JPH08277875A - Damping force adjusting type hydraulic shock absorber - Google Patents

Abstract

PURPOSE: To stabilize damping force on the contracting side and reduce restrictions on fitting space in a damping force adjusting type hydraulic shock absorber. CONSTITUTION: A piston 8 with a piston rod 9 connected thereto is fittingly mounted into a cylinder 2. An inner cylinder 3 is provided at the periphery of the cylinder to form an annular passage 6, and the annular passage 6 is communicated with the cylinder 2 through a passage 5. An outer cylinder 4 is provided at the periphery of the inner cylinder 3 to form a reservoir chamber 7. Damping force adjusting mechanism 15 is enclosed below the cylinder 2 in the outer cylinder 4. A cylinder upper chamber 2a is communicated with a cylinder lower chamber 2b through the annular passage 6 and the damping force adjusting mechanism 15. The cylinder lower chamber 2b is communicated with the reservoir chamber 7 through the damping force adjusting mechanism 15. On the contracting side, the check valve 14 of the piston 8 is opened, and damping force is generated by the flow of oil liquid between the cylinder 2 and the reservoir chamber 7, so that the pressure in the cylinder 2 does not become negative so as to stabilize damping force. Since the damping force adjusting mechanism 15 is disposed below the cylinder 2, restrictions on fitting space are reduced.

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.

In the damping force adjusting type hydraulic shock absorber, generally, a piston in which a piston rod is connected is slidably fitted in a cylinder in which an oil liquid is sealed, and is generated by the movement of the piston as the piston rod expands and contracts. The flow of the oil liquid is controlled by an orifice, a disc valve or the like to generate a damping force, and the damping force adjusting mechanism changes the passage area of the oil liquid to adjust the damping force. Then, the damping force adjusting mechanism is usually built in the piston portion in the cylinder, and the damping force is adjusted by operating the operating rod inserted through the piston rod from the outside to move the valve body of the damping force adjusting mechanism. Is supposed to do.

Further, in Japanese Utility Model Laid-Open No. 62-155242, a pressure chamber is formed at the back of a disc valve, which is a damping force generating mechanism of a main oil passage provided in a piston portion, and this pressure chamber is used as a fixed orifice. There is described a damping force adjustable hydraulic shock absorber which is communicated with a cylinder chamber on the upstream side of a disc valve via a variable orifice and is further communicated with a cylinder chamber on the downstream side of a disc valve via a variable orifice.

According to the damping force adjusting type hydraulic shock absorber, by opening and closing the variable orifice, the passage area between the two chambers in the cylinder is adjusted and the pressure in the pressure chamber is changed to open the disc valve. The initial pressure can be changed. In this way, the orifice characteristic and the valve characteristic can be adjusted, and the adjustment range of the damping force characteristic can be widened.

On the other hand, in Japanese Unexamined Patent Publication (Kokai) No. 4-313227, an oil liquid passage is provided outside the cylinder and a damping force adjusting mechanism is arranged on the side surface of the cylinder to reduce the size of the piston portion and the piston rod. Describes a damping force adjustable hydraulic shock absorber in which the operating rod is eliminated and the restriction on the design of the mounting portion shape of the piston rod on the vehicle body side is reduced.

[0007]

However, the conventional damping force adjusting type hydraulic shock absorber described above has the following problems.

As disclosed in Japanese Utility Model Laid-Open No. 62-155242, a damping force adjusting hydraulic shock absorber having a damping force generating mechanism in the piston portion is interposed between the cylinder chamber and the reservoir chamber. When the flow resistance of the piston portion with respect to the base valve becomes large, the outflow of the oil liquid into the reservoir chamber becomes excessive during the compression stroke, and one of the cylinder chambers becomes a negative pressure, so that a stable damping force cannot be obtained. As described above, since the damping force characteristic on the contraction side depends on the flow resistance of the base valve, there arises a problem that the adjustment range of the damping force characteristic on the contraction side becomes narrow.

Further, in the damping force adjusting hydraulic shock absorber in which the damping force adjusting mechanism is provided on the side surface of the cylinder as described in JP-A-4-3127227, the side surface of the cylinder of the damping force adjusting mechanism is used. The amount of protrusion to the part increases,
There is a problem that the restrictions on the mounting space on the vehicle become large.

The present invention has been made in view of the above points, and reduces restrictions on the mounting space, and
An object of the present invention is to provide a damping force adjustable hydraulic shock absorber capable of widening the adjustment range of damping force characteristics.

[0011]

In order to solve the above problems, a damping force adjusting hydraulic shock absorber according to the invention of claim 1 is slidable in a cylinder in which an oil liquid is sealed and in the cylinder. A piston that is fitted into the cylinder to define two cylinder chambers in the cylinder; a piston rod that has one end connected to the piston and the other end that extends to the outside of the cylinder;
A reservoir chamber that is connected to the cylinder and that compensates for a volume change in the cylinder due to expansion and contraction of the piston rod by compressing and expanding gas, and a cylinder chamber that is provided outside the cylinder and that extends from the one cylinder chamber during the extension stroke of the piston rod. An extension-side passage that circulates an oil liquid to the other cylinder chamber to generate a damping force, and a compression-side passage that circulates an oil liquid from the cylinder chamber to the reservoir chamber to generate a damping force during a compression stroke, The extension side passage is extended below the cylinder, and an extension side damping force adjusting mechanism for adjusting the passage area of the extension side passage is arranged below the cylinder.

In the damping force adjustable hydraulic shock absorber according to a second aspect of the present invention, in addition to the structure of the first aspect, the compression side passage is extended below the cylinder to adjust the passage area of the compression side passage. A contraction-side damping force adjusting mechanism is disposed below the cylinder.

In the damping force adjusting hydraulic shock absorber according to a third aspect of the present invention, in addition to the configuration of the first aspect, the extension side damping force adjusting mechanism adjusts the passage area of the extension side passage. And an extension side back pressure chamber that applies an internal pressure to the valve body of the extension side damping valve in the valve closing direction, and the extension side back pressure chamber and the cylinder chamber upstream of the extension side damping valve with flow path resistance. An extension upstream passage that communicates, an extension downstream passage that communicates the extension back pressure chamber and a cylinder chamber downstream of the extension damping valve, and an extension variable that adjusts the passage area of the extension downstream passage. And an orifice.

Further, in the damping force adjusting hydraulic shock absorber according to a fourth aspect of the present invention, in addition to the configuration of the second aspect, the extension side damping force adjusting mechanism has an extension side for adjusting the passage area of the extension side passage. A damping valve, an extension side back pressure chamber that applies an internal pressure to the valve body of the extension side damping valve in a valve closing direction, a passageway between the extension side back pressure chamber and a cylinder chamber upstream of the extension side damping valve. An extension upstream passage communicating with resistance, an extension downstream passage communicating the extension back pressure chamber and a cylinder chamber downstream of the extension damping valve, and an extension adjusting the passage area of the extension downstream passage. Side variable orifice, the compression side damping force adjusting mechanism, the compression side damping valve for adjusting the passage area of the compression side passage,
A compression-side back pressure chamber that applies an internal pressure to the valve body of the compression-side damping valve in a valve closing direction, and a compression upstream passage that connects the compression-side back pressure chamber and the cylinder chamber upstream of the compression-side damping valve. A compression downstream passage for communicating the compression back pressure chamber with a reservoir chamber downstream of the compression damping valve, and a compression variable orifice for adjusting the passage area of the compression downstream passage,
Further, the piston is provided with a check valve that allows the oil liquid to flow only from the other cylinder chamber to the one cylinder chamber during the compression stroke.

[0015]

With this construction, the damping force adjusting hydraulic shock absorber according to the first aspect controls the flow of the oil liquid generated in the expansion side passage or the contraction side passage with the expansion and contraction of the piston rod to control the damping force. Is generated, and the extension side damping force adjusting mechanism adjusts the passage area of the extension side passage to adjust the extension side damping force. Since the extension-side damping adjusting mechanism is arranged below the cylinder, it does not project to the side surface of the cylinder.

According to the damping force adjusting hydraulic shock absorber of the second aspect, in addition to the action of the first aspect, the contraction side damping force adjusting mechanism adjusts the passage area of the contraction side passage to reduce the contraction side damping force. adjust. Since the compression-side damping adjusting mechanism is arranged below the cylinder, it does not project to the side surface of the cylinder.

In the damping force adjusting hydraulic shock absorber according to a third aspect of the present invention, in addition to the function of the first aspect, in the extension side damping force adjusting mechanism, the oil liquid is in the extension side passage, and the extension upstream passage,
A damping force is generated by the extension-side variable orifice and the extension-side damping valve that flow through the extension-side back pressure chamber and the extension-side downstream passage, and at this time, the orifice characteristics change according to the passage area of the extension-side variable orifice. A change in the internal pressure of the extension side back pressure chamber changes the valve opening characteristic of the extension side damping valve and thus the valve characteristic.

According to the damping force adjusting hydraulic shock absorber of the fourth aspect, in addition to the function of the second aspect, in the extension side damping force adjusting mechanism, the oil liquid is in the extension side passage, and the extension upstream passage,
A damping force is generated by the extension-side variable orifice and the extension-side damping valve that flow through the extension-side back pressure chamber and the extension-side downstream passage, and at this time, the orifice characteristics change according to the passage area of the extension-side variable orifice. A change in the internal pressure of the extension side back pressure chamber changes the valve opening characteristic of the extension side damping valve and thus the valve characteristic. Further, in the compression side damping force adjusting mechanism, the oil liquid flows through the compression side passage, the compression upstream passage, the compression back pressure chamber and the compression downstream passage, and the damping force is adjusted by the compression variable orifice and the compression damping valve. Occurs,
At this time, the orifice characteristic changes in accordance with the passage area of the compression-side variable orifice, and the valve opening characteristic of the compression-side damping valve changes due to the change in the internal pressure of the compression-side back pressure chamber, which changes the valve characteristic.

[0019]

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

The first embodiment will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, the damping force adjusting hydraulic shock absorber 1 has a triple cylinder structure in which an inner cylinder 3 is provided on the outer circumference of a cylinder 2 and an outer cylinder 4 is further provided on the outer circumference thereof. An annular passage 6 (extension-side passage) is formed between the binder 2 and the inner cylinder 3 and communicates with an upper portion (a cylinder upper chamber 2a described later) of the cylinder 2 by a passage 5 provided in a side wall of the cylinder 2. And is extended below the cylinder 2. A reservoir chamber 7 is formed between the inner cylinder 3 and the outer cylinder 4. The cylinder 2 is filled with an oil liquid, and the reservoir chamber 7
Oil liquid and gas are enclosed inside.

A piston 8 is slidably fitted in the cylinder 2, and the piston 8 allows the cylinder 2 to move.
The inside is divided into two chambers, a cylinder upper chamber 2a and a cylinder lower chamber 2b. One end of a piston rod 9 inserted into the cylinder 2 is connected to the piston 8 by a nut 10, and the other end side of the piston rod 9 is a rod guide 11 attached to the upper ends of the cylinder 2 and the outer cylinder 4. Also, it is inserted into the oil seal 12 and extended to the outside of the cylinder 2.

The piston 8 allows only an oil liquid passage 13 for communicating between the cylinder upper and lower chambers 2a and 2b and the passage of the oil liquid from the cylinder lower chamber 2b side of the oil liquid passage 13 to the cylinder upper chamber 2a side. A check valve 14 is provided.

Below the cylinder 2 in the outer cylinder 4, a damping force adjusting mechanism 15 is provided concentrically with the cylinder 2. In the damping force adjusting mechanism 15, the tip small diameter portion of the bottom of the substantially bottomed cylindrical case 16 is fitted in the lower end portion of the cylinder 2, and the large diameter portion of the side surface is fitted in the inner cylinder 3, and A lid member 17 attached to the opening is fitted and fixed in a bottomed cylindrical cap member 18 attached to the lower end of the outer cylinder 4. The case 16 defines the cylinder lower chamber 2b, the annular passage 6 and the reservoir chamber 7.

A rotary actuator 19 (described later) is attached to the lid member 17, and the rotary actuator 19 is housed in a cap member 18. Here, as shown in FIG. 2, the axial end surface of the step portion 17a of the lid member 17 is brought into contact with the end surface of the case 16, and the axial end surface of the step portion 18a of the cap member 18 contacts the end surface of the lid member 17. It is in contact with the damping force adjustment mechanism
The axial load acting on 15 is applied from the lid member 17 to the cap member.
18 by directly acting on the rotary actuator
It is designed not to act on 19.

Next, the damping force adjusting mechanism 15 will be described in detail with reference to FIG.

As shown in FIG. 2, the damping force adjusting mechanism 15 includes
Two valve members 20 and 21 are fitted inside the case 16 to divide the inside of the case 16 into three oil chambers 16a, 16b and 16c. Disc valves 22 and 23, which will be described later, and annular fixing members 24 and 25 are concentrically stacked on the valve members 20 and 21, respectively. A guide member 26 having a substantially bottomed cylindrical shape is inserted through these, and a nut 27 is screwed to the tip end of the guide member 26 to be integrally connected, and the bottom side of the guide member 26 is attached to the lid member 17 to form the case 16. It is fixed inside.

An oil liquid passage 28 that connects the oil chamber 16a and the annular passage 6 is provided at the bottom of the case 16. Also,
An oil liquid passage 29 (compression side passage) that communicates the chamber 29a formed between the side wall of the case 16 and the inner cylinder 3 with the cylinder lower chamber 2b.
Is provided and extends below the cylinder 2, and the chamber 29a
Through the passage 30 provided on the side wall of the case 16 to the oil chamber 16b.
Is communicated to. Furthermore, on the side wall of the case 16, the oil chamber
An oil liquid passage 31 is provided which connects 16c with the reservoir chamber 7.

The valve member 20 is provided with an expansion side passage 32 and a disc valve 22 (expansion side damping valve) which communicate the oil chamber 16a with the oil chamber 16b. The disc valve 22 is
The extension side passage 32 is bent by receiving the pressure of the oil liquid on the oil chamber 16a side to open the valve, and allows the oil liquid to flow to the oil chamber 16b side to generate a damping force according to the opening degree. ing. On the back side of the disc valve 22, an annular movable member 33 slidably fitted to the outer peripheral portion of the fixed member 24 is abutted by the bias of a leaf spring 34. The movable member 33 and the extension side back pressure chamber 35 are formed.

The valve member 21 is provided with a compression side passage 36 for communicating the oil chamber 16b with the oil chamber 16c and a disc valve 23 (a compression side damping valve). The disc valve 23 is
The compression side passage 36 bends under the pressure of the oil liquid on the oil chamber 16b side to open the valve, allowing the oil liquid to flow to the oil chamber 16c side and generating a damping force according to the opening degree. ing. On the back side of the disc valve 23, an annular movable member 37 slidably fitted to the outer periphery of the fixed member 25 is abutted by the bias of a leaf spring 38, and the disc valve 23 and the fixed member 25 are attached. A contraction side back pressure chamber 39 is formed by the movable member 37.

Further, the valve member 21 includes oil chambers 16b, 16b.
A communication passage 40 for communicating between c and a check valve 41 that allows only the flow of oil liquid from the oil chamber 16c side of the communication passage 40 to the oil chamber 16b side.
Is provided. As shown in FIG. 3, the check valve 41 includes
The hole 41a is provided on the inner peripheral side so that the circulation of the contraction-side passage 36 can be always ensured.

The extension side back pressure chamber 35 is an upper cylinder chamber which serves as a cylinder chamber on the oil chamber 16a side, that is, on the upstream side, via a fixed orifice 42 (extension upstream side passage) provided in the disc valve 22 to provide flow path resistance. The oil chamber 16 communicates with the 2a side, and through ports 43 and 44 (expansion side variable orifices) provided on the side wall of the guide member 26 as expansion downstream side passages.
Lower cylinder chamber 2b, which is the cylinder chamber on the b side, that is, on the downstream side
Communicated to the side. The contraction side back pressure chamber 54 is provided in the disc valve 23 and is provided with a fixed orifice 45 for providing flow path resistance.
(Compression upstream passage), which communicates with the oil chamber 16b side, that is, the cylinder lower chamber 2b side that is the upstream cylinder chamber, and a port as a compression downstream passage provided on the side wall of the guide member 43. It communicates with the reservoir chamber 7 on the oil chamber 16c side, that is, on the downstream side through 46 and 47 (contraction side variable orifice).

A shutter 48 having a bottomed cylindrical shape is rotatably fitted in the guide member 26. As shown in FIG.
On the side wall of the shutter 48, the communication grooves 49, 50 are formed so as to correspond to the ports 43, 44 and the ports 46, 47 of the guide member 26, respectively.
Is provided. The ports 43 and 44 and the ports 46 and 47 are communicated with each other through the communication grooves 49 and 50, respectively, and the respective communication passage areas can be adjusted by rotating the shutter 48. Here, the communication groove 49 and the communication groove 50 are arranged at different angles with respect to the center of the shutter 48, and the ports 43, which are expansion side variable orifices,
The areas of the communication passages between 44 and the ports 46 and 47 that are contraction-side variable orifices are arranged such that when one is large, the other is small, and when one is small, the other is large.

An operating shaft 51 is coupled to the bottom of the shutter 48, and the operating shaft 51 is inserted through the bottom of the guide member 26 and connected to the operating shaft 52 of the rotary actuator 19 by a joint 53. Then, the shutter 48 can be positioned at a desired rotation position by the rotary actuator 19.

In the damping force adjusting hydraulic shock absorber 1, the piston rod 9 side is connected to the sprung side (vehicle body side) of the suspension device, and the cap member 18 side connected to the outer cylinder 4 is unsprung (wheel side). ) Is attached to the vehicle.

The operation of the first embodiment constructed as above will be described below.

During the extension stroke of the piston rod 9, the check valve 14 is closed by the movement of the piston 5 to pressurize the oil liquid on the cylinder upper chamber 2a side, and the damping force adjusting mechanism 15 is passed through the passage 5 and the annular passage 6. Flow into the oil liquid passage 28 of the oil chamber 16a, the extension side passage
32, the fixed orifice 42, the expansion side back pressure chamber 35, the port 43, the communication groove 49, the port 44, the oil chamber 16b, the passage 30, the chamber 29a, and the oil liquid passage 29 to flow into the cylinder lower chamber 2b. At this time,
When the pressure on the cylinder upper chamber 2a side reaches the valve opening pressure and the disc valve 22 opens, the oil liquid flows directly from the extension side passage 32 to the oil chamber 16b. On the other hand, as the piston rod 9 expands, the oil liquid that the piston rod 9 withdraws from the inside of the cylinder 2 is expanded from the reservoir chamber 4 to the passage 31 and the oil chamber.
16c to flow path 40, open check valve 41 to open oil chamber 2b
And is replenished to the cylinder lower chamber 2b side.

Therefore, before the disc valve 22 is opened, the piston speed is low, and the damping force of the orifice characteristic is generated according to the passage area between the ports 43 and 44, and the piston speed is increased and the cylinder upper chamber 1a side is increased. When the disc valve 22 opens due to an increase in the pressure of, the damping force of the valve characteristic is generated according to the opening degree. And rotary actuator
The shutter 48 is rotated by 19 to change the communication passage area between the ports 43 and 44, whereby the damping force characteristic can be adjusted.

In this case, the smaller the area of the communication passage between the ports 43 and 44, the larger the pressure loss and the higher the pressure in the extension side back pressure chamber 35, and this pressure acts in the valve closing direction of the disc valve 22. Therefore, the valve opening pressure of the disc valve 22 also increases. Therefore, by rotating the shutter 48, the port 43,
By changing the communication passage area between 44, the orifice characteristic and the valve characteristic change at the same time, so the damping force can be greatly changed from the low speed range of the piston speed to the high speed range, and the adjustment range of the damping force characteristic can be widened. can do.

During the compression stroke, the check valve 14 is opened by the movement of the piston 8 so that the oil liquid in the cylinder lower chamber 2b directly flows into the cylinder upper chamber 2a through the oil liquid passage 13. The pressures of 2a and 2b are the same, and no oil liquid flows in the extension side passage 32 of the damping force adjusting mechanism 15.

On the other hand, as the piston rod 9 is shortened, the amount of oil that has penetrated the piston rod 9 into the cylinder 2 is pressurized, and the lower cylinder chamber 2b moves to the oil passage 29 of the damping force adjusting mechanism 15 and the chamber. 29a and passage 30 to oil chamber 16b, check valve 41 closes, compression side passage 36, fixed orifice
45, the compression side back pressure chamber 39, the port 46, the communication groove 50, the oil chamber 16c and the passage 31, and then flows into the reservoir chamber 7. At this time,
When the pressure on the cylinder upper and lower chambers 2a, 2b reaches the valve opening pressure and the disc valve 23 opens, the oil liquid flows directly from the contracting side passage 36 to the oil chamber 16c.

Therefore, as in the extension stroke, the piston speed is low and before the disc valve 23 is opened,
When the damping force of the orifice characteristic is generated according to the communication passage area between the ports 46 and 47, the piston speed increases, the pressure in the cylinder upper and lower chambers 2a and 2b increases, and the disc valve 23 opens, the opening of the disc valve 23 occurs. The damping force of the valve characteristic is generated depending on the degree. Then, the shutter is rotated by the rotary actuator 19.
The damping force characteristic can be adjusted by rotating 48 to change the communication passage area between the ports 46 and 47.

In this case, the smaller the communication passage area between the ports 46 and 47, the larger the pressure loss and the higher the pressure in the side back pressure chamber 39, and this pressure acts in the valve closing direction of the disc valve 23. Therefore, the valve opening pressure of the disc valve 23 also increases. Therefore, by rotating the shutter 48, the port 46,
By changing the communication passage area between 47, the orifice characteristic and the valve characteristic change simultaneously, so the damping force can be greatly changed from the low speed region of the piston speed to the high speed region, and the damping force characteristic adjustment range can be widened. can do.

By rotating the shutter 48, the communication passage areas between the expansion side ports 43 and 44 and the contraction side ports 46 and 47 are changed, respectively, so that independent damping force is applied to the expansion side and the contraction side. The characteristics can be obtained. In this embodiment, the passage area between the expansion-side ports 43 and 44 and the contraction-side ports 46 and 47 depends on the rotational position of the shutter 48.
When one is large, the other becomes small, and when one is small, the other becomes large.Therefore, a combination of different types of damping force characteristics is different between the expansion side and the contraction side (for example, expansion side hard and contraction side soft, or , Combination of expansion side software and contraction side hardware) can be set.

Further, during the compression stroke of the piston rod 9, the check valve 14 prevents the flow resistance from acting between the cylinder upper and lower chambers 2a and 2b, so that the inside of the cylinder upper chamber 2a does not become a negative pressure. Thus, stable damping force can be obtained, and the setting range of damping force characteristics can be widened.

Further, the damping force adjusting mechanism 15 includes the cylinder 2
Since it is concentrically arranged in the lower part of the cylinder and is housed in the outer cylinder 4, it does not project to the side surface of the cylinder 2 and the restriction on the mounting space for the vehicle is reduced. Further, the load acting in the axial direction of the damping force adjusting mechanism 15 is directly applied from the lid member 17 to the cap member 18 so as not to act on the rotary actuator 19.
19 cases require less strength, rotary actuator
The size and weight of 19 can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment has substantially the same configuration as the first embodiment except that the shutter and the actuator of the damping force adjusting mechanism are different.
The same members as those in the first embodiment will be designated by the same reference numerals and only different portions will be described in detail below.

As shown in FIG. 5, in the damping force adjusting mechanism 54 of the damping force adjusting type hydraulic shock absorber 1 according to the second embodiment, the spool 55 is slidably fitted to the guide member 26, and the case A proportional solenoid actuator 57 is attached to the lid member 56 fitted to the open rear portion of 16.

The spool 55 is provided with a flow path 58 that connects the ports 43 and 44 on the extension side of the guide member 26 and a flow path 59 that connects the ports 46 and 47 on the contraction side. By the movement of the spool 55, the flow path 58 is always in communication with the upstream port 43 with a constant passage area, and adjusts the communication passage area with the downstream port 44. The flow passage 59 adjusts the communication passage area with the upstream port 46, and is always communicated with the downstream port 47 with a constant passage area. Therefore, depending on the position of the spool 55, the expansion-side port 44 and the contraction-side port 46 have one communication passage area that is small when the other communication passage area is large and one communication passage area that is small. At this time, the area of the other communication passage becomes large.

The spool 55 is biased to one side (upward in FIG. 5) by a spring 60, and is moved against the biasing force of the spring 60 by a proportional solenoid actuator 57, and the spool 55 is moved in response to the thrust force. By positioning, the communication passage area of the ports 44 and 46 can be adjusted. The guide member 26 is provided with a throttle passage 61 that causes an appropriate damping force to act on the movement of the spool 55 by causing the oil liquid to flow with the movement of the spool 55. In FIG. 5, 62 is a solenoid, 63 is a solenoid case, 64 is a retainer, 65 is an adjusting screw for adjusting the initial load of the spring 60, and 66 is a stopper for regulating the displacement amount of the spool 55.

With this configuration, when the solenoid 62 is energized, the spool 55 is moved according to the energized current, and the port
By changing the communication passage area of each of the 44 and the port 46, the damping force characteristics on the extension side and the contraction side can be adjusted, and the same effect as that of the first embodiment can be obtained.

Further, even if the damping force adjusting mechanism 54 vibrates in the axial direction with the stroke of the piston rod 9, the movement of the spool 55 is appropriately buffered by the throttle passage 61, so that the movement of the spool 55 is prevented. It is possible to sufficiently reduce the influence of vibrations on, and obtain stable damping force characteristics.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment has substantially the same structure as the second embodiment except that the structure of the solenoid actuator is different. Therefore, the same members as those of the second embodiment will be described below. Only different parts with numbers will be described in detail.

As shown in FIG. 6, in the damping force adjusting mechanism 67 of the damping force adjusting hydraulic shock absorber according to the third embodiment, the solenoid case 63 of the second embodiment is omitted, and the solenoid
68 is directly fitted to the cap member 18. Further, the cap member 18 is a magnetic material, and the lid member 56 and the retainer 64 are provided.
To form a magnetic path A for the magnetic field generated by the solenoid 68. In the third embodiment,
The adjusting screw 65 of the second embodiment is omitted.

With this structure, since the magnetic path A is formed by the cap member 18, the solenoid case 63 of the second embodiment shown in FIG. 5 can be omitted, and the damping force adjusting hydraulic shock absorber can be further improved. It can be miniaturized.

Next, a modification of the third embodiment will be described with reference to FIG. As shown in FIG. 7, the cap member 18
The magnetic fluid 70 is placed in the gap 69 provided between the bottom of the retainer 64 and the retainer 64.
Can be enclosed and the magnetic path B can be formed by the lid member 56, the cap member 18, the magnetic fluid 69 and the retainer 64. In this case, the gap 69 absorbs the axial dimension error of the lid member 56, the solenoid 68, the retainer 64, and the cap member 18, and ensures that a gap is created between them and the magnetic path is blocked. Can be prevented. Further, the solenoid 68 does not receive the load directly from the cap member 18. Instead of the magnetic fluid 70, magnetic powder or a magnetic material having elasticity can be used.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is the second embodiment shown in FIG.
Since the structure is substantially the same as that of the embodiment except that the structure of the damping force adjusting mechanism is different, the same members as those of the second embodiment will be designated by the same reference numerals, and only different portions will be described in detail. Explained.

As shown in FIG. 8, the damping force adjusting mechanism 71 of the damping force adjusting hydraulic shock absorber of the fourth embodiment has a cylindrical case 72 having a small diameter portion fitted in the lower end portion of the cylinder 2.
And a cylindrical case 73 having a diameter slightly larger than that of the case 72 fitted in the inner cylinder 3 are coupled to each other.
One valve member 74, 75 and one partition member 76 are fitted to each other, so that the insides of the cases 72, 73 have four oil chambers 77.
It is divided into a, 77b, 77c and 77d. Valve member 7
Disc valves 78 and 79 and annular fixing members 80 and 81 are concentrically overlapped with each other on 4 and 75.
A substantially cylindrical guide member 82 is inserted, and a nut 83 is screwed to one end of the guide member 82 and integrally joined. The other end of the guide member 82 is attached to the lid member 84, and the lid member 84
Is fitted into the opening of the case 74 and fixed in the cases 72 and 73.

The oil chamber 77a is directly connected to the cylinder lower chamber 2b through the one end opening 72a of the case 72. Oil chamber 77b
Is communicated with the annular passage 6 through an oil liquid passage 85 provided on the side wall of the joint between the case 72 and the case 73. Oil chamber 77
c is provided in the valve member 74 and the partition member 76, and the oil liquid passages 86, 87 communicating with each other in the assembled state thereof.
Through the oil chamber 77a. Also, the oil chamber 77d
Is communicated with the reservoir chamber 4 via an oil liquid passage 88 provided on the side wall of the case 73.

The valve member 74 is provided with an extension side passage 89 for communicating the oil chamber 77b with the oil chamber 77a. The extension side passage 89 includes a disc valve 78 (extension side damping valve) and the disc valve 78. Is also provided with a sub disk valve 90 with a low set opening pressure. The disc valve 78 and the sub-disc valve 90 bend and open when receiving the pressure on the oil chamber 77b side of the extension side oil liquid passage 89, allowing the oil liquid to flow to the oil chamber 77a side and opening the valve. A damping force is generated accordingly. On the rear side of the disc valve 78, a fixing member
An annular movable member 91 slidably fitted to the outer peripheral portion of 80 is abutted by the urging force of a spring 92, and the disk valve
78, the fixed member 80 and the movable member 91 to extend the back pressure chamber
93 is formed. In the figure, 94 is a spring receiver.

The valve member 75 is provided with a contraction side passage 95 for communicating the oil chamber 77c with the oil chamber 77d.
The disk 95 is provided with a disk valve 79 (compression-side damping valve) and a sub disk valve 96 whose initial set valve opening pressure is lower than that of the disk valve 79. The disc valve 79 and the sub-disc valve 96 are installed in the oil chamber 77
It receives pressure from the c side and bends to open the valve, allowing the oil liquid to flow to the oil chamber 77d side and generating a damping force according to the opening degree. On the back side of the disc valve 79, an annular movable member slidably fitted to the outer peripheral portion of the fixed member 81.
97 is abutted by the urging force of the spring 98, and the extension side back pressure chamber 99 is formed by the disc valve 79, the fixed member 81 and the movable member 97. In the figure, 100 is a spring receiver.

Further, the valve member 75 includes oil chambers 76c and 77.
The communication passage 101 for communicating between d and the oil chamber 77 of the communication passage 101
A check valve 102 that allows only the flow of the oil liquid from the d side to the oil chamber 77c side is provided. Similar to the check valve 41 shown in FIG. 3, the check valve 102 is provided with a hole 102a on the inner peripheral side thereof so that the circulation of the contraction side passage 95 can be always ensured.

The extension side back pressure chamber 93 is provided upstream of the extension stroke through the oil chamber 77b side, that is, the annular passage 6 via a fixed orifice 103 (extension upstream passage) provided in the disk valve 78 to provide flow passage resistance. Port on the side of the cylinder upper chamber 2a, which is the side cylinder chamber, and ports 104 and 105 provided on the side wall of the guide member 82 as passages on the downstream side of extension.
It is connected to the oil chamber 77c side via the (extension side variable orifice), that is, to the cylinder lower chamber 2b side which is the downstream cylinder chamber via the oil liquid passages 86, 87 and the oil chamber 77a. The contraction side back pressure chamber 99 is provided on the disc valve 79 via a fixed orifice 106 (contraction upstream side passage) for providing flow passage resistance, and via the oil chamber 77c side, that is, the oil liquid passages 86, 87 and the oil chamber 77a. Ports 107, 108 are connected to the cylinder lower chamber 2b side, which is the upstream cylinder chamber during the compression stroke, and are provided on the side wall of the guide member 82 as the compression downstream passages.
It communicates with the reservoir chamber 7 on the oil chamber 77d side, that is, on the downstream side, via the (shrinkage side variable orifice).

A spool 109 is slidably fitted on the guide member 82. The spool 109 has a guide member 82
Flow path 110 that connects the expansion side ports 104 and 105 and flow path 111 that connects the contraction side ports 107 and 108
Is provided. By moving the spool 109, the flow passage 110 is always in communication with the upstream port 104 with a constant passage area, and the communication passage area with the downstream port 105 is adjusted. The flow passage 111 adjusts the communication passage area with the upstream port 107, and
108 is always connected with a certain passage area. Therefore, the expansion side port 105 and the contraction side port
According to the position of the spool 109, when one communication passage area is large, the other communication passage area is small, and when one communication passage area is small, the other communication passage area is large.

The spool 109 is connected to the plunger 113 of the proportional solenoid actuator 112 mounted on the lid member 84. The spool 109 and the plunger 113 are connected to each other (upward in FIG. 8) by the spring 114.
The solenoid 115 is energized to move it against the urging force of the spring 114, and the spool 109 is positioned according to the thrust to adjust the communication passage area of the ports 105 and 107. You can do it.

The guide member 82 communicates with the oil chamber 77d and the oil chamber 116, and restricts the flow of the oil liquid between these chambers as the spool 109 and the plunger 113 move.
A throttling passage 117 is provided which exerts an appropriate damping force on the movement of 109 and the plunger 113. Also spool
109 includes a chamber on one end side of the spool in the guide member 82.
Passages 119 and spools 109 for communicating the flow path with the flow passages 111.
There is provided a throttle 120 for restricting the circulation of the oil liquid in the passage 119 associated with the movement of the spool 109 to exert an appropriate damping force on the movement of the spool 109. In FIG. 8, 121 is a solenoid case, 122 is a retainer, 123 is an adjusting screw for adjusting the initial load of the spring 114, and 123 is a stopper for regulating the displacement amount of the spool 109.

The operation of the fourth embodiment constructed as above will be described below.

During the extension stroke, the oil liquid on the cylinder upper chamber 2a side flows into the oil chamber 77b through the annular passage 6 and the oil liquid passage 85 of the damping force adjusting mechanism 71, and the opening pressure of the sub disk valve 90 is increased. When the pressure becomes higher than that, the sub-disk valve 90 opens, and the extension side passage 89, the fixed orifice 103, the extension side back pressure chamber 93, the port 104, the flow passage 110, the port 105, the oil chamber 77c,
Flows through the passages 87, 86, the oil chamber 77a and the opening 72a to the cylinder lower chamber 2b. At this time, when the pressure on the cylinder upper chamber 2a side further increases and reaches the valve opening pressure of the disc valve 78 to open the disc valve 78, the oil liquid directly flows from the extension side passage 89 to the oil chamber 77a. On the other hand, the oil liquid discharged from the piston rod 9 passes from the reservoir chamber 4 through the oil liquid passage 88, the oil chamber 77d, and the oil liquid passage 101, and opens the check valve 102 to replenish the oil chamber 77c, that is, the cylinder lower chamber 2b side. To be done.

Therefore, before the disc valve 78 is opened, the damping force is generated by the passage area of the port 105 and the sub-disc valve 90, and after the disc valve 78 is opened, the damping force is generated by the disc valve 78. Occurs. Then, similarly to the second embodiment, the passage area of the port 105 is changed by the movement of the spool 109 to directly change the damping force in the low speed region of the piston speed and the pressure in the extension side back pressure chamber 93. Thus, the valve opening characteristic of the disc valve 78 can be changed to change the damping force in the high speed region of the piston speed.

Further, during the compression stroke, the oil liquid on the cylinder lower chamber 2b side flows from the oil chamber 77a of the damping force adjusting mechanism 71 into the passages 86 and 87, the oil chamber 77c, and the compression side passage 95 through the opening 72a, When the pressure becomes higher than the opening pressure of the disc valve 96, the sub-disc valve 96 opens, and the fixed orifice 106, the compression side back pressure chamber 99, the port 107, the flow passage 111, the port 108, the oil chamber 77d and the oil liquid. It flows through the passage 88 to the reservoir chamber 7. At this time, the pressure on the cylinder lower chamber 2b side becomes even higher, reaching the valve opening pressure of the disc valve 79,
When 79 is opened, the oil liquid flows directly from the contraction side passage 95 to the oil chamber 77d.

Therefore, before the disc valve 79 is opened, the damping force is generated by the passage area of the port 107 and the sub-disc valve 96, and after the disc valve 79 is opened, the damping force is generated by the disc valve 79. Occurs. Then, similarly to the second embodiment, the passage area of the port 107 is changed by the movement of the spool 109 to directly change the damping force in the low speed region of the piston speed and the pressure in the compression side back pressure chamber 99. Thus, the valve opening characteristic of the disc valve 79 can be changed to change the damping force in the high speed region of the piston speed.

As described above, the spool 109 is moved in accordance with the current supplied to the solenoid 115 to change the area of the communication passages of the ports 105 and 107, so that the expansion side and the contraction side are the same as in the second embodiment. It is possible to adjust the damping force characteristic on the side.

Further, with respect to the vibration in the axial direction of the damping force adjusting mechanism 71 associated with the stroke of the piston rod 9, the throttle passage 117 and the throttle 120 in the passage 119 are used to spool 1.
The movement of 09 and the plunger 113 can be appropriately buffered, and the influence of the vibration can be sufficiently reduced.

In the first to fourth embodiments described above, the damping force adjusting mechanism adjusts the passage areas of the extension side and the contraction side passages to extend and adjust both the contraction side damping force. However, the present invention is not limited to this, and the damping force adjusting mechanism may adjust one damping force on the extension side via the annular passage 6 (the extension side passage). Further, in the damping force adjusting mechanisms of the first to fourth embodiments, the passage area of the variable orifice is changed to directly adjust the orifice characteristic and change the internal pressure of the back pressure chamber to change the valve characteristic. However, the damping force is not limited to this, and the damping force may be changed by a normal orifice area.

[0074]

As described in detail above, according to the damping force adjusting type hydraulic shock absorber of the present invention, since the extension side damping force adjusting mechanism is arranged below the cylinder, the damping force adjusting mechanism is There is no protrusion on the side surface portion, and it is possible to reduce the restriction on the mounting space for the vehicle (claim 1,
2). Further, by changing the passage area of the variable orifice by the damping force adjusting mechanism, the orifice characteristic can be directly adjusted, and the valve characteristic can be changed by changing the internal pressure of the back pressure chamber. ). Further, during the compression stroke of the piston rod, the damping force is generated by controlling the flow of the oil liquid between the cylinder chamber and the reservoir chamber, so that the cylinder chamber does not become negative pressure and a stable damping force is obtained. It has the excellent effect of being able to (claim 4).

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a damping force adjusting hydraulic shock absorber according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a damping force adjusting mechanism that is a main part of the apparatus of FIG.

FIG. 3 is a plan view of a check valve of the damping force adjusting mechanism of FIG.

FIG. 4 is a perspective view of a shutter of the damping force adjusting mechanism of FIG.

FIG. 5 is an enlarged view of a damping force adjusting mechanism which is a main part of a damping force adjusting hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 6 is an enlarged view of a damping force adjusting mechanism which is a main part of a damping force adjusting hydraulic shock absorber according to a third embodiment of the present invention.

FIG. 7 is an enlarged view of a damping force adjusting mechanism which is a main part of a modified example of the damping force adjusting hydraulic shock absorber according to the third embodiment of the present invention.

FIG. 8 is an enlarged view of a damping force adjusting mechanism which is a main part of a damping force adjusting hydraulic shock absorber according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Damping force adjusting hydraulic shock absorber 2 Cylinder 2a Cylinder upper chamber 2b Cylinder lower chamber 6 Annular passage (expansion side passage) 7 Reservoir chamber 9 Piston rod 15 Damping force adjusting mechanism 22 Disc valve (Extension side damping valve) 23 Disc valve ( Compression side damping valve) 29 Oil liquid passage (compression side passage) 35 Expansion side back pressure chamber 39 Compression side back pressure chamber 42 Fixed orifice (expansion upstream passage) 45 Fixed orifice (compression upstream passage) 43,44 Ports (expansion) Downstream passage, variable orifice) 46, 47 ports (shrinkage downstream passage, variable orifice)

Claims (4)

[Claims] 1. A cylinder in which an oil liquid is sealed, a piston slidably fitted in the cylinder to define two cylinder chambers in the cylinder, one end of which is connected to the piston and the other end of which is A piston rod extended to the outside of the cylinder, and compression of gas due to volume change in the cylinder connected to the cylinder due to expansion and contraction of the piston rod,
A reservoir chamber that compensates by expansion, an expansion-side passage that is provided outside the cylinder and that causes an oil liquid to flow from one cylinder chamber to the other cylinder chamber during the expansion stroke of the piston rod to generate a damping force, and a contraction A contraction side passage for generating an damping force by flowing oil liquid from the cylinder chamber to the reservoir chamber during the stroke, and the extension side passage is extended below the cylinder, and the passage area of the extension side passage is provided. A damping force adjusting hydraulic shock absorber, wherein an extension side damping force adjusting mechanism for adjusting is arranged below the cylinder. 2. The compression-side passage extends below the cylinder, and a compression-side damping force adjusting mechanism for adjusting the passage area of the compression-side passage is arranged below the cylinder. The damping force adjustable hydraulic shock absorber according to 1. 3. The extension-side damping force adjusting mechanism includes an extension-side damping valve that adjusts a passage area of the extension-side passage, and an extension-side back pressure chamber that applies an internal pressure to a valve body of the extension-side damping valve in a valve closing direction. An extension upstream side passage that connects the extension side back pressure chamber and an upstream side cylinder chamber of the extension side damping valve with a flow path resistance; and an extension side back pressure chamber and a downstream side of the extension side damping valve. The damping force adjusting hydraulic shock absorber according to claim 1, further comprising: an extension downstream passage that communicates with the cylinder chamber; and an extension variable orifice that adjusts a passage area of the extension downstream passage. . 4. The extension-side damping force adjusting mechanism includes an extension-side damping valve that adjusts a passage area of the extension-side passage, and an extension-side back pressure chamber that applies an internal pressure to a valve body of the extension-side damping valve in a valve closing direction. An extension upstream side passage that connects the extension side back pressure chamber and an upstream side cylinder chamber of the extension side damping valve with a flow path resistance; and an extension side back pressure chamber and a downstream side of the extension side damping valve. An extension downstream passage communicating with the cylinder chamber, and an extension variable orifice adjusting the passage area of the extension downstream passage,
The compression-side damping force adjusting mechanism includes a compression-side damping valve that adjusts the passage area of the compression-side passage, a compression-side back pressure chamber that applies internal pressure to the valve body of the compression-side damping valve in the valve closing direction, and the compression-side A compression upstream passage that communicates the back pressure chamber with the upstream cylinder chamber of the compression damping valve, and a compression downstream side that communicates the compression back pressure chamber with the reservoir chamber downstream of the compression damping valve. A passage and a contraction-side variable orifice that adjusts the passage area of the contraction downstream passage, and further, the piston is a non-return valve that allows the oil liquid to flow only from the other cylinder chamber to the one cylinder chamber during the compression stroke. The damping force adjustable hydraulic shock absorber according to claim 2, further comprising a valve.