Untitled record

[Detailed explanation of the device]

(Industrial application field) The present invention relates to a shock absorber, and more particularly to a shock absorber using an electrorheological fluid having a property that the viscosity increases as the applied voltage increases and the voltage becomes apparently gelled when the voltage exceeds a certain value. (Conventional technology) As shown in Fig. 7, the viscosity increases as the applied voltage increases, and the voltage is a certain value V.₁From the above, an electrorheological fluid having a property of apparently gelling, that is, solidifying is known. Then, as a shock absorber using this electrorheological fluid, there is one described in Japanese Patent Application Laid-Open No. 60-142334 (as another example, Japanese Patent Application Laid-Open No. 63-72934). The shock absorber is formed by a plurality of cylindrical electrodes in which pistons sliding in the cylinder are arranged coaxially, while the gap formed by the cylindrical electrodes is used as a fluid passage, and an electrorheological fluid is formed by changing the voltage applied to the cylindrical electrodes. The magnitude of the generated damping force is increased or decreased by changing the viscosity of the cylinder. (Problems that the device tries to solve) In the shock absorber, the gap between the cylindrical electrodes is kept constant, and the magnitude of the damping force is changed by utilizing the change in the viscosity of the electrorheological fluid. As a result, the range of change in the damping force is the range of change in the viscosity of the electrorheological fluid. Naturally limited by. An object of the present invention is to provide a shock absorber using an electrorheological fluid capable of increasing the range of change in damping force. (Means to solve the problem) The shock absorber according to the present invention is a cylinder that accommodates an electrorheological fluid and causes a piston rod to expand and contract from one end, and a member that is arranged inside the cylinder and divides the inside of the cylinder into two liquid chambers. A plurality of electrode pairs consisting of a partition member that defines or has a passage that communicates the two liquid chambers in combination with the cylinder, and a pair of electrodes that are arranged across the passage. It has a plurality of electrode pairs arranged so that the electrode pairs are spaced apart from each other in the circumferential direction, and each of the plurality of electrode pairs is connected to an external power source and has a voltage independent of the other electrode pairs. It can be applied, and it is related to the damping force that should be generated regardless of the position of the piston connected to the piston rod with respect to the cylinder, and the pair of electrodes of each electrode pair cannot move relative to each other. (Action and effect) A voltage is applied to each of the plurality of electrode pairs individually or simultaneously to any plurality of electrode pairs. In the latter case, the magnitude of the voltage applied to one electrode pair is made different from or the same as the magnitude of the voltage applied to the other electrode pair. Since each of the electrode pairs arranged in the circumferential direction can apply a voltage independently of the other electrode pairs and has a viscosity corresponding to the voltage applied by the electrorheological fluid, even at the same piston rod speed. , The flow rate can be changed. In addition, when an electrorheological fluid flows between a pair of electrodes in each electrode pair, it creates resistance depending on the viscosity. As a result, the range of change in the generated damping force can be increased. As a result of the damping force to be generated regardless of the position of the piston connected to the piston rod with respect to the cylinder, the damping force is determined only by the speed of the piston rod. That is, after applying a predetermined voltage to a predetermined pair of electrodes, the damping force is determined only by the speed of the piston rod, and it is easy to generate the damping force as designed. Further, since the pair of electrodes of each electrode pair cannot be moved relative to each other, the distance between each pair of electrodes and the manufacturing accuracy may be determined from the viewpoint of flowing an electrorheological fluid, and high accuracy when moving relative to each other is not required. Is. (Example) As shown in FIG. 1, the shock absorber 10 includes a cylinder 12 and a partition member 14 arranged inside the cylinder 12. The cylinder 12 and the partition member 14 are made of glass fiber reinforced resin. The cylinder 12 has a cylindrical shape with one end closed, and a cap 16 is screwed into the open end thereof. The piston rod 18 penetrates the cap 16 and extends into the cylinder 12, and the piston 20 is fixed to the end of the piston rod 18. The piston 20 is made liquidtight by the seal ring 22, and the air chamber 24 is defined by the piston 20 and the cap 16. The air chamber 24 communicates with the outside through the hole 26 of the cap 16. The partition member 14 partitions the inside of the cylinder 12 into two liquid chambers 28 and 30. Electrorheological fluids known per se are housed in the liquid chambers 28 and 30. In the illustrated embodiment, the rod 32 extends from the partition member 14, and the rod 32 projects outward through the closed end of the cylinder 12. The nut 34 is screwed into the end of the rod 32, and the rod 32 is fixed to the cylinder. As shown in FIG. 2, the partition member 14 is a member having a circular cross section, and is located with a clearance 36 in the radial direction from the inner peripheral surface 13 of the cylinder 12. This gap 36 is an annular shape and serves as a passage connecting the two liquid chambers 28 and 30. A plurality of electrode pairs are provided along the clearance 36 which is a passage. In the embodiment shown in FIG. 2, four electrode pairs 38, 40, 42, and 44 are arranged so that the electrode pairs are spaced apart from each other in the circumferential direction. Each electrode pair consists of a pair of electrodes arranged with a gap 36 in between. One of the electrodes 39a, 41a, 43a, and 45a is fitted into a recess provided on the inner peripheral surface of the cylinder 12 and attached to the cylinder 12. The other electrodes 39b, 41b, 43b, and 45b are fitted into recesses provided on the outer peripheral surface of the partition member 14 and attached to the partition member 14. The electrode on the cylinder side is connected to the power supply by a lead wire 46 extending from the cylinder to the outside, and the electrode on the partition member side is connected to the power supply by a lead wire 48 extending from the rod 32 to the outside. At the time of connection, the plurality of electrode pairs are connected so that each electrode pair can apply a voltage independently of the other electrode pair. The free piston 50 is arranged in the cylinder 12 at a distance from the partition member 14. The free piston 50 is formed in an annular shape, and is provided with a seal ring 52 on the outer circumference thereof and a seal ring 54 on the inner circumference thereof. The seal ring 52 is in close contact with the inner peripheral surface of the cylinder 12 and the seal ring 54 is in close contact with the outer peripheral surface of the rod 32, defining the gas chamber 56. The gas chamber 56 absorbs the volume change accompanying the expansion and contraction of the piston rod 18. In the embodiment shown in FIGS. 3 and 4, the shock absorber 60 includes a cylinder 62 and a partition member 64, and the partition member 64 is a piston. In this embodiment, the cylinder 62 can also be formed of metal in addition to the glass fiber reinforced resin. On the other hand, the partition member 64 is molded of glass fiber reinforced resin. The partition member 64 has a circular top 65a, a cylindrical skirt portion 65b integrated with the top 65a, and a spacer member 66, and is coupled to the piston rod 68 via the spacer member 66. The spacer member 66 is molded of a glass fiber reinforced resin. A passage 70 is provided in the partition member 64. In the illustrated embodiment, the passage 70 comprises four arcuate holes 71a and an annular clearance 71b. The four holes 71a are formed in the top 65a of the partition member 64, and the gap 71b is an annular shape formed between the partition member 64 and the spacer member 66. A plurality of electrode pairs 72 are provided along the passage 70. In the embodiment shown in FIG. 4, four electrode pairs 72 are arranged to face the holes 71a so that the electrode pairs are spaced apart from each other in the circumferential direction. Each electrode pair consists of a pair of electrodes 73a and 73b arranged with a gap 71b in between. One electrode 73a is attached to the inner peripheral surface of the skirt portion 65b of the partition member 64, and the other electrode 73b is attached to the outer peripheral surface of the spacer member 66. These electrodes are connected to the lead wire 74, and the lead wire 74 is guided to the outside through the piston rod 68. Then, a plurality of electrode pairs are connected to the power supply so that each electrode pair can apply a voltage independently of the other electrode pairs. The inside of the cylinder 62 is divided into two liquid chambers 76 and 78 by a partition member 64 which is a piston, and a free piston 80 is arranged at a distance from the partition member 64. The gas chamber 72 is defined by the free piston 80 and the cylinder 62. In electrorheological fluid, the applied voltage of each pair of electrodes, that is, the counter electrode, is V.₁When approaching, it apparently gels or solidifies. Therefore, the applied voltage is V₁In the vicinity, the area between the counter electrodes is immediately before the minimum change, and the damping force changes rapidly. The voltage just before this is V₂It is represented by. In Fig. 5a, the voltages applied to the counter electrodes of each of the four electrode pairs are all 0 to V.₂The electrorheological fluid flows between the counter electrodes of each electrode pair, and the damping force changes as shown in a in FIG. In Fig. 5b, the voltage applied to the counter electrode of one electrode pair 44 is V.₁With the above, the voltage applied to the counter electrode of each of the remaining three electrode pairs is 0 to V.₂When it is in the range of. V₁As shown by the diagonal lines, the electrorheological fluid between the counter electrodes of the electrode pair 44 to which the above voltage is applied gels, so that the area through which the fluid flows is reduced by that amount. The electrorheological fluid flows between the counter electrodes of each of the three electrode pairs, and the damping force changes as shown in b in Fig. 6. In Fig. 5c, the voltage applied to each of the two electrode pairs 44 and 38 is V.₁With the above, the voltage applied to the counter electrode of each of the remaining two electrode pairs is 0 to V.₂When it is in the range of. V₁The electrorheological fluid between the counter electrodes 44 and 38 to which the above voltage is applied is gelled, and the area through which the fluid flows is reduced by that amount. The electrorheological fluid flows between the opposite electrodes of the two electrode pairs, and the damping force changes as shown in c in Fig. 6. In Fig. 5d, the voltage applied to each of the three electrode pairs 44, 38, and 40 is V.₁With the above, the voltage applied to the counter electrode of the remaining one electrode pair is 0 to V.₂When it is in the range of. V₁The electrorheological fluid between the counter electrodes 44, 38, and 40 to which the above voltage is applied is gelled, and the area through which the fluid flows is reduced by that amount. The electrorheological fluid flows between the counter electrodes of one electrode pair, and the damping force changes as shown in d in Fig. 6. The voltage applied to each of the four electrode pairs is V₁As it approaches, the damping force approaches point P. Point P is, after all, the damping force when the area through which the fluid flows is minimized.

[Simple explanation of drawings]

FIG. 1 is a sectional view of a shock absorber, FIG. 2 is a sectional view cut along line 2-2 of FIG. 1, FIG. 3 is a sectional view of another embodiment of the shock absorber, and FIG. 4 is FIG. 3 is a plan view of the partition member shown in FIG. 3, 5 a, b, c and d are cross-sectional views showing the flow state of the electrorheological fluid, and 6 is a graph showing the correlation between voltage and damping force. Figure 7 is a graph showing the correlation between voltage and viscosity. 10, 60: Shock absorber, 12, 62: Cylinder, 14, 64: Partition member, 28, 30, 76, 78: Liquid chamber, 36, 70: Passage, 38, 40, 42, 44, 72: Electrode pair.