JPH0331947B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for a piston-piston rod assembly consisting of a piston and a piston rod to be slidably disposed within a cylinder, and for the displacement of the piston-piston rod assembly toward the extension side and the contraction side to be performed using hydraulic pressure. This invention relates to a hydraulic shock absorber that generates a damping force due to resistance force.

Hitherto, a hydraulic shock absorber is known in which a fixed throttle passage and a variable throttle passage are formed in the piston, and a damping force is obtained for the piston-piston rod assembly by the flow resistance generated when the oil passes through the respective throttle passages. It is being In this type of hydraulic shock absorber, when the displacement speed of the piston is in a low speed range, only the fixed throttle passage becomes the flow path area and exhibits a predetermined damping force characteristic, and when the piston is displaced at high speed,
The damping force is configured to change by opening the variable throttle passage and increasing the area of the flow passage.

By the way, from the perspective of vehicle ride comfort,
It is better not to increase the damping force of the hydraulic shock absorber too much. On the other hand, if the damping force is reduced, the steering stability of the vehicle may be impaired. Therefore, when the piston displacement speed is in the low speed range, the damping force is reduced in consideration of riding comfort, and when the piston displacement speed is in the high speed range, where steering stability is a problem, the damping force is reduced. A hydraulic shock absorber with adjustable damping force would be optimal. However, in the conventional hydraulic shock absorber described above, the orifice area is constant, so the damping force characteristics during low-speed displacement of the piston are constant, and the degree of freedom in setting the damping force is small. . For this reason, there is a drawback that either the ride comfort or the handling stability of the vehicle must be sacrificed to some extent.

The present invention was made in order to eliminate the drawbacks of the prior art described above, and the damping force characteristics are changed in three stages, thereby increasing the degree of freedom in setting the damping force in the low speed range of the piston displacement speed. The purpose is to provide an ambidextrous hydraulic shock absorber.

In order to achieve the above-mentioned object, the hydraulic shock absorber according to the present invention has a structure including a cylinder containing oil liquid and gas, one end of which is located within the cylinder,
a piston rod whose other end protrudes outward from the cylinder; a piston that is fitted into one end of the piston rod so as to be movable in the axial direction and defines two oil chambers within the cylinder; and an axis of the piston. The piston rod comprises a communication passage bored in the direction of the oil chamber and communicating the two oil chambers, a retainer that faces one end surface of the piston and is fitted into the piston rod so as to be movable in the axial direction thereof, and a plurality of discs. a disc valve assembly which is held between a piston and a retainer, and has one outer peripheral side brought into contact with and separated from the piston, and the other inner peripheral side brought into contact with and separated from the retainer, thereby communicating and cutting off the two oil chambers; Provided on a first disk that comes into contact with the piston or retainer among the disks forming the disk valve assembly,
an orifice located between the outer peripheral edge and the inner peripheral edge of the first disk and communicating the oil chambers; the first disk and a second disk adjacent to the first disk;
between the first and second disks, the first and second disks are provided on a circumferential side opposite to the one circumferential side that abuts the piston or the retainer, and
a spacer that separates circumferential edges of one circumferential side of the second disk such that they can approach each other, and increases or decreases the opening area of the orifice by causing the circumferential edges of the first and second disks to separate and approach each other; and the piston. Alternatively, it is characterized by comprising a fixed orifice formed in the piston rod to constantly communicate the two oil chambers.

With this configuration, until the first disk and second disk come into contact, the orifice provided on the first disk and the fixed orifice provided on the piston or piston rod serve as the flow path area, and the orifice The flow path formed becomes a variable throttle passage whose flow area decreases as the piston speed increases, while the fixed orifice functions as a fixed throttle passage whose flow area remains constant regardless of the piston speed. . The flow resistance generated when the oil passes through the variable throttle passage and the fixed throttle passage generates a damping force against the piston. Also, the speed of the piston increases, and the first and second
After the disk comes into contact, only the fixed throttle passage becomes the flow path area, and the damping force characteristics change. and,
At higher piston speeds, the disc valve assembly moves away from the piston or retainer and another variable restriction passage is created, resulting in a three-step change in damping force characteristics.

As a result, the degree of freedom in setting the damping force in the low piston displacement speed range increases, and by appropriately designing the opening area of the orifice and the thickness of the spacer, the damping force is small when the piston is displaced at low speeds.
It is possible to obtain a damping force characteristic in which a large damping force is obtained in the medium speed range, and the change becomes slow in the high speed range, making it possible to obtain a damping force characteristic that is almost ideal. This effect is achieved.

Embodiments of the present invention will be described below based on the drawings.

1 to 10 show a first embodiment of the present invention. In FIG. 1, 1 indicates a cylinder, one end of which is covered with a cap 2, and the other end of which is covered with a cap 2. A rod guide 3 and a seal member 4 are attached to the rod guide 3 and the seal member 4. Reference numeral 5 designates a piston rod, one end of which is located within the cylinder 1 via the rod guide 3 and the seal member 4, and the other end is projected outside the cylinder 1. A small diameter portion 5A is formed at the end of the piston rod 5 inside the cylinder 1, and a piston 6 that defines the inside of the cylinder 1 into two oil chambers A and B is inserted into the small diameter portion 5A. ing.
The piston 6 is slidably displaced along the inner wall of the cylinder 1 and is movable in the axial direction of the piston rod 5. Further, the piston 6 is provided with communication holes 7, 7, . . . having a large passage area in the axial direction and allowing oil fluid to flow between the oil chambers A and B.

Next, reference numeral 8 denotes a damping force generating mechanism provided facing the end surface of the piston 6 on the side facing the oil chamber A, and the damping force generating mechanism 8 has a structure as shown in FIG. That is, on the end surface of the piston 6 facing the oil chamber A, an annular protrusion 6A is formed on the outer circumferential side of the area where the communication hole 7 is formed. The small diameter portion 5A of the piston rod 5 has a protrusion 6A on the piston 6.
A retainer 9 is fitted so as to be movable in the axial direction so as to face the retainer 9 . The retainer 9 has a stepped side surface facing the piston 6, and a protrusion 9A that most protrudes toward the piston 6 is formed on the inner circumferential side. A stepped portion 9B is provided at a portion spaced a predetermined distance from the
Further, a large diameter portion 9C is formed apart from the piston 6.

10 indicates first, second, third and fourth disks 10A, 10B, from the side facing the piston 6.
10C and 10D, the inner peripheral edge of the disc valve assembly 10 has a larger diameter than the protrusion 9A of the retainer 9, and is interposed between the piston 6 and the retainer 9. ing. On the other hand, the stepped portion 5 formed on the piston rod 5
A spring receiver 11 is provided between B and the outer circumferential surface of the protrusion 6A of the piston 6, and the spring receiver 11 also has the function of positioning the disc valve assembly 10 in the radial direction.
A spring 12 is stretched between the retainer 1 and the retainer 9, and the spring 12 always urges the retainer 9 and the disc valve assembly 10 toward the piston 6. For this purpose, the disc valve assembly 1
0, the outer peripheral edge of the first disk 10A abuts the protrusion 6A of the piston 6, and the fourth disk 10A contacts the protrusion 6A of the piston 6.
The inner peripheral edge of D is brought into contact with the stepped portion 9B of the retainer 9. In a neutral state where there is no pressure difference between the oil chambers A and B, the protrusion 9 of the retainer 9
A is separated from the piston 6 by a distance l _a . Also, the first part of the disc valve assembly 10
As shown in FIG. 3, the disk 10A is provided with one or more orifices 13 on its side surface. Further, the first disk 10A is integrally provided with an annular protrusion 14 forming a spacer on the inner circumferential side thereof facing the second disk 10B. That is, each of the projections 14 is provided on the inner peripheral side opposite to the outer peripheral side where the first disk 10A contacts the projection 6A of the piston 6. As a result, the first disk 10A is separated from the second disk 10B by a predetermined distance l _b by the annular protrusion 14, and the distance l _b is the distance between the piston 6 and the protrusion 9A of the retainer 9. is less than or equal to the separation distance l _a . Furthermore, the spring bearing 11 is provided with one or more notched grooves 15, and as a result, between the oil chambers A and B, the first and second disks 10A formed by the notched groove 15, the orifice 13, and the protrusion 14 are formed. ,1
They are communicated with each other via the gap between 0B.
Furthermore, 16 is an orifice passage as a fixed orifice bored in the piston 6, and the orifice passage 16 opens into the oil chamber A on one side and opens into the communication hole 7 on the other side. As a result, oil chambers A and B
There is constant communication between them.

Thus, the above-mentioned damping force generating mechanism 8 includes the piston 6.
When the piston rod 5 is displaced to either the extension side or the contraction side, the flow path area between the oil chambers A and B is changed depending on the displacement speed. That is, first, the orifice passage 16 functions as a fixed throttle passage that communicates between the oil chambers A and B with a constant flow path area regardless of the displacement speed of the piston 6. Further, the protrusion 14 also forms an annular gap formed with a distance l _b between the first and second disks 10A and 10B, and a flow path via the orifice 13. 1st, 2nd
It is a variable throttle passage whose flow area changes depending on whether the disks 10A, 10B are brought closer to each other or separated from each other. Furthermore, when the displacement speed of the piston 6 becomes high, the disc valve assembly 10 separates from the stepped portion 9B of the retainer 9 or the protrusion 6A of the piston 6, thereby forming another variable throttle passage.

In addition, 17 in the figure indicates the piston 6 together with the spring receiver 11.
A stopper 18 for regulating the range of movement of the retainer 9 in the axial direction indicates an oil hole that is bored in the large diameter portion 9C of the retainer 9 and smoothes the action of pressure on the disc valve assembly 10. Further, 19 indicates a free piston provided in the cylinder 1, and an air chamber C is formed between the free piston 19 and the cap 2, and the air chamber C allows the piston rod 5 to enter the cylinder 1 by volume. compensation will be provided. Further, reference numerals 20 and 21 indicate brackets attached to the outer end of the cylinder 1 and the cap 2 of the piston rod 5, respectively.

The hydraulic shock absorber according to the present invention has the above-mentioned structure, and the bracket 20 is attached to the body side of the vehicle, and the bracket 21 is attached to the chassis side of the vehicle, so that vibrations of the vehicle can be buffered. First, when the piston 6 and the piston rod 5 are displaced in the extension direction, a pressure difference is generated between the oil chambers A and B, and oil flows from the oil chamber A to the oil chamber B. When the displacement speed of the piston 6 is in a low speed range, the second
In the state shown in the figure, the flow path between the oil chambers A and B is from the fixed throttle passage formed by the orifice passage 16, the annular gap formed between the first and second disks 10A and 10B by the protrusion 14, and the orifice 13. It is formed with a variable throttle passage. And piston 6
When the displacement speed increases, the retainer 9 is displaced in the direction approaching the piston 6, and the first disk 1
0A is bent, and the outer circumferential edge of the first disk 10A and the outer circumferential edge of the second disk 10B are brought close to each other, and the flow area of the variable throttle passage described above is reduced. During this time, a damping force is exerted on the piston 6 due to the flow resistance of the oil passing through the fixed throttle passage and the variable throttle passage.

Next, as shown in FIG. 4, when the first and second disks 10A and 10B come into contact, the variable throttle passage is closed, and only the fixed throttle passage consisting of the orifice passage 16 is opened between the oil chambers A and B. The area of the flow path changes, and the damping force applied to the piston 6 changes. However, in this state, the protrusion 9A of the retainer 9 is separated from the piston 6 by a distance l _c , and from this state to the state shown in FIG. 5 where the protrusion 9A of the retainer 9 comes into contact with the piston 6, The flow path area between oil chambers A and B is constant and does not change.

When the displacement speed of the piston 6 becomes even faster,
The pressure in the oil chamber A acts on the disc valve assembly 10, and as shown in FIG. The portion is spaced apart from the stepped portion 9B of the retainer 9, and a variable throttle passage is formed therebetween. Therefore, the flow path area from the oil chamber A to the oil chamber B increases, and the damping force applied to the piston 6 further changes.

On the other hand, when the piston 6 is displaced to the contraction side, the pressure on the oil chamber B side increases, the pressure inside the oil chamber A decreases, and a pressure difference is generated therebetween. This differential pressure causes the retainer 9, the disc valve assembly 10, and the piston 6 to be displaced to the left in the figure, and the retainer 9 comes into contact with the spring receiver 11. From this state, as shown in FIG. 7, the protrusion 6 of the piston 6
Until A bends the first disk 10A and its outer peripheral edge comes into contact with the second disk 10B, the fixed throttle passage by the orifice passage 16;
A flow path area consisting of a variable throttle passage is formed by the annular gap between the first and second disks 10A and 10B, and a predetermined damping force is generated by the flow resistance of the oil passing through them.

From this state, as shown in Figure 8,
Until the piston 6 and the protrusion 9A of the retainer 9 come into contact with each other, the orifice passage 16 becomes a fixed throttle passage and the damping force characteristics change. Furthermore, as shown in FIG. 9, when the disc valve assembly 10 is bent and its outer peripheral edge is separated from the protrusion 6A of the piston 6, the damping force characteristics for the piston 6 further change, and the damping force is divided into three stages. There is no fundamental difference from the elongation side in terms of changes.

FIG. 10 shows a damping force characteristic diagram of the hydraulic shock absorber according to the present invention. As is clear from the figure, the damping force on the piston 6 is symmetrical when it is extended and when it is contracted, and the damping force is extremely small when the piston 6 is displaced at low speed, rises rapidly in the middle speed range, and becomes gentle again when it is displaced at high speed. becomes. By appropriately selecting the distance l _b between the first and second disks 10A and 10B formed by the protrusion 14 as a spacer, the degree of freedom in setting the damping force, especially in the low speed range, is increased. It is possible to obtain near-ideal damping force characteristics.

Next, FIG. 11 shows a second embodiment of the present invention, and in this figure, the same components as those in FIG. However, in this embodiment, the first, second, third, and fourth disks 31A, 31B, 31C, and 31D constituting the disk valve assembly 31 are arranged not from the piston 6 side but from the retainer 9 side. has been done. The orifice 32 is provided on the first disk 31A that contacts the retainer 9. On the other hand, the first and second disks 31
The spacer formed between A and 31B is the first and second spacer.
It is composed of a spacer member 33 provided separately from the disks 31A and 31B. Moreover, the spacer member 33 is located on the outer peripheral side of the first disk 31A, and is positioned by having its outer peripheral edge abut against the spring receiver 11. That is, the spacer member 33 is disposed on the outer circumferential side opposite to the inner circumferential side where the first disk 31A contacts the stepped portion 9B of the retainer 9. Furthermore, the orifice passage forming the fixed orifice is not provided in the piston 6, but in the piston rod 5. That is,
A bottomed recess 5C is formed in the piston rod 5 from its distal end toward its proximal end. One end of the orifice passage 34 opens into the oil chamber A,
The other end is opened in the recess 5C. In this way, a fixed throttle passage is formed in which the oil chambers A and B are constantly in communication via the orifice passage 34 and the recess 5C.

Even if configured as described above, its operation is dependent on the first
There is no particular difference from the embodiment.

In each of the above-described embodiments, the disk valve assembly 10, 31 is formed of four disks, but the number is not necessarily limited to four as long as it is formed of a plurality of disks. The spacer is the protrusion 14 formed on the first disk 10A in the first embodiment or the first protrusion 14 formed on the first disk 10A in the second embodiment.
Although it has been explained that it is formed by the spacer member 33 interposed between the second disks 31A and 31B,
In addition, for example, it may be formed by an annular protrusion protruding from the second disk 10B side toward the first disk 10A side, or by bending the first disk 10A in a direction away from the second disk 10B. Ru. Furthermore, in addition to the above-mentioned fixed orifice, it is also possible to form a radial notch groove in the abutting portion of the protrusion 6A of the piston 6 with the first disk 10A. Furthermore, the retainer 9 includes a protrusion 9A, a stepped portion 9B, and a large diameter portion 9.
C, and the oil hole 18 is provided in the large diameter portion 9C, but the point is that the large diameter portion 9C is provided with the oil hole 18.
If the large diameter portion 9C and the oil hole 18 are formed, it is not necessarily necessary to provide the large diameter portion 9C and the oil hole 18. Furthermore, although a single-tube type hydraulic shock absorber has been described in the embodiments of the present invention, a double-tube type hydraulic shock absorber including an inner cylinder and an outer cylinder may be used.

[Brief explanation of the drawing]

1 to 10 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIG. 3 is a disk an external view of a first disk constituting a valve assembly;
4 to 9 are sectional views similar to FIG. 2 showing different operating states, FIG. 10 is a damping force characteristic diagram, and FIG. 11 is a second embodiment of the present invention. It is a sectional view similar to. 1...Cylinder, 5...Piston rod, 6...
... Piston, 7 ... Communication hole, 8 ... Damping force generation mechanism, 9 ... Retainer, 10, 31 ... Disc valve assembly, 10A, 31A ... First disk, 10B, 31B ... Second disk, 13,
32... Orifice, 14... Projection, 16, 34
... Orifice passage, 33 ... Spacer member.

Claims (1)

[Claims] 1 A cylinder filled with oil and gas, a piston rod having one end located within the cylinder and the other end protruding outside the cylinder, and a piston rod fitted into one end of the piston rod so as to be movable in the axial direction. ,
a piston defining two oil chambers in the cylinder; a communication passage bored in the axial direction of the piston and communicating the two oil chambers; It consists of a retainer inserted and fitted so as to be movable in the axial direction, and a plurality of disks, which are sandwiched between the piston and the retainer, so that one outer circumferential side approaches and separates from the piston, and the other inner circumferential side approaches and separates from the retainer. a disk valve assembly that connects and blocks communication between the two oil chambers by an orifice located between an outer circumferential edge and an inner circumferential edge of the oil chamber and communicating the two oil chambers;
and a second disk adjacent to the disk, the first and second disks are provided on a circumferential side opposite to the one circumferential side where the first and second disks contact the piston or the retainer, and the first and second disks The peripheral edges of one of the disks are spaced apart so that they can approach each other,
It is composed of a spacer that increases or decreases the opening area of the orifice by moving the peripheral edges of the first and second disks apart or approaching each other, and a fixed orifice that is formed on the piston or the piston rod and that constantly communicates the two oil chambers. Hydraulic shock absorber.