JPH0368252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a piston-piston rod assembly consisting of a piston and a piston rod that is slidably disposed within a cylinder, and a piston-piston rod assembly that includes a piston and a piston rod that is slidably disposed within a cylinder. This invention relates to a hydraulic shock absorber that generates a damping force due to hydraulic resistance against displacement.

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 in the high speed range of the piston displacement speed, where steering stability is a problem, the damping force is set to be large. A hydraulic shock absorber that can be set is optimal. However, in the conventional hydraulic shock absorber mentioned above, it is not possible to change the flow passage area to reduce the area when the piston speed becomes medium or high speed. There is no degree of freedom in setting the damping force characteristics, and therefore, 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 mentioned above.In the low speed range of the piston, the damping force is small, in the middle speed range, the damping force increases rapidly, and the high damping force is maintained in the high speed range. The object of the present invention is to provide a hydraulic shock absorber that exhibits damping force characteristics that can satisfy both vehicle riding comfort and handling stability requirements. It is.

In order to achieve the above-mentioned object, a hydraulic shock absorber according to the present invention includes a cylinder filled with oil liquid and gas;
a piston that is slidably inserted into the cylinder and defines the inside of the cylinder into two oil chambers; a piston rod that has one end connected to the piston and the other end that projects outside the cylinder; a communication passage formed in the piston and communicating between the two oil chambers; and a communication passage provided in at least one of the oil chambers of the piston at a position where the communication passage can be closed. A slider displaceable in the axial direction of the piston rod, a disc valve fixedly provided on the piston rod and in contact with the slider, and a disc valve that is bent by a predetermined amount when pressed by the slider. A stopper that comes into contact with the disc valve and a stopper that is provided on the disc valve, and the oil chamber on the other side of each of the oil chambers has a higher pressure than the oil chamber on the other side, and when the slider is separated from the piston. A passage for flowing oil from the oil chamber on the other side to the oil chamber on one side is provided between the disc valve and the stopper, and the oil flows through the passage when the disc valve is bent by a predetermined amount. The present invention is characterized in that it is configured to form a variable throttle passage that can reduce the flow area of the oil liquid.

With this configuration, in the low speed range of the piston until the slider deflects the disc valve by a predetermined amount, a small damping force is generated because the flow path area between the two oil chambers is relatively large. When the displacement speed of the piston reaches a medium speed range, a variable throttle passage is formed between the disc valve and the stopper to reduce the flow area of the oil flow passage through the passage,
Damping force increases rapidly. When the displacement speed of the piston reaches a high speed range, the aforementioned variable throttle passage is closed or its flow passage area becomes constant, so that high damping force characteristics can be maintained.

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

First, FIGS. 1 to 7 show a first embodiment of the present invention, and in FIG. 1, 1 indicates an inner cylinder 1.
A and an outer cylinder 1B. One end of the cylinder 1 is covered by a cap 2 fixed to the outer cylinder 1B. Further, a rod guide 3 and a seal member 4 are provided at the other end of the cylinder 1, and the rod guide 3 and seal member 4 are positioned by a cap 5 fixed to the outer cylinder 1B.

Reference numeral 6 indicates a piston inserted into the inner cylinder 1A so as to be able to reciprocate, and the piston 6 has a piston rod 7.
One end is fixedly provided with a bolt 8. The other end of the piston rod 7 passes through the rod guide 3, the seal member 4 and the cap 5 and projects to the outside. The interior of the inner cylinder 1A is defined by a piston 6 into oil chambers A and B, and an oil reservoir chamber C containing oil and compressed gas is formed between the inner cylinder 1A and the outer cylinder 1B. has been done. Between the oil chamber B and the oil reservoir chamber C is a throttle passage 9 bored in the inner cylinder 1A.
The oil chambers A and B are communicated with each other by one or more pairs of communication passages 10A and 10B formed in the piston 6. A reduction-side damping force generation mechanism 11 is provided on the side surface of the piston 6 facing the oil chamber A, and the reduction-side damping force generation mechanism 11 is connected to the oil chamber A through a communication path 10A. It is designed to provide resistance to the oil flowing towards the surface. On the other hand, an extension-side damping force generation mechanism 12 is provided on the side surface of the piston 6 facing the oil chamber B, and the extension-side damping force generation mechanism 12 is directed from the oil chamber A to the oil chamber B via the communication passage 10B. It is designed to provide resistance to flowing oil.

Therefore, based on Figures 2 and 3, the reduction side,
Each of the damping force generating mechanisms 11 and 12 on the extension side will be explained. The piston 6 is provided with an inner protrusion 6A and an outer protrusion 6B that protrude in an annular shape in the axial direction on the side surface facing the oil chamber A. An annular recess 13 is formed therein. On the other hand, an inner circumferential side protrusion 6C and an outer circumferential side protrusion 6D which protrude in an annular shape in the axial direction are also provided on the side surface of the piston 6 facing the oil chamber B.
An annular recess 14 is formed between each of the protrusions 6C and 6D. The communication passage 10A opens into the recess 13 on one side, passes through the piston 6 obliquely, and opens into the oil chamber B at a position on the outer periphery side of the outer periphery protrusion 6D. 15 is an annular projection 1 on the outer circumferential side
5A, the slider 15 is located within the recess 13, and its outer circumferential surface is slidably in contact with the inner circumferential surface of the protrusion 6B. Also,
In a non-operating state where no differential pressure is generated between the oil chambers A and B, one end surface of the slider 15 comes into contact with the inner wall of the recess 13 and closes the communication path 10A. As a result, when a pressure difference occurs between oil chambers A and B, oil chamber B
The hydraulic pressure inside can be reliably applied to the slider 15 through the communication path 10A. Next, reference numeral 16 indicates a disc valve having spring properties, and the disc valve 16 has one or more notched grooves 17 on its outer circumference, which serve as passages for communicating between the oil chambers A and B, as shown in FIG. 17,... are provided. And the disc valve 16
is a small-diameter disk 18 made of one or more spring members formed to have a smaller diameter than the position where the notch groove 17 is formed;
together with the protrusion 6A of the piston 6 and the piston rod 7.
It is held between the sleeve 19 and the sleeve 19 fitted into the sleeve 19. When there is no pressure difference between the oil chambers A and B, the disc valve 16 presses the annular protrusion 15A formed on the outer circumferential side of the slider 15 to bring the slider 15 into contact with the piston 6. The passage 10A is closed. Therefore, when the pressure inside the oil chamber B becomes high and this pressure acts on the slider 15 through the communication passage 10A, the slider 15 slides to the left in FIG. 2, bending the disc valve 16. It is becoming possible to do this. Further, the small diameter disk 18 is designed to be able to provide a predetermined resistance force to the deflection of the disk valve 16. moreover,
The notched groove 17 formed in the disc valve 16 is provided to extend radially inward from the contact portion with the protrusion 15A of the slider 15, and the portion of this notched groove 17 that is not covered by the protrusion 15A of the slider 15 is is the flow path area in the low speed range. Further, reference numeral 20 denotes a stopper that is slidably provided on the sleeve 19, and the stopper 20 has an annular projection 20 on its outer circumferential side facing the disk valve 16.
A is formed. A spring 22 is tensioned between the stopper 20 and a retainer 21 provided in contact with the stepped portion 7A of the piston rod 7. It is brought into contact with the outer periphery. On the other hand, when the pressure in the oil chamber B pushes the slider 15 and bends the disc valve 16, this pressure also acts on the stopper 20, causing it to immediately displace to the position where it contacts the retainer 21. There is. When the disc valve 16 is bent by a predetermined amount, the disc valve 16 is brought close to the stopper 20, so that a variable throttle passage is formed between the protrusion 20A of the stopper 20 and the disc valve 16. It's getting old.

Next, the extension-side damping force generation mechanism 12 will be described. One end of the communication passage 10B opens into the recess 14, and the other end opens toward the oil chamber A on the outer peripheral side of the protrusion 6B. And the protrusion 6C,
A disc valve 23 consisting of a plurality of discs is provided in contact with the disc valve 6D.
Disk valve 1 is attached to disk 23A that comes into contact with
Similar to No. 6, notch grooves 24, 24, . . . are formed on the outer periphery thereof. 25 is a retainer, and 26 is a spacer interposed between the retainer 25 and the disc valve 23. The spacer 26 is used to create high pressure in the oil chamber A, and this pressure is transferred to the recess 1 through the communication path 10B.
4 and when it acts on the disc valve 23, the disc valve 23 can be displaced in the direction away from the protrusion 6D.

Although this embodiment is constructed as described above, its operation will now be explained with reference to FIGS. 4 to 6.

First, the piston 6 is in a stationary state, and the oil chamber A,
When no differential pressure is generated between B, the state shown in FIG. 2 is reached. Therefore, the piston 6
When the oil chamber B is displaced in the direction indicated by the arrow A in the figure and enters the contraction stroke, the pressure in the oil chamber B increases and a pressure difference is generated between the oil chambers A and B. At this time, a part of the oil in the oil chamber B flows toward the oil sump chamber C through the throttle passage 9, but the oil sump chamber C
Since compressed gas is sealed inside and the flow area of the throttle passage 9 is small, the oil in the oil chamber B does not suddenly flow toward the oil reservoir chamber C. On the other hand, the pressure in the oil chamber A decreases due to the displacement of the piston 6.

Here, since the differential pressure between the oil chambers A and B is small at the initial stage of the displacement of the piston 6, even if the pressure in the oil chamber B acts on the slider 15 through the communication path 10A, the slider 15 The valve 16 is pressed to maintain the communication path 10A in a closed state.
On the other hand, since the notch groove 24 is formed in the disc 23A of the disc valve 23, the notch groove 24
A fixed orifice that communicates the oil chamber B and the oil chamber A is formed by the groove width and the plate thickness of the disk 23A. Therefore, the oil in the oil chamber B flows toward the oil chamber A through the fixed orifice, the recess 14, and the communication passage 10B, and the resistance force of the oil flowing through the fixed orifice causes the line O-A in FIG. A predetermined damping force is generated as shown in ₁ .

Next, when the displacement speed of the piston 6 is in a low speed range and reaches a predetermined value, the pressure in the oil chamber B becomes high, and this pressure acts on the slider 15 through the communication path 10A. is slidably displaced in the direction away from the piston 6 while bending the disc valve 16. As a result, the oil in the oil chamber B flows into the recess 13 via the communication path 10A. The pressure within this recess 13 acts on the stopper 20 via the notched groove 17, and the stopper 20 is activated by the spring 2.
2 to a position where it abuts against the retainer 21, resulting in the state shown in FIG. As a result, the part of the notched groove 17 formed in the disc valve 16 that is not covered by the projection 15A of the slider 15 becomes a passage, and in addition to the aforementioned fixed orifice, this passage also serves as a flow path between the oil chambers A and B. , the flow path area increases, so the damping force is expressed as line A ₁ in Figure 6.
−B Changes as shown in ₁ . Here, since the passage formed by the notched groove 17 is formed relatively large, the rate of change of the damping force with respect to the displacement speed of the piston 6 is small. Then, as the displacement speed of the piston 6 increases, the slider 15 moves the disc valve 1
However, when the flow area of the annular passage formed between the disc valve 16 and the projection 20A of the stopper 20 is larger than the passage area formed by the notch groove 17, the oil chambers A and B are bent further. The flow path area between the two does not change.

When the displacement speed of the piston 6 reaches a medium speed range, the slider 15 further slides in the direction away from the piston 6, and the disc valve 16 moves toward the stopper 20.
is displaced in a direction approaching protrusion A of. For this reason, the flow area of the annular passage between the disc valve 16 and the projection 20A of the stopper 20 is smaller than that of the passage formed by the notch groove 17. Therefore, the flow area between the oil chambers A and B is regulated by this annular passage, and this annular passage becomes a variable throttle passage and decreases according to the displacement speed of the piston 6. , the damping force increases rapidly and shows a significant change as shown by the line B ₁ -C ₁ in FIG.

Then, when the piston 6 is displaced at high speed, the slider 15 causes its protrusion 15A to move the disc valve 16 to the protrusion 20A of the stopper 20, as shown in FIG.
The above-mentioned variable throttle passage changes to a fixed orifice formed by the groove width and plate thickness of the notched groove 17, and this fixed orifice and the above-mentioned notched groove 24 of the disc valve 23 Since the fixed orifice formed by the above forms a flow path between the oil chambers A and B, a damping force having a characteristic shown by the line C ₁ -D ₁ in FIG. 6 is generated.

Therefore, during the contraction stroke of the piston 6,
At the initial stage of displacement, the damping force characteristic is at its inflection point A ₁
The damping force changes in the direction of decreasing in the middle speed range, and at the inflection point _B1 in the medium speed range, the damping force suddenly increases, and it comes to maintain an extremely high damping force in the high speed range.

Here, the line O-A ₁ , which is the characteristic of the damping force in the initial stage, shows that the slider 15 is
The resistance force until it bends and separates from the piston 6,
That is, the disc valve 16 and the small diameter disc 18
The spring force is determined by the spring force of the total number of springs 22 and the spring force of the spring 22. Furthermore, the damping force characteristic A ₁ −B ₁ in the low speed range is determined by the spring force of the disc valve 16 and the small diameter disc 18, the amount of movement of the stopper 20, the shape of the notch groove 17, the radial length of the projection 15A of the slider 15, etc. , and the characteristics of the medium speed range
B ₁ -C ₁ is determined by the spring force of the disc valve 16 and the small diameter disc 18, etc. Therefore, as shown in FIG. 7, the total number of disk valves 16 and small-diameter disks 18 is the thickness _la , the initial level difference l _b of the disk valve 16, and the moving distance of the stopper 20.
l _c , the distance d ₁ between the fulcrum position and the point of action of the disc valve 16, and the cutout groove 1 of the disc valve 16 by the slider 15 as shown by the chain line in FIG.
By appropriately setting the area of the uncovered portion 7, etc., desired damping force characteristics can be obtained.

On the other hand, when the piston 6 is displaced in the direction indicated by the arrow B in FIG. 1 and the piston rod 7 begins its extension stroke,
The pressure in the oil chamber A becomes high, and the oil in the oil chamber A flows into the recess 14 through the communication path 10B. When the displacement speed of the piston 6 is in a low speed range, the disc valve 23 is moved to the protrusion 6D of the piston 6.
, the oil in the recess 14 flows toward the oil chamber B through the fixed orifice formed by the groove width and plate thickness of the cutout groove 24 of the disk 23A _. Obtain the damping force with the characteristics shown in .
Further, when the speed of the piston 6 becomes high, the outer peripheral edge of the disc valve 23 is bent by the pressure in the oil chamber A introduced into the recess 14 and separated from the protrusion 6D of the piston 6. The area of the flow path between chambers A and B increases, and the damping force changes as shown by the line E ₁ -F ₁ in FIG. At this time, the slider 15 comes into contact with the piston 6, and the communication path 10A
Since the disc valve 16 is closed, excessive hydraulic pressure will not act on the disc valve 16 and damage the disc valve.

Next, FIGS. 8 and 9 show modifications of the first embodiment, and these modifications make it possible to control the initial stage of the damping force characteristics. In the modification shown in FIG. 8, a spacer 30 is interposed between the disk valve 16 and the small diameter disk 18.

With this configuration, the slider 15
When a pressure difference sufficient to deflect only the disc valve 16 is generated between the oil chambers A and B, the passage consisting of the notch groove 17 is opened, and its damping force characteristics are as shown in Fig. 6. , the initial stage characteristic is the line O-A′ ₁
Therefore, in the low speed range, the damping force characteristics shown by the dotted line can be obtained.

In the modification shown in FIG. 9, among the disks constituting the small diameter disk 18, the disk 18A that contacts the disk valve 16 and the disk 1
A spacer 30' is provided between the disk 8A and the adjacent disk 18B.

This causes the slider 15 to move to the disc valve 1.
6 and disk 18A is generated between oil chambers A and B, the passage formed by the notch groove 17 is opened, and the initial stage damping force characteristic is changed as shown in FIG. The line O- _A''1 is obtained, and the damping force characteristics shown by the dashed-dotted line are exhibited in the low speed range.

Furthermore, FIG. 10 shows another modification of the first embodiment, in which the slider 15 is not housed in the recess 13 of the piston 6', but is housed in the retainer 31. The piston 6' has protrusions 6A' and 6 similar to protrusions 6C' and 6D' formed on the side surface facing the oil chamber A on the side surface facing the oil chamber B.
A retainer 3 is formed on each protrusion 6A', 6B'.
1 are placed in contact with each other. The retainer 31 has protrusions 31A and 31B that protrude toward the side opposite to the surface that contacts the piston 6', respectively, on the inner and outer edges, and on the inner and outer edges. A through hole 32 is provided in the axial direction at the intermediate portion between the peripheral edge and the periphery.
is drilled. The outer circumferential surface of the slider 15 is in slidable contact with the inner circumferential surface of the protrusion 31B of the retainer 31, and when no differential pressure is generated between the oil chambers A and B, the slider 15 is in contact with the through hole 32. When the piston rod 7 is in a closed state and the oil chamber B becomes high pressure during the contraction stroke of the piston rod 7, this pressure flows into the communication passage 10.
A, the slider 15 can be acted on through the recess 13 and the through hole 32. Also, in the same figure, as shown in Figure 9,
A spacer 30' is interposed between the disks 18A and 18B of the small diameter disk 18.

Even with the configuration as described above, damping force characteristics similar to those shown in FIG. 9 are exhibited. Since the piston 6' has a symmetrical shape, its processing,
Easy to assemble.

Next, FIGS. 11 to 13 show the second embodiment of the present invention.
In this figure, the same components as those in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

However, 41 indicates a disc valve constituting the reduction side damping force generation mechanism 11', and the disc valve 41 is not provided with a notched groove unlike the disc valve 16 of the first embodiment described above, and the slider 15 protrusion 15A and stopper 20 protrusion 2
0A and a plurality of passage holes 42, 4 on the inner circumferential side from the contact part.
2,... are drilled. And piston 6
An orifice passage 43 is provided in which the oil chamber A and the communication passage 10a are constantly communicated. The orifice passage 43 allows oil chambers A and B to communicate with each other at all times.

By configuring as described above, the damping force characteristics during each stroke of the piston rod 7 on the contraction side and the expansion side are as shown in FIG. 13.

That is, when the pressure on the oil chamber B side becomes high during the contraction stroke of the piston rod 7, in the initial stage, the fixed orifice consisting of the notched groove 24 formed in the disk 23A of the disk valve 23 and the orifice passage 43 are used to move the pressure from the oil chamber B to the oil chamber A. A flow path for the oil liquid is formed, and a damping force shown by the line O-A ₂ in FIG. 13 is generated depending on the area of the flow path. At this stage, the flow path area is larger by 43 orifice passages than in the first embodiment, so the damping force is smaller in this embodiment. Next, when the displacement speed of the piston 6 reaches a predetermined value, the slider 15 moves away from the piston 6 and the stopper 20 moves to a position where it comes into contact with the retainer 21, and the passage hole 42 also moves from the oil chamber B to the oil chamber A. Since it becomes a flow path for oil fluid, the damping force changes, and the low-speed region damping force characteristic becomes as shown by the line A ₂ -B ₂ . and,
When the piston 6 reaches a medium speed range, the slider 15 bends the disc valve 41.
is brought close to the protrusion 20A of the stopper 20,
The annular passage formed therebetween is smaller than the total area of the passage hole 42, and this part becomes a variable throttle passage, which causes sudden changes in damping force as shown by the line B ₂ - C ₂ in Fig. 13. show. The changes in damping force in these low speed ranges and medium speed ranges are almost the same as in the first embodiment described above. Then, when the displacement of the piston 6 reaches a high speed range, the slider 15 slides to the end of its stroke, and the disc valve 41 moves toward the slider 1.
5 and the projection 20A of the stopper 20, the flow passage through the passage hole 42 of the disc valve 41 is blocked, and the flow from the oil chamber B to the oil chamber A is stopped again. The road area is the same as that at the initial stage, consisting only of the fixed orifice and the orifice passage 43, and a damping force characteristic as shown by the line C ₂ -D ₂ in FIG. 13 is obtained.

Therefore, with the configuration of this embodiment, damping force characteristics are on the same line in the initial stage and high speed range, and smaller damping force is generated in the low speed range and medium speed range. Of course, the damping force is small in the low speed range, and the damping force changes rapidly in the medium speed range.

FIG. 14 shows a modification of the second embodiment, in which an orifice passage 44 is formed in the piston rod 7 instead of the orifice passage 43 formed in the piston 6 in the second embodiment. It is in. A recess 45 is formed in the piston rod 7 in the axial direction from its tip surface, one end of the orifice passage 44 is opened in the recess 45, and the other end of the orifice passage 44 is attached to the retainer 21 on the outer peripheral surface of the piston rod 7. Rod guide 3 from position
The orifice passage 44 is a fixed orifice that communicates between the oil chambers A and B.

Even with this configuration, the operation is similar to that of the second embodiment described above, and the damping force characteristics shown in FIG. 13 are exhibited.

Further, FIG. 15 shows a third embodiment of the present invention, and FIGS. 16 and 17 each show a modification of the third embodiment, and in these figures, the same components as in the first embodiment are The same reference numerals will be given and the explanation thereof will be omitted.

However, the feature of this embodiment and its modifications is that, unlike the disc valve 16 shown in the first embodiment, the disc valve 51 constituting the reduction-side damping force generation mechanism 11'' is a second A passage hole 52 similar to the disc valve 41 of the embodiment,
In FIG. 15, an orifice groove 53 is formed in the projection 15A of the slider 15, and in FIG.
An orifice groove 54 is formed in the projection 20A of the stopper 20, and an orifice passage 55 is formed in the projection 20A of the stopper 20 in FIG.

These orifice grooves 53, 54 and orifice passage 55 allow oil to flow from oil chamber B to oil chamber A during the contraction stroke of piston rod 7, since slider 15 blocks communication passage 10A in the initial stage. It does not serve as a flow path for liquid. However, in the low speed range after the slider 15 is separated from the piston 6,
In medium speed range and high speed range, oil chamber B to oil chamber A
When the stopper 20 is in contact with the retainer 21, the disc valve 51
is held between the protrusion 20A of the stopper 20 and the protrusion 15A of the slider 15, the orifice groove 5
3, 54 and orifice passage 55 are oil chambers A, B.
It becomes a fixed orifice that communicates between the two.

As described above, in the third embodiment, the flow path area between the oil chambers A and B is different between the initial stage and the high speed range, and damping force characteristics substantially similar to those of the first embodiment are exhibited.

Further, FIGS. 18 and 19 show a fourth embodiment of the present invention, and in the figures, the same components as those in the first embodiment are designated by the same reference numerals, and the explanation thereof will be omitted.

However, in this embodiment, the extension side damping force generation mechanism 61
It is characterized by having the same configuration as the reduction side damping force generation mechanism 11. The piston 62 has a protrusion 62 similar to the inner circumferential side and outer circumferential side protrusions 62A and 62B that protrude toward the oil chamber A side.
C and 62D are also formed on the oil chamber B side. Similarly to the contraction side damping force generation mechanism 11, on the extension side damping force generation mechanism 61 side, a slider 63 having a protrusion 63A is provided in the recess 64, and a disc valve with a plurality of notched grooves 65 formed on the outer peripheral edge. 66 and a small diameter disk 67 are connected to the protrusion 62 of the piston 62.
It is fixed in a sandwiched state between C and the sleeve 68. The sleeve 68 has a protrusion 69A.
A stopper 69 having a
9 is a spring 7 stretched between it and the retainer 70.
1, it is normally biased in the direction of contacting the disc valve 66. Furthermore, during the contraction stroke and the extension stroke of the piston 62, the sliders 15 and 63 block the communication passages 10A and 10B, respectively, in those initial stages, so the flow between the oil chambers A and B at these early stages is In order to form a passage, an orifice passage 72 is bored in the piston 62, one end of which opens into the oil chamber A, and the other end of which opens into the communication passage 10A. Regardless of what happens, it becomes a fixed orifice that always communicates between oil chambers A and B.

By configuring as described above, as shown in Fig. 19, the damping force characteristic during the extension stroke is similar to the damping force characteristic during the contraction stroke, and a gentle damping force is generated in the low speed range, and a gentle damping force is generated in the medium speed range. The damping force increases rapidly and maintains a high damping force at high speeds.
As shown in the figure, the reason why the damping force during the extension stroke is larger than that during the contraction stroke is because the small diameter disk 18 is formed by three disks, and the small diameter disk 67 is formed by four disks. This is due to the fact that the small diameter disks 18, 6
If 7 is formed of the same number of disks, its damping force characteristics will be the same during both the contraction stroke and the extension stroke.

In each of the above-mentioned embodiments, a damping force generation mechanism is provided in the piston of a type of hydraulic shock absorber filled with high-pressure gas. The damping force generating mechanism may be provided in the damping force generating mechanism, and it can also be used in a single cylinder hydraulic shock absorber having a free piston. Furthermore, in the first to third embodiments, the damping force generation mechanism on the compression side is configured to include a slider, a disc valve, a stopper, etc., but this is configured as a damping force generation mechanism on the extension side, The reduction side damping force generation mechanism may be configured to be formed by a disc valve made up of a plurality of discs. Furthermore, although the stopper is movably provided and a spring is interposed between the stopper and the retainer, if the stopper is fixed to the retainer or the stepped portion of the piston rod, the spring or spring It is not necessary to provide a retainer and a retainer. Furthermore, if the piston or piston rod is provided with an orifice passage as in the second embodiment, it is not necessary to provide a cutout groove in the disc valve of the extension-side damping force generating mechanism consisting of a plurality of discs.

As explained in detail above, according to the hydraulic shock absorber according to the present invention, a small damping force is generated when the piston is displaced at low speed, the damping force increases rapidly in the medium speed range, and a high damping force is generated in the high speed range. Since the structure is equipped with a damping force generation mechanism that has damping force characteristics that maintain the damping force, a small damping force is generated in consideration of ride comfort during low-speed displacement of the piston that does not particularly affect the handling stability of the vehicle. , it is possible to generate an extremely large damping force during high-speed displacement of the piston, which may affect handling stability.

[Brief explanation of drawings]

1 to 7 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 view of the main part of FIG. 1, and FIG. 3 is a disc valve. The plan view of FIG. 4 and FIG. 5 are operation explanatory diagrams.
The figure is a damping force characteristic diagram, Figure 7 is a dimensional explanatory diagram of each component of the damping force generation mechanism, and Figures 8 to 10 are cross sections of main parts showing modifications of the first embodiment of the present invention. 11 to 13 show a second embodiment of the present invention, in which FIG. 11 is a sectional view of essential parts of a hydraulic shock absorber, FIG. 12 is a plan view of a disc valve, and FIG. 13 is a damping force Characteristic diagram, FIG. 14 is a sectional view of a main part showing a modification of the second embodiment, and FIGS. 15 to 17 are sectional views of main parts of a third embodiment of the present invention, showing different modifications, respectively. , Figures 18 and 19
The figures show a fourth embodiment of the present invention, in which FIG. 18 is a cross-sectional view of a main part of a hydraulic shock absorber, and FIG. 19 is a damping force characteristic diagram. 1...Cylinder, 6...Piston, 7...Piston rod, 10A, 10B...Communication path, 11,
11', 11''...reduction side damping force generation mechanism, 12,
61... Extension side damping force generation mechanism, 13, 14...
Recessed portion, 15, 63...Slider, 16, 23, 4
1,51,66...disc valve, 17,65
...Notch groove, 18,67...Small diameter disk, 2
0,69...stopper, 30,30'...spacer, 42,52...passage hole.

Claims (1)

[Claims] 1. A cylinder containing an oil liquid and a gas, a piston that is slidably inserted into the cylinder and defines the inside of the cylinder into two oil chambers, and one end of the piston. a piston rod that is connected and has its other end protruding outside the cylinder; a communication passage formed in the piston that communicates between the two oil chambers; and at least one side of each of the oil chambers of the piston. a slider disposed at a position capable of closing the communication passage on the oil chamber side of the piston rod and displaceable in the axial direction of the piston rod; a disc valve fixed to the piston rod and in contact with the slider; a stopper that comes into contact with the disc valve when the disc valve is pressed by the slider and deflects by a predetermined amount; and a stopper that is provided in the disc valve and is located between the one side of the oil chamber and the other side of each of the oil chambers. A passageway is provided between the disc valve and the stopper for causing oil to flow from the oil chamber on the other side to the oil chamber on the one side when the slider is separated from the piston. A hydraulic shock absorber configured to form a variable throttle passage capable of reducing the flow area of the oil flowing through the passage when the disc valve is deflected by a predetermined amount. 2. The hydraulic shock absorber according to claim 1, wherein the passage is a notched groove provided on the outer peripheral edge of the disc valve. 3. The hydraulic shock absorber according to claim 1, wherein the passage is a passage hole bored in the disc valve. 4. The hydraulic shock absorber according to claim 1, wherein the disk valve has one or more small diameter disks arranged in parallel to provide resistance to deflection of the disk valve. 5. The hydraulic shock absorber according to claim 4, further comprising a spacer interposed between the disc valve and the small-diameter disc to adjust the inflection point of the damping force characteristic. 6. The hydraulic shock absorber according to claim 4, wherein a plurality of the small diameter disks are provided, and a spacer is interposed between adjacent small diameter disks to adjust the inflection point of the damping force characteristic. vessel. 7. The hydraulic shock absorber according to claim 1, wherein the slider, disc valve, and stopper are configured as an extension-side damping force generation mechanism. 8. The hydraulic shock absorber according to claim 1, wherein the slider, disc valve, and stopper are configured as a reduction side damping force generation mechanism. 9. The hydraulic shock absorber according to claim 1, wherein the slider, disc valve, and stopper are provided on both sides of the piston to constitute a damping force generation mechanism on the extension side and the contraction side.