JPH04157224A - Hydraulic shockabsorber - Google Patents

Abstract

PURPOSE:To vary orifice characteristics according to the frequency of unspring weight of a suspension device by sliding a shutter by means of flow of oil liquid into the chamber of a guide caused by slide of piston and varying the opening of an orifice path on the side of the guide according to the frequency of the piston. CONSTITUTION:In extending stroke of a hydraulic shockabsorber, the pressurized oil liquid in an upper cylinder chamber 1a is flown into a lower cylinder chamber 1b through a bypass path 16 as a piston 2 is slid, while it is flown into the chamber 10a at the upper side of a cylindrical guide 10 through the orifice path 12a of a partition 12 according to the frequencies of the piston 2 to move a shutter 11 to a partition 13 side against the elastic force of a spring 17. When the frequency of the piston 2 is large, an orifice 15 is opened to produce a small damping force and, when it becomes small, the orifice path 15 is started to close to reduce the opening according to decrease of frequency of the piston 2, whereby the damping force is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic shock absorber used in a suspension system for a vehicle such as an automobile.

(Prior art) - A hydraulic shock absorber uses an orifice passage and a disc valve mechanism to control the flow of oil generated in a communication passage that communicates between two chambers due to the sliding of a piston in a cylinder. It generates a damping force. When the piston speed is low, the damping force characteristic (orifice characteristic) is shown in which the damping force changes quadratically according to the piston speed due to the restriction of the orifice passage, and when the piston speed exceeds a certain level, the piston is activated by the disc valve. Damping force characteristics (valve characteristics) in which the damping force changes linearly according to speed
I am trying to show this.

By the way, in order to improve the ride comfort and handling stability of a car, the damping force characteristic of the suspension system, which generates a small damping force during normal driving with small vibrations (large vibration frequencies) under the springs of the suspension system, must be adjusted. It is desirable to have damping force characteristics that generate a large damping force when turning or braking, which involves relatively slow and large movements (small vibration frequencies) under the spring.

Therefore, for example, Japanese Patent Publication No. 42-17787 discloses a hydraulic shock absorber in which valve characteristics are changed in accordance with the frequency of unsprung vibration of a suspension system. This hydraulic shock absorber generates a large damping force by increasing the valve opening pressure of the disc valve in response to small vibration frequencies (low frequency), and generates a large damping force by increasing the valve opening pressure of the disc valve in response to small vibration frequencies (high frequency). The idea is to improve riding comfort and steering stability by reducing the pressure (and thereby reducing the damping force).

(Problem to be Solved by the Invention) However, since small vibrations during normal driving and large movements during turning and braking occur in areas where the damping force is relatively small, it is difficult to reduce the damping force using the conventional hydraulic shock absorber. There is a problem in that simply changing the valve characteristics that control a relatively large area does not provide sufficient effects in improving ride comfort and handling stability.

The present invention has been made in view of the above points, and an object of the present invention is to provide a hydraulic shock absorber whose orifice characteristics change depending on the frequency of unsprung vibration of a suspension system.

(Means for Solving the Problems) In order to solve the above problems, the present invention controls the flow of oil that occurs in the oil passage that communicates between two cylinder chambers by the sliding of the piston in the cylinder. A hydraulic shock absorber that generates a damping force is provided with a cylindrical guide whose both ends communicate with the two cylinder chambers, and a shutter slidably fitted into the cylindrical guide. A chamber is formed on one side of the shutter and communicates with one of the two cylinder chambers via an orifice passage, and another orifice passage is bored in the side surface of the cylindrical guide, which is opened and closed by sliding of the shutter. A bypass passage is provided which communicates the two cylinder chambers through the orifice passage.

In addition, in a hydraulic shock absorber that generates damping force by controlling the flow of oil generated in a passage communicating between two cylinder chambers due to the sliding of a piston in a cylinder, both ends are connected to the two cylinder chambers, respectively. A cylindrical guide that communicates with the cylindrical guide and a shutter that slidably fits into the cylindrical guide are provided,
A chamber communicating with one of the two cylinder chambers via an orifice passage is formed on one side of the shutter within the guide, and a passage that opens and closes by sliding of the shutter is formed on a side surface of the cylindrical guide. A bypass passage is bored and communicates the two chambers through the orifice passage, and the bypass passage is connected to another orifice passage that generates a damping force by controlling the flow of oil in the bypass passage. A damping force generating mechanism comprising a generating valve is provided.

(Function) With this configuration, the shutter slides due to the flow of oil into the chamber in the cylindrical guide caused by the sliding of the piston, and the shutter is moved by the hole formed on the side of the guide in accordance with the frequency of vibration of the piston. The opening of the orifice passage or passage changes.

When the frequency of the piston is high, the opening degree of the orifice passage or the passage becomes large, and the flow resistance of the oil in the bypass passage becomes small (thereby, a small damping force is generated. As the opening degree of the orifice passage or the passage becomes smaller, the flow resistance of the oil in the bypass passage increases, and a large damping force is generated.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

A main part of a first embodiment of the present invention is shown in FIG.

In FIG. 1, a piston 2 is slidably fitted into a cylinder 1 filled with oil, and the piston 2 divides the inside of the cylinder 1 into two chambers, an upper cylinder chamber 1a and a lower cylinder chamber 1b. ing. The piston 2 is provided with an oil passage 3 on the extension side and an oil passage 4 on the contraction side, which communicate the upper cylinder chamber 1a and the lower cylinder chamber 1b. A damping force generation mechanism 5 consisting of an orifice passage 5a and a disc valve 5b that generates a damping force during the extension stroke is connected to the end surface of the piston 2 on the cylinder upper chamber 1a side through which oil from the contraction side oil passage 4 flows during the contraction stroke. A check valve mechanism 6 that allows this is provided.

7 is a piston rod, which extends through the piston 2 into the lower cylinder chamber ib and has a cylindrical passage member 8 at its end.
is screwed on. The piston rod 7 is meticulously arranged so that one end communicates with the inside of the passage member 8 in the cylinder lower chamber lb and the other end opens in the cylinder upper chamber la.
An oil passage 9 is bored through which the cylinder a and the cylinder lower chamber 1b communicate with each other. A cylindrical guide 10 is fitted inside the passage member 8, and the cylindrical guide 10 has two upper and lower parts.
A bottomed cylindrical shutter 11 that partitions the chamber 10a and iob.
are slidably fitted. Partition plates 12 and 13 are interposed at both ends of the cylindrical guide lO, and the partition plate 12 on the oil liquid passage 9 side has an orifice passage 12a, and the partition plate 13 on the cylinder lower chamber 1b side has a hole. 13a is bored. The upper chamber 10a defined by the shutter 11 in the cylindrical guide 10 is an orifice passage 12.
a and the oil passage 9 to communicate with the cylinder upper chamber 1a, and the lower chamber 10b communicates with the cylinder lower chamber 1b via the hole 13a.

Further, an oil passage 14 communicating with the oil passage 9 is formed between a groove provided on the outer surface of the cylindrical guide 10 and the inner peripheral surface of the passage member 8. An orifice passage 15 is bored in the side surface of the cylindrical guide 10 facing the oil passage 14, and an oil passage 9, an oil passage 14, and a lower chamber l in the cylindrical guide 10 are formed. The mouth and hole 13a constitute a bypass passage 16 that communicates the cylinder upper chamber 1a and the cylinder lower chamber 1b via the orifice passage 15.

The orifice passage 15 is open when the shutter 11 is located at the top (the position shown in FIG. 1);
The degree of opening changes according to the downward sliding movement in the figure of 1. The shape of the orifice passage 15 is determined by considering the relationship between the sliding amount of the shutter 11 and the opening area, for example.
As shown in FIGS. 2(a), (b), (c), and (d), the two sides of a triangle may be made into cubic curves, or the shape may be an oval, a circle, or a collection of small holes.

A spring 17 with a relatively weak spring force is provided between the shutter 11 and the partition plate 13 to always urge the shutter 11 upward (toward the partition plate 12 side). In the figure, 18 and 19 are spacers.

The operation of the first embodiment configured as above will be explained next.

Normally, the orifice passage 15 is opened by the upward movement of the shutter 11 by the elastic force of the spring 17, so during the extension stroke, the oil in the upper cylinder chamber la flows through the bypass passage 16 as the piston 2 slides. It circulates and flows into the cylinder lower chamber 1b. At this time, the oil in the cylinder upper chamber 1a flows into the upper chamber 10a of the cylindrical guide 10 through the orifice passage 12a of the partition plate 12 in accordance with the frequency of the piston 2, so that the shutter 11 is activated by the spring 17. It slides toward the partition plate 13 against the elastic force.

When the frequency of the piston 2 is large, the orifice passage 12
Since the amount of oil flowing into the chamber 10a after passing through a is small and the sliding amount of the shutter 11 is also small, the orifice passage 15 is in an open state, and the oil flows from the cylinder upper chamber 1a to the cylinder lower chamber 1b with small resistance. is distributed. Therefore, a small damping force is generated.

When the frequency of the piston 2 decreases, the orifice passage 12
As the amount of oil flowing into the chamber 10a through a increases and the amount of sliding of the shutter lO also increases, the orifice passage 15 begins to close, and as the frequency of the piston 2 decreases, the degree of opening decreases. The damping force increases. and,
When the orifice passage 15 is closed, the oil in the cylinder upper chamber 1a flows through the extension side oil passage 3 of the piston 2 and flows into the cylinder lower chamber 1b, and the damping force generating mechanism 5 generates a large damping force.

That is, during the extension stroke, when the frequency of the piston 2 is large as shown in FIG. If a damping force characteristic is obtained in which the damping force increases as the number of pistons decreases, and the frequency of the piston 2 falls below a predetermined value, the orifice passage 15
By closing the damping force generating mechanism 5 of the piston 2, a damping force characteristic that generates a large damping force can be obtained.

In this way, during normal running with small vibrations occurring under the spring of the suspension system, the frequency of the piston 2 of the hydraulic shock absorber is high, so the passage area of the orifice passage 15 is large and a small damping force is generated. As the amplitude of the vibration increases and the frequency decreases, the amount of movement of the shutter 11 increases (as the passage area of the orifice passage 15 decreases, the orifice characteristics change and a large damping force is generated. During turning or braking, which involves a relatively slow and large movement under the spring of the suspension system, the frequency of the piston 2 of the hydraulic shock absorber is small, so the orifice passage 15 closes and a large damping force is generated.In this way,
By changing the orifice characteristics according to the unsprung frequency of the suspension system, the ride comfort and steering stability of the vehicle can be improved.

On the other hand, during the retraction stroke, the oil in the lower cylinder chamber 1b is pressurized, so the pressure causes the shutter 11 to close the partition plate 1.
2 side, and the orifice passage 14 is in an open state. The oil in the lower cylinder chamber 1b is then transferred to the bypass passage 16.
The oil flows through the contraction side oil passage 4 with almost no resistance and flows into the cylinder upper chamber 1a. Therefore, almost no damping force is generated in the piston 2 during the contraction stroke.

At this time, as shown in FIG. 4, a check valve mechanism 20 having an orifice passage 12a in the partition plate 12 and allowing the oil to flow from the chamber 10a of the cylindrical guide lO into the bypass passage 16 is provided. Therefore, when changing from the extension stroke to the contraction stroke, the shutter 11 can be quickly moved toward the partition plate 12 to open the orifice passage 15.

In the first embodiment, a base valve mechanism (not shown) may be provided at the bottom of the cylinder l to generate a damping force during the contraction stroke.

A second example will be explained.

The main part of the second embodiment of the present invention is shown in FIG.

In FIG. 5, a piston 22 is slidably fitted into a cylinder 21 filled with oil.
2, the inside of the cylinder 21 is divided into two chambers: a cylinder upper chamber 21a and a cylinder lower chamber 21b. The piston 22 has an extension side oil passage 23 and a contraction side oil passage 2 which communicate the cylinder upper chamber 21a and the cylinder lower chamber 21b.
4 is drilled. Further, a damping force generating mechanism 25 consisting of an orifice passage 25a and a disc valve 25b that generates a damping force during the extension stroke is provided on the end surface of the piston 22 on the cylinder lower chamber 21b side, and a damping force generating mechanism 25, which is composed of an orifice passage 25a and a disc valve 25b, is provided on the end surface of the piston 22 on the cylinder upper chamber 21a side. A damping force generating mechanism 26 is provided which includes an orifice passage 26a b and a disc valve 26b that generates a damping force during the retraction stroke.

A piston rod 27 passes through the piston 22 and extends into the lower cylinder chamber 21b, and a cylindrical passage member 28 is screwed onto the end thereof. The piston rod 27 has
A passage member 2 whose one end is located in the cylinder lower chamber 21b along the axis
An oil passage 29 is provided which communicates with the inside of the cylinder 8 and whose other end opens into the cylinder upper chamber 21a to communicate the cylinder upper chamber 21a and the cylinder lower chamber 21b. A cylindrical guide 30 is fitted inside the passage member 28, and a pair of bottomed cylindrical shutters 31 and 32 are slidable in the cylindrical guide 30 with their openings opposed to each other. is mated to. A partition plate 33 having an orifice passage 33a and a partition plate 34 having an orifice passage 34a are interposed at both ends of the cylindrical guide 30, respectively. The interior of the cylindrical guide 30 is divided by shutters 31 and 32 into three chambers: a chamber 30a on the partition plate 33 side, a chamber 30b between the shutters 31 and 32, and a chamber 30c on the partition plate 34 side. A relatively weak spring 35 is interposed between the shutters 31 and 32 and urges the shutters 318 and 32 toward the end of the cylindrical guide 30, respectively.

The cylindrical guide 30 has one end communicating with the cylinder upper chamber 21a via the orifice passage 33a and the oil passage 29, and the other end communicating with the cylinder lower chamber 21 via the orifice passage hole 34a.
It communicates with b. An oil passage 36 communicating with the oil passage 29 is formed between the passage member 28 and the cylindrical guide 30, and oil is supplied to the side surface of the cylindrical guide 30 where the shutter 31 can be opened and closed by sliding. An orifice passage 37 is provided to communicate the liquid passage 36 and the chamber 30b. An orifice passage 38 that communicates the cylinder lower chamber 21b and the chamber 30b is bored in a side surface of the cylindrical guide 30 at a portion where the shutter 32 can be opened and closed by sliding. The oil passage 29, the oil passage 36, and the chamber 30b constitute a bypass passage 39 that communicates the cylinder upper chamber 21a and the cylinder lower chamber 21b via the orifice passages 37 and 38. Furthermore, the cylindrical guide 30 has a chamber 30b.
A check valve mechanism 40 is provided which has a passage 40a that allows fluid flow to the oil passage 36.

Note that the orifice passage 37 has a smaller passage area than the orifice passage 38 (and the passage area of the orifice passage 38 is smaller than the total passage area of the orifice passage 37 and the passage 18B40a).

Next, the operation of the second embodiment configured as above will be explained.

During the extension stroke, as in the first embodiment, the cylinder upper chamber 2
As the piston 22 slides, the oil in the cylinder 1a flows through the bypass passage 39 and flows into the cylinder lower chamber 21b, and the oil in the cylinder upper chamber 21a flows through the orifice passage 33a of the partition plate 33 into the cylindrical guide. 30 upper chamber 3
0a, and the shutter 31 slides toward the partition plate 34. At this time, the shutter 32 does not move and the orifice passage 3
8 is fully open.

When the frequency of the piston 22 is large, the amount of sliding of the shutter 31 is also small, so the orifice passage 37 is open, allowing the oil to flow from the cylinder upper chamber 21a to the cylinder lower chamber 21b with almost no resistance. Therefore, almost no damping force is generated.

As the frequency of the piston 22 decreases, the amount of sliding of the shutter 31 also increases, so the orifice passage 37 begins to close.
As the vibration frequency of the piston 31 decreases, the opening degree becomes smaller (and the generated damping force becomes larger). Then, when the orifice passage 37 closes, the oil in the cylinder upper chamber 21a flows into the oil liquid passage 23 on the extension side of the piston 22. through the cylinder lower chamber 21
b, and a large damping force is generated by the damping force generating mechanism 25.

During the retraction stroke, the oil in the cylinder lower chamber 21b flows into the piston 2.
2, it flows through the bypass passage 39 and flows into the cylinder upper chamber 21a. As in the case of the extension stroke, the oil in the cylinder lower chamber 21b passes through the orifice passage 34a of the partition plate 34 to the lower chamber 3Dc of the cylindrical guide 30.
The shutter 32 slides toward the partition plate 33. At this time, the shutter 31 does not move and the orifice passage 37 is fully open.

When the frequency of the piston 22 is large, the amount of sliding of the shutter 32 is also small, so the orifice passage 38 is in an open state, allowing the oil to flow from the cylinder lower chamber 21b to the cylinder upper chamber 21a with almost no resistance. Therefore, almost no damping force is generated.

As the frequency of the piston 22 decreases, the amount of sliding of the shutter 32 also increases (so the orifice passage 38 begins to close,
As the frequency of the piston 22 decreases, the degree of opening decreases and the generated damping force increases. When the orifice passage 38 is closed, the oil in the lower cylinder chamber 21b flows through the contraction side oil passage 24 of the piston 22 and enters the upper cylinder chamber 21.
a, and a large damping force is generated by the damping force generating mechanism 26.

That is, as shown in FIG. 6, when the frequency of the piston 22 is large in both the extension and contraction strokes,
A damping force characteristic having a small orifice characteristic can be obtained when the opening degree of the orifice passage 37 or 38 is large, and a damping force characteristic can be obtained in which the damping force increases as the frequency of the piston decreases. When the frequency of the piston 22 becomes lower than a predetermined value, the orifice passage 37 or the orifice passage 38 is closed and the damping force generating mechanism 25 or the damping force generating mechanism 26 of the piston 22 is closed.
It is possible to obtain damping force characteristics that generate a large damping force.

Note that by providing a base valve mechanism as in the first embodiment, the damping force during the compression stroke can be increased. Also, the orifice passage 33a of the partition plate 33.34
, 34a may be replaced with a check valve mechanism 20 shown in FIG. 4.

A third embodiment will be explained.

The third embodiment differs from the first embodiment only in that a damping force generation mechanism is provided in the bypass passage.
Hereinafter, members corresponding to those of the first embodiment are given the same numbers, and only different parts will be described in detail.

In FIG. 7, a partition member 41 that blocks the bypass passage 16 is fitted on the oil liquid passage 9 side with respect to the cylindrical guide lO in the passage member 8, and the partition member 41 blocks the flow of the bypass passage 16. A permissible bypass oil passage 42 is provided. An orifice passage 43 is provided on the end surface of the cylindrical guide 10 side of the partition member 41 to control the flow of oil in the bypass oil passage 42 during the extension stroke and generate a damping force.
A damping force generating mechanism 43 consisting of a disc valve 43b and a disc valve 43b is provided. The damping force generation mechanism 43 has a smaller flow resistance (has the characteristic of generating a small damping force) than the damping force generation mechanism 5 of the piston 2. It is provided at the end of the cylindrical guide lO on the partition member 41 side. In the partition plate 12, a passage portion 12b communicating with the orifice passage 12a is an oil passage 9.
The passage portion 12b extends to the side, and the passage portion 12b passes through the partition member 41 and opens facing the oil passage 9.

Note that the guide 10 is provided with a passage 15a having a large passage area in place of the orifice passage 15.

The operation of the third embodiment configured as above will be explained next.

As in the first embodiment, during the extension stroke, the cylinder upper chamber 1
As the piston 2 slides, the oil fluid in a flows into the bypass passage 1.
6 and flows into the cylinder lower chamber 1b. At this time,
The oil in the cylinder upper chamber 1a is transferred to the passage section 12b of the partition plate 12.
and the cylindrical guide 10 via the orifice passage 12a.
It flows into the upper chamber 10a and the shutter 11 closes the partition plate 13.
Slide to the side.

When the frequency of the piston 2 is large, the amount of sliding of the shutter 11 is also small, so the passage 15a remains open, and the oil in the upper cylinder chamber 1a flows into the lower cylinder chamber 1b through the bypass passage 16. Therefore, this oil flows through the bypass oil passage 42 and the damping force generating mechanism 43
A small damping force is generated by the orifice passage 43a and the disc valve 43b.

As the frequency of the piston 2 decreases, the amount of sliding of the shutter IO also increases, so the passage 15a begins to close when the piston 2 moves more than a predetermined amount. Therefore, the flow rate of the bypass passage 16 decreases, and the flow rate of the oil liquid passage 3 on the extension side of the piston 2 increases accordingly, and the damping force is increased by the damping force generation mechanism 5.
When 5a is closed, the oil flows only through the extension side oil passage 3, and the damping force generating mechanism 5 generates a large damping force.

That is, as shown in FIG. 8, when the frequency of the piston 2 is large, the orifice 43a of the damping force generating mechanism 43 provided in the bypass passage 16 and the disc valve 4
3b, the orifice characteristics and valve characteristics that generate a small damping force are obtained, and the damping force is increased by reducing the flow rate of the bypass passage in accordance with the decrease in the piston frequency and allowing the extension side oil liquid passage 3 to flow accordingly. becomes larger. When the frequency of the piston 2 becomes lower than a predetermined value, the orifice passage 15 is closed and the orifice passage 5a and the disc valve 5b of the damping force generation mechanism 5 provided in the piston 2 generate a large damping force. characteristics and valve characteristics can be obtained.

On the other hand, during the retraction stroke, the check valve mechanism 6 of the piston 2 is opened (thereby, almost no damping force is generated in the piston 2).

A fourth example will be described.

The fourth embodiment differs from the second embodiment only in that a damping force generation mechanism is provided in the bypass passage.
Hereinafter, members corresponding to those of the second embodiment are given the same numbers, and only different parts will be described in detail.

In FIG. 9, a partition member 44 for blocking the bypass passage 39 is fitted on the side of the oil passage 29 to the cylindrical guide 30 in the passage member 28, and the partition member 44 blocks the flow of the bypass passage 39. A permissible extension side bypass oil passage 45 and a contraction side bypass oil passage 46 are bored. On the end face of the partition member 44 on the side of the cylindrical guide 30, there is an extension side damping device which includes an orifice passage 47a and a disc valve 47b, which control the flow of oil in the extension side bypass oil liquid passage 45 to generate a damping force during the extension stroke. A force generating mechanism 47 is provided. The extension side damping force generation mechanism 47 has a smaller flow resistance than the damping force generation mechanism 25 of the piston 22 (has the characteristic of generating a small damping force. The end surface of the partition plate 44 on the oil passage 29 side has a contraction stroke. A check valve 48 is provided to allow the contraction-side bypass oil passage 46 to flow at times.A partition plate 33 provided at the end of the cylindrical guide 30 on the partition member 44 side communicates with the orifice passage 33a. The passage portion 33b extends toward the oil passage 29 side, and the passage portion 33b passes through the partition member 44 and is open facing the oil passage 29.

Further, a partition member 49 is provided to block a passage connecting the orifice passage 38 of the cylindrical guide 30 and the cylinder lower chamber 21b. and a contraction side oil passage 51 are bored. The end surface of the partition member 49 on the orifice passage 38 side is provided with a contraction side oil passage 50 during the contraction stroke.
Orifice 5 that generates damping force by controlling the flow of oil
A compression-side damping force generation mechanism 52 is provided, which includes a compression damping force generating mechanism 2a and a disc valve 52b. The compression-side damping force generation mechanism 52 has a characteristic that the flow path resistance is smaller than that of the damping force generation mechanism 26 of the piston 22 and generates a small damping force. A check valve 5 is provided on the end surface of the partition member 49 on the cylinder lower chamber 21b side to allow the extension side oil passage 51 to flow during the extension stroke.
3 is provided. Partition member 4 of cylindrical guide 30
The partition plate 34 provided at the end on the 9 side has a passage portion 34b that communicates with the orifice passage 34a and extends toward the cylinder lower chamber 21b, and the passage portion 34b passes through the partition member 49 and is connected to the cylinder lower chamber 21b. It is open inward.

In the fourth embodiment, the oil passage 36 constituting the bypass passage 39 is bored in the side wall of the guide 30. The guide 30 also includes orifice passages 37 and 38.
Instead, passages 37a and 38a with large passage areas are provided. Furthermore, the reverse valve mechanism 40 provided in the second embodiment is omitted. The operation of the fourth embodiment configured as above will be explained next.

During the extension stroke, the piston 22
If the frequency of vibration is large, the orifice 4 of the damping force generating mechanism 47 provided in the partition member 44 of the bypass passage 39
7a and the disc valve 47b provide orifice characteristics and valve characteristics that generate a small damping force,
The damping force is increased by reducing the flow rate of the bypass passage 39 in accordance with the decrease in the frequency of the piston and allowing the extension side oil liquid passage 23 to flow accordingly. When the frequency of the piston 22 becomes lower than a predetermined value, the passage 37a is closed and the damping force generating mechanism 2 provided in the piston 22 is closed.
5 orifice passage 25a and disc valve 25b
It is possible to obtain orifice characteristics and valve characteristics that generate a large damping force. At this time, shutter 3
2 does not move and the passage 311a is fully open, and the passage 3
The oil passing through 8a flows through the extension side oil passage 5 of the partition member 49.
1 flows through the cylinder and pushes open the check valve 53 to open the cylinder lower chamber 21b.
flows into.

During the retraction stroke, the oil flow is in the opposite direction to the extension stroke, but the partition member 49 moves in accordance with the sliding movement of the shutter 32.
The same damping force characteristics as in the extension stroke can be obtained by the compression side damping force generation mechanism 52 and the damping force generation mechanism 26 of the piston 22. That is, when the frequency of the piston 22 is large, the orifice 52a and the disc valve 52b of the damping force generating mechanism 52 provided in the partition member 49 of the bypass passage 39 have orifice characteristics and valve characteristics that generate a small damping force. As the frequency of the piston 22 decreases, the amount of flow through the bypass passage 39 is reduced and the contraction side oil passage 24 is made to flow accordingly, thereby increasing the damping force. When the frequency of the piston 22 falls below a predetermined value, the passage 38a is closed and the orifice passage 26a and the disc valve 26b of the damping force generation mechanism 26 provided in the piston 22 generate a large damping force. and valve characteristics can be obtained. At this time, the shutter 31 does not move and the passage 37a is fully open, and the oil that has passed through the passage 37a flows through the bypass oil passage 46 on the extension side of the partition member 44, pushes open the check valve 48, and moves onto the cylinder. It flows into the chamber 21a.

In the fourth embodiment, as shown in FIG. 10, the partition member 49 is omitted and instead an orifice passage 54a is provided which opens during the extension stroke to create no resistance and closes during the contraction stroke to reduce the passage area. A pressure control valve 54 having a passage 3
It may be provided in a passage connecting 8a and the cylinder lower chamber 21b. In this case, in order to make the pressure in the chamber 30b of the cylindrical guide 30 lower than the pressure in the chamber 30a or 30c, the orifice passage of the pressure control valve 54 has a larger passage area than the orifice passage 47a of the extension damping force generation mechanism 47. It is necessary to make the passage area of 54a larger. Also,
A base valve mechanism (not shown) that generates a damping force during the contraction stroke is provided at the bottom of the cylinder 21, and a reservoir chamber is provided on the outer periphery of the cylinder 21 and communicates with the cylinder lower chamber 21b via the base valve mechanism. (not shown) is provided.

With this configuration, an effect similar to that shown in FIG. 9 can be obtained during the extension stroke, and when the frequency of the piston 22 is large during the contraction stroke, the passage 38a is opened and the base valve mechanism (not shown) is activated. When a small damping force is generated and the frequency of the piston 22 is small, the opening degree of the passage 38a is small (
Therefore, when the passage 38a is closed, a large damping force is obtained by the damping force generating mechanism 26 of the piston 22 and the base valve mechanism.

The main part of the fifth embodiment is illustrated and explained in FIG. 11.

A piston rod 61 is inserted into the cylinder 60 filled with oil. A small diameter portion 61a is formed at the inner end of the cylinder 60 of the piston rod 61.
In S 61 a, the inside of the cylinder 60 is connected to the cylinder upper chamber 60a.
A piston 62 defined between the cylinder lower chamber 60b and the cylinder lower chamber 60b is fitted and fixed to a cylindrical passage member 63 by -.

The piston 62 is provided with a contraction side oil passage 64 that communicates the cylinder upper chamber 60a and the cylinder lower chamber 60b, and oil passages 65 on both the extension side and the contraction side. A check valve mechanism 66 is provided on the cylinder upper chamber 60a side of the piston 61 to allow the flow of oil in the oil passage 64 during the contraction stroke. A passage 67 is formed in the end surface of the piston 61 on the side of the cylinder upper chamber 60a, which constantly communicates the cylinder upper chamber 60a and the oil passage 65.

A cylindrical guide 68 is fitted into the cylindrical passage member 63, and an oil passage 69 is bored in the side wall of the guide 68 to communicate the oil passage 65 with the cylinder lower chamber 60b. It is set up. A passage member interior chamber 63a is formed above the guide 68 within the passage member 63.

The upper guide member 68 has two upper and lower chambers 70a,
A low cylindrical shutter 71 partitioning into 70b is slidably fitted. A valve plate 72 serving as a check valve mechanism is provided at the upper part of the cylindrical guide member 68, and an orifice passage 72a connecting the passage member inner chamber 63a and the upper chamber 70a is provided in the valve plate 72. Further, the valve plate 72 is biased against the upper part of the guide member 68 by a trivet-shaped spring member 73 having several legs.

The shutter 71 is urged toward the inner upper part of the guide member 68 by a spring 74. A cylindrical damping force adjusting member 75 is provided at the lower end of this spring. A ring-shaped disk is provided between the lower end surface of the guide member 68 and the fulcrum member 77, which provides resistance to the flow of oil from the oil passage 69 to the cylinder lower chamber 60b during the extension stroke and generates a damping force. A valve 76 is provided, and the inner circumferential side of the disc valve 76 is urged downward by the damping force adjusting member 75, and the outer circumferential side is pressed against the guide member 68. Then, by changing the urging force of the spring 74 of the damping force adjustment member 75, the damping force during the extension stroke is adjusted.

Oil passages 75a and 77a are provided in the centers of the damping force adjusting member 75 and the fulcrum member 77, respectively. In addition, an orifice passage 78 is provided in the middle of the oil passage 69 provided in the guide 68, which communicates the oil passage 69 with a lower chamber 70b inside the guide 68, and whose communication is interrupted by a shutter 71. There is. And the oil passage 75a
and 77a constitute a bypass passage 79 that communicates the cylinder upper chamber 60a and the cylinder lower chamber 60b via the orifice passage 78.

The operation of the fifth embodiment configured as above will be explained next.

Normally, the orifice passage 78 is opened by the upward movement of the shutter 71 by the elastic force of the spring 74, so during the extension stroke, as the piston 62 slides, the oil in the upper cylinder chamber 60a flows into the passage 67 and the passage. Member inner chamber 63a
, passes through the oil passage 69, and flows into the cylinder lower chamber 60b via the bypass passage 79. At this time, the oil in the passage member inner chamber 63a flows into the orifice 7 according to the frequency of the piston 62.
2a into the upper chamber 70a of the guide 68, the shutter 71 slides downward against the elastic force of the spring 74. The shutter 7 corresponds to the frequency of this piston 62.
The adjustment of the damping force of the orifice passage 78 by the sliding movement in step 1 is the same as in the first embodiment described above.

Next, the damping force adjustment of the disc valve 76 will be explained.

When the shutter 71 does not slide, the spring 74 is in an extended state, so the force urging the damping force adjustment member 75 is weak, and the outer peripheral side of the disc valve 76 is weakly pressed against the guide member 68. The disc valve 76 provides a relatively small damping force with valve characteristics. On the other hand, when the shutter 71 slides, the spring 74 is compressed, so that the force that urges the damping force adjusting member 75 downward becomes stronger as the shutter 71 slides, and the outer peripheral side of the disc valve 76 is guided. It is strongly pressed by the member 68, and the damping force by the disc valve 76 increases.

During the retraction stroke, the check valve mechanism 66 causes the oil to flow from the cylinder lower chamber 60b to the cylinder upper chamber 60a through the oil passage 64 with almost no resistance, and almost no damping force is generated in the piston 62, causing the base (not shown) to flow. The damping force is generated by the valve.

Therefore, in the fifth embodiment, the orifice characteristics can be changed according to the vibration frequency during the extension stroke, and the valve characteristics can also be changed as the shutter 71 slides.

In this embodiment, the cylindrical guide, shutter, and bypass passage, which constitute the essential parts of the present invention, are provided in the piston portion, but they may also be provided in the base valve portion.

(Effects of the Invention) By having the hydraulic shock absorber of the present invention configured as described above in detail, the shutter that opens and closes the orifice passage slides due to the flow of oil caused by the sliding of the piston, and the vibration frequency of the piston is When is large, the opening degree of the orifice passage is large and a small damping force is generated, and when the frequency of the piston is small, the opening degree of the orifice passage is small and a large damping force is generated. As a result, during normal driving with small vibrations under the spring of the suspension system, a small damping force is generated, and the amplitude of the vibration increases and the frequency decreases (as the orifice characteristics change, a large damping force is generated). Also, when turning or braking, which involves a relatively slow and large movement under the spring of the suspension system, the orifice passage closes and a large damping force is generated.
By changing the orifice characteristics according to the unsprung frequency of the nest suspension device, the excellent effect of improving the ride comfort and steering stability of the vehicle is achieved.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the main part of the first embodiment of the present invention, FIG. 2 is a diagram illustrating the shape of the orifice passage in the embodiment of the present invention, and FIG. 3 is a diagram of the device of FIG. 1. Figure 4, a diagram showing the damping force characteristics on the extension side, shows the essentials of the device shown in Figure 1, which is equipped with a check valve mechanism to quickly move the shutter when switching from the extension stroke to the contraction stroke. 5 is a vertical sectional view of the main part of the second embodiment of the present invention. FIG. 6 is a diagram showing the damping force characteristics of the device in FIG. 5. FIG. 7 is a diagram showing the damping force characteristics of the device in FIG. FIG. 8 is a diagram showing the damping force characteristics on the extension side of the device shown in FIG. 7; FIG. 9 is a longitudinal sectional view of the main part of the third embodiment of the invention; FIG. 9 is a diagram showing the main part of the fourth embodiment of the invention. FIG. 10 is a vertical cross-sectional view of the main part of the apparatus shown in FIG. 9 but omitting the damping force generation mechanism on the compression side provided in the bypass passage, and FIG. 11 is a longitudinal cross-sectional view of the main part of the apparatus shown in FIG. FIG. 3 is a vertical cross-sectional view of the main part of the embodiment. 1.21...Cylinder la, 21a...Cylinder upper chamber lb, 21b...-Cylinder lower chamber 2.22...Piston 10.30...Cylindrical guide 11, 31, 32...Shutter 15.37.3
8--Orifice passage 16.39--Bypass passage

Claims (2)

[Claims] (1) In a hydraulic shock absorber that generates a damping force by controlling the flow of oil generated in an oil passage communicating between two cylinder chambers due to the sliding of a piston in a cylinder, both ends are connected to the two cylinders. A cylindrical guide communicating with each chamber and a shutter slidably fitted to the cylindrical guide are provided, and within the guide, on one side of the shutter, one of the two cylinder chambers and one orifice passage are provided. forming a chamber that communicates with each other through the cylindrical guide; another orifice passage that opens and closes when the shutter slides is formed on the side surface of the cylindrical guide; and the two cylinder chambers communicate with each other through the orifice passage. A hydraulic shock absorber characterized by having a bypass passage. (2) In a hydraulic shock absorber that generates damping force by controlling the flow of oil generated in a passage communicating between two cylinder chambers due to the sliding of a piston in a cylinder, both ends are connected to the two cylinder chambers. A cylindrical guide that communicates with each other and a shutter that slidably fits into the cylindrical guide are provided,
A chamber communicating with one of the two cylinder chambers via an orifice passage is formed on one side of the shutter within the guide, and a passage that opens and closes by sliding of the shutter is formed on a side surface of the cylindrical guide. A bypass passage is bored and communicates the two chambers through the orifice passage, and the bypass passage is connected to another orifice passage that generates a damping force by controlling the flow of oil in the bypass passage. A hydraulic shock absorber characterized by being provided with a damping force generation mechanism consisting of a generation valve.