JP2003014028A - Hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] [Problem] In a low piston speed range,
Providing a hydraulic shock absorber with improved flexibility in setting damping characteristics. SOLUTION: During a contraction stroke of a hydraulic shock absorber 10, in a low piston speed range, a cylinder lower chamber 11b is provided.
Flows into the communication port 20a of the communication disk 20 via the notch 21a of the notch disk 21 and deflects the inner peripheral portion Y of the slit disk 19 upward. When the inner peripheral portion Y of the slit disk 19 opens, a damping force (small) of the valve characteristics is generated. The slit 19b of the slit disk 19 does not generate a pulling force in the circumferential direction at the inner peripheral portion Y, and the inner peripheral portion Y is easily bent, so that a small valve characteristic can be obtained in a low speed region of the piston speed at the time of backflow. And the degree of freedom in setting the attenuation characteristics can be improved.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber for attenuating the vibration of a vibration object such as a vehicle such as an automobile and a railway vehicle, a washing machine, and a building structure. About the vessel. 2. Description of the Related Art As an example of a conventional hydraulic shock absorber, Japanese Utility Model Laid-Open No.
This prior art will be described with reference to FIGS. 6 to 9. FIG. Since the contraction-side disk valve has the same configuration as the extension-side disk valve, only the extension-side disk valve will be described. [0003] A hydraulic shock absorber 1 according to this prior art includes a cylinder 2 in which an oil liquid is sealed, and an upper and lower cylinder 2 inside the cylinder 2.
A piston 3 is defined in the chamber (only the lower chamber is shown in FIG. 6), and the piston 3 is provided with an extension-side oil liquid passage 3a communicating the upper and lower chambers. A valve seat 3b on which the extension-side disc valve 4 is detachably mounted is provided downstream of the extension-side oil liquid passage 3a of the piston 3. The extension-side disk valve 4 which is detachably seated on the valve seat 3b is formed by laminating a plurality of disks.
From the side, the first disk 5, the second disk 6, and the annular disk 7 are stacked in this order. The first disk 5 has an arc-shaped opening 5a on the inner peripheral side (FIG. 7), and the outer peripheral edge is separated from the valve seat 3b when the oil liquid flows (normal flow) during the extension stroke. . The second disk 6 has an arc-shaped opening 6a on the inner peripheral side,
It has a notch 6b extending in the radial direction that determines the damping force of the orifice characteristic during the contraction stroke (backflow) (FIG. 8). The annular disk 7 is provided so as to entirely cover the second disk 6, and the first disk 5 and the second disk 6
Unlike this, it has no openings and notches (FIG. 9). Then, during the contraction stroke, the compressed oil liquid in the lower chamber of the cylinder flows (backflows) into the opening 6a through the notch 6b of the second disk 6, and the inner peripheral portion X of the first disk 5 (The hatched portion in FIG. 7) is bent toward the extension-side oil liquid passage 3a (upward) to open the valve, and a damping force of valve characteristics is generated according to the valve opening pressure of the inner peripheral portion X of the first disk 5. . As described above, the damping force is increased in the low-speed range of the operating speed (piston speed) of the hydraulic shock absorber 1 by the valve characteristic generated by the bending of the inner peripheral portion X of the first disk 5, and the piston speed of the hydraulic shock absorber 1 is increased. The vibration reduction function in the low-speed range is enhanced. By the way, in the above-mentioned prior art, when the inner peripheral portion X of the first disk 5 shown in FIG. 7 is bent, a force for pulling the inner peripheral portion X in the circumferential direction is applied. Therefore, there is a problem that the valve rigidity is high, and the degree of freedom in setting the valve characteristics in the low-speed range of the piston speed at the time of the backflow is low. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. By setting the rigidity of the inner peripheral portion of the disk to an arbitrary rigidity, the valve opening pressure of the disk can be arbitrarily set, and the piston speed at the time of reverse flow is increased. It is an object of the present invention to provide a hydraulic shock absorber capable of improving the degree of freedom in setting the damping characteristic in the low speed range. [0010] In order to solve the above-mentioned problems, the present invention provides a cylinder filled with an oil liquid, and two chambers slidably fitted in the cylinder and slidably inserted in the cylinder. A piston provided between the two chambers, an oil liquid passage through which oil flows by sliding of the piston, a valve seat provided downstream of the oil liquid passage, and a valve seat. A disk valve, which is provided with a disk valve which is detached and seated, wherein the disk valve has a slit provided on an inner peripheral side and having a circumferentially extending opening and a slit extending radially outward from the opening. And a communication disk having a communication port which opens to the outer peripheral side from the opening of the slit disk and communicates with the downstream side of the valve seat is sequentially laminated from the valve seat side. [0011] With such a configuration, the rigidity of the inner peripheral portion of the slit disk can be set to an arbitrary rigidity by the slit provided in the slit disk, and the valve opening pressure of the inner peripheral portion of the slit disk can be arbitrarily set. It is possible to improve the degree of freedom in setting the damping characteristic in a low piston speed range at the time. Next, an embodiment of the present invention will be described below with reference to FIGS. This embodiment shows an example in which the present invention is applied to a single-tube hydraulic shock absorber. In a hydraulic shock absorber 10, a piston 13 having a piston band 12 on its outer periphery is slidably fitted in a cylinder 11 in which an oil liquid is sealed.
Reference numeral 3 defines the inside of the cylinder 11 as two upper and lower chambers 11a and 11b. The piston 13 is connected to a small-diameter portion 14a of the piston rod 14 by an extension-side disc valve 1 described later.
8 and the compression-side disk valve 23 are fixed by a nut 15. The upper end of the piston rod 14 extends outside the cylinder 11 via a rod guide and a rod seal (both not shown) provided at the upper end of the cylinder 11. At the lower end of the cylinder 11, a gas chamber (not shown) filled with high-pressure gas is provided in series with the cylinder lower chamber 11b. Is defined in a liquid-tight and air-tight manner by a free piston (not shown) which slides freely. The piston 13 is provided with an extension-side oil passage 13a and a contraction-side oil passage 13b that communicate between the upper cylinder chamber 11a and the lower cylinder chamber 11b. Is the extension side oil liquid passage 13
An expansion-side valve seat 16a located downstream of a and a compression-side valve seat 16b located downstream of the compression-side oil liquid passage 13b are formed. On the inner peripheral side of the piston 13, the extension side valve seat 1 is provided.
6a and a position recessed in the axial direction with respect to the compression-side valve seat 16b, and the expansion-side inner seat 17a and the compression-side inside in which the inner peripheral sides of the expansion-side disk valve 18 and the compression-side disk valve 23 described below are clamped. The sheet 17b is formed. An extension-side disc valve 18 is provided on the lower end surface of the piston 13.
The slit disk 19, the communication disk 20, the notch disk 21, and the annular disk 22 are sequentially laminated from the extension side valve seat 16a side. As shown in FIG.
Are provided with an arc-shaped (C-shaped) opening 19a extending in the circumferential direction on the inner peripheral side, and a plurality of slits 19b, 19b,. The slits 19b are provided in the circumferential direction.
They are provided at substantially equal intervals with an interval of °. The openings 19a and the slits 19b are formed by punching a thin steel plate by pressing or the like. Here, a plurality of straight openings are respectively extended along the circumferential direction of the slit disk 19 without making the opening 19a an arc-shaped opening, and these are connected to form a polygonal opening. You may do it. Each slit 19b is provided so as to extend to a substantially radially outer center portion of a communication port 20a provided in the communication disk 20 in a state of being overlapped with a communication disk 20 described later. Thereby, the inner peripheral portion Y (hatched portion in FIG. 2) sandwiched between the slits 19b is easily bent with a circumscribed circle (dashed portion in FIG. 2) contacting the tip of each slit 19b as a fulcrum. On the inner peripheral side of the opening 19a, a ring portion 19c is provided via a bridging portion 19d. The ring portion 19c is fitted to the small diameter portion 14a of the piston rod 14 to fix the slit disk 19 to a predetermined position. It is centered on the position. As shown in FIG. 3, the communication disk 20 is provided with an arc-shaped (C-shaped) communication port 20a on the inner peripheral side thereof. As shown in FIG. In addition to communicating with the distal end side of each slit 19b provided in the notch 19, it communicates with a notch 21a of a notch disk 21 described later. A ring portion 20b is provided on the inner peripheral side of the communication port 20a via a bridging portion 20c. The ring portion 20b is fitted to the small-diameter portion 14a of the piston rod 14 to connect the communication disk 20 to the piston rod 14. Centering is performed at a predetermined position. The ring portion 20b is provided with the slit disk 19
When stacked on top, the slit 19 of the slit disk 19
b, so as to cover the opening 19a of the slit disk 19 except for a part of the tip side. As shown in FIG. 4, the notched disk 21
U-shaped notch 21 forming a fixed orifice on the outer peripheral edge
a, 21a... are provided, and each of the notches 21a is provided at four locations at substantially equal intervals at 90 ° intervals in the circumferential direction. When the notches 21a of the notch disk 21 are stacked on the communication disk 20, the notches 21a extend substantially radially inward with respect to the opening 20a of the communication disk 20, and communicate with the cylinder lower chamber 11b. Let me. On the notched disk 21, two annular disks 22 are stacked. In addition, the annular disk 2
The extension-side damping force can be adjusted by appropriately adjusting the number of sheets. When the communication disk 20, the notch disk 21 and the annular disk 22 are stacked, each notch 21a forming a fixed orifice provided in the notch disk 21 is formed.
Is larger than the total flow area (S2) of the tip side portion of each slit 19b communicating with the opening 20a in the axial direction when the communication disk 20 is stacked on the slit disk 19. Is set. As described above, the total flow area of the front end portion of each slit 19b is set so as not to be larger than the total flow area of each notch 21a of the notch disk 21 (S
2 <S1), the inner peripheral portion Y of the slit disk 19 can be bent upward in FIG. 5, as described later. A compression-side disc valve 23 is provided on the upper end surface of the piston 13, and the compression-side disc valve 23
The compression side notch disk 24 provided with U-shaped notches 24a, 24a,... Forming a fixed orifice on the outer peripheral side from the compression side valve seat 16b side, the annular disk 25, and the smaller diameter than the annular disk 25. The annular disks 26 are sequentially stacked. The contraction-side damping force can be adjusted by appropriately adjusting the number of the annular disks 25 or the small-diameter annular disks 26. The operation of the above embodiment configured as described above will be described. During the extension stroke of the hydraulic shock absorber 10, in the low-speed range of the piston speed, the oil liquid in the cylinder upper chamber 11 a flows through the notch 24 a of the contraction-side notch disk 24 and the contraction-side oil liquid passage 13 b of the piston 13. Cylinder lower chamber 11
b (reverse flow), and a slit 1 provided in a slit disk 19 on the extension side oil liquid passage 13 a of the piston 13.
9b, flows into the cylinder lower chamber 11b (normal flow) through the communication port 20a of the communication disk 20 and the notch 21a of the notch disk 21. At this time, a damping force having an orifice characteristic is generated by the notch 24a and the tip portion of the slit 19b. The orifice characteristic during the extension stroke is determined by the total area of the notch 24a and the tip of the slit 19b. By appropriately setting the opening area of the tip of the slit 19b, 24a can be omitted. In this case, the contraction-side notch disk 24 constituting the contraction-side disc valve 23 can be a simple annular disk having no notch, thereby preventing erroneous assembly. In the high speed range of the piston speed, the piston 13
The pressure of the oil flowing through the expansion-side oil liquid passage 13a increases.
The extension-side disc valve 18 is opened (separated from the extension-side valve seat 16a), and a damping force having valve characteristics corresponding to the opening degree is generated. On the other hand, during the contraction stroke of the hydraulic shock absorber 10, in the low piston speed range, first, the cylinder lower chamber 1
1b flows into the cylinder upper chamber 11a (forward flow) through the contraction-side oil liquid passage 13b of the piston 13 and the notch 24a of the contraction-side notch disk 24, and the notch disk 2
The fluid flows into the cylinder upper chamber 11a (reverse flow) through the notch 21a, the communication port 20a of the communication disk 20, and the distal end portion of the slit 19b provided in the slit disk 19.
At this time, a damping force having an orifice characteristic is generated by the notch 24a, the notch 21a, the communication port 20a, and the distal end portion of the slit 19b. In the low speed range where the piston speed is slightly higher, the oil flows as shown by the arrow in FIG.
The oil liquid flowing into the inside of the slit disk 19
As shown in FIG. 5 (the hatched portion in FIG. 2), the extension side oil liquid passage 1
3a (upward), so that it flows into the extension-side oil liquid passage 13a of the piston 13 through the gap created between the slit disk 19 and the communication disk 20, and flows into the cylinder upper chamber 11a (backflow). ). At this time, when the inner peripheral portion Y of the slit disk 19 opens, a damping force (small) of the valve characteristics is generated. In the high speed range of the piston speed, the piston 13
, The pressure of the oil flowing through the contraction-side oil liquid passage 13b increases.
The compression-side disk valve 23 is opened (separated from the valve seat 16b), and a damping force (large) of valve characteristics corresponding to the opening degree is generated. As described above, in the present embodiment, the inner peripheral portion Y of the slit disk 19 does not generate the force for pulling the disk in the circumferential direction as described in the related art due to the slit 19b provided in the slit disk 19. In addition, since the rigidity is weakened to bend easily, an appropriate damping force characteristic (small valve characteristic) can be obtained in a low piston speed range, and the steering stability can be improved. The slit 19b provided on the slit disk 19 is formed by pressing (punching).
Since it can be formed at the same time as the opening 19a, it can be formed extremely inexpensively. In particular, there is no need to use an expensive valve material having a smaller plate thickness. In the above embodiment, the slits 19b extending radially outward from the openings 19a provided in the slit disk 19 are provided at substantially equal intervals at 90 ° intervals in the circumferential direction. The number of slits is not limited to the above, and the number of slits may be changed as appropriate, and may not be equal.
In this case, it is possible to easily cope with a specification having different damping characteristics depending on an applied vehicle type and the like, and the degree of freedom of tuning (the degree of freedom of setting the damping characteristics) is increased (the number of slits is small → high damping force shift, slit Many → low damping force). In the above-described embodiment, the slit 19 b extending radially outward from the opening 19 a provided in the slit disk 19 is provided with the communication port 20 a provided in the communication disk 20.
Although it is shown that it is provided so as to extend substantially to the center in the radial direction outside, the length of the slit in the radial direction may be appropriately adjusted. Also in this case, it is possible to easily cope with the one having a different specification of the damping characteristic according to the applied vehicle type and the like, and the degree of freedom of tuning (the degree of freedom of setting the damping characteristic) is increased (the slit is short → closed to the high damping force, Long slits → low damping force). Further, in order to set the rigidity of the slit disk 19 lower (set softer), the inner peripheral portion Y
A plurality of holes are formed in (a hatched portion in FIG. 2) along a circumscribed circle (a broken line portion in FIG. 2) contacting the tip of the slit 19b, and a thin portion extending in the circumferential direction is formed in the portion. You may. However, when the rigidity is set by forming a hole, the communication disk 2 is placed on the slit disk 19.
The total value of the flow path area of the tip side portion of each slit 19b communicating with the opening 20a in the axial direction and the flow path area of the above-mentioned hole when the 0 is stacked is the notch 2 provided in the notch disk 21.
The flow area is set so as not to be larger than the total value of the flow path area 1a. Further, in the above-described embodiment, the valve structure of the present invention is applied to the extension-side disk valve 18, but may be adopted to the compression-side disk valve. In the above-described embodiment, the case where the present invention is applied to a single-cylinder hydraulic shock absorber has been described. Can be higher. As described above, according to the present invention, a disk valve is provided with a slit disk having an opening provided on the inner peripheral side and a slit extending radially outward from the opening. Since the communication disk having a communication port which opens to the outer peripheral side from the opening of the slit disk and communicates with the downstream side of the valve seat is sequentially laminated from the valve seat side, the rigidity of the inner peripheral portion of the slit disk is arbitrary by the slit. Since the valve opening pressure at the inner peripheral portion of the slit disk can be arbitrarily set as the rigidity of the slit disk, the degree of freedom in setting the damping characteristic in the low-speed range of the piston speed at the time of backflow can be improved. [0048]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged sectional view showing a piston portion of a hydraulic shock absorber according to the present invention. FIG. 2 is a plan view showing the slit disk in FIG. FIG. 3 is a plan view showing the communication disk in FIG. 1; FIG. 4 is a plan view showing the notched disk in FIG. 1; FIG. 5 is an enlarged sectional view of a piston portion of FIG. 1, showing an operating state. FIG. 6 is an enlarged cross-sectional view of a piston portion according to the related art. FIG. 7 is a plan view showing a first disk in FIG. 6; FIG. 8 is a plan view showing a second disk in FIG. 6; FIG. 9 is a plan view showing the annular disk in FIG. 6; [Description of Signs] 10 Hydraulic shock absorber 11 Cylinder 13 Piston 13a Extension-side oil liquid passage (oil liquid passage) 13b Contraction-side oil liquid passage (oil liquid passage) 14 Piston rod 16a Extension-side valve seat 16b Contraction-side valve seat 18 Extension Side disk valve 19 Slit disk 19a Opening 19b Slit 20 Communication disk 20a Opening

Claims (1)

Claims: 1. A cylinder filled with an oil liquid, a piston slidably inserted into the cylinder and defining the cylinder as two chambers, and a piston provided between the two chambers. A hydraulic fluid passage including an oil fluid passage through which an oil fluid flows by sliding of the piston, a valve seat provided downstream of the oil fluid passage, and a disc valve which is separated from and seated on the valve seat. In the device, the disc valve has a slit disk provided with an opening extending in the circumferential direction provided on the inner peripheral side and a slit extending radially outward from the opening, and an outer peripheral side opening from the opening of the slit disk. A hydraulic shock absorber, wherein a communication disk having a communication port communicating with a downstream side of the valve seat is sequentially laminated from the valve seat side.