodiment of the present invention, the electrorheological fluid can be smoothly circulated near the boundary between the inner cylinder electrode and the flow path, and a stable damping force can be obtained.

It is a longitudinal cross-sectional view which shows the shock absorber as a cylinder apparatus by 1st Embodiment. It is a longitudinal cross-sectional view which expands and shows the A section in FIG. It is a longitudinal cross-sectional view which shows a spacer alone. It is the longitudinal cross-sectional view which looked at the outer cylinder electrode and spacer by 2nd Embodiment from the same position as FIG. 2 with the inner cylinder electrode.

  Hereinafter, a cylinder device according to an embodiment of the present invention will be described with reference to the accompanying drawings, taking as an example a case where the cylinder device is applied to a shock absorber provided in a vehicle such as a four-wheeled vehicle.

  1 to 3 show a first embodiment of the present invention. In FIG. 1, a shock absorber 1 as a cylinder device is configured as a damping force-adjustable hydraulic shock absorber (semi-active damper) using an electrorheological fluid 2 containing hydraulic oil or the like enclosed therein. The shock absorber 1 constitutes a suspension device for a vehicle together with a suspension spring (not shown) made of, for example, a coil spring. In the following description, one end side of the shock absorber 1 in the axial direction is referred to as the “upper end” side, and the other end side in the axial direction is referred to as the “lower end” side. The other end side in the axial direction may be the “upper end” side.

  The shock absorber 1 includes an inner cylinder electrode 3, an outer cylinder 4, a piston 6, a piston rod 9, a rod guide 10, a bottom valve 13, an outer cylinder electrode 18, a flow path 20, an introduction part 21, and an upper spacer 22. ing.

  The inner cylinder electrode 3 is formed as a cylindrical body extending in the axial direction, and the electrorheological fluid 2 is sealed inside. A piston rod 9 is inserted inside the inner cylinder electrode 3, and the outer cylinder 4 and the outer cylinder electrode 18 are provided outside the inner cylinder electrode 3 so as to be coaxial.

  The lower end side of the inner cylinder electrode 3 is fitted and attached to the valve body 14 of the bottom valve 13, and the upper end side is fitted and attached to the rod guide 10. The inner cylinder electrode 3 is provided with a plurality of introduction portions 21 which will be described later, located on the upper side in the vicinity of the rod guide 10. Further, on the outer peripheral side of the inner cylindrical electrode 3, a plurality of partition walls 19 to be described later are provided spirally. Here, the inner cylinder electrode 3 is made of a material serving as a conductor, and is configured as a negative electrode. The inner cylinder electrode 3 is electrically connected to the negative electrode of the battery 25 through an outer cylinder 4, a rod guide 10, a bottom valve 13 and the like which will be described later.

  The outer cylinder 4 forms an outer shell of the shock absorber 1 and is formed as a cylindrical body by a material serving as a conductor. The outer cylinder 4 is provided on the outer periphery of the inner cylinder electrode 3 and the outer cylinder electrode 18, and forms a reservoir chamber A communicating with the flow path 20 between the outer cylinder electrode 18. In this case, the lower end side of the outer cylinder 4 is a closed end by fixing the bottom cap 5 using welding means or the like.

  On the other hand, the upper end side of the outer cylinder 4 is an open end. On the opening end side of the outer cylinder 4, for example, a caulking portion 4 </ b> A is formed to be bent inward in the radial direction. The caulking portion 4A holds the outer peripheral side of the annular plate body 12A of the seal member 12 in a retaining state.

  Here, the inner cylinder electrode 3 and the outer cylinder 4 constitute a cylinder, and an electrorheological fluid 2 (ERF: Electro Rheological Fluid) is sealed in the cylinder. In FIGS. 1 and 2, the encapsulated electrorheological fluid 2 is shown as colorless and transparent.

  The electrorheological fluid 2 changes its properties depending on the electric field (voltage). That is, the viscosity of the electrorheological fluid 2 changes according to the applied voltage, and the flow resistance (damping force) changes. The electrorheological fluid 2 is composed of, for example, a base oil (base oil) made of silicon oil or the like, and particles (fine particles) mixed (dispersed) in the base oil to change the viscosity according to changes in the electric field. ing.

  As will be described later, the shock absorber 1 generates a potential difference in the flow path 20 between the inner cylinder electrode 3 and the outer cylinder electrode 18 and controls the viscosity of the electrorheological fluid 2 passing through the flow path 20. Thus, the generated damping force is controlled (adjusted).

  An annular reservoir chamber A is formed between the inner cylinder electrode 3 and the outer cylinder 4, more specifically, between the outer cylinder electrode 18 and the outer cylinder 4. In the reservoir chamber A, a gas serving as a working gas is sealed together with the electrorheological fluid 2. This gas may be atmospheric pressure air or a compressed gas such as nitrogen gas. The gas in the reservoir chamber A is compressed to compensate for the entry volume of the piston rod 9 when the piston rod 9 is contracted (contraction stroke).

  The piston 6 is slidably provided in the inner cylinder electrode 3. The piston 6 partitions the inside of the inner cylinder electrode 3 into a rod side oil chamber B located on the upper side and a bottom side oil chamber C located on the lower side. The piston 6 is formed with a plurality of oil passages 6A and 6B that allow the rod-side oil chamber B and the bottom-side oil chamber C to communicate with each other in the circumferential direction.

  Here, the shock absorber 1 according to the embodiment has a uniflow structure. For this reason, the electrorheological fluid 2 in the inner cylinder electrode 3 is always directed toward the flow path 20 from the rod-side oil chamber B through the introduction portion 21 described later in both the contraction stroke and the extension stroke of the piston rod 9. It circulates in the direction (direction of arrow F in FIG. 2).

  In order to realize such a uniflow structure, the upper end surface of the piston 6 is opened when, for example, the piston 6 is slid downward in the inner cylinder electrode 3 during the reduction stroke (contraction stroke) of the piston rod 9. In other cases, there is provided a contraction-side check valve 7 that closes. The contraction-side check valve 7 allows the electrorheological fluid 2 in the bottom side oil chamber C to flow in each oil passage 6A toward the rod side oil chamber B, and the electrorheological fluid 2 in the opposite direction. Is prevented from flowing. That is, the compression side check valve 7 allows only the flow of the electrorheological fluid 2 from the bottom side oil chamber C to the rod side oil chamber B.

  On the lower end surface of the piston 6, for example, an extension-side disc valve 8 is provided. When the piston 6 slides upward in the inner cylinder electrode 3 during the extension stroke (elongation stroke) of the piston rod 9, the extension-side disc valve 8 causes the pressure in the rod-side oil chamber B to reach the relief set pressure. When it exceeds, the valve is opened, and the pressure at this time is relieved to the bottom side oil chamber C side through each oil passage 6B.

  The piston rod 9 as a rod is axial in the inner cylinder electrode 3 (the axial direction of the inner cylinder electrode 3 and the outer cylinder 4, that is, the same direction as the central axis of the shock absorber 1, and upward and downward in FIG. 1). It extends to. The lower end of the piston rod 9 is connected (fixed) to the piston 6 in the inner cylinder electrode 3, and the upper end extends through the rod-side oil chamber B to the outside of the inner cylinder electrode 3 and the outer cylinder 4. In this case, the piston 6 is fastened to the lower end side of the piston rod 9 using a nut 9A or the like. On the other hand, the upper end side of the piston rod 9 protrudes outside through the rod guide 10. The lower end of the piston rod 9 may be further extended to be a double rod type shock absorber that protrudes outward from the bottom portion (for example, the bottom cap 5) side.

  The rod guide 10 is provided to be fitted to the upper ends of the inner cylinder electrode 3 and the outer cylinder 4. The rod guide 10 is formed as a stepped cylindrical body and closes the upper ends of the inner cylinder electrode 3 and the outer cylinder 4. The rod guide 10 supports the piston rod 9 and is formed, for example, as a cylindrical body having a predetermined shape by performing molding processing, cutting processing, or the like on a metal material, a hard resin material, or the like. In this case, the rod guide 10 can be formed using a material made of an insulator, a dielectric, a high resistance, or the like, for example, a resin material, when a valve body 14 described later is a metal material (conductor). The rod guide 10 positions the upper part of the inner cylinder electrode 3 and the upper part of the outer cylinder electrode 18 at the center of the outer cylinder 4. At the same time, the rod guide 10 guides (guides) the piston rod 9 so as to be slidable in the axial direction on the inner peripheral side thereof.

  Here, the rod guide 10 is positioned on the upper side and is inserted into the inner peripheral side of the outer cylinder 4, and the inner diameter of the inner cylindrical electrode 3 is positioned on the lower end side of the large diameter part 10 </ b> A. It is formed by the small diameter part 10B inserted by the side. A guide bush 11 that guides the piston rod 9 so as to be slidable in the axial direction is inserted into the inner peripheral side of the small-diameter portion 10B of the rod guide 10. The guide bush 11 is formed, for example, by applying a tetrafluoroethylene coating to the inner peripheral surface of a metal cylinder. Further, on the outer peripheral side of the small diameter portion 10B, an upper spacer 22 described later is provided below the large diameter portion 10A.

  An annular seal member 12 is provided between the large diameter portion 10 </ b> A of the rod guide 10 and the caulking portion 4 </ b> A of the outer cylinder 4. The seal member 12 includes an annular plate body 12A made of a metallic annular plate that is in contact with the upper surface of the large diameter portion 10A, and an elastic member fixed to the inner diameter side of the annular plate body 12A by means such as baking. And an elastic body 12B made of a resin material having The seal member 12 is sealed (sealed) between the piston rod 9 and the piston rod 9 in a liquid-tight and air-tight manner when the inner peripheral side of the elastic body 12B is in sliding contact with the outer peripheral surface of the piston rod 9.

  On the lower end side of the inner cylinder electrode 3, a bottom valve 13 is provided between the inner cylinder electrode 3 and the bottom cap 5. The bottom valve 13 communicates or blocks the bottom side oil chamber C and the reservoir chamber A. For this purpose, the bottom valve 13 includes a valve body 14, an extension-side check valve 15 and a disc valve 16. The valve body 14 partitions the reservoir chamber A and the bottom oil chamber C between the bottom cap 5 and the inner cylinder electrode 3.

  In the valve body 14, oil passages 14 </ b> A and 14 </ b> B that allow the reservoir chamber A and the bottom side oil chamber C to communicate with each other are formed at intervals in the circumferential direction. A step portion 14C is formed on the upper surface side of the valve body 14, and the lower end of the inner cylinder electrode 3 is fitted and fixed to the step portion 14C. An annular lower spacer 17 is fitted and attached to the stepped portion 14 </ b> C on the outer peripheral side of the inner cylindrical electrode 3. Here, when the rod guide 10 described above is a metal material (conductor), the valve body 14 may be formed using a material made of an insulator, a dielectric, a high resistance, or the like, for example, a hard resin material. it can.

  The extension check valve 15 is provided on the upper surface side of the valve body 14, for example. The extension-side check valve 15 opens when the piston 6 slides upward in the extension stroke of the piston rod 9, and closes at other times. The extension side check valve 15 allows the electrorheological fluid 2 in the reservoir chamber A to flow through each oil passage 14A toward the bottom side oil chamber C, and the electrorheological fluid 2 flows in the opposite direction. To prevent it. That is, the extension side check valve 15 allows only the flow of the electrorheological fluid 2 from the reservoir chamber A side to the bottom side oil chamber C side.

  The reduction-side disc valve 16 is provided on the lower surface side of the valve body 14, for example. The disc valve 16 on the reduction side opens when the pressure in the bottom side oil chamber C exceeds the relief set pressure when the piston 6 slides downward in the reduction stroke of the piston rod 9, and the pressure at this time Is relieved to the reservoir chamber A side through each oil passage 14B.

  The lower spacer 17 holds the lower end side of the outer cylindrical electrode 18 in a state of being positioned in the axial direction and the radial direction. The lower spacer 17 is formed as an insulator or a high resistance body by using, for example, an electrically insulating material (isolator), and between the inner cylinder electrode 3 and the outer cylinder electrode 18, between the valve body 14 and the outer cylinder electrode 18, Are electrically insulated from each other. The lower spacer 17 is formed with a plurality of oil passages 17A that allow the flow passage 20 to communicate with the reservoir chamber A.

  The outer cylinder electrode 18 is provided outside the inner cylinder electrode 3 so as to surround the inner cylinder electrode 3. The outer cylinder electrode 18 is formed by a pressure tube that is positioned between the inner cylinder electrode 3 and the outer cylinder 4 and extends in the axial direction. The outer cylinder electrode 18 is made of a material that becomes a conductor (for example, a metal material), and constitutes a cylindrical positive electrode. The outer cylinder electrode 18 forms a flow path 20 communicating with the rod-side oil chamber B between the outer cylinder electrode 18 and the inner cylinder electrode 3. The outer cylinder electrode 18 is electrically connected to a positive electrode of a battery 25 described later.

  The outer cylinder electrode 18 is held in a state in which the lower end side is positioned in the upper, lower and radial directions with respect to the valve body 14 of the bottom valve 13 via the lower spacer 17. On the other hand, the upper end side of the outer cylinder electrode 18 is held in a state of positioning in the upward, downward and radial directions with respect to the rod guide 10 via an upper spacer 22 described later.

  Here, in the embodiment, in order to clearly illustrate the shape of the characteristic portion of the upper spacer 22, the shock absorber 1 in a state where the gap between the inner cylinder electrode 3 and the outer cylinder electrode 18 is exaggerated more than the actual one is illustrated. Show. In the actual shock absorber 1, the outer cylinder electrode 18 is arranged with a slight gap outside the inner cylinder electrode 3. For example, the clearance dimension (diameter distance dimension) between the inner peripheral surface of the outer cylindrical electrode 18 and the outer peripheral surface of the inner cylindrical electrode 3 is 1 mm or less in the case of a general passenger car (excluding trucks). Is set. Thereby, the flow path area of the flow path 20 formed between the outer cylinder electrode 18 and the inner cylinder electrode 3 is smaller than the opening area of the introduction part 21 corresponding to this flow path 20.

  A plurality of partition walls 19 are provided on the outer peripheral surface of the inner cylindrical electrode 3 so as to extend spirally upward and downward. Each partition wall 19 is formed as a protrusion protruding from the outer peripheral surface of the inner cylinder electrode 3, and the tip portion of the protrusion contacts the inner peripheral surface of the outer cylinder electrode 18. Thus, each partition wall 19 forms a plurality of flow paths 20 between the inner cylinder electrode 3 and the outer cylinder electrode 18. Each partition wall 19 is made of a polymer material having elasticity such as elastomer and having electrical insulation properties, for example, synthetic rubber. Each partition wall 19 is fixed (adhered) to the inner cylindrical electrode 3 using, for example, an adhesive.

  Each flow path 20 is spirally divided by each partition wall 19, so that a plurality of flow paths 20 are formed between the inner cylinder electrode 3 and the outer cylinder electrode 18. In each flow path 20, the electrorheological fluid 2 in the inner cylindrical electrode 3 flows from the upper side, which is one end side in the axial direction, to the lower side, which is the other end side, by the movement of the piston rod 9. Each flow path 20 is always in communication with the rod-side oil chamber B at the upper side, which is the upstream side in the flow direction of the electrorheological fluid 2, by an introduction portion 21 described later provided in the inner cylinder electrode 3. That is, as shown in FIG. 2 by the arrow F indicating the flow direction of the electrorheological fluid 2, the shock absorber 1 flows from the rod-side oil chamber B through the introduction portions 21 in both the contraction stroke and the extension stroke of the piston 6. The electrorheological fluid 2 is introduced into the path 20. The electrorheological fluid 2 introduced into each flow path 20 is moved forward and backward by the forward / backward movement of the piston rod 9 in the inner cylinder electrode 3 (that is, while the contraction stroke and the extension stroke are repeated). 20 flows from the upper end side toward the lower end side.

  At this time, the electrorheological fluid 2 flows into the respective flow paths 20 from the inner cylindrical electrode 3 by the movement of the piston rod 9 on the expansion side and the contraction side, and passes through the flow paths 20 on one end side in the axial direction. It flows toward the other end side. Then, the electrorheological fluid 2 that has flowed through each flow path 20 flows out from the lower end side of the outer cylindrical electrode 18 to the reservoir chamber A through the oil path 17A of the lower spacer 17.

  In each flow path 20, resistance is applied to the electrorheological fluid 2 circulated by the piston 6 sliding in the inner cylinder electrode 3. For this purpose, the outer cylinder electrode 18 is connected to the positive electrode of the battery 25 serving as a power source via, for example, a high voltage driver (not shown) that generates a high voltage. The battery 25 (and high voltage driver) serves as a voltage supply unit (electric field supply unit), and the outer cylinder electrode 18 serves as an electrode (electrode) that applies an electric field (voltage) to the electrorheological fluid 2 in the flow path 20. In this case, both end sides of the outer cylinder electrode 18 are electrically insulated by the electrically insulating spacers 17 and 22. On the other hand, the inner cylinder electrode 3 is connected to the negative electrode (ground) via the rod guide 10, the bottom valve 13, the bottom cap 5, the outer cylinder 4, a high voltage driver, and the like.

  The high voltage driver boosts the DC voltage output from the battery 25 based on a command (high voltage command) output from a controller (not shown) for variably adjusting the damping force of the shock absorber 1. Supply (output) to the outer cylinder electrode 18. Thereby, a potential difference corresponding to the voltage applied to the outer cylinder electrode 18 is generated between the outer cylinder electrode 18 and the inner cylinder electrode 3, that is, in each flow path 20, and the viscosity of the electrorheological fluid 2 is reduced. Change. In this case, the shock absorber 1 changes the generated damping force characteristics (damping force characteristics) into a soft characteristic (soft characteristic) and a hard characteristic (hard characteristic) according to the voltage applied to the outer cylinder electrode 18. (Hard characteristics) can be continuously adjusted. The shock absorber 1 may be capable of adjusting the damping force characteristics in two stages or three or more stages without being continuous.

  The introduction part 21 introduces the electrorheological fluid 2 from the inner cylindrical electrode 3 toward each flow path 20, and a plurality of introduction parts 21 are provided so as to correspond to each flow path 20. Each introduction portion 21 is provided at an upper portion of the inner cylindrical electrode 3 on the upstream side in the flow direction when the electrorheological fluid 2 flows through each flow path 20. In this case, each introducing portion 21 is formed as a lateral hole penetrating the inner cylindrical electrode 3 in the radial direction with a gap in the circumferential direction. That is, the rod side oil chamber B in the inner cylinder electrode 3 communicates with each flow path 20 by each introduction portion 21.

  Next, a configuration of the upper spacer 22 as a spacer that is a characteristic part of the embodiment will be described.

  The upper spacer 22 constitutes an electric field strength reducing member disposed between the upper part of the inner cylindrical electrode 3 and the upper part of the outer cylindrical electrode 18 (hereinafter simply referred to as the spacer 22). The spacer 22 is held on the rod guide 10 side in a state where the upper end side of the outer cylinder electrode 18 is positioned in the axial direction and the radial direction. Like the lower spacer 17, the spacer 22 is formed as an insulator or a high-resistance material by using, for example, an electrically insulating material (isolator), and the rod guide 10 is interposed between the inner cylinder electrode 3 and the outer cylinder electrode 18. And the outer cylinder electrode 18 are kept in an electrically insulated state.

  As shown in FIG. 3, the spacer 22 has a large-diameter cylindrical portion 22A positioned on the upper side (large-diameter portion 10A side of the rod guide 10) and a lower end portion of the large-diameter cylindrical portion 22A via a step portion 22B. A small-diameter cylindrical portion 22C formed to have a diameter is included. Further, an inverted J-shaped notch 22D is formed over the entire circumference of the small diameter cylindrical portion 22C from the lower end of the small diameter cylindrical portion 22C toward the radially outer side from the lower end of the small diameter cylindrical portion 22C. The cutout portion 22D can smoothly introduce the electrorheological fluid 2 from the introduction portion 21 toward the flow path 20 by forming the upper portion facing the introduction portion 21 in a concave arc shape. Further, the electroviscous fluid 2 that has flowed out of the introduction portion 21 can be smoothly introduced toward the lower side by eliminating the flow toward the upper side (the large diameter portion 10A side of the rod guide 10) by the cutout portion 22D. The generation of vortices can be suppressed.

  As shown in FIG. 2, the spacer 22 is disposed outside the inner peripheral surface of the large-diameter cylindrical portion 22 </ b> A and the small-diameter cylindrical portion 22 </ b> C at an upper position of the inner cylindrical electrode 3. It is fitted. Moreover, the upper side part of the outer cylinder electrode 18 is attached to the outer peripheral side of the small diameter cylinder part 22C in an externally fitted state. Further, the upper end of the large diameter cylindrical portion 22A is in contact with the lower end surface of the large diameter portion 10A of the rod guide 10.

  Here, as shown in FIG. 2, a notch portion 22 </ b> D is formed in the lower portion of the small-diameter cylindrical portion 22 </ b> C facing the introduction portion 21 so as to cut out the small-diameter cylindrical portion 22 </ b> C from the inner diameter side. Thereby, in the lower portion of the small diameter cylindrical portion 22C, the plate thickness dimension t of the small diameter cylindrical portion 22C is gradually (downwardly and gradually) directed downward (downstream in the flow direction of the flow path 20). ) A plate thickness reduction portion 22E to be reduced is formed. In the plate thickness reducing portion 22E, the upper portion continuous (facing) to the introduction portion 21 is an arc surface forming portion 22E1 having a concave arc-shaped inner peripheral surface, and the lower side from the outer peripheral side of the arc surface forming portion 22E1 is the upper side. It becomes the wedge-shaped part 22E2 expanded in diameter toward the lower side. The plate thickness reducing portion 22 </ b> E has a linear outer peripheral surface along the inner peripheral surface of the outer cylinder electrode 18.

  The notch 22 </ b> D of the spacer 22 forms a part of the flow path from the introduction part 21 to the flow path 20. In addition, the plate thickness reducing portion 22E is formed such that the plate thickness dimension t gradually changes and decreases from the position of the introduction portion 21 toward the lower side. In addition, the introduction path 23 extends from the upper end of the introduction part 21 to the tip of the wedge-shaped part 22E2 of the spacer 22, and the downstream side of the flow path 20 from the tip of the wedge-shaped part 22E2 is the main flow path 24.

  Thus, when the electrorheological fluid 2 is introduced from the rod-side oil chamber B to the flow path 20 through the introduction part 21, the electric field strength acting on the electrorheological fluid 2 in the introduction path 23 is reduced by the plate thickness reduction part 22E. It becomes the lowest at the position of the introduction part 21 where the plate thickness dimension t is the maximum. Thereby, the electric field strength at the position of the introducing portion 21 is smaller than the electric field strength after passing through the introducing portion. When the electrorheological fluid 2 flows through the notch 22D, the plate thickness dimension t of the plate thickness reducing portion 22E gradually decreases, and the flow path area increases as the distance from the introduction portion 21 increases. Along with this, the electric field strength acting on the electrorheological fluid 2 gradually increases as the distance from the introducing portion 21 increases. When the electrorheological fluid 2 passes through the plate thickness reducing portion 22E and reaches the main flow path 24, the electric field strength acting on the electrorheological fluid 2 becomes maximum (maximum).

  The battery 25 has a positive electrode connected to the outer cylinder electrode 18 via a high voltage driver (not shown). The battery 25 serves as a voltage supply unit (electric field supply unit) to the outer cylinder electrode 18. Accordingly, the battery 25 softens the generated damping force characteristic (damping force characteristic) according to the magnitude of the voltage (electric field) applied to the electrorheological fluid 2 (electrorheological fluid) flowing in the flow path 20. It is continuously adjusted between (soft) characteristics (soft characteristics) and hard (hard characteristics).

  The shock absorber 1 according to the first embodiment has the above-described configuration, and the operation thereof will be described next.

  When mounting the shock absorber 1 on a vehicle such as an automobile, for example, the upper end side of the piston rod 9 is attached to the vehicle body side, and the lower end side (bottom cap 5 side) of the outer cylinder 4 is set to the wheel side (axle side). Install. When the vehicle is traveling, if upward and downward vibrations occur due to road surface unevenness or the like, the piston rod 9 is displaced from the outer cylinder 4 so as to expand and contract. At this time, a potential difference is generated in each flow path 20 using the battery 25 in accordance with a command from the controller, and the generated damping force of the shock absorber 1 is controlled by controlling the viscosity of the electrorheological fluid 2 passing through each flow path 20. Adjust the variable.

  During the extension stroke of the piston rod 9, the compression side check valve 7 of the piston 6 is closed by the movement of the piston 6 in the inner cylinder electrode 3. Before the disc valve 8 of the piston 6 is opened, the electrorheological fluid 2 in the rod side oil chamber B is pressurized and flows into the flow paths 20 through the introduction portions 21 of the inner cylinder electrode 3. At this time, the electrorheological fluid 2 corresponding to the movement of the piston 6 flows from the reservoir chamber A into the bottom oil chamber C by opening the extension check valve 15 of the bottom valve 13.

  On the other hand, during the compression stroke of the piston rod 9, the movement of the piston 6 in the inner cylinder electrode 3 opens the compression-side check valve 7 of the piston 6, and the expansion-side check valve 15 of the bottom valve 13 closes. The electrorheological fluid 2 in the bottom side oil chamber C flows into the rod side oil chamber B before the bottom valve 13 (disc valve 16) is opened. At the same time, the electrorheological fluid 2 corresponding to the amount that the piston rod 9 has entered the inner cylinder electrode 3 flows from the rod-side oil chamber B into the flow paths 20 through the introduction portions 21 of the inner cylinder electrode 3.

  Therefore, in any case (both during the expansion stroke and during the contraction stroke), the electrorheological fluid 2 that has flowed into each flow path 20 has a potential difference between each flow path 20 (between the outer cylinder electrode 18 and the inner cylinder electrode 3). Pass through the respective flow paths 20 toward the outlet side (lower side) with a viscosity corresponding to the potential difference between them and flow out from each flow path 20 to the reservoir chamber A through the oil path 17A of the lower spacer 17. At this time, the shock absorber 1 generates a damping force corresponding to the viscosity of the electrorheological fluid 2 that passes through each flow path 20 in the flow path 20 and can buffer (attenuate) the vertical vibration of the vehicle.

  By the way, during the operation of the shock absorber 1 described above, the electrorheological fluid 2 maintains high fluidity in the inner cylinder electrode 3 because there is no influence by the electric field. On the other hand, in each flow path 20, the electric field between the outer cylinder electrode 18 and the inner cylinder electrode 3 acts, so that the viscosity of the electrorheological fluid 2 is greatly increased. Therefore, when the electrorheological fluid 2 having high fluidity is suddenly introduced into the channel 20 having poor fluidity, the difference in fluidity causes the vicinity of the boundary between the inner cylindrical electrode 3 and the channel 20, that is, In addition, there is a possibility that the flow velocity of the electrorheological fluid 2 locally increases at the introducing portion 21 and causes cavitation. In this case, the flow of the electrorheological fluid 2 may be disturbed and the damping force may become unstable.

  Therefore, in the first embodiment, the piston rod 9 moves between the inner cylinder electrode 3 and the outer cylinder electrode 18 from the upstream side toward the downstream side in the axial direction (in the rod side oil chamber). Each flow path 20 through which the electrorheological fluid 2 of B) flows is provided. Further, an introduction portion 21 for introducing the electrorheological fluid 2 from the inner cylinder electrode 3 toward each flow path 20 is provided. On this basis, the electric field strength applied to the electrorheological fluid 2 in the introduction portion 21 of each flow path 20 is in the vicinity of the introduction portion 21 of each flow path 20 so as to be smaller than the electric field strength after passing through the introduction portion 21. A spacer 22 as an electric field strength reducing member made of an insulating material or a high resistance material is provided in the structure.

  Accordingly, the spacer 22 can gradually increase the electric field strength even when the electrorheological fluid 2 having high fluidity is suddenly introduced into the flow path 20 having poor fluidity. Thereby, the electrorheological fluid 2 maximizes the viscosity of the electrorheological fluid 2 at a position where the electrorheological fluid 2 is switched from the introduction passage 23 to the main passage 24 while gradually increasing the viscosity of the electrorheological fluid 2 in the introduction passage 23 starting from the introduction portion 21. Can be. As a result, cavitation due to a rapid increase in the flow velocity of the electrorheological fluid 2 can be prevented, so that the flow of the electrorheological fluid 2 can be made smooth and the damping force can be stabilized.

  In addition, the configuration in which the electric field strength applied to the electrorheological fluid 2 gradually increases after passing through the introducing portion 21, that is, the plate thickness reducing portion 22 E (notch portion 22 D), The spacer 22 holding the upper side is used and formed as a part thereof. Thereby, the damping force of the shock absorber 1 can be stabilized without increasing the number of parts to be assembled.

  Further, the cutout portion 22D (plate thickness reducing portion 22E) of the spacer 22 has an upper portion facing the introduction portion 21 formed in a concave arc shape. Thereby, the electrorheological fluid 2 can be smoothly introduced from the introduction part 21 toward the flow path 20 while gradually reducing the thickness t of the thickness reduction part 22E.

  Next, FIG. 4 shows a second embodiment of the present invention. The feature of this embodiment is that the wedge-shaped portion of the plate thickness reducing portion provided in the spacer is configured to reduce the diameter from the upper side to the lower side. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 4, the outer cylinder electrode 31 according to the second embodiment is substantially the same as the outer cylinder electrode 18 according to the first embodiment, with the upper portion on the outer peripheral side of the inner cylinder electrode 3 via an upper spacer 32 described later. Is retained. However, the outer cylinder electrode 31 according to the second embodiment is the first in that a tapered portion 31A having a diameter reduced toward the lower side is provided at a height position corresponding to the lower side position of the introducing portion 21. This is different from the outer cylinder electrode 18 according to the embodiment.

  The upper spacer 32 according to the second embodiment constitutes an electric field strength reducing member disposed between the upper part of the inner cylindrical electrode 3 and the upper part of the outer cylindrical electrode 31 (hereinafter simply referred to as the spacer 32). The spacer 32 includes a large-diameter cylindrical portion 32A, a stepped portion 32B, a small-diameter cylindrical portion 32C, a notch portion 32D, and a plate thickness reducing portion 32E in substantially the same manner as the spacer 22 according to the first embodiment. The plate thickness reducing portion 32E is formed by the arcuate surface forming portion 32E1 and the wedge-shaped portion 32E2. However, the spacer 32 according to the second embodiment is such that the wedge-shaped portion 32E2 of the plate thickness reducing portion 32E is reduced in diameter from the upper side to the lower side so as to follow the tapered portion 31A of the outer cylindrical electrode 31. This is different from the spacer 22 according to the first embodiment.

  Thus, also in the second embodiment configured in this way, it is possible to obtain substantially the same operational effects as the operational effects of the first embodiment described above.

  In the first embodiment, the wedge-shaped portion 22E2 of the plate thickness reducing portion 22E forming the upper spacer 22 is formed in a wedge shape by increasing the diameter of the inner peripheral surface from the upper side to the lower side. On the other hand, in the second embodiment, the wedge-shaped portion 32E2 of the plate thickness reducing portion 32E forming the upper spacer 32 is formed in a wedge shape by reducing the diameter of the outer peripheral surface from the upper side to the lower side. However, the present invention is not limited to these configurations. For example, the inner peripheral surface of the wedge-shaped portion may be enlarged and the outer peripheral surface may be reduced in diameter to form a wedge shape. In addition to the wedge shape, other shapes may be used as long as the electric field strength of the electrorheological fluid 2 flowing through the introduction path 23 can be gradually changed.

  In each embodiment, the case where the shock absorber 1 has a uniflow structure has been described as an example. However, the present invention is not limited to this, and the shock absorber may have a biflow structure. In addition, when it is set as the biflow structure, when the advancing / retreating direction of the rod is reversed, the introduction portion becomes the outflow portion.

  In each embodiment, the case where it was set as the structure which arrange | positions the buffer 1 in the up-down direction was mentioned as an example, and was demonstrated. However, the present invention is not limited to this, and can be arranged in a desired direction according to the attachment object, for example, by being inclined and arranged within a range where aeration does not occur.

  In each embodiment, the case where the electrorheological fluid 2 is configured to flow from the upper end side (one end side) in the axial direction toward the lower end side (the other end side) has been described as an example. However, the present invention is not limited to this, and, for example, a structure that flows from the lower end side toward the upper end side according to the arrangement direction of the shock absorber 1, from the left end side (or right end side) to the right end side (or left end side). A structure that flows toward the one end side from the other end side in the axial direction, such as a structure that flows toward the rear end side (or the front end side) from the front end side (or the rear end side). it can.

  In each embodiment, the structure which forms the introducing | transducing part 21 in the inner cylinder electrode 3 was demonstrated. However, the present invention is not limited to this. For example, the introduction portion may be formed in a rod guide or a spacer. Further, the configuration in which the rod guide 10 and the upper spacer 22 are provided separately has been described. However, the rod guide and the spacer may be formed integrally. Further, the configuration in which the spacer 22 is provided on the outer cylinder electrode 18 is shown. However, when the introduction portion is configured to extend in the radial direction to a position where the introduction portion abuts on the outer cylinder electrode 18, the spacer 22 is provided on the inner cylinder electrode 3. It is good also as a structure. In that case, the spacer 22 is configured to be an inverted J-shaped notch from the lower end of the small-diameter cylindrical portion 22C toward the inside in the radial direction.

  In each embodiment, the case where the shock absorber 1 as a cylinder device is used in a four-wheeled vehicle has been described as an example. However, the present invention is not limited to this. For example, a shock absorber used for a motorcycle, a shock absorber used for a railway vehicle, a shock absorber used for various mechanical devices including general industrial equipment, a shock absorber used for a building, etc. The present invention can be widely used as various shock absorbers (cylinder devices) for buffering a target object. Furthermore, the embodiments are exemplifications, and it is needless to say that partial replacements or combinations of the configurations shown in the different embodiments are possible. That is, the design of the cylinder device (buffer) can be changed without departing from the gist of the present invention.

  As the cylinder device based on the above-described embodiment, for example, the following modes can be considered.

  As a first aspect, a cylinder apparatus in which an electrorheological fluid whose fluid properties are changed by an electric field is sealed and a rod is inserted therein, an inner cylinder electrode serving as electrodes having different potentials, and the inner cylinder electrode The electrorheological fluid is formed by movement of the rod from one end side to the other end side in the axial direction, formed between an outer cylinder electrode provided on the outside of the cylinder, and the inner cylinder electrode and the outer cylinder electrode. And an electric field strength applied to the electrorheological fluid in the introduction part of the flow path passes through the introduction part. An electric field strength reducing member made of an insulator or a high resistance material is provided in the vicinity of the introduction portion of the flow path so as to be smaller than the electric field strength after.

  As a second aspect, in the first aspect, the electric field strength reducing member is configured such that the electric field strength increases as the distance from the introduction portion increases.

  As a third aspect, in the first aspect, the electric field strength lowering member is configured such that the electric field strength gradually increases as the distance from the introduction portion increases.

  As a fourth aspect, in any one of the first to third aspects, an insulator that defines a gap between the rod guide that supports the rod and the electrode between the inner cylinder electrode and the outer cylinder electrode, or A spacer made of a high resistance body is provided, and the spacer forms the electric field strength reducing member.

  As a fifth aspect, in any one of the first to fourth aspects, the electric field strength reducing member is formed such that the flow passage area of the flow passage increases as the distance from the introduction portion increases.

  As a sixth aspect, in any one of the first to fifth aspects, the electric field strength reducing member is formed so that the electrorheological fluid does not flow on a side opposite to a direction toward the outflow portion of the flow path. Yes.

  As a seventh aspect, in any one of the first to sixth aspects, the introduction part becomes an outflow part depending on the advancing and retreating direction of the rod.

  As an eighth aspect, in any one of the first to seventh aspects, the inner cylinder electrode is a cylinder on which a piston provided at an end portion of the rod slides, and the introduction section is the inner cylinder. The electric field strength reducing member is formed on the side surface of the electrode, and is provided on the inner surface of the outer cylinder electrode.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  The present application claims priority based on Japanese Patent Application No. 2017-068219 filed on Mar. 30, 2017. The entire disclosure including the specification, claims, drawings, and abstract of Japanese Patent Application No. 2017-068219 filed on March 30, 2017 is incorporated herein by reference in its entirety.

  DESCRIPTION OF SYMBOLS 1 Buffer (cylinder apparatus) 2 Electrorheological fluid 3 Inner cylinder electrode (cylinder) 6 Piston 9 Piston rod (rod) 10 Rod guide 18, 31 Outer cylinder electrode 20 Flow path 21 Introducing part 22, 32 Upper spacer (electric field strength reduction) Element)

Claims (8)

A cylinder device,
The cylinder device is filled with an electrorheological fluid whose properties change due to an electric field,
The cylinder device is
A rod inserted into the cylinder device;
An inner cylinder electrode;
An outer cylinder electrode,
The inner cylinder electrode and the outer cylinder electrode are electrodes having different potentials,
The outer cylinder electrode is provided outside the inner cylinder electrode,
The cylinder device is
An annular channel formed between the inner cylinder electrode and the outer cylinder electrode, in which the electrorheological fluid flows by movement of the rod from one end side in the axial direction toward the other end side;
An introduction part for introducing the electrorheological fluid into the flow path;
Have
The electric field strength applied to the electrorheological fluid in the introduction part is smaller than the electric field intensity applied to the electrorheological fluid in the flow path after the electrorheological fluid passes through the introduction part. A cylinder device characterized in that an electric field strength reducing member made of an insulator or a high resistance is provided in the vicinity of an introduction portion of a flow path. The cylinder device according to claim 1,
The cylinder device according to claim 1, wherein the electric field strength reducing member is configured such that the electric field strength increases as the distance from the introduction portion increases. The cylinder device according to claim 1,
The cylinder device according to claim 1, wherein the electric field strength reducing member is configured to gradually increase the electric field strength as the distance from the introduction portion increases. The cylinder device according to any one of claims 1 to 3,
Between the inner cylinder electrode and the outer cylinder electrode,
A rod guide for supporting the rod;
A spacer made of an insulator or a high-resistance body that defines an interval between the inner cylinder electrode and the outer cylinder electrode is provided;
The cylinder device, wherein the spacer forms the electric field strength reducing member. The cylinder device according to any one of claims 1 to 4,
The cylinder device according to claim 1, wherein the electric field strength reducing member is formed so that a flow path area of the flow path increases as the distance from the introduction portion increases. The cylinder device according to any one of claims 1 to 5,
The electric field strength reducing member is formed so that the electrorheological fluid does not flow on a side opposite to a direction toward the outflow portion of the flow path. The cylinder device according to any one of claims 1 to 6,
The cylinder device according to claim 1, wherein the introduction portion serves as an outflow portion depending on a forward / backward direction of the rod. The cylinder device according to any one of claims 1 to 7,
The piston provided at the end of the rod is provided slidably in the inner cylinder electrode,
The introduction portion is formed in a side surface of the inner cylinder electrode,
The cylinder device according to claim 1, wherein the electric field strength reducing member is provided on an inner surface of the outer cylinder electrode.

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