JP2003322195A - Damping force adjustable hydraulic shock absorber - Google Patents

Abstract

(57) [Problem] To provide a damping force adjusting type hydraulic shock absorber capable of adjusting valve characteristics with a simple structure. SOLUTION: A piston 5 to which a piston rod 8 is connected is fitted in a cylinder 2 in which an oil liquid is sealed. Disc valves 1 in the oil passages 14 and 15 on the extension and contraction sides of piston 5
8 and 19 are provided, and a magnet 20 is provided to face the disk valves 18 and 19. The yokes 6, 7 are attached to both ends of the piston 5, and the coil 22 is built in the yoke 6. By energizing the coil 22 through the conducting wire 23 and applying a magnetic field to the magnet 20 from the coil 22, the disc valve of the magnet 20
Adjust the suction force for the 18, 18
Valve opening pressure can be adjusted, damping force (valve characteristics)
Can be adjusted.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force-adjustable hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile. 2. Description of the Related Art A hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile has a damping force characteristic in order to improve riding comfort and steering stability in accordance with road surface conditions, running conditions, and the like. There is a damping force-adjustable hydraulic shock absorber in which the pressure can be appropriately adjusted. In general, a damping force adjusting type hydraulic shock absorber slidably fits a piston having a piston rod connected to a cylinder filled with an oil liquid so as to divide the cylinder into two chambers.
The piston has a main oil passage and a bypass passage that communicate the two chambers in the cylinder.The main oil passage has a damping force generating mechanism consisting of an orifice and disk valve, and the bypass passage has its passage area adjusted. The damping force adjusting valve is provided. [0004] With this configuration, the damping force is reduced by opening the bypass passage by the damping force adjusting valve to reduce the flow resistance of the oil liquid between the two chambers in the cylinder. , The damping force is increased by increasing the flow resistance. As described above, the damping force characteristic can be appropriately adjusted by opening and closing the damping force adjustment valve. However, when the damping force is adjusted only by the passage area of the bypass passage as described above, the damping force depends on the restriction of the orifice of the oil passage in a low piston speed range. Can be greatly changed, but in the middle and high speed regions of the piston speed, the damping force characteristic greatly changes because the damping force depends on the opening degree of the damping force generating mechanism (such as a disc valve) of the main oil passage. Can not do. Therefore, as described in, for example, Japanese Patent Application Laid-Open No. 7-332425, a back pressure chamber (pilot chamber) is formed at the back of the disc valve as a damping force generating mechanism for the main oil liquid passage. Pilot-type damping force adjustment by connecting the pressure chamber to the cylinder chamber on the upstream side of the disk valve via a fixed orifice, and connecting it to the cylinder chamber on the downstream side of the disk valve via a flow control valve (pilot control valve) A valve is known. According to this damping force adjusting type hydraulic shock absorber, by opening and closing the flow control valve, the area of the communication passage between the two chambers in the cylinder is directly adjusted, and the back pressure is reduced by the pressure loss generated in the flow control valve. The opening pressure of the disc valve can be changed by changing the pressure in the chamber. In this way, the orifice characteristics (the damping force is approximately proportional to the square of the piston speed) and the valve characteristics (the damping force is approximately proportional to the piston speed) can be adjusted, and the adjustment range of the damping force characteristics can be widened. can do. [0008] However, in the conventional damping force adjusting type hydraulic shock absorber having the pilot type damping force adjusting valve, since the pilot chamber is formed, the structure is complicated and the number of parts is large. It takes up space, requires a high manufacturing cost, is difficult to reduce in size, and poses a problem in terms of mountability on a vehicle. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a damping force-adjustable hydraulic shock absorber capable of adjusting valve characteristics with a simple structure and capable of being downsized. With the goal. [0010] In order to solve the above-mentioned problems, a damping force-adjustable hydraulic shock absorber according to the first aspect of the present invention comprises a cylinder in which an oil liquid is sealed, and a cylinder in which the oil liquid is filled. A slidably fitted piston, a piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, and an oil passage for flowing an oil liquid by movement of the piston in the cylinder And a damping force generating mechanism for controlling the flow of the oil liquid in the oil passage to generate a damping force, wherein the damping force generating mechanism comprises a valve body made of a magnetic material for opening and closing the oil passage, A permanent magnet facing the body and a coil for applying a magnetic field to the permanent magnet are provided. With this configuration, by energizing the coil and applying a magnetic field from the coil to the permanent magnet, the attractive force of the permanent magnet to the valve body is adjusted, and the valve opening pressure of the valve body is adjusted. An embodiment of the present invention will be described below in detail with reference to the drawings. The damping force adjusting type hydraulic shock absorber 1 according to the present embodiment has a double cylinder structure in which an outer cylinder 3 is provided on the outer periphery of a cylinder 2 and a reservoir 4 is formed between the cylinder 2 and the outer cylinder 3. I have. In cylinder 2, piston 5
Are slidably fitted, and the interior of the cylinder 2 is defined by the piston 5 into two chambers, an upper cylinder chamber 2A and a lower cylinder chamber 2B. A yoke 6 is provided at an end of the piston 5 on the cylinder upper chamber 2A side, a yoke 7 is provided at an end of the cylinder lower chamber 2B side, and a hollow piston rod 8 is provided on the piston 5 and the yokes 6, 7. The small-diameter portion 9 on one end side is inserted and fixed by a nut 10. The other end of the piston rod 8 is inserted through a rod guide 11 and an oil seal 12 mounted on upper ends of the cylinder 2 and the outer cylinder 3 and extends to the outside. At the lower end of the cylinder 2, the lower cylinder 2
A base valve 13 for partitioning B and the reservoir 4 is provided. An oil liquid is sealed in the cylinder upper and lower chambers 2A and 2B, and an oil liquid and a gas are sealed in the reservoir 4. As shown in FIGS. 2 and 3, the piston 5 is provided with four extending-side oil passages 14 communicating between the cylinder upper and lower chambers 2A and 2B at equal intervals along the circumferential direction. Similarly, four contraction-side oil passages 15 are arranged between these extension-side oil passages. A valve seat 16 is provided on the end face of the piston 5 on the side of the cylinder lower chamber 2B so as to surround the four openings of the extension-side oil passage 14.
The upper end of the cylinder upper chamber 2A is provided with a valve seat 17 so as to surround the four openings of the contraction side oil passage 15.
Is protruding. A disc valve 18 (a damping force generating mechanism, a valve body) for controlling the flow of the oil liquid in the expansion-side oil passage 14 is seated on the valve seat 16, and the oil seat of the contraction-side oil passage 15 is mounted on the valve seat 17. Disk valve 19 for controlling flow (damping force generation mechanism, valve body)
Is seated. The disk valve 18 or 19 is provided with an orifice (not shown) for constantly communicating between the cylinder upper and lower chambers 2A and 2B. The contraction-side oil passage 15 has a cylindrical magnet 20.
(Permanent magnet) is inserted, and the magnet 20 is sandwiched between a pair of support portions 21 projecting radially inward of the contraction-side oil passage 15. Here, the flow passage area of the contraction-side oil passage 15 is such that the extension-side oil passage 14
Is set so as to be substantially equal to the flow path area. Both ends of the magnet 20 face the disc valves 18 and 19 seated on the valve seats 16 and 17 with a predetermined gap. The piston 5 is a non-magnetic material, and the disc valves 18, 19 are magnetic materials. The piston 5, for example, as a sintered metal, can be molded integrally with the magnet 20, or
After the piston 5 is formed as a single unit, the magnet 20 may be press-fitted. In the drawings, reference numeral 21 denotes a piston ring. The yoke 6 on the cylinder upper chamber 2A side is provided with a coil 2
2, a conductor 23 connected to the winding of the coil 22 is inserted into the hollow piston rod 8, and extends from the tip to the outside. The yoke 6 is formed with four irregularities in the radial direction so as to face four magnets 20 provided on the piston 5. Also, cylinder lower chamber 2B
Similarly, the four yokes 7 are formed with four irregularities in the radial direction so as to face the four magnets 20 provided on the piston. Small diameter parts of yokes 6, 7 and piston rod 8
Numeral 9 denotes a magnetic material, and the yoke 6, 7 and the small-diameter portion 9 of the piston rod 8 respond to a magnetic field generated by energizing the coil 22.
The disk valves 18, 19 and the magnet 20 form a closed magnetic circuit through a gap between the disk valves 18, 19 and the magnet 20. The base valve 13 is provided with extension-side and contraction-side oil passages 24, 25 for communicating the cylinder lower chamber 2B and the reservoir 4. A check valve that allows only the flow of the oil liquid from the reservoir 4 side to the cylinder lower chamber 2B side in the expansion side oil passage 24
The contraction-side oil passage 25 is provided with a damping force generating mechanism 27 including an orifice and a disk valve for giving resistance to the flow of the oil liquid from the cylinder lower chamber 2B side to the reservoir 4 side. In the figure, reference numeral 28 is a rebound stopper. Next, the operation of the embodiment constructed as described above will be described. During the extension stroke of the piston rod 8, the movement of the piston 5 causes the oil liquid in the cylinder upper chamber 2A to flow through the extension oil passage 14 to the cylinder lower chamber 2B, and the orifices of the disc valves 18, 19 and the disc valve 1
The damping force is generated by opening the valve of 8. At this time, the amount of oil that the piston rod 8 has withdrawn from the inside of the cylinder 2 flows from the reservoir 4 through the extension-side oil passage 24 of the base valve 13, opens the check valve 26, and flows into the cylinder lower chamber 2B. The gas in the reservoir 4 expands. Also, during the compression stroke of the piston rod 8, the movement of the piston 5 causes the oil liquid in the cylinder lower chamber 2B to flow through the compression oil path 15 to the cylinder upper chamber 2A, thereby causing the disc valves 18 and 19 to move. Orifice and disc valve 1
The damping force is generated by opening the valve of No.9. At this time, the amount of oil liquid that the piston rod 8 has entered into the cylinder 2 flows from the cylinder lower chamber 2B through the contraction-side oil passage 25 of the base valve 13, flows into the reservoir 4 via the damping force generation mechanism, and Compress the gas in 4. The magnet 20 and the disc valves 18, 19
Constitutes the above-described magnetic circuit, and the magnetic flux generated between them causes the magnets 20 to attract the disk valves 18 and 19 in the valve closing direction. Wire from outside
By energizing the coil 22 through 23, a magnetic field can be generated in the above-described magnetic circuit by the coil 22,
When the polarity of the magnetic field by the coil 22 matches the polarity of the magnetic field by the magnet 20, the disk valve 1 of the magnet 20
When the attraction to the discs 8, 19 increases, and when the polarity is reversed, the attraction to the disc valves 18, 19 of the magnet 20 decreases. As a result, the valve opening pressures (valve characteristics) of the disc valves 18 and 19 can be adjusted according to the current supplied to the coil 22, and the damping force can be adjusted. As described above, with a relatively simple structure, the valve characteristics can be adjusted, the riding comfort and the steering stability of the vehicle can be improved, and the hydraulic shock absorber can be downsized, It is possible to improve the mountability on a vehicle. The magnet 20 and the disc valves 18,1
9 to provide stable damping force without interference between the magnet 20 and the disc valves 18 and 19 even when iron powder or the like is adsorbed and deposited on the magnet 20. Can be. As described above, by inverting the direction of current supply to the coil 22 and inverting the magnetic poles of the coil 22, the attraction force of the magnet 20 can be increased or decreased, and the disc valves 18 and 19 can be opened. Although the pressure can be adjusted over a wide range, the coil 22 generates a magnetic field that is the same as or opposite to the polarity of the magnet 20 by using only one direction of current to the coil 22.
The valve opening pressure of 18, 19 may be increased or decreased. In this case, the adjustment range of the damping force characteristic is reduced, but the control circuit for the current flowing through the coil 22 can be simplified. In the above-described embodiment, the magnet 20 is provided in the contraction-side oil passage 15.
The present invention is not limited to this.
The piston 5 may be inserted into a portion of the piston 5 which is different from these oil passages. Further, in the above embodiment, the piston 5 is provided with the extension side and the contraction side 14, 15 and the compression side oil passage 15 is provided with the magnet 20, but the present invention is not limited to this. Instead, a bypass oil passage may be provided outside the cylinder, and the damping force generating mechanism according to the present invention including a magnet or the like may be provided in the bypass oil passage. As described in detail above, according to the damping force-adjustable hydraulic shock absorber according to the first aspect of the present invention, the coil is energized to apply a magnetic field from the coil to the permanent magnet. By adjusting the attraction force of the permanent magnet to the valve element, the valve opening pressure of the valve element can be adjusted. As a result, the damping force
(Valve characteristics) can be controlled, and the riding comfort and steering stability of the vehicle can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a damping force adjustable hydraulic shock absorber according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a top view of the piston of FIG. 2; [Description of Signs] 1 Damping Force Adjustable Hydraulic Shock Absorber 2 Cylinder 5 Piston 8 Piston Rod 14 Extension Oil Path 15 Contraction Oil Path 18, 19 Disc Valve (Damping Force Generating Mechanism, Valve Body) 20 Magnet (Permanent Magnet) 22 coils

Claims (1)

Claims: 1. A cylinder filled with an oil liquid, a piston slidably fitted in the cylinder, and one end connected to the piston and the other end out of the cylinder. An extended piston rod, an oil passage through which oil is circulated by movement of the piston in the cylinder, and a damping force generation mechanism that controls the flow of the oil in the oil passage to generate a damping force. The damping force generating mechanism includes a valve body made of a magnetic material that opens and closes the oil passage, a permanent magnet facing the valve body, and a coil that applies a magnetic field to the permanent magnet. Damping force adjustable hydraulic shock absorber.