JPH0260900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber suitable for being attached to a vehicle such as an automobile and used for damping vibrations.

1 and 2 show hydraulic shock absorbers according to the prior art.

In the figure, 1 is a cylinder, 2 is a piston rod protruding into the cylinder 1, and 3 is a piston that is fixed to the piston rod 2 and slides along the inner wall of the cylinder 1. The inside of the cylinder 1 is defined by the piston 3 into two oil chambers A and B, and when the piston 3 is displaced in an extension stroke or a contraction stroke, one oil chamber is moved from one oil chamber to the other oil chamber. The structure is such that a damping force is generated by the oil flowing through the shaft, thereby providing a vibration damping effect.

Next, the damping force generation mechanism will be explained.
Reference numerals 4 and 5 indicate valve seats formed near the outer periphery on both sides of the piston 3, and 6 and 7 indicate protrusions provided on the inner periphery on both sides of the piston 3, respectively. It is now slightly more prominent. Further, 8 and 9 are disk valves that are inserted into the piston rod 3, and whose inner circumferential portions are in contact with the protrusions 6 and 7, respectively, and whose outer circumferential portions are in contact with the valve seats 4 and 5, and 10 and 11 are the respective disk valves. Valve 8,9
12 and 13 are washers that also serve as regulating portions that regulate the degree of opening of each of the disc valves 8 and 9, respectively. The valve 8, spacer 10, and washer 12 are held between the piston 3 and a stepped portion 2A formed on the piston rod 2, and the disc valve 9, spacer 11, and washer 13 are held between the lock nut 14 screwed onto the piston 3 and the piston rod 2. The disk valve 8,
9 are pressed in the direction of contacting the valve seats 4 and 5, respectively, to apply an initial load. The disc valves 8 and 9 come into contact with the protrusions 6 and 7 and the valve seats 8 and 9, respectively, so that annular oil chambers 15 and 16 are formed between the disc valves 8 and 9 and each side of the piston 3. has been done.

Next, 17 and 18 indicate communication passages provided in the piston 3, and one of the communication passages 17 is the oil chamber A.
and the annular oil chamber 16, and the other communication passage 18
2 communicates the oil chamber B with the annular oil chamber 15, and as shown in FIG. It is being Further, reference numeral 19 denotes an orifice formed by cutting out a part of the valve seat 4, and the oil chamber A and the annular oil chamber 15 are constantly connected through a restriction through the orifice 19.

The hydraulic shock absorber according to the prior art has the above-mentioned structure, and its operation will be explained next.

Assume that the piston 3 and the piston rod 2 are now in a contraction stroke in which they are displaced in the direction of the arrow X in the figure. As a result, the pressure inside the oil chamber B becomes high, and a pressure difference is generated between the oil chamber B and the oil chamber A. For this reason, the oil in the oil chamber B flows from the communication passage 18 into the annular oil chamber 15 and into the oil chamber A via the orifice 19 formed in the valve seat 4. Since the passage area of the orifice 19 is narrowed, a predetermined damping force acts upon passing through this portion. When the piston 3 is displaced at high speed, the pressure within the oil chamber B increases, and this pressure is guided into the annular oil chamber 15 and acts on the disc valve 8. When the pressure acting on the disc valve 8 becomes greater than the spring force of the disc valve 8, the outer peripheral edge portion deforms and separates from the valve seat 4. As a result, the passage area from the annular oil chamber 15 to the oil chamber A increases, and the damping force characteristic changes in two stages.

On the other hand, when the piston 3 is displaced in the direction of the arrow Y and is in the extension stroke, the high-pressure oil in the oil chamber A first flows through the orifice 19 into the annular oil chamber 15. The oil flows into the oil chamber B through the communication passage 18. Therefore, when the oil flows from the oil chamber A into the annular oil chamber 15 through the orifice 19, a first stage damping force is generated. When the displacement of the piston 3 increases, the pressure within the oil chamber A is guided into the annular oil chamber 16 via the communication passage 17 and acts on the disc valve 9. When the pressure acting on the disc valve 9 becomes greater than the spring force of the disc valve 9, the disc valve 9 opens, the passage area increases, and the second stage damping force characteristic is exhibited.

However, in the hydraulic shock absorber according to the prior art described above, its damping force characteristics, especially the damping force characteristics in the initial stage, that is, the first stage, are determined by the orifice 19 in both the extension stroke and the contraction stroke. There was a drawback that the damping force characteristics during the stroke could not be made to differ from each other.

The present invention has been made in view of the drawbacks of the prior art described above, and is a hydraulic shock absorber capable of exhibiting different damping force characteristics in the extension stroke and contraction stroke in the initial stage of the damping force characteristic. The purpose is to provide the following.

In order to achieve the above object, the present invention adopts a configuration including a cylinder, a piston rod whose distal end protrudes into the cylinder, and a piston rod which is fixedly attached to the distal end of the piston rod and which extends inside the cylinder. a piston defining two chambers; a plurality of communication passages bored in the piston so as to communicate between the two chambers; a valve seat on one side formed on one side of the piston; and a valve seat on the other side formed on the other side of the piston so as to surround the opening on the other side of the remaining communication passages among the communication passages; A disc valve is disposed on one side of the piston so as to sit on and off the one side valve seat, and generates a damping force on the reduction side, and a disc valve is disposed on the other side of the piston so as to sit on and off the other side valve seat. In a hydraulic shock absorber comprising a disk valve that is provided and generates an extension damping force, at least one of the one side valve seat and the other side valve seat is a first valve seat,
A second valve seat having a shorter protrusion length than the first valve seat is formed on the inner peripheral side of the first valve seat, and the piston is disposed between the piston and one disc valve. A valve body is provided, which is disposed off the second valve seat when the piston is displaced in one direction, and is always seated on the second valve seat when the piston is displaced in the other direction; A first orifice is provided between the disk valve and the first valve seat when the valve body is seated on the second valve seat, and the valve body is seated on the second valve seat. a second orifice formed between the valve body and the second valve seat;
Further, the second orifice is formed to have a smaller passage area than the first orifice.

By configuring as described above, when the piston rod and piston are displaced in either the contraction side or the expansion side, each disc valve generates a damping force, and it can be used as an ambidextrous hydraulic shock absorber. act. At this time, when the piston is displaced in one direction, the valve body first separates from the second valve seat and opens the valve, and an initial damping force is generated by the oil flowing through the first and second orifices. When the piston speed becomes high, one disc valve opens. During this time, the initial damping force is set by the resistance force flowing through the first and second orifices. Also, when the piston is displaced to the other side, the valve body first moves to the second position.
The valve is seated on the valve seat and closed, and an initial damping force is generated by the oil flowing only through the second orifice,
When the piston speed becomes high, the other disc valve opens. During this time, the initial damping force is set by the resistance force flowing through the second orifice. Thereby, the damping force characteristics can be made different between the extension stroke and the contraction stroke.

Next, embodiments of the present invention will be described based on the drawings.

First, FIGS. 3 to 8 show a first embodiment of the present invention, and the same components in FIGS. shall be taken as a thing. However, on the side surface of the piston 3 facing the oil chamber A, there is a first valve seat 21 formed in an annular shape;
A second valve seat 22 is formed which is connected to the inner side of the valve seat and has a shorter protrusion length than the second valve seat 22. A disc valve 8 is provided on the first valve seat 21 so as to be seated on and off, and a valve body 23 is provided on the second valve seat 22.
It is provided so that it can be seated and taken off. The annular oil chamber 15 is defined by the valve body 23 into an oil chamber 15A between the valve body 23 and the piston 3 and an oil chamber 15B between the valve body 23 and the disc valve 8.

The valve body 23 is a disc spring as shown in FIG. The inner circumferential portion 23
A is clamped between the protrusion 6 of the piston 3 and the disc valve 8, and the outer peripheral part 23B is attached to the second valve seat 2.
2. Further, as the valve body, as shown in FIG. 6, an annular plate body 24,
The plate body 24 may be formed by a spring 25 that presses the second valve seat 22 and the protrusion 6 of the piston 3 in a direction.

Next, 26 indicates a first orifice formed by notching the first valve seat 21, and 27 indicates a notch provided in the second valve seat 22 in a state continuous with the first orifice 26. The second orifice formed by the method shown in FIG. First orifice 2
6 is formed between the disc valve 8 and the piston 3 by seating the disc valve 8 on the first valve seat 21, and its passage area is as follows:
The groove width D formed by both ends of the notch portion of the first valve seat 21 (see FIG. 4), and the first valve seat 21
The projection length H ₁ (see FIG. 8) is formed by the projection length H 1 (see FIG. 8). On the other hand, the second orifice 27 is opened when the valve body 23 is seated on the second valve seat 22.
3 and the piston 3, and its passage area is determined by the groove width D consisting of both ends of the notch portion of the second valve seat 21 and the protrusion length H of the second valve seat 22. ₂ (see FIG. 7), and the second orifice 27 has a smaller passage area than the first orifice 26.

This embodiment is constructed as described above, and its operation will be explained next.

First, the piston 3 is displaced in the direction of arrow X in the figure,
When the piston rod 2 is contracted, the oil chamber B
The pressure inside becomes high, and the oil in the oil chamber B flows into the oil chamber 15A through the communication path 18. However, the valve body 23
is seated on the second valve seat 22 as shown in FIG. 7, so the oil in the oil chamber 15A flows into the oil chamber A through the second orifice 27, and the oil When passing through the second orifice 27, a predetermined damping force is generated.

Next, when the displacement of the piston 3 becomes high and the pressure in the oil chamber B rises, this pressure acts on the valve body 23 through the communication passage 18, and the valve body 23 moves to the second position as shown in FIG. from the valve seat 22. However, since the spring force of the disc valve 8 is greater than the spring force of the valve body 23, the disc valve 8 is held in a state seated on the first valve seat 21, and therefore the passage area to the oil chamber A is 2 orifice 2
Since the first orifice 26 has a larger passage area than the first orifice 7, the damping force characteristics change.

When the piston 3 moves faster, the pressure inside the oil chamber B becomes extremely high, and this pressure acts on the disc valve 8 to open it, further expanding the passage area and increasing the damping force. Characteristics change in three stages.

On the other hand, when the piston 3 is displaced in the direction of the arrow Y in the figure, the pressure in the oil chamber A increases, and the oil in the oil chamber A flows into the oil chamber 15A via the second orifice 27. The oil flows from the passage 18 toward the oil chamber B. Then, when flowing through the second orifice 27, a first stage damping force is generated.

However, even if the piston 3 is displaced at high speed and the pressure in the oil chamber A becomes high, this pressure presses the valve body 23 in the direction of seating on the second valve seat 22 in the oil chamber 15B. The valve body 23 does not open.

When the piston 3 displaces at a higher speed, the oil chamber A
The internal pressure is led into the annular passage 16 via the communication passage 17, acts on the disc valve 9, and displaces the disc valve 9 from the valve seat 5, so that the damping force characteristic is displaced in two stages.

As mentioned above, in the extension stroke of the piston rod 2, the damping force characteristics change in two stages, and in the contraction stroke, the damping force characteristics change in three stages. By appropriately setting the protruding lengths of the second valve seats 21 and 22, the initial damping force characteristics before the disc valves 8 and 9 open can be made different between the extension stroke and the contraction stroke.

Next, FIGS. 9 to 12 show a second embodiment of the present invention. In this embodiment, the communication passage bored in the piston 3 is a communication passage parallel to the axis of the piston 3. 17' and 18'.
The side surface of the piston 3 facing the oil chamber A is composed of an arcuate portion 21'A and radial portions 21'B, 21'B, and a first valve seat 21 is arranged to surround each communication passage 18'. ', 21', . . . are formed, and second valve seats 22', 22', . The first and second valve seats 21' and 22' are provided with first and second orifices 26' and 26', respectively.
7' is formed. In addition, the second valve seat 2
The valve body 23', which is seated and separated from the valve body 2', has a cross-shaped outer shape as shown in FIG. The flat portion 2 shown in FIG.
3'A, or a bent portion 23'B is formed as shown in FIG. 11C. on the other hand,
As shown in FIG. 12, on the side of the piston 3 facing the oil chamber B, there is a valve seat 5' surrounding the communication passage 17';
5',... are formed.

Even with this configuration, the same effect as in the first embodiment described above is achieved. And the communication path 17', 1
8' is bored in the axial direction of the piston 3, so
Its processing becomes easy.

Furthermore, FIGS. 13 and 14 show a third embodiment of the present invention, in which the arcuate shape of the first valve seat 21' shown in the second embodiment described above is Inside part 21'A and radial part 21'
A second valve seat 22'' is formed along the entire circumference of the inner side of the valves B and 21'B, and the second valve seat 22'' also has an arcuate portion 22''A and a radial portion 22''B, 2.
2''B.The valve body 23' is formed to be inclined along the curved shape of the radial portion 22''B of the second valve seat 22''.

With this configuration, when the valve body 23' is closed, the valve body 23' is brought into contact with the entire circumference of the second valve seat 22'', so that no unreasonable pressure is applied to the valve body 23'. This will not damage the valve body 23' or cause oil leakage.

In each of the above embodiments, the valve bodies 23 and 23' were described as being provided between the disk valve 8 and the piston 3, but the valve bodies 23 and 23' were provided between the piston 3 and the disk valve 9. Alternatively, it may be provided between the piston 3 and both the disk valves 8 and 9. Furthermore, the groove widths of the first orifices 26, 26' and the second orifices 27, 27' are not only the same, but also
The groove width of the second orifices 27, 27' may be narrowed. Furthermore, although the disc valves 8 and 9 are shown as having the same number of discs, by making the numbers different, the damping force characteristics in the extension stroke and the contraction stroke can be made to be different as a whole. can. Furthermore, communication path 1
7, 17', 18, and 18' are each provided in a configuration of four, but it goes without saying that the number is not restricted. Furthermore, the valve bodies 23, 2
If the spring force of 3' is made extremely weak,
Since the valve opens immediately when the pressure in the oil chamber B increases, the damping force characteristics in the contraction stroke change in two stages.

As described in detail above, according to the hydraulic shock absorber according to the present invention, there is a space between the piston and at least one of the disc valves on the extension side and the contraction side, which opens when the piston is displaced in one direction. A valveable valve body is provided, and when the piston is displaced to one side, an initial damping force is generated by the oil flowing through the first and second orifices, and when the piston is displaced to the other side, only the second orifice is generated. Since the initial damping force is generated by the oil flowing through the hydraulic shock absorber, an ambidextrous hydraulic shock absorber can be obtained in which the damping force characteristics at the initial stages of the extension stroke and the contraction stroke are different. In addition, by simply installing the valve body between the disk valve and the piston on either the contraction side or the expansion side, different characteristics can be obtained on the contraction side and expansion side, reducing the number of parts and hydraulic damping. The valve structure of the device can be simplified.

[Brief explanation of drawings]

Figures 1 and 2 show the prior art;
FIG. 1 is a partial vertical cross-sectional view of a hydraulic shock absorber, FIG. 2 is a left side view of a piston, FIGS. 3 to 8 show a first embodiment of the present invention, and FIG. Partial longitudinal sectional view, Figure 4 is a left side view of the piston, Figure 5 is a left side view of the piston.
Figure A is an external view of the valve body, Figure 5B is a sectional view of the valve body,
FIG. 6 is a sectional view of the main part showing a modified example of the valve body, FIGS. 7 and 8 are enlarged views of the main part of FIG. 3 showing different operating states, and FIGS. The second embodiment is shown, FIG. 9 is a partial vertical sectional view of the hydraulic shock absorber, FIG. 10 is a left side view of the piston,
FIG. 11A is an external view of the valve body, FIG. 11B is a sectional view thereof, and FIG. 11C is a sectional view showing a modification of the valve body.
FIG. 12 is a right side view of the piston, and FIGS. 13 and 14 show a third embodiment of the present invention.
The figure is an external view of the piston, and FIG. 14 is a partial sectional view of the piston. 1...Cylinder, 2...Piston rod, 3...
...Piston, 5... Valve seat, 8, 9... Disc valve, 17, 17', 18, 18'... Communication passage, 21, 21'... First valve seat, 22, 2
2', 22''... second valve seat, 23, 23'...
...Valve body, 24...Plate body, 25...Spring, 26,2
6'...first orifice, 27,27'...second
orifice.

Claims (1)

[Claims] 1 a cylinder, a piston rod whose distal end protrudes into the cylinder; a piston which is fixed to the distal end of the piston rod and defines two chambers in the cylinder; a plurality of communication passages bored to communicate between the two, and one side valve seat formed on one side of the piston so as to surround one side opening of a part of the oil passage among the communication passages. , the other side valve seat formed on the other side of the piston so as to surround the other side opening of the remaining communication passage among the communication passages, and the one side of the piston so as to be seated on and off the one side valve seat. a disc valve disposed on the other side of the piston to generate a damping force on the compression side; and a disc valve disposed on the other side of the piston so as to sit on and off the valve seat on the other side and generate a damping force on the extension side. In the shock absorber, at least one of the one-side valve seat and the other-side valve seat is a first valve seat, and an inner peripheral side of the first valve seat protrudes beyond the first valve seat. forming a second valve seat having a shorter length;
When the piston is displaced in one direction, the second disc valve is disposed between the piston and one disc valve.
A valve body is disposed that is always seated on the second valve seat when the piston is displaced from the second valve seat, and the disc valve is seated on the first valve seat. a first valve seat formed between the disc valve and the first valve seat when
a second orifice formed between the valve body and the second valve seat when the valve body is seated on the second valve seat; A hydraulic shock absorber characterized in that the passage area is smaller than that of the first orifice.