JP3025854B2 - Hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile.

[0002]

2. Description of the Related Art In general, a hydraulic shock absorber mounted on a suspension system of a vehicle uses an orifice passage and a disk to move an oil liquid generated in a communication passage communicating between two chambers by sliding a piston in a cylinder. The damping force is generated by controlling by a valve mechanism. When the piston speed is low, a damping force characteristic (orifice characteristic) in which the damping force changes in a quadratic curve according to the piston speed due to the restriction of the orifice passage is shown. The damping force characteristic (valve characteristic) in which the damping force changes linearly according to the speed is shown.

[0003] In order to improve the riding comfort and steering stability of a vehicle, orifice characteristics and valve characteristics that generate a small damping force during normal running with fine vibrations under the spring of the suspension device are desired. It is desired to have an orifice characteristic and a valve characteristic that generate a large damping force when turning or braking with relatively slow large movement under the spring.

Therefore, conventionally, for example, Japanese Utility Model Laid-Open Publication No.
As described in Japanese Patent No. 46, the orifice characteristic on the extension side is changed according to the unsprung frequency of the suspension, and when the frequency is low, the passage area of the orifice is reduced to generate a large damping force. On the other hand, there has been proposed a hydraulic shock absorber in which, when the vibration frequency is high, the ride comfort and the steering stability are improved by increasing the passage area of the orifice to reduce the damping force.

However, in the conventional hydraulic shock absorber described above, since only the orifice characteristics on the extension side are changed, there is a problem that a sufficient effect on the contraction side cannot be obtained to improve the riding comfort and the steering stability. .

[0006] In view of the above points, the present applicant has
Japanese Patent Application No. 2-283852 discloses a frequency-sensitive hydraulic system in which the orifice characteristics on both the extension side and the contraction side change in accordance with the unsprung frequency of the suspension, or the valve characteristics change in addition thereto. A shock absorber is proposed.

[0007]

However, the one described in Japanese Patent Application No. 2-283852 has the following problems.

In the hydraulic shock absorber described in Japanese Patent Application No. 2-283852, the shutter is displaced by the pressure of oil generated according to the frequency of the stroke of the piston rod to open and close the bypass passage. When the frequency is large, a small damping force (soft characteristic) is generated, and when the frequency is small, a large damping force (hard characteristic) is generated. FIG. 14 shows the damping force characteristics of this hydraulic shock absorber. FIG. 14 shows the damping force characteristics when the piston rod of the hydraulic shock absorber is stroked at a frequency at which the speed at the center of the stroke is constant. And show the case where the frequency is small.

In the hydraulic shock absorber described in Japanese Patent Application No. 2-283852, when the direction of the stroke of the piston rod changes when the vibration frequency is low and the shutter is displaced and the damping force is increased, the shutter is closed. Since the direction of displacement also changes, the damping force characteristic is temporarily switched from the hard side to the soft side with the movement of the shutter, and then returns to the hard side again. As described above, the switching of the damping force characteristic during the extension side or the contraction side stroke causes a problem that an impact is generated and the riding comfort of the vehicle is deteriorated.

The present invention has been made in view of the above points, and provides a frequency-sensitive hydraulic shock absorber in which a damping force automatically has a soft characteristic when the direction of a stroke changes. The purpose is to do.

[0011]

According to a first aspect of the present invention, two cylinder chambers are communicated with each other through a main oil passage and a bypass passage. A hydraulic shock absorber for controlling a flow of an oil liquid generated in an oil liquid passage and a bypass passage to generate a damping force, and adjusting a damping force characteristic by adjusting a passage area of the bypass passage. A non-return valve provided only inside the two cylinder chambers and allowing only the flow of the oil liquid from one of the two cylinder chambers to the other chamber; an oil liquid passage bypassing the check valve; A shutter which is slidably inserted into the guide and defines the inside of the guide as two chambers, and opens the oil passage when the shutter moves to one side, and opens the oil passage when moved to the other side. Closing shutter mechanism, A spring for urging the shutter to one side, a communication path for communicating the one chamber with the other chamber of the cylinder chamber with respect to the shutter in the guide, and an orifice provided in the communication path. It is characterized by comprising.

According to a second aspect of the present invention, two cylinder chambers are communicated with each other through a main oil passage and a bypass passage, and a flow of oil generated in the main oil passage and the bypass passage by sliding of a piston in the cylinder. Controlling the damping force by controlling the passage area of the bypass passage to adjust the damping force characteristics, provided in the bypass passage, one of the two cylinder chambers A first check valve permitting only the flow of the oil liquid from the chamber to the other chamber; and a first check valve provided in series with the first check valve to allow the two cylinder chambers to move from the other chamber to the one chamber. A second check valve that allows only the flow of the oil liquid, a first oil liquid passage that bypasses the first check valve, and a second oil liquid passage that bypasses the second check valve And a guide and a guide slidably fitted in the guide. A shutter that defines the interior as two chambers, the first and second oil liquid passages are both opened when the shutter is at the neutral position, and the first oil liquid passage is closed when moved to one side, A shutter mechanism for closing the second oil liquid passage when moved to the other side, a spring for elastically holding the shutter at the neutral position, a chamber on the other side with respect to the shutter in the guide, A first communication passage for communicating the other of the two cylinder chambers, and a second communication passage for communicating the one side chamber and one of the two cylinder chambers to the shutter in the guide. And an orifice provided in at least one of the first and second communication passages.

[0013]

With this configuration, in the first aspect, since the shutter is normally moved to one side by the spring, the oil liquid passage is open and a small damping force is generated. When the piston strokes to the other chamber side of the two cylinder chambers, the oil in the cylinder chamber flows into the guide through the communication passage with the sliding of the piston, the shutter moves to the other side, and the shutter moves. The passage area of the oil passage decreases according to the amount, the passage area of the bypass passage decreases, and the damping force increases. At this time, if the frequency of the stroke of the piston is large, the flow resistance of the orifice becomes large and the amount of movement of the shutter becomes small, so that the damping force becomes small.If the frequency is small, the flow resistance of the orifice becomes small and the amount of movement of the shutter becomes small. As it increases, the damping force increases. Here, when the direction of the stroke is switched and the piston strokes toward one of the two cylinder chambers,
Since the bypass passage is communicated with the check valve, the damping force is reduced.

In the second invention, the shutter is normally held at the neutral position by a spring.
Since both the second oil liquid passages are open, the bypass passage is open, and a small damping force is generated. When the piston strokes to one side, the flow of the oil liquid caused by the sliding of the piston causes the oil liquid to flow into and out of the cylinder chamber and the guide through the first and second communication passages, and the shutter moves to one side. By moving, the passage area of one of the first and second oil liquid passages is reduced according to the movement amount of the shutter, and the passage area of the bypass passage is reduced to increase the damping force. If the frequency of the piston stroke is large, the flow resistance of the orifice becomes large and the amount of movement of the shutter becomes small, so that the damping force becomes small. If the frequency is small, the flow resistance of the orifice becomes small and the amount of movement of the shutter becomes large. The damping force increases. At this time, since the bypass passage is communicated via the first and second check valves, when the direction of the stroke of the piston is switched from one side to the other side, the first or second check valve is switched. By opening the first and second oil liquid passages to close the closed side of the first and second oil liquid passages, the bypass passage is communicated, so that the damping force is reduced.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The first embodiment will be described with reference to FIG. As shown in FIG. 1, a piston 2 is slidably fitted in a cylinder 1 in which oil is sealed.
Thereby, the inside of the cylinder 1 is divided into two chambers, an upper cylinder chamber 1a and a lower cylinder chamber 1b. A main oil liquid passage 3 that communicates the upper cylinder chamber 1a and the lower cylinder chamber 1b with the piston 2
The main oil passage 3 is provided with a damping force generating mechanism 3a.
(Large damping force) is provided.

The piston rod 4 connected to the piston 2
Is provided with a bypass passage 5 for communicating the cylinder upper chamber 1a and the cylinder lower chamber 1b. The bypass passage 5 has a damping force generating mechanism 5a (small damping force) and a cylinder lower chamber 1b.
Check valve 6 that allows only flow from the cylinder to the cylinder upper chamber 1a
And an oil liquid passage 7 that bypasses the check valve 6. A shutter mechanism 8 is provided in the oil liquid passage 7.

The shutter mechanism 8 includes a guide 9 communicating with the oil liquid passage 7 and a shutter 10 which is slidably fitted in the guide 9 and defines the inside of the guide 9 as two chambers 9a and 9b. When the shutter 10 moves to one side (chamber 9a side), the oil liquid passage 7 is opened, and when the shutter 10 moves to the other side (chamber 9b side), the oil liquid passage 7 is closed. The shutter mechanism 8 includes a spring for urging the shutter 10 to one side where the oil liquid passage 7 opens.
11 are provided. In addition, a communication path 12 that communicates the chamber 9a with the cylinder upper chamber 1a is provided.
An orifice 13 is provided.

The operation of the first embodiment configured as described above will now be described.

Normally, the shutter 10 is moved by the spring 11 to the chamber 9a.
Since the oil passage 7 is moved to the side and the oil passage 7 is open, the bypass passage 5 is communicated with the oil passage 7 regardless of whether the check valve 6 is opened or closed. Therefore, a small damping force is generated by the damping force generating mechanism 5a with respect to the expansion and contraction stroke of the piston rod 4.

During the extension stroke of the piston rod 4, the check valve 6 is closed, and the oil liquid in the cylinder upper chamber 1a is pressurized.
The shutter flows into the chamber 9a of the guide 9 through the communication passage 12 and
10 is moved to the room 9b side.

In this case, if the frequency of the stroke of the piston rod 4 is large, the flow resistance of the orifice 13 of the communication passage 12 becomes large, so that the amount of oil flowing into the chamber 9a during the extension stroke is small and the shutter 10 Is small, the oil liquid passage 7 remains open. Therefore, the bypass passage 5
Are connected by the oil liquid passage 7, so that the damping force generating mechanism 5a
Generates a small damping force.

When the frequency of the stroke of the piston rod 4 is small, the flow resistance of the orifice 13 in the communication passage 12 is reduced, so that the amount of oil flowing into the chamber 9a during the extension stroke increases, and Since the movement amount of 10 becomes large,
The passage area of the oil liquid passage 7 is reduced. Therefore, the oil liquid in the cylinder chamber 1a flows to the cylinder chamber 1b through the bypass passage 5, and the damping force generated according to the passage area of the oil liquid passage 7 increases. Then, when the frequency of the stroke of the piston rod 4 decreases and the oil liquid passage 7 is closed by the shutter 10, the bypass passage 5 is shut off and the cylinder upper chamber 1a is closed.
The internal oil liquid flows into the cylinder lower chamber 1b through the main oil liquid passage 3, and a large damping force is generated by the damping force generating mechanism 3a.

Here, when the stroke of the piston rod 4 is switched from the extension side to the contraction side, the check valve 6 is opened and the bypass passage 5 is communicated, so that the damping force is reduced. During the contraction stroke, the check valve 6 is opened and the bypass passage 5 is communicated, so that a small damping force is always generated.

As described above, when the frequency of the stroke of the piston rod 4 is large, a soft characteristic that generates a small damping force during the expansion and contraction strokes is obtained, and when the frequency of the stroke is reduced during the extension stroke, a hard characteristic that generates a large damping force is obtained. Switch to. Also, when the direction of the stroke switches from the extension side to the contraction side, that is, when the piston speed is zero,
Regardless of the position of the shutter 10, the check valve 6 opens and the damping force characteristic is switched to the soft characteristic. Therefore, since the damping force characteristic does not switch from the hard side to the soft side during the contraction stroke, an impact is generated by this switching, and the riding comfort of the vehicle can be improved.

In the above embodiment, the example in which the shutter 10 closes the oil passage 7 has been described. However, the present invention is not limited to this, and the shutter 10 can be used if the passage area of the oil passage 7 is reduced. The oil liquid may be allowed to flow even in a closed state.

A second embodiment will be described with reference to FIGS. As shown in FIG. 2, a piston 15 is slidably fitted in a cylinder 14 in which an oil liquid is sealed,
This piston 15 causes the inside of the cylinder 14 to become a cylinder chamber 14a
And a cylinder chamber 14b. The piston 15 is provided with main oil passages 16 and 17 for connecting the cylinder chambers 14a and 14b to each other. Further, at the end of the piston 15 on the cylinder chamber 14a side, the oil in the main oil passage 17 is provided. A damping force generating mechanism 18 comprising a disk valve for controlling the flow of the liquid to generate a damping force is provided, and at the end of the piston 15 on the cylinder chamber 14b side, the flow of the oil liquid in the main oil liquid passage 16 is controlled. There is provided a damping force generating mechanism 19 comprising an orifice 19a for generating a damping force and a disk valve 19b.

Reference numeral 20 denotes a piston rod, which is a cylinder chamber 14
A cylindrical passage member 21 is screwed to one end of the cylinder chamber 14b extending through the piston 15 from the side a and fixed to the piston 15. On the piston rod 20,
An oil liquid passage 22 communicating the cylinder chamber 14a and the inside of the passage member 21 provided on the cylinder chamber 14b side is provided along the axis, and the passage member 21 and the oil liquid passage 22 form the cylinder chamber. A bypass passage is provided for communicating the cylinder chamber 14a with the cylinder chamber 1b. The other end of the piston rod 20 is
It is inserted through a rod guide (not shown) and a seal member (not shown) provided at the end of the cylinder 14, and extends to the outside of the cylinder 14.

On the outer periphery of the cylinder 14, a piston rod 20
There is provided a reservoir chamber (not shown) for compensating the ingress and egress of the oil liquid that has entered and exited the cylinder 14 with the stroke.

In the passage member 21, there is provided a partition member 23 for partitioning the inside of the bypass passage into the cylinder chamber 14a side and the cylinder chamber 14b side, and the partition member 23 has an oil connecting the cylinder chamber sides to each other. Liquid passages 24 and 25 are provided.
At the end of the partition member 23 on the cylinder chamber 14a side, there is provided a damping force generating mechanism 26 composed of a disk valve for controlling the flow of the oil in the oil liquid passage 25 to generate a damping force.
The orifice 27a and the disc valve 27b, which generate damping force by controlling the flow of the oil in the oil
Is provided. The damping force generating mechanisms 26 and 27 provided on the partition member 23 have orifice characteristics and valve characteristics that generate a smaller damping force than the damping force generating mechanisms 18 and 19 provided on the piston 15. is there.

A cylindrical guide 28 is provided in the passage member 21, and a plug 29 is fitted into an end of the guide 28 on the partition member 23 side. The plug 29 is screwed and fixed to the partition member 23 and a tubular passage member 30 that passes through the plug 29. An annular oil liquid passage 31 communicating with the cylinder chamber 14a and an annular oil liquid passage 32 communicating with the cylinder chamber 14b are provided between the passage member 21 and the guide 28.

On the side wall of the guide 28, ports 33 and 34 communicating with the oil passage 31 and a port 35 communicating with the oil passage 32 are provided. The port 34 is provided with the cylinder chamber 14b from the inside of the guide 28 to the oil liquid passage 31 side, that is, from the cylinder chamber 14b side.
A first check valve 36 that allows only the flow of the oil liquid to the 14a side is provided. Further, the port 33 constitutes a first oil liquid passage that bypasses the first check valve 36. The opening of the guide 28 on the side of the cylinder chamber 14b is a second check valve that allows only the flow of oil from the inside of the guide 28 to the cylinder chamber 14b, that is, from the cylinder chamber 14a to the cylinder chamber 14b. It communicates with the cylinder chamber 14b via 37. The port 35 connects the second oil passage that bypasses the second check valve 37 and the chamber 28b of the guide 28 described later with the cylinder chamber.
A second communication passage communicating with the 14b side is formed.

In the guide 28, a bottomed cylindrical shutter 38 is slidably fitted with the bottom thereof facing the plug 29 side, and the guide 28 and the shutter 38 constitute a shutter mechanism. The inside of the guide 28 is defined by the bottom of the shutter 38 as two chambers, a chamber 28a and a chamber 28b. And room 28a
A cylinder chamber 14 is provided via a passage member 30 as a first communication passage.
The chamber 28b is in communication with the cylinder chamber 14b through a second check valve 37.

Grooves 39 and 40 are provided along the circumferential direction on the outer periphery of the intermediate portion in the axial direction of the shutter 38, and the side wall of the shutter 38 has a passage for communicating the inside of the groove 39 with the chamber 28b.
A passage 42 is provided for communicating the chamber 41 with the inside of the groove 41 and the chamber 40b. The groove 39 is provided to face the port 33 and the port 34 of the guide 28, and the groove 40 is provided to face the port 35 of the guide 28. When the shutter 38 is at the neutral position shown in FIG.
39 communicates with port 33 and port 34 and groove 40
Communicates with the port 35 (see FIG. 4A), and the shutter 38
As the groove slides toward the check valve 37, the groove 39 and the port 35 are kept in communication with the groove 40 and the port 35 and the groove 39 and the port 34.
When the shutter 38 slides toward the plug 29, the groove 39 and the port 33 are kept in communication with the groove 40 and the port.
The area of the communication passage with 35 is reduced, and the communication path is shut off (see FIG. 4C). 2 and 4, the communication between the groove 39 and the port 34 is interrupted by the sliding of the shutter 38 toward the plug 29 (FIG. 4C).
However, the groove 39 and the port 34 may be always in communication.

The plug 29 fitted to the guide 28 is provided with a valve mechanism 43 for controlling the flow of oil between the passage member 30 and the chamber 28a in the guide 28, and a partition plate 44 having an orifice 44a.

As shown in FIG. 3, the valve mechanism 43 is a valve body.
45, a notch disk 46 and a disk 47, when the oil liquid flows from the passage member 30 to the chamber 28a in the guide 28,
Valve body 45, notch disk 46 and disk 47 by hydraulic pressure
The notch 46a of the notch disk 46 forms an orifice (the passage area is determined by the width of the notch 46a and the thickness of the notch disk 46), and the flow of the oil liquid is controlled by the orifice. When the oil liquid flows from the chamber 28a in the guide 28 to the passage member 30, the valve body 45 is bent by the hydraulic pressure and separated from the notch disk 46, so that the notches 46a,
The oil liquid is allowed to flow through the hole 47a of the disk 47 and the orifice 44a of the partition plate 44. Therefore, when the oil liquid flows from the chamber 28a in the guide 28 to the passage member 30, the flow of the oil liquid is controlled by the orifice 44a of the partition plate 44. The passage area of the orifice formed by the notch 27a is smaller than the orifice 44a of the partition plate 44, and the passage area of the opening itself of the notch 27a is larger than the passage area of the orifice 44a of the partition plate 44.

A spring 48 is provided between the shutter 38 and the partition plate 44.
And a spring 49 is provided between the shutter 38 and the check valve 37.
The shutter 38 is elastically held at the neutral position by the springs 48 and 49.

The operation of the second embodiment configured as described above will now be described.

Normally, since the shutter 38 is elastically held at the neutral position by the springs 48 and 49, FIG.
As shown in the figure, the port 33 of the guide 28 and the groove of the shutter 38
The port 39 of the guide 39 and the groove 40 of the shutter 38 communicate with each other, and the oil passage 31 and the oil passage 32 communicate with each other through the chamber 28b, so that the bypass passage is open. Therefore, a small damping force is generated in both the expansion and contraction strokes of the piston rod 20.

During the extension stroke of the piston rod 20, the oil liquid in the cylinder chamber 14a is pressurized, and the oil liquid passage 22, the passage member 3
0, guide 2 through valve mechanism 43 and orifice 44a
8 and moves the shutter 38 to the check valve 37 side.

In this case, if the frequency of the stroke of the piston 15 is large, the flow resistance of the orifice due to the notch 33a of the valve mechanism 43 increases, so that the oil flowing into the chamber 28a in the guide 28 through the passage member 30 is increased. Since the amount of liquid is small and the amount of downward movement of the shutter 38 is small, the port 33 communicates with the groove 39 and the port 35 communicates with the groove 40.The bypass passage is open, so the oil in the cylinder chamber 14a passes through the bypass passage. It flows and flows into the cylinder chamber 14b. Therefore, a small damping force is generated by the orifice characteristics and valve characteristics of the damping force generation mechanism 27 of the partition member 23.

When the frequency of the stroke of the piston 15 is small, the flow resistance of the orifice due to the notch 46a of the valve mechanism 43 is reduced, so that the oil liquid flowing into the chamber 28a in the guide 28 through the passage member 30 is reduced. And the amount of downward movement of the shutter 38 increases, so that the area of the communication passage between the groove 39 and the port 33 decreases. On the other hand, the groove 39 and the port 34 and the groove 40 and the port 35 remain in communication. Therefore, the oil liquid on the cylinder chamber 14a side flows to the cylinder chamber 14b through the bypass passage, and the damping force generated according to the area of the communication passage between the groove 39 and the port 33 increases.

Then, the frequency of the stroke of the piston 15 further decreases, and the amount of downward movement of the shutter 38 increases, so that the communication between the groove 39 and the port 33 is established as shown in FIG. When shut off and the bypass passage is shut off,
The oil liquid in the cylinder chamber 14a flows into the cylinder chamber 14b only through the oil liquid passage 3 of the piston 15, and a large damping force is generated by the orifice characteristics and valve characteristics of the damping force generating mechanism 19 of the piston 15.

Here, when the stroke of the piston rod 20 is switched from the extension side to the contraction side, the port 34 communicates with the groove 39 and the port 35 communicates with the groove 40.
The oil fluid on the b side is supplied to the oil fluid passage 32 of the bypass passage, port 35,
The fluid flows through the groove 40, the passage 42, the chamber 28b, the passage 41, the groove 39, and the port 34, opens the first check valve 36, and flows through the oil liquid passage 31 toward the cylinder chamber 14a. Therefore, a small damping force is generated by the orifice characteristics and the valve characteristics of the damping force generation mechanisms 26 and 27 of the partition member 23.

During the contraction stroke of the piston rod 20, the oil liquid in the cylinder chamber 14b is pressurized, and the oil liquid passage 32, the port 35,
It flows into the guide 28 through the groove 40 and the passage 42 and moves the shutter 38 toward the plug 29. At this time, the movement amount and speed of the shutter 38 are controlled by the flow resistance when the oil liquid in the chamber 28a in the guide 28 flows through the orifice 44a of the partition plate 44 as the shutter 38 moves.

In this case, when the frequency of the stroke of the piston rod 20 is large, the flow resistance of the orifice 44a is increased, so that the amount of oil flowing from the chamber 28a in the guide 28 into the passage member 30 is reduced. The amount of the oil liquid flowing from the cylinder chamber 14b through the oil liquid passage 32 into the chamber 28b in the guide 28 is reduced. Therefore, since the amount of movement of the shutter 38 toward the plug 29 is small, the port 33, the groove 39, and the port 35
And the groove 40 are in communication with each other, and since the bypass passage is open, the oil liquid in the cylinder chamber 14b flows through the bypass passage and flows into the cylinder chamber 14a. Therefore, a small damping force is generated by the damping force generating mechanism 26 of the partition member 23 and the orifice characteristics and valve characteristics of the orifice 27a.

If the frequency of the stroke of the piston rod 20 is small, the flow resistance of the orifice 44a becomes small, so that the amount of oil flowing from the chamber 28a in the guide 28 into the passage member 30 increases, and the cylinder Oil passage from chamber 14b
The amount of the oil liquid flowing into the chamber 28b in the guide 28 through 32 increases. Therefore, the amount of movement of the shutter 38 toward the plug 29 increases, and the area of the communication passage between the groove 40 and the port 35 decreases. On the other hand, the groove 39 and the port 33 remain in communication. Therefore, the oil liquid on the cylinder chamber 14b side flows to the cylinder chamber 14a side through the bypass passage, and the damping force generated according to the area of the communication passage between the groove 40 and the port 35 increases.

Then, the frequency of the stroke of the piston 15 further decreases, and as shown in FIG. 4C, when the communication between the port 35 and the groove 40 is cut off and the bypass passage is cut off, the cylinder chamber 14b Of the piston 15
It flows into the cylinder chamber 14a only through 16 and 17. Therefore, the damping force generating mechanism 18 of the piston 15 and the orifice
A large damping force is generated by the orifice characteristics and valve characteristics of 19a.

Here, when the stroke of the piston rod 20 is switched from the contracted side to the extended side, the port 33 and the groove 39 communicate with each other, so that the oil liquid in the cylinder chamber 14a passes through the oil liquid passage in the bypass passage. 31, the port 33, the groove 39, the passage 41 and the chamber 28b, and the second check valve 37 is opened to open the cylinder chamber 14
Flow to b side. Therefore, the damping force generating mechanism 27 of the partition member 23
A small damping force is generated due to the orifice characteristics and valve characteristics of.

As described above, in both the extension stroke and the contraction stroke of the piston rod 20, when the frequency of the stroke is large, the soft characteristic is changed to a small damping force, and when the frequency is small, the soft characteristic is changed. Switch to the hard characteristic that generates a large damping force. At the same time, the direction of the stroke of the piston rod is switched from the extension side to the contraction side or from the contraction side to the extension side, and at the same time, the damping force characteristic is switched to the soft characteristic side regardless of the position of the shutter 38. Therefore,
When the frequency of the stroke is small, the damping force characteristic is switched to the soft side once when the direction of the stroke is switched, that is, when the piston speed is zero, as shown in FIG. I will return. Therefore, when the frequency of the stroke is small,
Since the damping force characteristic does not switch from the hard side to the soft side during the extension or contraction stroke, it is possible to prevent the occurrence of an impact due to this switching and improve the riding comfort of the vehicle. FIG. 13 shows damping force characteristics when the piston rod of the hydraulic shock absorber of the present embodiment is stroked at a frequency at which the speed at the center of the stroke is constant. In the frequency, the case where the frequency is small is shown.

Next, a third embodiment of the present invention will be described with reference to FIGS. The third embodiment is similar to the second embodiment.
Since only the guide port, shutter and second check valve are different from those in the embodiment, the same members as those in the second embodiment are denoted by the same reference numerals, and only the different portions will be described in detail. I do.

As shown in FIG. 5, a port 50 (first oil liquid passage) communicating with the oil liquid passage 31 is provided on the side wall of the guide 28A.
Port 52 communicating with the oil liquid passage 32 (port 52
And a port 53 are provided.

A groove 54 is formed on the outer periphery of the intermediate portion in the axial direction of the shutter 38A along the circumferential direction, and the ports 50, 51 and 52, 53 of the guide 28A are connected to the groove by sliding of the shutter 38A.
The communication is interrupted via 54. Here, the ports 51 and 53 are arranged so as to always communicate with the groove 54 irrespective of the position of the shutter 38A, and the ports 50 and 52 correspond to the shutter 38A shown in FIGS. When the shutter 38A moves downward in the drawing, the port 52 and the groove 54 remain in communication with each other while the port 50 communicates with the groove 54 when in the neutral position shown in FIG.
When the shutter 38A moves upward in the figure, the port 50 and the groove 54 remain in communication with each other, and the port 52 and the groove 54 are closed. It is arranged such that the area of the communication passage with the passage 54 is reduced and cut off (see FIG. 6C).

The port 51 is provided with a first check valve 36A which allows only the flow of the oil from the groove 54 to the oil passage 31 side, that is, from the cylinder chamber 14b to the cylinder chamber 14a. The port 53 is provided with a second check valve 55 that allows only the flow of the oil from the groove 54 to the oil passage 32, that is, from the cylinder chamber 14a to the cylinder chamber 14b. .

The partition plate 44 attached to the plug 29 is provided with an oil liquid passage 44b (having a small fluid resistance) in place of the orifice 44a of the second embodiment, and the chamber is provided from the cylinder chamber 14a side.
It acts as an orifice only for the flow of the oil liquid to 28Aa, and does not act as a resistance to the flow of the oil liquid in the opposite direction. The room 28Ab in the guide 28A
Is a second communication passage and a valve mechanism as an orifice.
It communicates with the cylinder chamber 14b via 56. The valve mechanism 56 has the same structure as the above-described valve mechanism 43, and acts as an orifice only for the flow of the oil liquid from the cylinder chamber 14b side to the chamber 28Ab side. No resistance is applied.

The operation of the third embodiment configured as described above will now be described.

As in the second embodiment, normally, the shutter 38A
Is elastically held at a neutral position by springs 48 and 49, and as shown in FIG.
Since the port 50 and the port 52 communicate with each other via the groove 54 of the shutter 38A, the bypass passage is open.

During the extension stroke of the piston rod 20, the oil liquid in the cylinder chamber 14a is pressurized, and the oil liquid passage 22, the passage member 3
0, flows into the chamber 28Aa in the guide 28A through the valve mechanism 56 and the passage 31b, and moves the shutter 38A downward in FIG. 5 according to the frequency of the stroke by the orifice of the valve mechanism 43. b) port as shown
By changing the passage area between the groove 50 and the groove 54, the second
As in the embodiment, the passage area of the bypass passage is adjusted.
At this time, when the stroke of the piston rod 20 is switched from the extension side to the contraction side, at the same time, the first check valve 36A is opened to bypass the port 50 and the groove 54, so that the bypass passage is opened. Therefore, the damping force characteristic is switched to the soft side.

On the other hand, during the compression stroke of the piston rod 20, the oil liquid in the cylinder chamber 14b is pressurized, flows into the chamber 28Ab in the guide 28A through the valve mechanism 56, and opens the shutter 38A according to the frequency of the stroke. By moving upward in FIG. 5 and changing the passage area between the port 52 and the groove 54 as shown in FIG. 6C, the passage area of the bypass passage is adjusted in the same manner as in the second embodiment. . At this time, when the stroke of the piston rod 20 is switched from the contracted side to the extended side, the second check valve 55 is opened to bypass the port 52 and the groove 54, so that the bypass passage is opened, so that the damping force is provided. The characteristics are switched to the software side.

In this way, as in the second embodiment, both the extension stroke and the contraction stroke of the piston rod 20
When the frequency of the stroke is large, the characteristic is switched to a soft characteristic that generates a small damping force, and when the frequency is small, the characteristic is switched to a hard characteristic that generates a large damping force. At the same time as the direction of the stroke of the piston rod is switched from the extension side to the contraction side or from the contraction side to the extension side,
The damping force characteristic switches to the soft characteristic side regardless of the position of the shutter 38A.

In the third embodiment, the chamber 28 of the guide 28A is
Valve mechanisms are provided on both sides of the Aa side and 28Ab side to control the movement of the shutter 38A by controlling the flow of oil into each chamber.However, a valve mechanism is provided only in one of the chambers. It is also possible to control the movement of the shutter 38A to both sides by controlling the flow of oil in and out of the chamber.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. The fourth embodiment is similar to the second embodiment.
Since only a guide, a shutter and first and second check valves are different from those of the first embodiment, the same members as those of the first embodiment are denoted by the same reference numerals, and only different portions will be described in detail. explain.

As shown in FIG. 8 to FIG.
A pair of oil liquid passages 31a and 31b communicating with the cylinder chamber 14a and a pair of oil liquid passages 32a and 32b communicating with the cylinder chamber 14b are provided between the cylinder and the guide 28B. A port 57 communicating with the oil liquid passage 31a is provided on a side wall of the guide 28B.
a port 57b (the first oil liquid passage) communicating with the oil liquid passage 31b, a port 58a communicating with the oil liquid passage 32a, and the oil liquid passage 32
A port 58b (second oil liquid passage) communicating with the port b is provided.

The guide 28B has a bottomed cylindrical shutter 38B.
Is slidably fitted, and the bottom of the guide 28
The inside of B is defined as two rooms, a room 28Ba and a room 28Bb. An annular groove 59 is formed along the circumferential direction on the outer periphery of the intermediate portion of the shutter 38B.
The shutter 38B slides and the port
The ports 57a and 57b and the ports 58a and 58b communicate with each other via a groove 59 and are cut off. Where port 57a
, 57b and ports 58a, 58b, as shown in FIG. 7, all communicate with the groove 59 when the shutter 38B is in the neutral position (see (a)), and as the shutter 38B moves downward in FIG. While the ports 57a and 58b and the groove 59 remain in communication with each other, the area of the communication passage between the port 57b and the groove 59 is reduced and shut off (see (b)), and as the shutter 38B moves upward in the drawing, the port 57b and the port 58
The communication path area between the port 58b and the groove portion 59 is reduced while the communication between the a and the groove portion 59 is established, so that the port 58b and the groove portion 59 are blocked (see (c)).

The port 57a of the guide 28B is provided with a first check valve 60 which permits only the flow of the oil from the groove 59 to the oil passage 31a. The port 58a has a groove 59. Second that allows only the flow of the oil liquid from the side to the oil liquid passage 32a side
The check valve 61 is provided.

The chamber 28Ba in the guide 28B communicates with the cylinder chamber 14a via the valve mechanism 43 and the orifice 44a, as in the first embodiment. The chamber 28Bb is connected to the oil passage 62 Cylinder chamber via 62 (second communication passage)
Connected to 14b side.

The operation of the fourth embodiment configured as described above will now be described.

As in the second embodiment, normally, the shutter 38B
Is elastically held at a neutral position by springs 48 and 49, and as shown in FIG.
Since the port 57b communicates with the port 58b via the groove 59 of the shutter 38B, the oil passage 31b and the oil passage 32b communicate with each other to open the bypass passage.

During the extension stroke of the piston rod 20, the oil liquid in the cylinder chamber 14a is pressurized and the oil liquid passage 22, the passage member 3
0, guide 2 through valve mechanism 43 and orifice 44a
8B, the shutter 38B is moved downward in FIG. 8 according to the stroke frequency by the valve mechanism 43, and the state shown in FIG. 7A is changed to the state shown in FIG. The passage area of the bypass passage is adjusted by changing the passage area between the groove and the groove 59 as in the second embodiment. At this time, when the stroke of the piston rod 20 is switched from the extension side to the contraction side, the first check valve 60 is opened to bypass the port 57b and the groove 59, so that the bypass passage is opened, so that the damping force is reduced. The characteristics are switched to the software side.

On the other hand, during the contraction stroke of the piston rod 20, the oil liquid in the cylinder chamber 14b is pressurized, flows into the chamber 28Bb in the guide 28B through the oil liquid passage 62, and flows through the orifice 44a on the chamber 28Ba side. By moving the shutter 38B upward in FIG. 8 in accordance with the frequency of the stroke, the state shown in FIG. 7A is changed to the state shown in FIG. 7C, and the passage area between the port 58b and the groove 59 is changed. As in the second embodiment, the passage area of the bypass passage is adjusted. At this time, when the stroke of the piston rod 20 is switched from the contracted side to the extended side, the second check valve 61 is opened and the port 58b and the groove
Since the bypass passage is opened by bypassing 59, the damping force characteristic is switched to the soft side.

In this way, as in the second embodiment, both the extension stroke and the contraction stroke of the piston rod 20
When the frequency of the stroke is large, the characteristic is switched to a soft characteristic that generates a small damping force, and when the frequency is small, the characteristic is switched to a hard characteristic that generates a large damping force. At the same time as the direction of the stroke of the piston rod is switched from the extension side to the contraction side or from the contraction side to the extension side,
The damping force characteristic switches to the soft characteristic side regardless of the position of the shutter 38B.

In this embodiment, the valve mechanism 43 and the orifice 44a are provided on the chamber 28Ba side of the guide 28B. However, they are provided on the chamber 28Bb side to control the flow of the oil in the oil passage 62. The same effect can be obtained by controlling the amount of movement of the shutter 38B. Also,
As in the second embodiment, these may be provided on both sides of the chambers 28Ba and 28b.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 schematically shows a hydraulic shock absorber based on the same principle as the third and fourth embodiments.

As shown in FIG. 11, a piston 64 is slidably fitted in a cylinder 63 in which an oil liquid is sealed, and the piston 64 urges the inside of the cylinder 63 into an upper cylinder chamber 63a and a lower cylinder chamber 63b. Are defined in two rooms. Piston 64
Is provided with a main oil liquid passage 65 for communicating the cylinder upper chamber 63a and the cylinder lower chamber 63b, and the main oil liquid passage 65 is provided with a damping force generation mechanism 65a (large damping force).

The piston rod 66 connected to the piston 64
Is provided with a bypass passage 67 for communicating the cylinder upper chamber 63a and the cylinder lower chamber 63b. Bypass passage 67
Are arranged in series with a damping force generating mechanism 67a (small damping force), a first check valve 68 allowing only the flow from the cylinder lower chamber 63b side to the cylinder upper chamber 63a side, and a check valve 68. A second check valve 69 allowing only the flow from the cylinder upper chamber 63a side to the cylinder lower chamber 63b side; a first oil liquid passage 70 bypassing the first check valve 68; A second oil liquid passage 71 that bypasses the check valve 69 and a shutter mechanism 72 are provided.

The shutter mechanism 72 includes the first and second check valves 6.
A guide 73 communicating with the first and second oil liquid passages 70 and 71 and a guide 73 slidably fitted in the guide 73.
It comprises a shutter 74 defining the inside thereof as two chambers 73a and 73b. When the shutter 74 is at the neutral position shown in FIG. 11, the first and second oil liquid passages 70 and 71 are both opened, and when the shutter 74 moves to one side (the chamber 73a side), the first
The second oil passage 71 is closed and the second oil passage 71 is opened to communicate with the first check valve 68. When the shutter 74 moves to the other side (toward the chamber 73b), the second oil passage 71 is closed. Close the first oil liquid passage 70
Is opened to communicate with the second check valve 69. The shutter mechanism 72 is provided with springs 75 and 76 for elastically holding the shutter 74 at the neutral position. Room 73
b and a first communication passage 77 for communicating the cylinder upper chamber 63a and a communication passage 78 for communicating the chamber 73a with the cylinder lower chamber 63b.
The first communication passage 77 has an orifice 79
Is provided.

The operation of the fifth embodiment configured as described above will now be described.

Normally, the shutter 74 is held at the neutral position by the springs 75 and 76, and the first and second oil liquid passages 70 and 71
As a result, the bypass passage 67 communicates with the bypass passage 67, so that the damping force characteristic becomes a soft characteristic in both the expansion and contraction strokes of the piston rod 66.

During the extension stroke of the piston rod 66, the oil liquid in the cylinder upper chamber 63a is pressurized, flows into the chamber 73b of the guide 73 through the first communication passage 77, and moves the shutter toward the chamber 73a. .

In this case, if the frequency of the stroke of the piston rod 66 is large, the flow resistance of the orifice 79 increases, so that the chamber 73b passes through the first communication passage 77 during the extension stroke.
Since the amount of the oil liquid flowing into the shutter 74 is small and the amount of movement of the shutter 74 is small, the bypass passage 67 is communicated and the damping force characteristic is a soft characteristic.

If the frequency of the stroke of the piston rod 66 is small, the flow resistance of the orifice 79 is small, so that the amount of oil flowing into the chamber 73b through the first communication passage 77 during the extension stroke is reduced. As the amount of movement of the shutter 74 increases and the amount of movement of the shutter 74 increases, the passage area of the first oil liquid passage 70 decreases and the generated damping force increases. When the first oil liquid passage is closed, the bypass passage 67 is closed by the second check valve 69 during the extension stroke, so that the damping force characteristic becomes a hard characteristic.

Here, when the stroke of the piston rod 66 switches from the extension side to the contraction side, at the same time, the bypass passage
67 is communicated by the second oil liquid passage 71 and the first check valve 68, so that the damping force characteristic becomes a soft characteristic.

During the compression stroke of the piston rod 66, the oil liquid in the cylinder lower chamber 63b is pressurized, flows into the chamber 73a of the guide 73 through the second communication passage 78, and moves the shutter 74 toward the chamber 73b. Let it. At this time, since the oil liquid in the chamber 73b flows through the first communication passage 77 to the cylinder upper chamber 63a, the amount of movement of the shutter 74 is determined by the flow resistance of the orifice 79 in the first communication passage 77.

In this case, if the frequency of the stroke of the piston rod 66 is large, the flow resistance of the orifice 79 increases, so that the chamber 73a passes through the second communication passage 78 during the contraction stroke.
Since the amount of the oil liquid flowing into the shutter 74 is small and the amount of movement of the shutter 74 is small, the bypass passage 67 is communicated and the damping force characteristic is a soft characteristic.

When the frequency of the stroke of the piston rod 66 is small, the flow resistance of the orifice 79 is small, so that the amount of oil flowing into the chamber 73a through the second communication passage 78 during the extension stroke is reduced. Since the amount of movement increases and the amount of movement of the shutter 74 increases, the passage area of the second oil passage 71 decreases, and the generated damping force increases. Then, when the first oil liquid passage is closed, the bypass passage 67 is closed by the first check valve 68 during the contraction stroke, so that the damping force characteristic becomes a hard characteristic.

Here, when the stroke of the piston rod 66 is switched from the contracted side to the extended side, at the same time, the bypass passage
67 is communicated by the first oil liquid passage 70 and the second check valve 69, so that the damping force characteristic becomes a soft characteristic.

As described above, in the same manner as the third and fourth embodiments, in both the extension stroke and the contraction stroke of the piston rod, when the frequency of the stroke is large, a soft damping force is generated. When the frequency is low, the characteristic is switched to a hard characteristic that generates a large damping force. Further, at the same time as the direction of the stroke of the piston rod is switched from the extension side to the contraction side or from the contraction side to the extension side, the damping force characteristic is switched to the soft characteristic side regardless of the position of the shutter 74.

In this embodiment, as shown in FIG. 12, the connection between the first and second check valves 68 and 69 and the cylinder upper and lower chambers 63a and 63b and the connection between the first and second communication passages 77 and 78 are established. Cylinder upper and lower chamber 63a
, 63b, the same effect can be obtained. In FIG. 12, the elements corresponding to the elements in FIG. 11 are denoted by the same reference numerals.

In the present embodiment, the orifice 79 is
Is provided in the second communication passage 78, or may be provided in both the first and second communication passages 77 and 78.

[0090]

As described in detail above, the hydraulic shock absorber of the present invention switches to a soft characteristic that generates a small damping force when the frequency of the stroke is large in both the extension stroke and the contraction stroke. On the other hand, when the frequency is small, the characteristic is switched to a hard characteristic that generates a large damping force. Further, at the same time when the direction of the stroke is switched from the extension side to the contraction side or from the contraction side to the extension side, the damping force characteristic is switched to the soft characteristic side regardless of the position of the shutter. in this way,
In both the extension stroke and the contraction stroke, the damping force characteristics are switched according to the frequency of the stroke, so that the riding comfort and the steering stability of the vehicle can be improved. Further, when the frequency of the stroke is small, the damping force characteristic switches once to the soft side when the direction of the stroke is switched, that is, when the piston speed is zero, and then returns to the hard side again. Since the damping force characteristic does not switch from the hard side to the soft side during the elongation or contraction stroke, no shock is generated due to the switching of the damping force characteristic, and the ride comfort can be improved. It has excellent effects.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a main part of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a second embodiment of the present invention.

FIG. 3 is an exploded perspective view of a valve mechanism 43 of the apparatus of FIG.

FIG. 4 is a diagram showing a positional relationship between a guide port and a shutter groove of the apparatus shown in FIG. 1;

FIG. 5 is a longitudinal sectional view of a main part of a third embodiment of the present invention.

6 is a diagram showing a positional relationship between a guide port and a shutter groove of the apparatus of FIG. 5;

FIG. 7 is a diagram showing a positional relationship between a port of a guide and a groove of a shutter according to a fourth embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a main part of a fourth embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of the side surface of FIG. 8;

FIG. 10 is a cross-sectional view taken along line AA of FIG. 8;

FIG. 11 is a longitudinal sectional view schematically showing a main part of a fifth embodiment of the present invention.

FIG. 12 is a longitudinal sectional view schematically showing another configuration of the fifth embodiment of the present invention.

FIG. 13 is a diagram showing a damping force characteristic of the hydraulic shock absorber according to the present invention.

FIG. 14 is a diagram showing damping force characteristics of a conventional frequency-sensitive hydraulic shock absorber.

[Explanation of symbols]

 1,14,63 Cylinder 1a, 1b, 14a, 14b, 63a, 63b Cylinder chamber 2,15,64 Piston 3,16,17,65 Main oil passage 5,67 Bypass passage 6 Check valve 7 Oil passage 8 , 72 Shutter mechanism 11 Spring 12 Communication passage 13 Orifice 21 Passage member (bypass passage) 22 Oil liquid passage (bypass passage) 28, 28A, 28B Guide member (shutter mechanism) 30 Passage member (first communication passage) 33, 50 , 57b port (first oil liquid passage) 35 port (second oil liquid passage, second communication passage) 36,36A, 60,68 first check valve 37,55,61,69 second Check valve 38 Shutter (shutter mechanism) 43 Valve mechanism (orifice) 44a Orifice 48,49 Spring 39,45b Port (second oil fluid passage) 56 Valve mechanism (second communication passage, orifice) 62 Oil fluid passage ( (Second communication passage) 70 First oil passage 71 Second oil passage 77 First communication passage 78 Second communication passage 79 Orifice 75, 76 Spring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16F 9/00-9/58 B60G 17/08

Claims (2)

(57) [Claims] The two cylinder chambers are communicated with each other through a main oil passage and a bypass passage, and the flow of an oil liquid generated in the main oil passage and the bypass passage by sliding of a piston in the cylinder is controlled to reduce the damping force. A hydraulic shock absorber that adjusts a damping force characteristic by adjusting a passage area of the bypass passage. The hydraulic shock absorber is provided in the bypass passage and moves from one chamber of the two cylinder chambers to the other chamber. Check valve that allows only the flow of the oil liquid, an oil liquid passage that bypasses the check valve, a guide, and a shutter that is slidably inserted into the guide and defines the inside of the guide as two chambers. A shutter mechanism that opens the oil liquid passage when the shutter moves to one side and closes the oil liquid passage when moved to the other side, a spring that biases the shutter to one side, and the guide. The said A hydraulic shock absorber comprising: a communication passage for communicating a chamber on one side with the cutter and the other chamber of the cylinder chamber; and an orifice provided in the communication passage. 2. The two cylinder chambers are communicated with each other through a main oil passage and a bypass passage, and damping force is controlled by controlling the flow of oil in the main oil passage and the bypass passage due to sliding of a piston in the cylinder. A hydraulic shock absorber that adjusts a damping force characteristic by adjusting a passage area of the bypass passage. The hydraulic shock absorber is provided in the bypass passage and moves from one chamber of the two cylinder chambers to the other chamber. A first check valve permitting only the flow of the oil liquid, and a first check valve which is provided in series with the first check valve and controls only the flow of the oil liquid from the other chamber of the two cylinder chambers to one chamber. An allowable second check valve, a first oil liquid passage bypassing the first check valve, a second oil liquid passage bypassing the second check valve, a guide and the guide Is slidably fitted inside the guide and defines the inside of the guide as two chambers A shutter, wherein when the shutter is in the neutral position, the first and second oil liquid passages are both opened, and when the shutter is moved to one side, the first oil liquid passage is closed;
A shutter mechanism for closing the second oil liquid passage when moved to the other side, a spring for elastically holding the shutter at the neutral position, a chamber on the other side with respect to the shutter in the guide, A first communication passage for communicating the other of the two cylinder chambers, and a second communication passage for communicating the one side chamber and one of the two cylinder chambers to the shutter in the guide. And an orifice provided in at least one of the first and second communication passages.