JPH0331946B2 - - 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 of the fixed orifice 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. Become something. 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 and communicating with the oil chamber, a retainer fitted into the piston rod so as to be movable in the axial direction with one side end surface of the piston facing each other, and a plurality of discs. a disc valve assembly which is held between a piston and a retainer, and has an outer circumferential portion on one side that comes into contact with and separates from the piston, and an inner circumferential portion of the other side that makes contact with and separates from the retainer, thereby communicating and cutting off the two oil chambers; , an orifice formed on an outer peripheral edge or an inner peripheral edge of a first disk that comes into contact with the piston or retainer among the disks forming the disk valve assembly, and that constantly communicates both the oil chambers; between the first disk and a second disk adjacent to the first disk, the first disk is provided on a circumferential side opposite to one circumferential side where the first disk abuts the piston or the retainer, and the first disk and the second disk the peripheral edges of one of the disks are spaced apart such that they can approach each other, and the peripheral edges of one of the first and second disks are close to each other,
The present invention is characterized in that it includes a spacer that makes the flow path area of the orifice variable by being spaced apart.

With this configuration, until the first disk and the second disk come into contact, the flow path area of the orifice becomes a variable throttle passage that decreases as the piston speed increases, and the piston speed increases. After the first and second disks abut, the orifice acts as a fixed restrictor passage, and as the piston speed increases further, the disk valve assembly separates from the piston or retainer,
Since a variable throttle passage is formed, the damping force characteristics change in three stages.

As a result, the degree of freedom in setting the damping force in the low piston displacement speed range is increased, and by appropriately designing the opening area of the fixed orifice and the thickness of the spacer, the damping force is small when the piston is displaced at low speeds, and the damping force is small in the medium speed range. In this case, it is possible to obtain a large damping force, and at the same time, it is possible to exhibit a damping force characteristic that changes slowly in the high speed range, and it is possible to obtain a damping force characteristic that is almost ideal. play.

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 to the outside of 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 notched grooves 13 forming fixed orifices on its outer peripheral edge. Further, a plurality of projections 14, 14, . . . forming spacers are formed on the inner peripheral side of the first disk 10A on the side facing the second disk 10B.
That is, each of the protrusions 14 is formed on the inner circumferential side opposite to the outer circumferential side where the first disk 10A contacts the protrusion 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 each of the protrusions 14,
The distance l _b is equal to or shorter than the above-mentioned separation distance l _a between the piston 6 and the protrusion 9A of the retainer 9. Furthermore, the spring receiver 11 has one
Or a plurality of notch grooves 15 are provided, and as a result,
Between the oil chambers A and B are first and second disks 1 formed by a notch groove 15, a notch groove 13, and a protrusion 14.
They are communicated with each other through a gap between 0A and 10B.

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 protrusion 1 forming the spacer
4, a flow path is formed in the gap between the first and second disks 10A and 10B with a distance l _b , and this flow path is formed by a notch due to the proximity and separation between the first and second disks 10A and 10B. The groove 13 becomes a variable throttle passage whose flow area changes. Next, the flow path formed by the notched groove 13 formed in the first disk 10A is a fixed throttle passage whose flow path area is constant regardless of the displacement speed of the piston 6, that is, the differential pressure between the oil chambers A and B. It's summery. 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, 16 in the figure indicates the piston 6 together with the spring receiver 11.
A stopper 17 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. Reference numeral 18 indicates a free piston provided in the cylinder 1. An air chamber C is formed between the free piston 18 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 19 and 20 indicate brackets attached to the end of the piston rod 5 outside the cylinder 1 and to the cap 2, respectively.

The hydraulic shock absorber according to the present invention has the above-mentioned structure, and the bracket 19 is attached to the body side of the vehicle, and the bracket 20 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 variable, consisting of a fixed throttle passage formed by the aforementioned notched groove 13 and an annular gap formed between the first and second disks 10A and 10B by the protrusion 14. It is formed by a constricted passage. When the displacement speed of the piston 6 increases, the retainer 9 is displaced in a direction approaching the piston 6, and the first disk 10A is bent, and the outer peripheral edge of the first disk 10A and the second disk 10B are bent.
The outer circumferential edge of the variable throttle passage becomes 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 formed by the notch groove 13 is opened between the oil chambers A and B. The flow path area is the piston 6
The damping force changes. However, in this state, the protrusion 9A of the retainer 9 is at a distance l _c from the piston 6.
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 the oil chambers A and B remains constant.
It 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 formed by the notch groove 13 and the first and second
A flow path area is formed by a variable throttle path between the disks 10A and 10B, and a predetermined damping force is generated by the flow resistance of the oil passing through the flow path area.

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 notch groove 13 forms 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 moves at low speed, rises rapidly in the middle speed range, and becomes gentle again when it moves at high speed. becomes. And notch groove 13
By appropriately selecting the shape of the spacer and the distance l _b between the first and second disks 10A and 10B formed by the protrusion 14 serving as a spacer, the degree of freedom in setting the damping force, especially in the low speed range, increases. 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 21A, 21B, 21C, and 21D constituting the disk valve assembly 21 are arranged not from the piston 6 side but from the retainer 9 side. has been done. And the first disk 21
The cutout groove 22 formed at A is provided on the inner peripheral side thereof. On the other hand, the first and second disks 21A,
The spacer formed between the disks 21B is constituted by a spacer member 23 provided separately from the first and second disks 21A and 21B. Moreover, the spacer member 23 is located on the outer peripheral side of the first disk 21A,
It is positioned by its outer peripheral edge coming into contact with the spring receiver 11. That is, the spacer member 23
The first disk 21A is located at the stepped portion 9B of the retainer 9.
It is arranged on the outer circumferential side opposite to the inner circumferential side where it comes into contact with.

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 embodiments, the disk valve assemblies 10 and 21 are formed of four disks, but the number is not necessarily limited to four as long as the disk valve assemblies 10 and 21 are 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 23 interposed between the second disks 21A and 21B,
In addition, it can also be formed, for example, by protruding from the second disk 10B toward the first disk 10A or by bending the first disk 10A in a direction away from the second disk 10B. Furthermore, although the retainer 9 has been described as being composed of a protrusion 9A, a stepped portion 9B, and a large diameter portion 9C, and an oil hole 17 is provided in the large diameter portion 9C, the point is that the retainer 9 includes the protrusion 9A and the stepped portion 9C.
B is formed, it is not necessarily necessary to provide the large diameter portion 9C and the oil hole 17. 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 path, 8 ... Damping force generation mechanism, 9 ... Retainer, 10, 21 ... Disk valve assembly, 10A, 21A ... First disk, 10B, 21B ... Second disk, 13,
22...Notch groove, 14...Protrusion, 23...Spacer member.

Claims (1)

[Claims] 1 A cylinder filled with oil and gas, a piston rod with one end located within the cylinder and the other end protruding from 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, and a piston rod with one end surface of the piston facing each other. It consists of a retainer inserted and fitted so as to be movable in the axial direction, and a plurality of disks, which are held between the piston and the retainer so that the outer circumferential portion on one side is in contact with and away from the piston, and the inner circumferential portion on the other side is in contact with the retainer. A disc valve assembly that connects and disconnects the two oil chambers by moving toward and away from each other, and a first disc that contacts the piston or retainer among the discs forming the disc valve assembly; formed,
an orifice that constantly communicates both the oil chambers, the first disk and a second disk adjacent to the first disk;
The first disk is provided on a circumferential side opposite to the one circumferential side where the first disk abuts the piston or the retainer, and the circumferential edge of one of the first and second disks is A hydraulic shock absorber comprising spacers that are spaced apart so that they can approach each other, and that allow the flow path area of the orifice to be varied by moving the circumferential edges of one of the first and second disks closer to each other and further away from each other. .