JP6892378B2 - Cylinder device - Google Patents

Description

The present invention relates to a cylinder device mounted on a vehicle such as an automobile or a railroad vehicle and preferably used to buffer the vibration of the vehicle.

Generally, a vehicle such as an automobile is provided with a cylinder device represented by a hydraulic shock absorber between the vehicle body (upper spring) side and each wheel (unsprung) side. Here, Patent Document 1 describes a vibration damper (buffer) using an electrorheological fluid as a working fluid. This vibration damper has a triple tube structure composed of three cylinders, an inner cylinder, an electrode cylinder, and an outer cylinder, and the flow path of the electrorheological fluid is between the inner cylinder and the electrode cylinder.

International Publication No. 2014/135183

In the case of the technique described in Patent Document 1, the damping force may decrease (insufficient) as the temperature of the electrorheological fluid rises. In addition, the damping force may decrease (insufficient) as the voltage is applied for a long time.

An object of the present invention is to provide a cylinder device capable of suppressing a decrease (insufficient) in damping force.

In order to solve the above-mentioned problems, the cylinder device according to the present invention is a cylinder device in which an electrorheological fluid whose properties change due to an electric potential is sealed and a rod is inserted inside, and the rod is inserted. The electric potential is provided between the cylinder, the outer cylinder provided on the outer peripheral side of the inner cylinder, and the inner cylinder and the outer cylinder, and the rod moves forward and backward from one end side to the other end side in the axial direction. A passage through which the viscous fluid flows is formed between the inner cylinder and the first cylinder as an electrode, and is formed between the first cylinder and the outer cylinder, and the electrorheological fluid and the electrorheological fluid are sealed. A reservoir chamber, a rod guide provided so as to close one end of the inner cylinder and the outer cylinder to support the rod, and an imparting portion for applying an electric potential from an electric potential supply unit to the first cylinder. A second cylinder having a potential on the ground side is provided between the first cylinder having a positive potential and the outer cylinder having a potential on the ground side.

The cylinder device of the present invention can suppress a decrease (insufficiency) in the damping force.

FIG. 5 is a cross-sectional view showing a shock absorber according to an embodiment. Front view showing the inner cylinder and the partition wall. Front view showing an electrode cylinder and a partition wall. Block diagram showing batteries, high voltage units, and shock absorbers. FIG. 5 is a cross-sectional view showing a shock absorber according to a modified example.

Hereinafter, the cylinder device according to the embodiment 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 attached to a vehicle such as a four-wheeled vehicle.

1 to 4 show embodiments. In FIG. 1, the shock absorber 1 as a cylinder device is configured as a damping force adjusting type hydraulic shock absorber (semi-active damper) whose damping force can be adjusted, and is used as a hydraulic oil (electrorheological fluid) to be sealed inside. The electrorheological fluid 2 is used. The shock absorber 1, also called an electrorheological damper, can form a suspension device for a vehicle together with, for example, a suspension spring (not shown) made of a coil spring. That is, the shock absorber 1 is provided between the vehicle body and the wheels (neither of which is shown), which is between the two relative moving members of the vehicle. For example, as shown in FIG. 4 described later, when the shock absorber 1 is mounted on a four-wheeled vehicle, each vehicle corresponds to each wheel (left front wheel, right front wheel, left rear wheel, right rear wheel). A total of four shock absorbers 1 can be provided.

By the way, the shock absorber of Patent Document 1 using an electrorheological fluid as a hydraulic oil has a triple tube structure composed of three cylinders of an inner cylinder, an electrode cylinder and an outer cylinder. In the case of such a shock absorber, the damping force may decrease (insufficient) as the temperature of the electrorheological fluid rises. That is, the resistance value of the electrorheological fluid decreases as the temperature rises. On the other hand, since the power that can be supplied has an upper limit, the current required to apply the required high voltage may be insufficient. As a result, the voltage application may be insufficient and the damping force may decrease. In addition, the damping force may decrease (insufficient) as the voltage is applied for a long time. That is, as a positive voltage is applied to the electrode cylinder, particles (urethane particles) of the electrorheological fluid may be deposited on the outer peripheral surface side of the electrode cylinder on the reservoir chamber side. As a result, the particle concentration (urethane concentration) of the electrorheological fluid flowing through the flow path may decrease, and the damping force may decrease. Therefore, while the conventional shock absorber has a triple tube structure, the shock absorber 1 of the embodiment is composed of four cylinders, that is, an inner cylinder 3, an electrode cylinder 18, an additional cylinder 19, and an outer cylinder 4. It has a quadruple pipe structure.

That is, as shown in FIG. 1, the shock absorber 1 of the embodiment includes an inner cylinder 3, an outer cylinder 4, a piston 7, a piston rod 10, a rod guide 11, a bottom valve 13, and a first cylinder. The electrode cylinder 18 and an additional cylinder 19 as a second cylinder are included. In this case, two intermediate cylinders, the electrode cylinder 18 and the additional cylinder 19, are provided between the inner cylinder 3 and the outer cylinder 4. In the following description, one end side in the axial direction of the shock absorber 1 will be referred to as the "lower end" side, and the other end side in the axial direction will be referred to as the "upper end" side. The "upper end" side may be used, and the other end side in the axial direction may be the "lower end" side.

The inner cylinder 3 is formed as a cylindrical cylinder extending in the axial direction, and an electrorheological fluid 2 is enclosed therein. A piston rod 10 is inserted inside the inner cylinder 3. In addition to the outer cylinder 4, the electrode cylinder 18 and the additional cylinder 19 are provided on the outside of the inner cylinder 3 so as to be coaxial.

The inner cylinder 3 is attached so that the lower end side is fitted to the valve body 14 of the bottom valve 13. The upper end side of the inner cylinder 3 is fitted and attached to the rod guide 11. On the upper end side of the inner cylinder 3 and below the rod guide 11, a plurality of (for example, 4) oil holes 3A that always communicate with the electrode passage 20 are formed as lateral holes in the radial direction separated in the circumferential direction. There is. That is, the rod-side oil chamber B in the inner cylinder 3 communicates with the electrode passage 20 (previous stage side electrode passage 20A) by the oil hole 3A. Further, as shown in FIGS. 1 and 2, an inner partition wall 21 described later is spirally wound and provided on the outer peripheral side of the inner cylinder 3.

The outer cylinder 4 forms the outer shell of the shock absorber 1 and is formed as a cylindrical body. The outer cylinder 4 is provided on the outer peripheral side of the inner cylinder 3, the electrode cylinder 18, and the additional cylinder 19. The outer cylinder 4 forms a reservoir chamber A communicating with the electrode passage 20 between the electrode cylinder 18 and the additional cylinder 19. In this case, the lower end side of the outer cylinder 4 is a closed end that is closed by a bottom cap 5 using welding means or the like. The bottom cap 5 constitutes a base member together with the valve body 14 of the bottom valve 13. The upper end side of the outer cylinder 4 is an open end. A sealing member 6 is provided on the open end side of the outer cylinder 4 to seal the piston rod 10 in a liquid-tight and airtight manner.

Here, the inner cylinder 3 and the outer cylinder 4 form a cylinder, and the electrorheological fluid 2 is sealed in the cylinder. In addition, in FIG. 1 (and FIGS. 2, 3 and 5), the enclosed electrorheological fluid 2 is represented by colorless and transparent. The electrorheological fluid 2 called ERF (Electro Rheological Fluid) is a fluid (functional fluid) whose properties change depending on an electric field (voltage). That is, the electrorheological fluid 2 (hereinafter referred to as ERF2) is a fluid whose viscosity changes according to the applied voltage and the flow resistance (damping force) changes.

ERF2 is composed of, for example, a base oil (base oil) made of silicon oil or the like, and particles (fine particles) that are mixed (dispersed) in the base oil and whose viscosity changes according to a change in an electric field, for example, urethane particles. Has been done. In ERF2, when a voltage is applied, urethane particles are crosslinked (connected in a chain) to generate a resistance force against the flow of oil, so that the damping force can be increased. That is, by applying a voltage, the shear stress of ERF2 increases and the damping force increases. The shock absorber 1 of the embodiment generates a potential difference in the electrode passage 20 between the inner cylinder 3 and the electrode cylinder 18 and between the electrode cylinder 18 and the additional cylinder 19, and the viscosity of the ERF 2 passing through the electrode passage 20. By controlling the (resistance force), the generated damping force is controlled (adjusted).

An annular reservoir chamber A serving as a reservoir tank is formed between the inner cylinder 3 and the outer cylinder 4, more specifically, between the electrode cylinder 18 (and the additional cylinder 19) and the outer cylinder 4. .. In the reservoir chamber A, a gas serving as a working gas is sealed together with ERF2. The gas may be air in an atmospheric pressure state, or a gas such as compressed nitrogen gas may be used. The gas in the reservoir chamber A is compressed to compensate for the approaching volume of the piston rod 10 when the piston rod 10 is contracted (contracting stroke).

The piston 7 is slidably provided in the inner cylinder 3. The piston 7 divides the inside of the inner cylinder 3 into a rod-side oil chamber B as a first chamber and a bottom-side oil chamber C as a second chamber. A plurality of oil passages 7A and 7B that enable communication between the rod-side oil chamber B and the bottom-side oil chamber C are formed in the piston 7 so as to be separated from each other in the circumferential direction.

Here, the shock absorber 1 according to the embodiment has a uniflow structure. Therefore, the ERF 2 in the inner cylinder 3 is always directed from the rod side oil chamber B (that is, the oil hole 3A of the inner cylinder 3) toward the electrode passage 20 in both the contraction stroke and the expansion stroke of the piston rod 10. It circulates in one direction (that is, the direction of the arrow F indicated by the alternate long and short dash line in FIGS. 1 to 3).

In order to realize such a uniflow structure, a valve is opened on the upper end surface of the piston 7 when, for example, the piston 7 is slidably displaced downward in the inner cylinder 3 in the contraction stroke (shrinkage stroke) of the piston rod 10. A check valve 8 on the contraction side that closes the valve at other times is provided. The contraction side check valve 8 allows the oil liquid (ERF2) in the bottom side oil chamber C to flow in each oil passage 7A toward the rod side oil chamber B, and the oil liquid flows in the opposite direction. Stop it from flowing. That is, the contraction-side check valve 8 allows only the flow of ERF2 from the bottom-side oil chamber C to the rod-side oil chamber B.

For example, a disc valve 9 on the extension side is provided on the lower end surface of the piston 7. In the extension side disc valve 9, the pressure in the rod side oil chamber B exceeds the relief set pressure when the piston 7 slides upward in the inner cylinder 3 in the extension stroke (extension stroke) of the piston rod 10. And the pressure at this time is relieved to the bottom side oil chamber C side via each oil passage 7B.

The piston rod 10 as a rod is axially oriented in the inner cylinder 3 (the inner cylinder 3 and the outer cylinder 4, and thus in the same direction as the central axis of the shock absorber 1, and in the vertical direction of FIGS. 1 to 3). It is extending. That is, the piston rod 10 is inserted inside the shock absorber 1. The lower end of the piston rod 10 is connected (fixed) to the piston 7 in the inner cylinder 3, and the upper end thereof extends to the outside of the inner cylinder 3 and the outer cylinder 4 through the rod-side oil chamber B. In this case, the piston 7 is fixed (fixed) to the lower end side of the piston rod 10 by using a nut 10A or the like. On the other hand, the upper end side of the piston rod 10 projects to the outside via the rod guide 11.

The rod guide 11 is provided so as to close one end (upper end) of the inner cylinder 3 and the outer cylinder 4. The rod guide 11 supports the piston rod 10. That is, the rod guide 11 guides the piston rod 10 so as to be slidable in the axial direction on the inner peripheral side thereof.

A bottom valve 13 is provided on the lower end side of the inner cylinder 3 so as to be located between the inner cylinder 3 and the bottom cap 5. The bottom valve 13 communicates with and shuts off 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 check valve 15, and a disc valve 16.

The valve body 14 defines a reservoir chamber A and a bottom side oil chamber C between the bottom cap 5 and the inner cylinder 3. Oil passages 14A and 14B that enable communication between the reservoir chamber A and the bottom side oil chamber C are formed in the valve body 14 at intervals in the circumferential direction, respectively.

The extension side check valve 15 is provided, for example, on the upper surface side of the valve body 14. The extension-side check valve 15 opens when the piston 7 slides and displaces upward during the extension stroke of the piston rod 10, and closes at other times. The extension side check valve 15 allows the oil liquid (ERF2) in the reservoir chamber A to flow in each oil passage 14A toward the bottom side oil chamber C, and the oil liquid flows in the opposite direction. To prevent. That is, the extension-side check valve 15 allows only the flow of ERF2 from the reservoir chamber A side to the bottom-side oil chamber C side.

The disc valve 16 on the reduction side is provided, for example, on the lower surface side of the valve body 14. The disc valve 16 on the reduction side opens when the pressure in the oil chamber C on the bottom side exceeds the relief set pressure when the piston 7 slides and displaces downward in the reduction stroke of the piston rod 10. Is relieved to the reservoir chamber A side via each oil passage 14B.

An electrode cylinder 18 made of a pressure tube extending in the axial direction is provided between the inner cylinder 3 and the outer cylinder 4. The electrode cylinder 18 is supported by the rod guide 11 and the valve body 14 via holding members 17 and 17. The holding members 17 and 17 are formed of, for example, an electrically insulating material (isolator). The upper holding member 17 keeps the inner cylinder 3 and the rod guide 11 and the electrode cylinder 18 electrically insulated from each other. The lower holding member 17 keeps the inner cylinder 3, the additional cylinder 19, and the valve body 14 and the electrode cylinder 18 in an electrically insulated state.

The electrode cylinder 18 serves as a first cylinder (first intermediate cylinder) between the inner cylinder 3 and the outer cylinder 4. The electrode cylinder 18 is formed by using a conductive material and constitutes a tubular electrode. That is, the electrode cylinder 18 has a positive potential. On the other hand, the additional cylinder 19 is a second cylinder (second intermediate cylinder) between the inner cylinder 3 and the outer cylinder 4. The additional cylinder 19 is provided on the outside of the electrode cylinder 18. The additional cylinder 19 has a potential on the ground side (ground side) like the inner cylinder 3 and the outer cylinder 4. That is, the additional cylinder 19 which is the potential on the ground side (GND potential) is provided between the electrode cylinder 18 which is the potential on the positive side and the outer cylinder 4 which is the potential on the ground side.

The electrode cylinder 18 forms an electrode passage 20 (more specifically, a front-stage side electrode passage 20A as a passage) communicating with the rod-side oil chamber B between the electrode cylinder 18 and the inner cylinder 3. That is, the electrode cylinder 18 surrounds the outer peripheral side of the inner cylinder 3 over the entire circumference, so that the electrode cylinder 18 forms an annular passage between the inner peripheral side of the electrode cylinder 18 and the outer peripheral side of the inner cylinder 3. Is forming. Further, the electrode cylinder 18 forms an electrode passage 20 (more specifically, a rear electrode side electrode passage 20B) communicating with the reservoir chamber A between the electrode cylinder 18 and the additional cylinder 19. That is, the additional cylinder 19 surrounds the outer peripheral side of the electrode cylinder 18 over the entire circumference, so that the additional cylinder 19 forms an annular passage between the outer peripheral side of the electrode cylinder 18 and the inner peripheral side of the additional cylinder 19. Is forming.

As shown in FIGS. 1 and 3, an oil hole 18A that constantly communicates the front-stage side electrode passage 20A and the rear-stage side electrode passage 20B is separated in the circumferential direction as a radial lateral hole on the lower end side of the electrode cylinder 18. (For example, four) are formed. Further, on the outer peripheral side of the electrode cylinder 18, an outer partition wall 23, which will be described later, is spirally wound and provided. Further, as shown in FIG. 1, a return portion 18B is provided on the outer peripheral surface of the electrode cylinder 18 above the additional cylinder 19 so as to cover the opening edge of the additional cylinder 19. The return portion 18B is formed as, for example, a protruding portion that protrudes radially outward from the outer peripheral surface of the electrode cylinder 18 in a brim shape over the entire circumference. Such a return portion 18B guides the ERF2 flowing out from the rear electrode side electrode passage 20B to the reservoir chamber A downward.

In the embodiment, the rod-side oil chamber B and the reservoir chamber A are communicated with each other by the electrode passage 20. The electrode passage 20 includes a front-stage electrode passage 20A through which ERF2 flowing from the inner cylinder 3 side through the oil hole 3A of the inner cylinder 3 flows downward, and an oil hole of the electrode cylinder 18 from the front-stage side electrode passage 20A. It is composed of a rear-stage side electrode passage 20B in which ERF2 flowing in through 18A flows upward. In the front stage side electrode passage 20A, a plurality of inner flow paths 22 are formed by the plurality of inner partition walls 21. Also in the rear electrode side electrode passage 20B, a plurality of outer flow paths 24 are formed by the plurality of outer partition walls 23.

The electrode passages 20 (20A, 20B) are passages through which ERF2 flows, and the sliding of the piston 7 causes the flow of ERF2. That is, when the piston rod 10 advances and retreats in the inner cylinder 3 (that is, while repeating the contraction stroke and the expansion stroke), the ERF2 in the electrode passage 20 (20A, 20B) advances and retreats to the front stage side electrode passage. It flows from the upper end side to the lower end side in the axial direction of 20A, and flows from the lower end side to the upper end side in the axial direction of the rear electrode passage 20B. Then, the ERF2 of the rear-stage side electrode passage 20B flows out from the upper end side of the additional cylinder 19 to the reservoir chamber A. At this time, a potential difference is generated in the electrode passage 20 according to the voltage applied to the electrode cylinder 18, and the viscosity of ERF2 changes. That is, by changing the voltage applied to the ERF2 in the electrode passage 20, the ERF2 can be cured and the damping force of the shock absorber 1 can be adjusted. In this case, the contribution of the fluid to the damper damping force is proportional to the length of the flow path through which the ERF2 flows. Therefore, in the embodiment, the electrode passage 20 is composed of the front-stage side electrode passage 20A and the rear-stage side electrode passage 20B. Further, in the embodiment, the inner partition wall 21 as a flow path forming member is provided in the front stage side electrode passage 20A, and the outer partition wall 23 as a flow path forming member is provided in the rear stage side electrode passage 20B.

As shown in FIGS. 1 and 2, a plurality (4) inner partition walls 21 are provided between the inner cylinder 3 and the electrode cylinder 18. Each inner partition wall 21 extends obliquely around the circumference between the inner cylinder 3 and the electrode cylinder 18. The inner partition wall 21 is provided, for example, fixed to the outer peripheral side of the inner cylinder 3 by adhesion or the like. The inner partition wall 21 is formed of an insulating material, for example, a polymer material such as synthetic rubber or synthetic resin. The inner partition wall 21 forms a plurality (4) inner flow paths 22 between the inner cylinder 3 and the electrode cylinder 18, that is, in the front stage side electrode passage 20A. That is, each inner partition wall 21 partitions the flow of ERF2 into a plurality of inner flow paths 22 (guides the flow of ERF2) between the inner peripheral side of the electrode cylinder 18 and the outer peripheral side of the inner cylinder 3. .. In each inner flow path 22, ERF2 flows from the upper end side to the lower end side in the axial direction as the piston rod 10 moves forward and backward. As shown in FIG. 2, each inner partition wall 21 is formed in a spiral shape having a portion extending in the circumferential direction. As a result, the inner flow path 22 formed between the adjacent inner partition walls 21 is also a spiral flow path having a portion extending in the circumferential direction. That is, each inner flow path 22 is a flow path in which ERF2 flows in the clockwise direction when viewed from the upper side (oil hole 3A side) in the axial direction of the inner cylinder 3 to the lower side. As a result, the length of the flow path from the oil hole 3A of the inner cylinder 3 to the oil hole 18A of the electrode cylinder 18 can be made longer than that of the flow path extending linearly in the axial direction.

As shown in FIGS. 1 and 3, a plurality (4) outer partition walls 23 are provided between the electrode cylinder 18 and the additional cylinder 19. Each outer partition wall 23 extends obliquely around the circumference between the electrode cylinder 18 and the additional cylinder 19. The outer partition wall 23 is provided, for example, fixed to the outer peripheral side of the electrode cylinder 18 (or the inner peripheral side of the additional cylinder 19) by adhesion or the like. The outer partition wall 23 is formed of an insulating material, for example, a polymer material such as synthetic rubber or synthetic resin. The outer partition wall 23 forms a plurality (4) outer flow paths 24 between the electrode cylinder 18 and the additional cylinder 19, that is, in the rear electrode side electrode passage 20B. That is, each outer partition wall 23 partitions the flow of ERF2 into a plurality of outer flow paths 24 (guides the flow of ERF2) between the inner peripheral side of the additional cylinder 19 and the outer peripheral side of the electrode cylinder 18. .. ERF2 flows in each outer flow path 24 from the lower end side to the upper end side in the axial direction as the piston rod 10 moves forward and backward. As shown in FIG. 3, each outer partition wall 23 is formed in a spiral shape having a portion extending in the circumferential direction. As a result, the outer flow path 24 formed between the adjacent outer partition walls 23 is also a spiral flow path having a portion extending in the circumferential direction. That is, each outer flow path 24 is a flow path in which ERF2 flows in the clockwise direction when viewed from the lower side (oil hole 18A side) in the axial direction of the electrode cylinder 18 to the upper side. As a result, the length of the flow path from the oil hole 18A of the electrode cylinder 18 to the upper end edge of the additional cylinder 19 can be made longer than that of the flow path extending linearly in the axial direction.

The electrode passage 20 imparts resistance to the fluid flowing by sliding the piston 7 in the outer cylinder 4 and the inner cylinder 3, that is, the electrorheological fluid that becomes ERF2. For this purpose, the electrode cylinder 18 is connected to the positive electrode of the battery 25 as a power source via, for example, an electrode connecting portion 26 and a high voltage unit 27 that generates a high voltage. In this case, as shown in FIG. 4, the high voltage unit 27 is connected to four shock absorbers 1 (electrode cylinders 18) mounted on the vehicle. That is, in the embodiment, the electric power from the battery 25 is supplied to the four shock absorbers 1 via one high voltage unit 27.

The battery 25 and the high voltage unit 27 serve as a voltage supply unit (electric field supply unit), and the electrode cylinder 18 applies an electric field (voltage) to ERF2, which is a fluid in the electrode passage 20, that is, an electrorheological fluid as a functional fluid. It becomes an electrode (electrod) to be applied. Further, the electrode connecting portion 26 electrically connects between the outside of the outer cylinder 4 of the shock absorber 1 and the electrode cylinder 18. The electrode connecting portion 26 includes, for example, an electrode pin 26A connected to the electrode cylinder 18, and a case member (not shown) that supports the electrode pin 26A with respect to the outer cylinder 4 and the additional cylinder 19. ing.

The electrode pin 26A is a portion that applies an electric field from the battery 25 and the high voltage unit 27 to the electrode cylinder 18 (applies a voltage). The case member is fixed to the outer cylinder 4 and the additional cylinder 19, and electrically insulates between the outer cylinder 4 and the additional cylinder 19 and the electrode pin 26A. Further, both ends of the electrode cylinder 18 are electrically insulated by electrically insulating holding members 17 and 17. On the other hand, the inner cylinder 3 and the additional cylinder 19 are connected to the negative electrode (ground) via the rod guide 11, the bottom valve 13, the bottom cap 5, the outer cylinder 4, the high voltage driver, and the like. As a result, the outer cylinder 4, the inner cylinder 3, and the additional cylinder 19 have potentials on the ground side. In the embodiment, the electrode connecting portion 26 is provided so as to penetrate the outer cylinder 4 and the additional cylinder 19, but the present invention is not limited to this, and for example, the electrode connecting portion may be provided on the rod guide.

The high voltage unit 27 includes a controller 27A which is a control device for variably adjusting the damping force of the shock absorber 1, and a high voltage driver 27B which boosts the DC voltage output from the battery 25. The controller 27A is also called a central ECU. For example, the controller 27A calculates a required damping force based on a detection value from a detection sensor that detects a vehicle state quantity such as a vehicle height sensor, and generates this damping force. The command (high voltage command) required for the above is output to the high voltage driver 27B. The high-voltage driver 27B is also called an "HV Box" and includes a booster circuit (not shown).

The high voltage driver 27B boosts the DC voltage output from the battery 25 based on the command output from the controller 27A and supplies (outputs) it to the electrode cylinder 18. As a result, a potential difference is generated between the electrode cylinder 18 and the inner cylinder 3 and in the electrode passage 20 between the electrode cylinder 18 and the additional cylinder 19 according to the voltage applied to the electrode cylinder 18, and the electrorheological viscosity is generated. The viscosity of the fluid ERF2 changes. In this case, the shock absorber 1 changes the characteristic of the generated damping force (damping force characteristic) from the hard characteristic (hard characteristic) to soft according to the voltage (for example, 0 to 5 kV) applied to the electrode cylinder 18. (Soft) characteristics (soft characteristics) can be continuously adjusted. The shock absorber 1 may have a damping force characteristic that can be adjusted in two or a plurality of stages even if the damping force characteristic is not continuous.

The shock absorber 1 according to the embodiment has the above-described configuration, and its operation 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 10 is attached to the vehicle body side, and the lower end side (bottom cap 5 side) of the outer cylinder 4 is on the wheel side (axle side). Install. When the vehicle travels, when vibrations in the upward and downward directions occur due to unevenness of the road surface or the like, the piston rod 10 is displaced so as to extend or contract from the outer cylinder 4. At this time, the high voltage unit 27 generates a potential difference in the electrode passages 20 (20A, 20B) based on the command of the controller 27A, and controls the viscosity of ERF2 passing through the respective passages 22 and 24 in the electrode passage 20. By doing so, the generated damping force of the shock absorber 1 is variably adjusted.

For example, during the extension stroke of the piston rod 10, the check valve 8 on the contraction side of the piston 7 is closed by the movement of the piston 7 in the inner cylinder 3. Before opening the disc valve 9 of the piston 7, the oil liquid (ERF2) in the oil chamber B on the rod side is pressurized and flows into the electrode passages 20 (20A, 20B) through the oil hole 3A of the inner cylinder 3. At this time, the oil liquid corresponding to the movement of the piston 7 flows from the reservoir chamber A into the bottom side oil chamber C by opening the extension side check valve 15 of the bottom valve 13.

On the other hand, during the contraction stroke of the piston rod 10, the contraction side check valve 8 of the piston 7 opens due to the movement of the piston 7 in the inner cylinder 3, and the extension side check valve 15 of the bottom valve 13 closes. Before opening the bottom valve 13 (disc valve 16), the oil liquid in the bottom side oil chamber C flows into the rod side oil chamber B. At the same time, the oil liquid corresponding to the amount of the piston rod 10 infiltrated into the inner cylinder 3 flows from the rod side oil chamber B into the electrode passage 20 (20A, 20B) through the oil hole 3A of the inner cylinder 3.

In either case (during the expansion stroke and the contraction stroke), the oil liquid flowing into the electrode passage 20 (20A, 20B) has a potential difference between the electrode passage 20 (20A, 20B) (the electrode cylinder 18, the inner cylinder 3 and the inner cylinder 3). It passes through the electrode passage 20 (20A, 20B) toward the outlet side with a viscosity corresponding to the potential difference between the additional cylinder 19 and the electrode cylinder 18 and the upper end of the additional cylinder 19 from the electrode passage 20 (20A, 20B). It flows into the reservoir chamber A through the edge. At this time, the shock absorber 1 generates a damping force according to the viscosity of the ERF 2 passing through the flow paths 22 and 24 in the electrode passages 20 (20A, 20B), and buffers (damps) the vertical vibration of the vehicle. Can be done.

Here, the shock absorber 1 of the embodiment has a quadruple tube structure composed of four cylinders of an inner cylinder 3, an electrode cylinder 18, an additional cylinder 19, and an outer cylinder 4. Therefore, the electrode passage 20 can be provided not only between the inner cylinder 3 and the electrode cylinder 18, but also between the electrode cylinder 18 and the additional cylinder 19. That is, the electrode passage 20 is composed of an outward path and a return path between the front electrode passage 20A between the inner cylinder 3 and the electrode cylinder 18 and the rear electrode passage 20B between the electrode cylinder 18 and the additional cylinder 19. be able to. Therefore, the length of the electrode passage 20, that is, the length of the flow path through which the ERF2 flows can be doubled as compared with the conventional shock absorber having a triple tube structure. Therefore, the damping force based on the viscous resistance of the ERF2 in the electrode passage 20 can be doubled, and the shortage of the damping force when the ERF2 becomes high temperature can be suppressed.

Moreover, in the embodiment, the inner partition wall 21 is provided between the inner cylinder 3 and the electrode cylinder 18, and the outer partition wall 23 is provided between the electrode cylinder 18 and the additional cylinder 19. As a result, since the inner flow path 22 and the outer flow path 24 are spiral, the flow path length can be made longer than that of the flow path extending linearly in the axial direction. As a result, the damping force can be improved from this aspect as well.

Further, in the case of the conventional triple tube structure, since the outer peripheral side of the electrode cylinder is the reservoir chamber, ERF particles (urethane particles) may be deposited on the outer peripheral surface of the electrode cylinder. Even in the case of the conventional triple tube structure, ERF particles do not accumulate between the electrode cylinder and the inner cylinder. It is considered that this is because the ERF flows in the electrode passage between the electrode cylinder and the inner cylinder, that is, the flow velocity of the ERF in the electrode passage is faster than the flow velocity of the ERF on the reservoir chamber side. On the other hand, in the embodiment having a quadruple tube structure, both the inner peripheral side and the outer peripheral side of the electrode cylinder 18 have an electrode passage 20 (front stage side electrode passage 20A, rear stage side electrode passage 20B) through which ERF2 flows. Become. That is, in the triple tube structure, the outer peripheral side (reservoir chamber) of the electrode cylinder on which the particles of the electrorheological fluid are deposited becomes the posterior side electrode passage 20B through which ERF2 flows in the quadruple tube structure. Therefore, it is possible to suppress the accumulation of ERF2 particles on the surface of the electrode cylinder 18. As a result, it is possible to suppress a shortage of damping force due to a decrease in the particle concentration (urethane concentration) of ERF2. Since the outer peripheral surface of the additional cylinder 19 facing the reservoir chamber A has a ground potential (GND potential), ERF2 particles do not accumulate.

Further, in the case of the conventional triple tube structure, it is necessary to coat (coat) the insulating powder on the outside of the electrode cylinder. The coating of the insulating powder suppresses the application of a voltage to the ERF on the reservoir chamber side. That is, in the case of the conventional triple tube structure, it is necessary to coat the electrode cylinder with an insulating powder to prevent sparks from occurring due to insufficient withstand voltage of the working gas (nitrogen gas) on the upper side of the reservoir chamber. .. Further, it is necessary to suppress insufficient suction at the bottom valve due to hardening of the ERF (increased viscosity) by applying a voltage on the lower side of the reservoir chamber. On the other hand, in the embodiment, since the additional cylinder 19 is provided between the electrode cylinder 18 and the outer cylinder 4, the electric field to the reservoir chamber A can be shielded by the additional cylinder 19. As a result, the portion of the electrode cylinder 18 covered by the additional cylinder 19 does not need to be coated with an insulator (coating with an insulating film), and the amount of insulating powder used can be reduced.

Further, a return portion 18B is provided on the outer peripheral surface of the electrode cylinder 18 so as to be located above the upper end opening edge of the additional cylinder 19. That is, the portion where the ERF2 flows upward from the rear-stage side electrode passage 20B may be the air layer (gas chamber) of the reservoir chamber A. In this case, aeration (cavitation) may occur, but since the ERF2 flowing out from the rear electrode passage 20B goes downward along the return portion 18B, the aeration can be suppressed.

The output current to the shock absorber 1 is proportional to the length of the flow path of the ERF2. Therefore, in the case of the embodiment (quadruple tube structure), the output current from the high voltage driver 27B to each shock absorber 1 is doubled as compared with the conventional structure (triple tube structure), and the high voltage driver 27B Fever may increase. Here, when the high-voltage driver 27B is directly attached to each shock absorber 1, the heat of the shock absorber 1 is transferred to the high-voltage driver 27B, so that the temperature of the high-voltage driver 27B also rises from this aspect as well. there's a possibility that. Therefore, in the embodiment, as shown in FIG. 4, the high-voltage unit 27 including the high-voltage driver 27B is located at a location away from the shock absorber 1, specifically, the environmental temperature and the environmental temperature of the shock absorber 1. It is placed in a place where the installation surface temperature is low. That is, the high-voltage driver 27B constitutes the high-voltage unit 27 together with the controller 27A, and the high-voltage unit 27 in which the high-voltage driver 27B and the controller 27A are integrated is installed at a low temperature such as under the seat of the vehicle body. It is placed in a place. As a result, it is possible to suppress an increase in the temperature of the high voltage unit 27 including the high voltage driver 27B. Further, the high voltage unit 27 and each shock absorber 1 can be connected by a high voltage harness 28, respectively. That is, a high voltage can be applied to the shock absorber 1 by using the high voltage harness 28.

In the embodiment, the electrode passage 20 is an example of a round-trip path (a front-stage side electrode passage 20A and a rear-stage side electrode passage 20B are in series) having a turn (U-turn) in the middle (lower end side). I mentioned and explained. However, the present invention is not limited to this, and for example, as in the modified example shown in FIG. 5, the electrode passage 31 may be composed of the first electrode passage 31A and the second electrode passage 31B extending in parallel. In this case, the ERF2 flowing out from the oil hole 3A of the inner cylinder 3 branches into the first electrode passage 31A and the second electrode passage 31B on the upper side of the electrode cylinder 32, and the inside of the first electrode passage 31A is on the lower side. And flows downward in the second electrode passage 31B. The ERF2 flowing from the upper side to the lower side in the first electrode passage 31A passes through the oil hole 32A provided on the lower end side of the electrode cylinder 32 and the oil hole 33A provided on the lower end side of the additional cylinder 33. It flows out to the reservoir chamber A. The ERF2 that has flowed from the upper side to the lower side in the second electrode passage 31B flows out to the reservoir chamber A through the oil hole 33A provided on the lower end side of the additional cylinder 33.

In such a modification, the entire axial direction of the electrode cylinder 32 can be covered by the additional cylinder 33. That is, the additional cylinder 33 as the second cylinder can prevent the electrode cylinder 32 as the first cylinder from being exposed to the air layer (gas chamber) of the reservoir chamber A. Therefore, the electrode cylinder 32 does not need to be coated with an insulator, that is, to be coated with an insulating film. Further, the modified example is common to the embodiment in that the flow path length is shorter than that of the embodiment, but the outer peripheral side of the second cylinder (electrode cylinder) is the flow path. That is, in the modified example, as in the embodiment, both the inner peripheral side and the outer peripheral side of the electrode cylinder 32 are the electrode passages 31 (first electrode passage 31A, second electrode passage 31B) through which the ERF2 flows. .. Therefore, it is possible to suppress the accumulation of ERF2 particles on the surface of the electrode cylinder 32. As a result, it is possible to suppress a shortage of damping force due to a decrease in the particle concentration (urethane concentration) of ERF2.

In the embodiment and the modified example, a case where a quadruple tube structure, that is, a configuration in which an electrode cylinder 18 and an additional cylinder 19 are provided between the inner cylinder 3 and the outer cylinder 4, has been described as an example. However, the present invention is not limited to this, and for example, two sets of a first cylinder (electrode cylinder) and a second cylinder (additional cylinder) may be provided between the inner cylinder and the outer cylinder. That is, a 6-layer pipe structure may be formed in which the inner cylinder, the first cylinder, the second cylinder, the first cylinder, the second cylinder, and the outer cylinder are arranged in this order from the inner side in the radial direction. In other words, it can be an even-numbered pipe structure having a quadruple pipe structure or more.

In the embodiment and the modified example, the electrode pin 26A for applying a voltage to the electrode cylinder 18 is provided so as to penetrate the outer cylinder 4 and the additional cylinder 19 from the outside of the outer cylinder 4, thereby providing the electrode pin 26A. The case where the first cylinder (electrode cylinder 18) is connected (contacted) with the first cylinder (electrode cylinder 18) has been described as an example. However, the present invention is not limited to this, and for example, the rod guide may be provided with an imparting portion that connects (contacts) with the first cylinder (electrode cylinder).

In the embodiment and the modified example, the case where four partition walls 21 and 23 are provided as the flow path forming members for regulating the directions of the flow paths 22 and 24 has been described as an example. However, the present invention is not limited to this, and for example, a configuration in which two or three partition walls are provided, or a configuration in which five or more partition walls are provided may be provided. In that case, the number of partition walls can be appropriately set according to the required performance (damping performance), manufacturing cost, specifications, and the like.

In the embodiment and the modified example, a case where a plurality of flow paths 22 and 24 are formed by a plurality of partition walls 21 and 23 has been described as an example. However, the present invention is not limited to this, and for example, one flow path may be formed by one partition wall (flow path forming member).

In the embodiments and modifications, the case where the partition walls 21 and 23 are formed of a polymer material such as synthetic rubber or synthetic resin has been described as an example. However, the present invention is not limited to this, and the flow path may be formed by using a material other than the polymer material, that is, various materials (insulating materials) having electrical insulating properties.

In the embodiment and the modified example, the case where both the inner flow path 22 and the outer flow path 24 are spiral flow paths has been described as an example. However, the present invention is not limited to this, and for example, the flow path may be a meandering flow path. That is, in the embodiment, as shown in FIG. 2, the inner partition wall 21 is spiral and orbits uniformly in the same direction from the upper end side to the lower end side of the inner cylinder 3. Further, as shown in FIG. 3, the outer partition wall 23 has a spiral shape and orbits uniformly in the same direction from the lower end side to the upper end side of the electrode cylinder 18. On the other hand, for example, the partition wall may be configured to be folded back in the middle (the circumferential direction is reversed from the middle, the clockwise direction is changed to the counterclockwise direction, or the counterclockwise direction is changed to the clockwise direction). Good.

In the embodiment and the modified example, the inner partition wall 21 and the outer partition wall 23, which are flow path forming members, are provided both between the inner cylinder 3 and the electrode cylinder 18 and between the electrode cylinder 18 and the additional cylinder 19. This case was explained as an example. However, the present invention is not limited to this, and for example, a configuration is provided between the inner cylinder and the first cylinder (electrode cylinder), or between the first cylinder (electrode cylinder) and the second cylinder (additional cylinder). May be. Further, the flow path forming member may be omitted.

In the embodiment and the modified example, the case where the shock absorber 1 is arranged in the vertical direction has been described as an example. However, the present invention is not limited to this, and the arrangement can be made in a desired direction according to the mounting target, for example, the arrangement can be tilted within a range that does not cause aeration.

In the embodiment and the modified example, 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 two-wheeled vehicle, a shock absorber used for a railroad vehicle, a shock absorber used for various mechanical devices including general industrial equipment, a shock absorber used for a building, and the like. It can be widely used as various shock absorbers (cylinder devices) for buffering.

As the cylinder device based on the embodiment described above, for example, the one described below can be considered.

(1). The first aspect is a cylinder device in which an electrorheological fluid whose properties change due to an electric potential is sealed and a rod is inserted inside, the inner cylinder into which the rod is inserted and the outer circumference of the inner cylinder. A passage provided between the outer cylinder provided on the side and the inner cylinder and the outer cylinder, through which the electrorheological fluid flows by advancing and retreating the rod from one end side to the other end side in the axial direction. A reservoir chamber formed between the inner cylinder and serving as an electrode, a reservoir chamber formed between the first cylinder and the outer cylinder, and filled with the electrorheological fluid and the working fluid, and the inner cylinder. It has a rod guide that is provided so as to close one end of the outer cylinder and supports the rod, and an imparting portion that applies an electric potential from the electrorheological fluid supply portion to the first cylinder, and has a potential on the positive side. A second cylinder having a potential on the ground side is provided between the first cylinder and the outer cylinder having a potential on the ground side.

According to this first aspect, by providing the second cylinder between the first cylinder and the outer cylinder, not only between the inner cylinder and the first cylinder but also between the first cylinder and the outer cylinder. , Can be a passage through which electrorheological fluid flows. Thereby, for example, the length of the flow path through which the electrorheological fluid flows can be lengthened. In this case, the damping force can be improved (the adjustment range of the damping force is increased), and for example, even if the temperature of the electrorheological fluid rises, it is possible to prevent the damping force from decreasing (insufficient).

Further, the outer peripheral surface side of the first cylinder, which has a positive potential, can be a passage through which the electrorheological fluid flows. Therefore, particles (urethane particles) are less likely to be deposited on the outer peripheral surface side of the first cylinder, and it is possible to suppress a decrease in the particle concentration (urethane concentration) of the electrorheological fluid. Therefore, it is possible to prevent the damping force from decreasing (insufficient) due to the decrease in particle concentration.

Further, of the outer peripheral surface of the first cylinder having a positive potential, the portion covered with the second cylinder having a potential on the ground side needs to form an insulating film for blocking the electric field to the reservoir chamber side. It disappears. That is, the portion where the insulating coating is required can be reduced, and the amount of the insulating powder applied (the amount of the insulating powder used) can be reduced.

(2). In the second aspect, in the first aspect, the electrorheological fluid flows between the inner cylinder and the first cylinder and / or between the first cylinder and the second cylinder. A flow path forming member for forming a flow path is provided, and the flow path has a spiral or meandering shape having a portion extending in the circumferential direction.

According to this second aspect, since the flow path has a spiral or meandering shape, the flow path length can be lengthened as compared with a flow path extending linearly in the axial direction. Thereby, the damping force can be improved.

1 Shock absorber (cylinder device)
2 ERF (Electrorheological Fluid)
3 Inner cylinder 4 Outer cylinder 10 Piston rod 11 Rod guide 18, 32 Electrode cylinder (1st cylinder)
19,33 additional cylinder (second cylinder)
20,31 Electrode passage 20A Front stage side electrode passage (passage)
20B Rear electrode passage 21 Inner partition wall (flow path forming member)
22 Inner flow path (flow path)
23 Outer partition wall (flow path forming member)
24 Outer flow path (flow path)
25 Battery (electric field supply unit)
26A Electrode pin (giving part)
27 High voltage unit (electric field supply unit)
27B high voltage driver (electric field supply unit)
31A First electrode passage (passage)
31B Second electrode passage A Reservoir chamber

Claims (2)

A cylinder device in which an electrorheological fluid whose properties change due to an electric field is sealed and a rod is inserted inside.
The inner cylinder into which the rod is inserted and
An outer cylinder provided on the outer peripheral side of the inner cylinder and
A passage provided between the inner cylinder and the outer cylinder and through which the electrorheological fluid flows by advancing and retreating the rod from one end side to the other end side in the axial direction is formed between the inner cylinder and the inner cylinder. , The first cylinder that becomes the electrode,
A reservoir chamber formed between the first cylinder and the outer cylinder and in which the electrorheological fluid and the working fluid are sealed.
A rod guide provided so as to block one end of the inner cylinder and the outer cylinder and supporting the rod,
An applying unit that applies an electric field from the electric field supply unit to the first cylinder,
Have,
A cylinder device characterized in that a second cylinder having a potential on the ground side is provided between the first cylinder having a potential on the positive side and the outer cylinder having a potential on the ground side. A flow path forming member for forming a flow path through which the electrorheological fluid flows is provided between the inner cylinder and the first cylinder and / or between the first cylinder and the second cylinder. ,
The cylinder device according to claim 1, wherein the flow path has a spiral or meandering shape having a portion extending in the circumferential direction.

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