JPH06264954A - Hydraulic buffer of damping force adjusting type - Google Patents

Abstract

PURPOSE:To absorb impact by increasing damping force automatically for input of large impact in a hydraulic buffer. CONSTITUTION:A piston 3 connected to a piston rod 4 is fitted in a cylinder 2 in which oil is sealed. Main oil passages 6, 7 (large attenuation force) on the expansion/shrinkage side are provided in the piston 3, and a bypass passage B (small damping farce) is provided in the piston rod 4. The area of passage of the bypass passage B is adjusted by a rotary shutter 18 to change over damping force. Guide members 28, 29 are fixed on the piston rod 4, and a shutter 34 is provided in such a way that it can slide and held elastically by springs 30, 31. An orifice 38 is provided in the bypass passage B, and both sides of the orifice 38 are communicated with chambers 28b, 29b on both sides of the shutter 34 via auxiliary passages 36, 37, respectively. When large impact is input in the piston rod 4, flow rate in the bypass passage B increases, a difference in pressure between the upper and lower streams of the orifice 38 occurs, and the shutter moves to restrict the bypass passage B. Consequently, damping force increases.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile, a damping force can be appropriately adjusted in order to improve ride comfort and steering stability in accordance with road surface conditions, running conditions and the like. There is a damping force adjustable hydraulic shock absorber.

Conventionally, as a hydraulic shock absorber of this type, for example, as disclosed in Japanese Utility Model Laid-Open No. 58-70533, a piston, to which a piston rod is connected, is slid in a cylinder filled with oil liquid. A damping force generation mechanism (orifice, disc, etc.) that fits as much as possible and connects the two chambers in the cylinder defined by this piston with the main oil liquid passage and the bypass passage to generate a large damping force in the main oil liquid passage. There is a bypass passage provided with a damping force generating mechanism having a small damping force and a damping force adjusting valve for opening and closing the bypass passage.

With this configuration, when the damping force adjusting valve is opened, the oil in the cylinder flows mainly through the bypass passage due to the sliding of the piston accompanying the expansion and contraction of the piston rod, and a small damping force is applied to both the expansion side and the contraction side. Occurs, and the damping force characteristic becomes a soft characteristic. Also, when the damping force adjusting valve is closed, the piston slides as the piston rod expands and contracts, causing the oil in the cylinder to flow only through the main oil passage and generate a large damping force on both the expansion and contraction sides. The force characteristic becomes a hard characteristic. In this way, the damping force characteristic can be switched by opening and closing the damping force adjusting valve.

By selecting the damping force characteristic on the soft side during normal traveling, it is possible to absorb the vibration due to the unevenness of the road surface and improve the riding comfort, and at the time of turning, accelerating, braking and high speed. By selecting the damping force characteristics on the hard side during traveling, it is possible to suppress changes in the posture of the vehicle body and improve steering stability. Furthermore, by combining a damping force adjusting hydraulic shock absorber with a control device and an actuator, the damping force characteristics are automatically switched according to the road surface condition, running condition, etc., to improve the riding comfort and steering stability. There is a suspension controller.

[0006]

However, in the above-mentioned conventional damping force adjusting type hydraulic shock absorber, when the damping force characteristic on the soft side is selected, a sufficient damping force is not generated for a large impact input. There is a problem that bottoming is likely to occur and riding comfort deteriorates.

The present invention has been made in view of the above points, and an object thereof is to provide a damping force adjustable hydraulic shock absorber that automatically switches the damping force characteristic to the hard side in response to a large impact input. And

[0008]

In order to solve the above-mentioned problems, the present invention defines a cylinder in which an oil liquid is enclosed and a slidable fit in the cylinder to define two chambers in the cylinder. And a piston rod having one end connected to the piston and the other end extended to the outside of the cylinder,
A main oil liquid passage and a bypass passage for communicating the two chambers in the cylinder, and a damping force adjusting valve for adjusting the passage area of the bypass passage are provided, and the damping force is adjusted by adjusting the passage area of the bypass passage. In the possible damping force adjusting hydraulic shock absorber, an orifice is provided in the bypass passage, and a shutter that moves by the pressure difference between the upstream side and the downstream side of the orifice to reduce the passage area of the bypass passage is provided. And

[0009]

With this configuration, when the flow velocity of the oil liquid in the bypass passage is small, the shutter is open because the pressure difference between the upstream side and the downstream side of the orifice is small, so the damping force adjusting valve The damping force characteristic is set by
When the flow velocity of the oil liquid in the bypass passage is high, the pressure difference between the upstream side and the downstream side of the orifice is large, so the shutter moves and the passage area of the bypass passage is narrowed. Switch.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, in a damping force adjusting hydraulic shock absorber 1, a piston 3 is slidably fitted in a cylinder 2 in which an oil liquid is sealed. Is divided into two chambers, a cylinder upper chamber 2a and a cylinder lower chamber 2b. One end side of a piston rod 4 penetrates the piston 3, and the piston rod 4 is fixed to the piston 3 by screwing a cylindrical passage member 5 at its tip. The other end of the piston rod 4 extends to the outside of the cylinder 2 through a rod guide (not shown) and a seal member (not shown) provided at the end of the cylinder 2. Further, the cylinder 2 is provided with a reservoir chamber (not shown) for compensating the volume change in the cylinder 2 due to the intrusion and retreat of the piston rod 4 by compressing and expanding the gas.

The piston 3 is provided with an extension-side main oil liquid passage 6 and a compression-side main oil liquid passage 7 which connect the cylinder upper chamber 2a and the cylinder lower chamber 2b. And piston 3
A damping force generation mechanism 8 including an orifice and a disc valve that controls the flow of the oil liquid in the extension side main oil liquid passage 6 to generate a damping force is provided on the end surface of the cylinder lower chamber 2b side of the piston. A damping force generating mechanism 9 including a disk valve that controls the flow of the oil liquid in the compression side main oil liquid passage 7 to generate a damping force is provided on the end surface of the cylinder 3 on the cylinder upper chamber 2a side.

The piston rod 4 is provided with an oil liquid passage 10 having one end communicating with the cylinder upper chamber 2a and the other end communicating with the passage member 5 on the cylinder lower chamber 2b side.
The bypass passage B for connecting the cylinder upper chamber 2a and the cylinder lower chamber 2b is constituted by 10 and the passage member 5.

A substantially cylindrical guide member is provided in the passage member 5.
11 is fitted. Then, one end of the guide member 11 is provided with a check valve 12 that allows the flow of the oil liquid from the inside of the guide member 11 to the cylinder upper chamber 2a side and blocks the flow in the opposite direction, and the other end thereof. A check valve 13 is provided in the guide member 11 to allow the oil liquid to flow from the guide member 11 to the cylinder lower chamber 2b side and prevent the oil liquid from flowing in the opposite direction.

In the bypass passage B, between the passage member 5 and the guide member 11, an oil liquid passage 14 communicating with the cylinder upper chamber 2a side and an oil liquid passage 15 communicating with the cylinder lower chamber 2b side.
And a pair of holes 17 communicating with the oil liquid passage 14 and a pair of holes 17 communicating with the oil liquid passage 15 are provided on the side wall of the guide member 11. Then, the oil passage 14 and the hole
16 bypasses the check valve 12, and the oil passage 15 and the hole 17 bypass the check valve 13.

A cylindrical rotary shutter 18 is rotatably fitted in the guide member 11 as a damping force adjusting valve.
The side wall of the rotary shutter 18 is provided with a pair of openings 19 facing the hole 16 of the guide member 11 and a pair of openings 20 facing the hole 17. Opening 19, 20
Are extended in the circumferential direction of the rotary shutter 18, and the opening 19 is formed in a substantially wedge shape whose diameter increases toward one side, and the opening 20 is formed on the opposite side. It is formed in a substantially wedge shape whose diameter gradually increases. Then, by rotating the rotary shutter 18, the communication passage area formed by the alignment of the hole 16 and the opening 19 is changed to adjust the passage area of the oil liquid passage that bypasses the check valve 12, and The area of the communication passage formed by the alignment of the hole 17 and the opening 20 is changed to adjust the passage area of the oil liquid passage that bypasses the check valve 13.

In this case, when the communication path between the hole 16 and the opening 19 is fully opened, the communication path between the hole 17 and the opening 20 is fully closed, and as the rotary shutter 18 is rotated to one side from this state, the hole is opened.
At the same time as the communication area between 16 and the opening 19 becomes smaller,
The communication passage area between the hole 17 and the opening 20 is increased, and when the communication passage between the hole 16 and the opening 19 is fully closed, the communication passage between the hole 17 and the opening 20 is fully opened. FIG. 2 shows the passage area (damping force coefficient) formed by the hole 16 and the opening 19 and the passage area (damping coefficient) formed by the hole 17 and the opening 20 with respect to the rotation angle of the rotary shutter 18.

An operating rod 21 is connected to the rotary shutter 18, and the operating rod 21 penetrates the check valve 12 and extends along the piston rod 4 to the outside thereof. The rotary shutter 18 can be rotated from the outside of 1. The rotary shutter 18 is constructed by joining three members 18a, 18b, 18c with an operating rod 21. In the figure, reference numeral 22 denotes a bearing that rotatably supports the rotary shutter 18 with a small torque, and an oil liquid passage is formed in its inner peripheral portion.

A valve body 23 is fitted into the opening of the passage member 5 on the cylinder lower chamber 2b side. The valve body 23 is provided with an oil liquid passage 24 and an oil liquid passage 25 that connect the inside of the passage member 5 and the cylinder lower chamber 2b. Then, at both ends of the valve body 23, a damping force generation mechanism 26 and an oil liquid passage which are composed of an orifice and a disc valve for controlling the flow of the oil liquid in the oil liquid passage 24 to generate a damping force.
A check valve 27 that allows the flow of the oil liquid from the cylinder lower chamber 2b side of 25 to the inside of the passage member 5 is provided.

Next, the configurations of the orifice and the shutter, which are the main parts of the present invention, will be described.

The piston rod 4 has a cylindrical guide member 28 having a flange 28a formed at one end thereof at a portion sandwiching the opening 10a on the cylinder upper chamber 2a side of the oil passage 10, and a flange 29a at one end thereof. A cylindrical guide member 29 in which is formed is externally fitted, and an annular space is formed between the guide members 28 and 29 and the piston rod 4. Guide member
28 is a flange 28 due to the elastic force of springs 30 and 31 described later.
a is in contact with and fixed to the step portion 32 of the piston rod 4, and the guide member 29 is in contact with the spacer 33 fixed to the piston rod 4 together with the piston 3 by the elastic force of the springs 30 and 31. It is fixed.

A cylindrical shutter 34 having flanges 34a and 34b at both ends is fitted between the guide members 28 and 29 and the piston rod 4 so as to be slidable along the axial direction of the piston rod 4. There is. The flange 34a on one end side of the shutter 34 is fitted into the guide member 28 to form a chamber 28b between the piston rod 4 and the guide member 28, and the flange 34b on the other end side is inside the guide member 29. To form a chamber 29b between the piston rod 4 and the guide member 29. In addition, the piston rod 4 is provided on the side wall of the shutter 34.
A port 35 facing the opening 10a is provided. A spring 30 is interposed between the flange 34a of the shutter 34 and the flange 28a of the guide member 28, and the spring 31 is interposed between the flange 34b of the shutter 34 and the flange 29a of the guide member 29.
The shutter 34 is elastically held at a position where the port 35 is aligned with the opening 10a of the piston rod 4 by the elastic force of the springs 30 and 31.

On the side wall of the piston rod 4, there is an oil liquid passage 10
Is provided with an auxiliary passage 36 that connects the chamber 28b with the chamber 28b, and an auxiliary passage 37 that connects the oil liquid passage 10 with the chamber 29. The guide member 28 includes a stepped portion 28 that regulates the movement range of the shutter 34 so that the auxiliary passage 36 is not blocked by the movement of the shutter 34.
c is provided. Similarly, the guide member 29 is provided with a step portion 29c for restricting the movement range of the shutter 34 so that the auxiliary passage 37 is not blocked by the movement of the shutter 34. Further, in the oil liquid passage 10, an orifice 38 is provided between the opening portion of the auxiliary passage 36 and the opening portion of the auxiliary passage 37, and one side of the orifice 38 of the oil liquid passage 10 has the auxiliary passage 36 therebetween. Is communicated with the chamber 28b, and the other side of the orifice 38 is communicated with the chamber 29b through the auxiliary passage 37. The passage area of the orifice 38 is set larger than the passage area formed by the openings 19 and 20 of the rotary shutter 18 and the holes 16 and 17 of the guide member 11 which constitute the damping force adjusting valve.

The pressure difference generated between the upstream side and the downstream side of the orifice 38 due to the flow velocity of the oil liquid flowing through the oil liquid passage 10 is transmitted to the chambers 28b and 29b through the auxiliary passages 36 and 37,
The pressure difference between the chambers 28b and 29b acts to move the shutter 34 to the spring 3
It is designed to move against the 0, 31 elastic force.
FIG. 3 shows an outline of a hydraulic circuit model of the damping force adjusting hydraulic shock absorber 1 configured as described above.

The operation of this embodiment having the above-described structure will be described below.

The damping force characteristic can be switched by operating the operating rod 21 from the outside to rotate the rotary shutter 18.

By rotating the rotary shutter 18, the hole 16 and the opening
When the communication passage with 19 is fully opened and the communication passage with the hole 17 and the opening 20 is fully closed, during the extension stroke of the piston rod 4, the oil liquid on the cylinder upper chamber 2a side in the bypass passage B is The check valve 12 is closed to flow through the oil liquid passage 14, the hole 16 and the opening portion 19, and the check valve 13 is opened to open the oil liquid passage of the valve body 23.
It flows through 24 to the cylinder lower chamber 2b side. Therefore, a small damping force is generated by the passage area between the hole 16 and the opening 19 and the damping force generating mechanism 26. On the other hand, during the compression stroke of the piston rod 4, the check valve 13 is closed and the communication passage between the hole 17 and the opening 20 is closed, so the bypass passage B is closed. Therefore, the oil liquid flows only through the contraction side main oil liquid passage 7 of the piston 3, and a large damping force is generated by the damping force generation mechanism 9. Therefore, the damping force characteristic is a soft characteristic on the extension side and a hard characteristic on the contraction side.

The rotary shutter 18 is rotated to one side from the above position to reduce the area of the communication passage between the hole 16 and the opening 19,
When the communication passage between 17 and the opening 20 is opened, the oil liquid on the cylinder upper chamber 2a side flows to the cylinder lower chamber 2b side in the bypass passage B during the extension stroke of the piston rod in the same manner as above. The damping force increases as the area of the communication passage between the hole 16 and the opening 19 decreases. On the other hand, during the compression stroke of the piston rod 4, in the bypass passage B, the oil liquid on the cylinder lower chamber 2b side opens the check valve 27 of the valve body 23 and closes the check valve 13 of the guide member 11 to close the oil. The liquid flows through the liquid passage 15, the hole 17 and the opening 20, and further the check valve 12 is opened to flow to the cylinder upper chamber 2a side. Therefore, the portion opened by the hole 17 and the opening 20 becomes an orifice, and a small damping force (orifice characteristic) corresponding to the communication passage area is generated. Therefore, the damping force characteristics are medium characteristics on both the extension side and the contraction side.

The rotary shutter 18 is rotated further to the one side from the above position to completely close the communication path between the hole 16 and the opening 19,
When the communication path between the piston 20 and the opening 20 is fully opened, the check valve 12 is closed during the extension stroke of the piston rod 4, and the hole 16 and the opening 19 are closed.
The bypass passage B is closed because the communication passage to and is closed. Therefore, the oil liquid flows only through the extension-side main oil liquid passage 6 of the piston 3, and a large damping force is generated by the damping force generation mechanism 8. On the other hand, during the compression stroke of the piston rod 4, in the same way as above, the oil liquid on the lower cylinder chamber 2b side flows to the upper cylinder chamber 2a side in the bypass passage B, and the communication passage between the hole 17 and the opening 20 is formed. The damping force (orifice characteristic) decreases as the area increases. Therefore, the damping force characteristics are hard characteristics on the extension side and soft characteristics on the contraction side.

As described above, different damping force characteristics can be set on the extension side and the contraction side, and further, the rotary shutter can be set.
Since the communication passage areas of the hole 16 and the opening 19, and the hole 17 and the opening 20 can be continuously changed according to the rotation angle of 18, the passage areas of the extension side and the contraction side bypass passage B can be changed. The damping force characteristic can be adjusted continuously. By closing the hole 16 and the hole 17 by the rotary shutter 18 and closing the bypass passage B, the expansion and contraction can be made to have a hard characteristic on both sides.

Next, the operation of the orifice and the shutter, which are the main parts of the present invention, will be described.

Due to the flow velocity of the oil liquid flowing through the oil liquid passage 10, a pressure difference is generated between the upstream side and the downstream side of the orifice 38, and the downstream side has a negative pressure with respect to the upstream side. Therefore, the auxiliary passage 36
Alternatively, since the pressure of the chamber 28b or the chamber 29b communicating with the downstream side of the orifice 38 via the auxiliary passage 37 becomes lower than that of the chamber communicating with the upstream side, this pressure difference causes the shutter 34 to have an elastic force of the springs 30, 31. It moves to the low pressure chamber side against.

At this time, when the flow velocity of the oil liquid flowing through the oil liquid passage 10 is small, the pressure difference generated by the orifice 38 is small, so that the movement amount of the shutter 34 is small and the port 35 of the shutter 34 and the opening portion of the oil liquid passage 10 are small. Since the area of the communicating passage formed by 10a is large enough, almost no flow resistance occurs. When the flow velocity of the oil liquid flowing through the oil liquid passage 10 increases, the movement amount of the shutter 34 due to the pressure difference generated by the orifice 38 increases and the communication passage area formed by the port 35 and the opening 10a decreases, so that the oil liquid passage 10 is closed. Flow resistance acts on the flowing oil liquid.

The operation of the shutter 34 during the extension stroke of the piston rod 4 will be described below with reference to FIG. 4 which schematically shows the main part of this embodiment.

When the piston velocity is small and the flow velocity of the oil liquid flowing through the oil liquid passage 10 is small, the pressure loss due to the orifice 38 is small, so that there is almost no pressure difference between the upstream side and the downstream side of the orifice 38. Therefore, the pressures of the chamber 28b and the chamber 29b become substantially equal, so that as shown in FIG. 4A, the shutter 34 allows the port 35a and the opening 10a to communicate with each other with a sufficiently large passage area by the elastic force of the spring 34. Will be held in the neutral position. Therefore, the damping force characteristic set by the damping force control valve is not affected.

When a large impact is input to the piston rod 4 and the piston speed increases and the flow velocity of the oil liquid flowing through the oil liquid passage 10 increases, the pressure loss due to the orifice 38 increases, so that the chamber 28b on the upstream side of the orifice 38 increases. On the other hand, the pressure in the chamber 29b on the downstream side becomes low. Due to this pressure difference, as shown in FIG. 4B, the shutter 34 causes the spring 30,
It moves to the chamber 29b side against the elastic force of 31 and the communication passage area between the port 35a and the opening 10a becomes smaller. Therefore, since the flow resistance acts on the oil liquid flowing through the oil liquid passage 10, that is, the bypass passage B, the damping force generated becomes large. In this way, the bypass passage B is automatically adjusted against a large impact.
The passage area is narrowed, a large damping force is generated, and the shock can be absorbed.

FIG. 5 shows the damping force characteristics on the extension side of the damping force adjusting hydraulic shock absorber 1. In FIG. 5, indicates a hardware characteristic,
Shows the soft characteristic, and the broken line shows the characteristic when the shutter 34 is not provided and the opening 10a is always fully opened.

Similarly, on the contraction side, the shutter 34 moves to the chamber 28b side due to the pressure difference between the upstream side and the downstream side of the orifice 38, so that the passage area of the bypass passage B is reduced by damping the input of a large impact. Increases power and absorbs shock.

As described above, when the piston speed exceeds a predetermined value, the shutter 34 reduces the passage area of the bypass passage B, so that the damping force characteristic can be automatically switched to the hard side with respect to a large impact input. It is possible to absorb impact and prevent bottoming. Further, since bottoming is prevented, the damping force on the soft side can be set to be sufficiently small and the riding comfort can be improved.

Particularly, in the case of the damping force adjustable hydraulic shock absorber having different damping force characteristics on the extension side and the contraction side as in the present embodiment, one of the extension side and the contraction side has a soft characteristic,
When a large impact is input to the soft characteristic side, the damping force can be automatically increased to absorb the impact, and the riding comfort can be effectively improved.

Another embodiment described above will be described with reference to FIG. In FIG. 6, the same members as those in the embodiment shown in FIG. 1 are designated by the same reference numerals, and only different portions will be described. As shown in FIG. 6, a cylindrical shutter 39 is slidably fitted in the oil liquid passage 10 of the piston rod 4,
It is also possible to provide the port 40 on the side wall of the shutter 39 and provide the orifice 41 in the shutter. 4 in FIG.
Reference numerals 1 and 42 are springs that elastically hold the shutter 39 in a neutral position in which the port 40 is aligned with the opening 10a.

With this configuration, the orifice generated by the flow velocity of the oil liquid in the oil liquid passage 10 is the same as in the above embodiment.
When the shutter 39 moves due to the pressure difference between the upstream side and the downstream side of 41, and the flow velocity of the oil liquid flowing through the oil liquid passage 10 is small, the passage area between the port 40 and the opening 10a is sufficiently large and the flow velocity becomes large. The passage area of the port 40 and the opening 10a is reduced. In this way, when the piston speed exceeds a predetermined value, the shutter 39 narrows the passage area of the bypass passage B, so that the damping force characteristic can be automatically switched to the hard side with respect to the input of a large impact, and the impact is absorbed. It is possible to prevent bottoming. Further, since bottoming is prevented, the damping force on the soft side can be set to be sufficiently small and the riding comfort can be improved.

In this embodiment, the damping force adjusting type hydraulic shock absorber having different damping force characteristics on the extension side and the contraction side has been described, but the present invention is not limited to this, and the passage area of the bypass passage is adjusted. It can also be applied to a normal damping force adjustable hydraulic shock absorber having the same damping force characteristics on the extension side and the contraction side.

[0044]

As described above in detail, the damping force adjusting hydraulic shock absorber of the present invention is provided with an orifice in the bypass passage,
Since a shutter that moves by the pressure difference between the upstream side and the downstream side of the orifice to narrow the passage area of the bypass passage is provided, when the flow velocity of the oil liquid in the bypass passage is small, the shutter is located between the upstream side and the downstream side of the orifice. Since the shutter is open because the pressure difference is small, the damping force characteristic is set by the damping force adjusting valve, and when the flow velocity of the oil liquid in the bypass passage is high, the pressure difference between the upstream side and the downstream side of the orifice is Since it is large, the shutter moves to reduce the passage area of the bypass passage, so that the damping force characteristic is automatically switched to the hard side. As a result, the damping force characteristic is automatically switched to the hard characteristic in response to a large impact input, and the impact is absorbed, so that bottoming can be prevented. Furthermore, since bottoming is prevented, the damping force on the soft side can be set to a sufficiently small value, and the excellent riding comfort can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing an attenuation coefficient with respect to a rotation angle of a rotary shutter of the apparatus shown in FIG.

FIG. 3 is a circuit diagram showing an outline of a hydraulic circuit configured by the device of FIG.

FIG. 4 is a diagram schematically showing a main part of the apparatus shown in FIG.

5 is a diagram showing a damping force characteristic on the extension side of the device of FIG.

FIG. 6 is a vertical cross-sectional view showing a main part of another embodiment of the present invention.

[Explanation of symbols]

 1 Damping force adjusting hydraulic shock absorber 2 Cylinder 3 Piston 4 Piston rod 6 Extension side main oil liquid passage (main oil liquid passage) 7 Compression side main oil liquid passage (main oil liquid passage) 18 Rotating shutter (damping force adjustment valve) 34,39 Shutter 38,41 Orifice B Bypass passage

Claims (1)

[Claims] 1. A cylinder in which an oil liquid is sealed, a piston slidably fitted in the cylinder and defining two chambers in the cylinder, one end of which is connected to the piston and the other end of which is the cylinder. A piston rod extended to the outside, a main oil liquid passage and a bypass passage communicating the two chambers in the cylinder, and a damping force adjusting valve adjusting the passage area of the bypass passage are provided, and the passage of the bypass passage is provided. In a damping force adjusting hydraulic shock absorber capable of adjusting damping force by adjusting the area, an orifice is provided in the bypass passage, and the bypass passage is moved by a pressure difference between the upstream side and the downstream side of the orifice. A damping force adjusting hydraulic shock absorber, which is provided with a shutter for narrowing the area.