JPH03113139A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To spread the degree of freedom in setting the damping force characteristic by forming a back pressure chamber on the opposite side to the piston of a disk valve and installing a subdisc valve which is opened and closed by the hydraulic pressure in the back pressure chamber. CONSTITUTION:As for an extension side disk valve 28 or a contraction side disk valve 29, a hydraulic pressure is introduced into a back pressure chamber 14 or 15 through bypass passages 38 and 40 from a cylinder upper chamber 3 or cylinder lower chamber 4 on the side generating the hydraulic pressure supplied from communication passages 10 and 11. Accordingly, a pressure in the opposite direction to the direction for opening a valve is applied on the subdisc valves 28 and 29, and a damping force characteristic having a large gradient is obtained. Further, when the hydraulic pressure supplied from the cylinder chambers 3 and 4 increases, the subdisc valves 28 and 29 are opened, and damping force having the smaller gradient is obtained. Thus, the optimum damping force characteristic corresponding to the vehicle can be set.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a hydraulic shock absorber used in vehicles and the like.

(Prior Art) Hitherto, a hydraulic shock absorber capable of obtaining a high damping force has been proposed, for example, in Japanese Utility Model Application Laid-Open No. 62-184237.

This hydraulic shock absorber is divided into two cylinder chambers by a piston that is slidably fitted into the cylinder, and a communication passage (growth side boat) that communicates the two cylinder chambers is provided in the piston. A disc valve (leaf valve) is provided on the downstream side that is opened and closed by the hydraulic pressure in the communication passage, a back pressure chamber is provided on the opposite side of the piston part of the disc valve, and the communication passage and the back pressure chamber are connected to the disc valve. A communicating orifice is provided in the back pressure chamber, and a communication hole is provided in the back pressure chamber to communicate the back pressure chamber with the cylinder chamber on the downstream side of the disc valve, thereby making the back pressure chamber a decompression chamber. In addition, the area that receives hydraulic pressure from the disc valve or back pressure chamber (pressure receiving surface m
) is set smaller than the area (pressure receiving area) that receives hydraulic pressure from the communication passage.

According to this configuration, the high pressure on the communication passage side and the reduced pressure on the back pressure chamber side are applied to the disc valve from both sides, and the actual oil pressure on the pressure receiving surface on the communication passage side of the disc valve is reduced. Since the hydraulic pressure at the pressure-receiving surface on the back pressure chamber side is reduced by the amount of hydraulic pressure actually applied, a high damping force can be obtained without increasing the number of disc valves.

Incidentally, FIG. 11 shows a damping force characteristic diagram of this hydraulic shock absorber. As shown in this figure, compared to the damping force characteristics of a hydraulic shock absorber without a back pressure chamber (shown by the broken line), the above hydraulic shock absorber can obtain a damping force characteristic with a large slope.

(Problems to be Solved by the Invention) However, the conventional hydraulic shock absorber described above had the following problems.

The larger the pressure-receiving area on the back-pressure chamber side of the disc valve to which the hydraulic pressure is applied, the greater the slope of the damping force characteristic can be obtained.However, since the damping force characteristic has a single slope, there is less freedom in setting it and it is difficult to set the vehicle. There was a problem in that it was not possible to set the optimum damping force characteristics according to the driving characteristics of the vehicle.

Furthermore, if the damping force is set so that a high damping force is obtained under normal usage conditions, an extremely high damping force will be generated if the piston of the hydraulic shock absorber moves suddenly, such as when the vehicle runs over a step. There is a risk that the
In order to withstand the large hydraulic pressure inside the cylinder when such high damping force is generated, hydraulic shock absorbers must be installed in advance, such as increasing the thickness of the cylinder plate, increasing the strength of the welded parts, and increasing the rigidity of the sealing member. The strength of each member must be increased, leading to an increase in the amount of riding and an increase in cost.

The present invention has been made in view of the above problems, and its purpose is to provide a hydraulic shock absorber that can obtain damping force characteristics with a large slope and has a large degree of freedom in setting.

(Means for Solving the Problems) The hydraulic shock absorber of the present invention has two parts inside the cylinder by a partition member.
divided into two cylinder chambers, and the partition member is provided with a communication passage that communicates the two cylinder chambers, and a disc valve that opens and closes by hydraulic pressure in the communication passage to generate a damping force,
A back pressure chamber is provided on the side opposite to the partition member of the disc valve, and the back pressure chamber is communicated with a cylinder chamber on the side where the disc valve provided with the back pressure chamber generates the hydraulic pressure received from the communication passage. In addition to providing a bypass passage, a sub-disk valve is provided that opens and closes using hydraulic pressure in the back pressure chamber to generate a damping force, and the opening pressure of the sub-disc valve is set higher than the pressure when the disc valve opens. It is characterized by this.

(Function) With this configuration, hydraulic pressure is introduced from the cylinder chamber on the side that generates hydraulic pressure received from the disc valve or the communication passage into the back pressure chamber via the bypass passage, and the disc valve receives pressure in the direction of opening. Since pressure is applied in the opposite direction, it is possible to obtain a damping force with a damping force characteristic with a large slope.
When the oil pressure from the cylinder chamber increases, the sub-disc valve opens and a damping force with a small gradient is generated.

In this way, it is possible to obtain a damping force that changes from a damping force characteristic with a large slope to a damping force characteristic with a small slope as the hydraulic pressure rises from the cylinder chamber, so the degree of freedom in damping force characteristics is expanded, and , it is possible to suppress the increase in damping force when the piston moves suddenly.

(Example) Next, an example of the present invention will be described based on the drawings. First, a first embodiment will be described based on FIGS. 1 through 5.

The hydraulic shock absorber 1 of this embodiment is a damping force adjustable hydraulic shock absorber in which the damping force can be switched between a hard characteristic and a soft characteristic by external operation.

A piston 5 or a piston ring 6, which is a partition member that divides the inside of the cylinder 2 into two chambers, an upper cylinder chamber 3 and a lower cylinder chamber 4, is slidably fitted into the cylinder 2. Note that the piston 5 is fitted and attached to the lower end of a piston row door, which will be described later.

An annular groove 8.9 is formed in the upper and lower end surfaces of the piston 5. Further, the piston 5 is formed with an extension passage IO and a compression passage 11 that communicate the cylinder upper chamber 3 and the cylinder lower chamber 4, and one of the expansion passages 10 has a groove 9 on the upper surface. One of the contraction-side advancement passages 11 opens into the groove 9 on the upper surface, and the other opens outside the groove 8 on the lower surface.

On the lower end surface of the piston 5, an extension side disc valve 12 is stacked to generate a damping force during the extension stroke of the hydraulic shock absorber, and is provided so as to close the groove 8. Furthermore, a compression-side disc valve 13 is stacked on the upper end surface of the piston 5 to generate a damping force during the compression stroke, and is provided so as to close the groove 9. These disc valves 12,
13, when the oil pressure in the grooves 8 and 9 reaches a predetermined value (Pz, p+), the outer circumferential side is bent to cause the oil to flow, thereby generating a damping force.

An extension pressure chamber 14 and a contraction pressure chamber 15 are provided on the opposite side of each disc valve 12, 13 from the piston 5, respectively. These back pressure chambers14. Is is
It is formed by a cylindrical holder 16 and 17 with a bottom,
A disc valve 12.13 is installed inside the back pressure chamber 14.15.
A sealing mechanism is provided to maintain liquid tightness even when the cap is bent. This sealing mechanism consists of an annular spring 18.19
and a retainer 2 that supports the inner peripheral sides of the springs 18 and 19.
0.21 is slidably provided on the inner periphery of the holder 16.17, and the disc valve 1 is moved by the elastic force of the spring 18.19.
2.13 Cylindrical slide retainer 22.2
It consists of 3. Furthermore, communication holes 18a and 19a are formed in the annular spring 18.19, and the retainer 20.21
Cutouts 20a and 21a are formed in the inner side and the outer side to communicate with each other.

Each holder 16.17 is formed with a passage 24.25 that communicates each back pressure chamber 14.15 with each cylinder chamber 3.4.
It opens into annular grooves 25 and 27 formed on the opposite side from groove 15. and the groove 26.2 of the holder 16.17.
On the surface where 7 is formed, a growth side sub-disk valve 28 and a contraction side sub-disk valve 29 are stacked, respectively, and are provided so as to close the valley grooves 26 and 27.

These sub-disc valves 28, 29 are connected to the back pressure chamber 14.
．． When the oil pressure in the disc valve 12.15 reaches a predetermined pressure (P2.112) higher than the pressure at which the disc valve 12.13 opens, the outer circumferential side is bent to cause the oil to flow, and at that time, a damping force is generated. It is something.

An orifice passage 3 consisting of a notch is provided on the seat surface of the lower holder 16 that is in contact with the extension side sub-disc valve 28.
0 is formed.

A through hole 7a is formed on the axis of the piston rod 7, and a shutter 31 is rotatably fitted into the through hole 7a on the lower end side of the piston rod 7. and,
The shutter 31 has one end protruding outside and is connected to the other end of a control bin 32, and can be rotated from the outside by operating the control bin 32.

On the outer periphery of the shutter 31, three grooves 3:1, 34.35 forming a bypass passage are formed along the axial direction. The first groove 33 communicates between a hole 36 that communicates between the cylinder upper chamber 3 and the through hole 7a and a hole 37 that communicates the extended Bizen pressure chamber 14 and the through hole 7a. A first bypass passage 38 is configured to introduce hydraulic pressure into the expansion Bizen pressure chamber 14.

In addition, the second groove 34 communicates the cylinder lower chamber 4 with a hole 39 that communicates the compression Bizen pressure chamber 15 and the through hole 7a.
A second bypass passage 4o is configured to introduce hydraulic pressure from the cylinder lower chamber 4 to the contracted Bizen pressure chamber 15.

The groove 35 @3 constitutes a third bypass passage 42 that communicates between a small-diameter orifice hole 41 (shown in FIG. 3) that communicates between the cylinder upper chamber 3 and the through hole 7a, and the cylinder lower chamber 4. .

The first groove 33 and the second groove 34 are connected to the shirt shirt 31.
are provided on opposite sides in the radial direction of the holes 3 and 3.
6 and the hole 39 are also provided on opposite sides in the radial direction of the piston rod 7, the rotation of the shutter 31 simultaneously opens and closes the first bypass passage 38 and the second bypass passage 40.

The operation related to the above configuration will be explained.

The shutter 31 opens the first and second bypass passages 38
．． 40 is closed and the third bypass passage 42 is opened (
3 and 4), the communication between the cylinder upper chamber 3 and the extended Bizen pressure chamber 14, and between the cylinder lower chamber 4 and the contracted Bizen pressure chamber 15 is cut off, and each back pressure chamber 14, 15 has no hydraulic pressure. is not introduced, and the cylinder upper chamber 3 and the cylinder lower chamber 4 are in communication via the third bypass passage 42.

Therefore, in the low speed range of the piston 5, the orifice hole 41 of the third bypass passage 42 generates a damping force having a quadratic orifice characteristic shown by the line AI+al in FIG.

In the high speed range of the piston 5, when the hydraulic pressure in the communication passage 10.11 reaches the valve opening pressure (P+, P+), the disc valve 12.13 opens and becomes a linear valve as shown by line A2+82 in Fig. 5. It generates a characteristic damping force, and the disc valve 12
．． Since no pressure is applied to 13 from the back pressure chambers 14 and 15, the damping force characteristic has a small gradient. In addition, at this time, the back pressure chamber 14. Is contains oil, or the amount of deflection of the disc valve 12.13 is small, and there is also a leak of oil from the back pressure chamber 1.4.15, so the disc valve 12. .13 back pressure chamber for operation 14.
The oil in Is has no effect.

Next, operate the shutter 31 to open the first bypass passage 3.
8 and the second bypass passage 4o are opened and the third bypass passage 42 is closed.

At this time, the cylinder upper chamber 3 and the expansion Bizen pressure chamber 14 are communicated, and the cylinder lower chamber 4 and the contraction Bizen pressure chamber 15 are communicated. And, the cylinder upper chamber 3 and the cylinder lower chamber 4 are as follows.
They are communicated through an orifice passage 30 provided in the lower holder 16.

To explain the damping force characteristics at this time, the back pressure chambers 14 and 15
Since hydraulic pressure is introduced into the back pressure chamber 1 and presses the disc valves 12 and 13 from the opposite side of the piston 5,
At 4.15, the valve opens with a higher pressure (P3.p:+) than when hydraulic pressure is not introduced. Therefore, until the disc valves 12 and 13 open in the low speed range of the piston 5, the orifice passage 30 is used as shown in 81 in FIG. b. A damping force having a quadratic orifice characteristic shown in the line is generated.

In the high speed range of the piston 5, the disc valve 12.13 is pressed from the opposite side of the piston 5 by the hydraulic pressure in the back pressure chamber 14.15, so that the pressure at 82. in FIG. A damping force with a linear valve characteristic with a large slope as shown by the b2 line is generated. Then, the pressure of the oil in the back pressure chamber 14.15 further increases, and the opening pressure of the sub-disc valve 28.29 (
P2. I) When reaching 2), the sub-disc valve 28
．． 29 is opened and 83 in FIG. A damping force with a valve characteristic with a small gradient as shown by the b3 line is generated.

In this way, when no hydraulic pressure is introduced into the back pressure chambers 14 and 15, a low damping force characteristic (soft characteristic) is obtained, and the back pressure chamber 1
By introducing hydraulic pressure into 4.15, high damping force characteristics (hard characteristics) can be obtained, and in heart characteristics,
It is possible to change the valve characteristic from a valve characteristic having a large gradient to a valve characteristic having a small gradient.

And disc valve 12.1: l communication path 10°1
1 side pressure receiving area and back pressure chamber 14. By changing the pressure-receiving area on the Is side and changing the rigidity of the disc valve 12.13 or the sub-disk valve 28.29 (changing the number and material), the opening pressure and gradient of each valve characteristic can be arbitrarily set. It is possible to set the optimum damping force characteristics according to the driving characteristics of the vehicle.

Next, a second embodiment of the present invention will be described based on FIGS. 6 and 7. Note that the same reference numerals are given to the members corresponding to those of the first embodiment.

The hydraulic shock absorber 43 of this embodiment is an application of the present invention to a hydraulic shock absorber that can change damping force depending on the position of a piston, which is a partition member.

A piston 5, which divides the inside of the cylinder 2 into two chambers, an upper cylinder chamber 3 and a lower cylinder chamber 4, is slidably fitted into the cylinder 2 via a piston ring. In addition,
The piston 5 is fitted and attached to the lower end of a piston rod 7, which will be described later.

The piston 5 is formed with an extension bias passage IO and a contraction bias passage 11 that communicate the cylinder lower chamber 3 and the cylinder lower chamber 4, and the lower end surface of the piston 5 is provided with an extension stroke passage of a hydraulic shock absorber. A compression side disc valve 12 is provided on the upper end surface of the piston 5 to generate a damping force during the compression stroke.
There are three. Note that these configurations are the same as those of the first embodiment, so detailed explanations will be omitted.

An orifice passage 44 consisting of a notch is formed in the seat surface of the piston 5 that the extension side disc valve 12 abuts, and the cylinder upper chamber 3 and the cylinder lower chamber 4 are always communicated with each other through a small flow path area.

A holder 16.
17, and each holder 16, 17 has annular grooves 16a, 17a formed therein.
There is a sealing member 45 made of an elastic body such as a ring shape.
．． 46 are provided. Then, the sealing member 45 of the holder 16, 17 and the expansion side disc valve 12 come into contact with each other, and the inside of the groove 16a is sealed to form the expansion pressure chamber 14. contact, the inside of the concave groove 17a is sealed, and the Bizen pressure chamber 15 is formed.

Each holder 16.17 is formed with a passage 24.25 that communicates each back pressure chamber 14.15 with each cylinder chamber 3.4.
On the opposite side, an expansion side sub-disc valve 28 and a contraction side sub-disc valve 29 are provided, respectively. The configuration of the sub-valves 28 and 29 is also the same as that of the first embodiment, so a detailed explanation will be omitted. In addition, an orifice passage consisting of a notch is provided on the seat surface of the holder 16.17 that the suff disk valve 28.29 comes into contact with.
．． 30 is formed.

The piston rod 7 consists of a rod 47 that protrudes from one end to the outside of the cylinder 2, and a bolt member 48 screwed to the other end of the rod 47. It is fixed with a nut 49 such as .17.

Holes are formed in each of the rod 47, bolt member 48, and nut 49 along the axis, and these holes constitute an insertion hole 50. One end of a metering pin 51 fixed to the bottom side of the cylinder 2 is inserted into the insertion hole 50 . As shown in FIG. 7, the metering pin 51 has two large diameter portions 51a, 51b and 3.
The diameter in the axial direction consisting of the small diameter portions 51c, 51d, and 51e is changed as appropriate. A cylindrical collar 52 that can be fitted freely
is arranged with a certain gap from the inner periphery of the insertion hole 50, and the lower end of the collar 52 is connected to the seat portion 5 formed on the nut 49 for fixing the piston 5 to the piston rod 7.
3, and the upper end is in contact with the lower end of a cylindrical guide 54, which will be described later.

The guide 54 is connected to the large diameter portion 51a of the metering pin 51 so that a certain distance is created between the guide 54 and the inner circumference of the insertion hole 50.

51b is formed with an inner diameter larger than the outer diameter, and a large diameter portion 54a is formed on the outer periphery of the large diameter portion 54a.
The guide 54 is urged downward by a spring 55 interposed between the step portion 47a formed on the inner periphery of the rod 47. Further, a passage hole 56 is formed at the lower end of the guide 54 to communicate the gap between the guide 54 and the metering pin 51 and the gap between the collar 52 and the inner periphery of the insertion hole 50. 1=1 person A seal portion 54b that can be slidably fitted onto the large diameter portions 51a and 51b of the thetalin d pin 51 is formed, and the guide 54
The upper end of the stopper 5 is fixed to the inner circumference of the insertion hole 50.
7 can come into contact with it. Here, the inner diameters of the seal portion 54b of the guide 54 and the hole 49a of the nut 49 are set to dimensions that fit relatively tightly into the large diameter portions 51a, 51b of the metering pin 51.

The gap between the guide 54 and the insertion hole 50 is communicated with the cylinder upper chamber 3 through a passage groove 58 formed between the rod 47 and the bolt member 48.

The pitch dimension P of the large diameter portions 51a, 51b of the metering pin 51 and the dimension between the lower end of the nut 49 and the upper end of the guide 54 are set to be the same, as shown in FIG.

A passage 59 is formed by a chamfered portion on the outer peripheral surface of the bolt member 48 where the piston 5 is fitted, and this passage 59 and the insertion hole 50 are connected to a communication hole 60 formed in the bolt member 48. It is communicated with. Further, the one passage 59 and each back pressure chamber 14.15 are communicated with each other through a plurality of cutouts 16b and 17b formed in the holder 16.17. With the above configuration, each back pressure chamber 14.15 is connected to the nut 4.
9 hole 49a, the gap between the collar 52 and the inner periphery of the insertion hole 50, the communication hole 60, the passage 59, and the notches 16b, 17b
The passage groove 58 , the gap between the outer periphery of the guide 54 and the inner periphery of the insertion hole 50 , the seal portion 54 b of the guide 54 , and the guide 54 The gap between the inner circumference of the metering pin 51 and the outer circumference of the metering pin 51, the passage hole 56, the collar 52 and the insertion hole 50
It communicates with the cylinder upper chamber 3 via a bypass passage 62 consisting of a gap between the inner peripheries, a communication hole 60, a passage 59, and notches 16b and 17b.

Then, the lower end of the collar 52 or the seat portion 53 of the nut 49
(Situation shown to the left of the center line in Figure 6)
When the bypass passage 61 that communicates each back pressure chamber 14, 15 with the cylinder lower chamber 4 is cut off, and the upper end of the guide 54 comes into contact with the stopper 57 (the state shown on the right side from the center line in FIG. 6). At this time, the bypass passage 62 that communicates each back pressure chamber 14, 15 with the cylinder upper chamber 3 is blocked.

The operation related to the above configuration will be explained. Note that the damping force characteristics are the same as those of the first embodiment, and will therefore be explained with reference to FIG. 5.

The hole 49 of the nut 49 is shown by the broken line in FIG.
In the relative position of the piston 5 and the metering pin 51 such that the seal portion 54b of the guide 54 is located at the large diameter portions 51a and 51b of the metering pin 51, the damping force characteristics of the hydraulic shock absorber 43 are as follows. become.

The bypass passage 61 is connected to the large diameter portion 5 of the metering pin 51.
1b and the hole 49a of the nut 49, the bypass passage 62 is closed by fitting into the large diameter portion 51 of the metering pin 51.
a and the seal portion 54b of the guide 54, so each back pressure chamber 14.15 has a cylinder upper chamber 3.
Or hydraulic pressure is not introduced from the cylinder lower chamber 4. Therefore, similarly to the first embodiment, in the low speed range of the piston 5, the damping force is applied to the orifice passage 4 formed in the piston 5.
4, the quadratic orifice characteristic (A□o in Figure 5)
al line), and during the extension stroke of the piston 5 in the high-speed range, the expansion side disc valve 12 and during the contraction stroke, the contraction side disc valve 13 have the respective valve characteristics (A2+82 line in FIG. 5).

Next, as shown by the solid line in FIG.
9a and the seal portion 54b of the guide 54 or the small diameter portions 51b and 51e of the metering pin 51, the damping force characteristics are as follows.

First, in the low speed range of the piston 5, a damping force of orifice characteristics is obtained by the orifice passage 44.30 formed in the piston 5 and the holder 16 (line 81 and line b1 in FIG. 5).

During the extension stroke of the piston 5 in the high-speed range, the collar 52 is urged downward by the spring 55 via the guide 54, and the lower end of the collar 52 is pushed toward the seat portion 53 of the nut 49, as shown on the left side from the center line in FIG. , the bypass passage 61 that communicates the cylinder lower chamber 4 and each back pressure chamber 14.15 is blocked, and the hydraulic pressure in the cylinder upper chamber 3 passes through the bypass passage 62 and is transferred to each back pressure chamber 14.15. will be introduced in Therefore, the expansion side disc valve 12 or the expansion side back pressure chamber] 4
The damping force is suppressed by the hydraulic pressure in the cylinder upper chamber 3 side introduced into the inner cylinder, and a damping force with a valve characteristic with a large gradient is obtained.Furthermore, the hydraulic pressure in the extension Bizen pressure chamber 14 increases and the extension side sub-disc valve 28 is opened. When the valve pressure is reached, the extension side sub-disc valve 28 opens and a damping force with a valve characteristic with a small gradient is obtained (Bt-a*!l in Fig. 5).
- Also, in the retraction stroke, as shown on the right side of the center line in FIG. 54 comes into contact with the stopper 57, the bypass passage 62 that communicates the cylinder upper chamber 3 and each back pressure chamber 14, 15 is cut off, and the hydraulic pressure in the cylinder lower chamber 4 is transferred via the bypass passage 61 to each back pressure chamber 14, 15. It is introduced into chamber 14.15.

Therefore, the compression side disc valve 13 or the compression Bizen pressure chamber I
5 is suppressed by the hydraulic pressure in the cylinder lower chamber 4 side, and a damping force with a valve characteristic with a large gradient is obtained, and when the hydraulic pressure in the compression chamber 15 increases further, the compression side sub-disk valve 29 opens. Thus, a damping force having a valve characteristic with a small gradient can be obtained (b2-b X-ray in FIG. 5).

In addition, when switching from hard characteristics to soft characteristics, each back pressure chamber 14. The hydraulic pressure in Is is released into the cylinder upper chamber 3 or the cylinder lower chamber 4 through orifice passages 3G, :lO formed in the holder 16.17.

And the communication path 10゜ll of the disc valve 12.13
By changing the pressure receiving area on the side and the pressure receiving area on the back pressure chamber 14.15 side, and changing the rigidity (number of disc valves, material) of the disc valve 12.13 or sub disc valve 28.29, the characteristics of each valve can be adjusted. The valve pressure and slope can be set arbitrarily, and the optimal damping force characteristics can be set according to the driving characteristics of the vehicle.

Next, a third embodiment of the present invention will be described based on FIGS. 8 to 10. Note that the same reference numerals are given to the members corresponding to those of the first embodiment.

The hydraulic shock absorber 63 of this embodiment is an application of the present invention to a hydraulic shock absorber capable of generating a damping force according to the frequency of vibrations occurring in a vehicle.

A piston 5, which is a partition member that partitions the inside of the cylinder 2 into two chambers, an upper cylinder chamber 3 and a lower cylinder chamber 4, is slidably fitted into the cylinder 2 via a piston ring 6. Note that the piston 5 is fitted and attached to the lower end of a piston rod 7, which will be described later.

The piston 5 is formed with an extension bias passage 10 and a contraction bias passage 11 that communicate the cylinder upper chamber 3 and the cylinder lower chamber 4, and the lower end surface of the piston 5 is provided with an extension stroke passage of a hydraulic shock absorber. A compression side disc valve 12 is provided on the upper end surface of the piston 5 to generate a damping force during the contraction stroke.
3 is provided. Note that these configurations are the same as those of the first embodiment, so detailed explanations will be omitted. A rewiring passage 64 is formed in which the extension side disc valve 12 comes into contact, and the cylinder upper chamber 3 and the cylinder lower chamber 4 are always communicated with each other through a small flow path area.

A holder 16.17 is provided on the side of the disc valve 12.13 opposite the piston 5. The holders 16 and 17 and fulcrum means 65 and 66, which will be described in detail later, constitute an extended Bizen pressure chamber 143 and a contracted Bizen pressure chamber 15, respectively. Each back pressure chamber 14.15 includes a notched passage 57.68 formed in the piston 5, a plurality of rounded portions 69 formed in the piston rod 7, and a passage 70 formed in the holder 16.17. 71, a bypass passage 72.
73 communicates with the communication passages 10 and 11. The bypass passages 72, 73 have orifices 74a, 7
A check valve mechanism 74,75 is provided, which is formed in the bypass passage 72.5a.
Oily orifice 7 flowing from 73 to back pressure chamber 14゜15
The fulcrum means 65.66 is used to suppress the increase in the oil pressure in the back pressure chamber 14.15 by throttling the oil pressure in the back pressure chamber 14.15, and to widen the hydraulic fluid in the back pressure chamber 14.15.
．． 1: Spherical backup disks 76 and 77 provided in contact with l, retainers 78 and 79 that fit into the holders 16 and 17, and presses the retainers 78 and 79 toward the backup disks 76 and 77. It consists of elastic members ao and ai for urging and sealing between the back pressure chambers 14 and 15 and the lower cylinder chamber 4. Retainer 78.
The portion of 79 that comes into contact with the backup disks 76 and 77 is formed into a curved shape,
6, 77 can be smoothly deformed. Also,
The retainer 78.79 and the elastic member 80.81 are fixed by baking.

Each holder 1.6.17 is formed with a passage 24.25 that communicates each back pressure chamber 14.15 with each cylinder chamber 3, 4, and the back pressure chamber 14.15 of the holder 16.17 is On the opposite side, an expansion side sub-disc valve 28 and a contraction side sub-disc valve 29 are provided, respectively. The configurations of these sub-disk valves 28 and 29 are also the same as in the first embodiment, so detailed explanations will be omitted.

Next, the operation of the hydraulic shock absorber 63 having the above structure will be explained.

In the low speed range of the piston 5, the orifice passage 64 formed in the piston 5 generates a damping force having a quadratic orifice characteristic shown by lines CI and CI in FIG.

Further, in the high speed range of the piston 5, the following occurs. When driving on rough paved roads, etc.

Since the frequency of pressure changes in the cylinder upper chamber 3 and cylinder lower chamber 4 increases, the pressure increase in the back pressure chamber 14.15 is reduced by the check valve mechanism 7 provided in the bypass passage 72.73.
4.75 orifices 74a, 75a. Therefore, the position where the backup disks 76 and 77 contact the disk valve 12.13 (the fulcrum point when opening the valve) remains radially inward, and the valve opens at a low pressure.
A damping force with a valve characteristic with a small gradient as shown by the C2+C2 line in the figure is generated.

Further, when the vehicle turns, etc., the frequency of pressure changes in the upper cylinder chamber 3 and lower cylinder chamber 4 is low, so the orifices 74a and 75a cannot suppress the pressure increase in the back pressure chamber 14.15. Therefore, the oil pressure in the back pressure chamber 14.15 increases, and the backup disks 76, 77 are pushed toward the disk valve 12.13, and the abutment positions move radially outward, opening the disk valve 12.13. The fulcrum at the time of the valve is changed outward, and the back pressure chamber 14.
The hydraulic pressure in Is pushes the disc valve 12.13 through the backup disc 76.77. This increases the pressure when the disc valve opens,
0 in Fig. 1O due to the orifice passage 64 until the valve opens.
A damping force is generated according to the orifice characteristic shown by the 1+dt line, and after the valve is opened, a damping force having a large slope of the valve characteristic shown at C2, dz in FIG. 10 is generated. Furthermore, the back pressure chamber 14.
When the oil pressure in Is rises to P2y pt, the sub-disc valves 28.29 open and C3, d in Fig. 10.
: Generates a damping force with a valve characteristic with a small slope shown in +. Note that the position of contact with the Danosk valve +2-1:l of the backup pressure chamber 14゜15 moves radially outward in proportion to the magnitude of the oil pressure in the back pressure chamber 14゜15. As the vehicle rises, the damping force gradually decreases in inverse proportion as shown by the broken line in FIG.

In this way, the damping force generated can be reduced when the frequency is high, and the damping force generated can be increased when the frequency is low. As a result, when driving on rough pavement, the damping force is reduced, improving ride comfort, and when turning, the damping force is increased, improving handling stability, achieving both ride comfort and handling stability. or planned.

In each of the above embodiments, the piston 5 is provided with the damping force generating mechanism of the present invention, but the present invention is not limited to this, and the damping force generating mechanism of the present invention is provided on the bottom side of a dual-tube hydraulic shock absorber. Good too. That is, the above configuration prevents the flow of oil in the communication path of the partition member that partitions the inside of the inner cylinder and between the inner and outer cylinders (between the inner cylinder and the outer cylinder), which is caused by the sliding of the piston inside the inner cylinder. The damping force generation mechanism is used for control (ψ) (effects of the invention) As explained in detail above, the present invention provides a back pressure chamber on the side opposite to the piston of the disc valve, and also reduces the hydraulic pressure in the back pressure chamber. Since a sub-disc valve is provided that opens and closes due to the hydraulic pressure in the back pressure chamber, the disc valve is suppressed by the hydraulic pressure in the back pressure chamber and generates a damping force with a damping force characteristic with a large slope.When the hydraulic pressure in the back pressure chamber increases further, the sub-disc valve causes It is possible to generate a damping force with a small damping force characteristic, and this combination expands the degree of freedom in setting the damping force characteristic, making it possible to set the optimal damping force characteristic according to the vehicle, and also increasing the damping force characteristic. Since it does not become too large, there is no need to increase the strength of each member of the hydraulic shock absorber.
Increase in weight and cost can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part showing a first embodiment of the hydraulic shock absorber of the present invention, and FIG. 2 shows the relationship between piston loft and shutter when the hydraulic shock absorber shown in FIG. 1 has hard characteristics. 2(a) is a sectional view taken along the IIa-lIc line in FIG. 1, FIG. 2(b) is a sectional view taken along the nb-nb line in FIG.
) is a cross-sectional view taken along the line lIc-lIc in Figure 1, Figure 2(d) is a cross-sectional view taken along the line nd-nd in Figure 1, and Figure 3 is a cross-sectional view taken when the hydraulic shock absorber shown in Figure 1 has soft characteristics. 4 shows a horizontal cross section of the piston rod and shutter shown in FIG. 3, and FIG.
) is a sectional view taken along line IVa-■a in FIG. 3, and FIG. 4(b) is a sectional view taken along line ffb-IVb! in FIG. Cross-sectional view, Figure 4 (C,) is the third
Figure 4(d) is the IV in Figure 3.
d-ffd line sectional view, FIG. 5 is a diagram showing the damping force characteristics of the hydraulic shock absorber shown in FIG. 1, and FIG. 6 is a main part showing the second embodiment of the hydraulic shock absorber of the present invention. 7 is a diagram showing the relationship between the relative position of the piston and the metering bin and the damping force in the hydraulic shock absorber shown in FIG. 6; FIG. 9 is a sectional view taken along line IX-IX in FIG. 8; FIG. 1O is a diagram showing the damping force characteristics of the hydraulic shock absorber shown in FIG. 8; FIG. 11 is a diagram showing the damping force characteristics of a conventional hydraulic shock absorber. 2... Cylinder 3... Cylinder upper chamber 4... Cylinder lower chamber 5... Piston (partition member) 10... Extension side communication passage 11... Contraction side communication passage 12... Extension side Disc valve 13...Compression side disc valve 14...Elongation side back pressure chamber 15...Compression side back pressure chamber 28...Elongation side sub-disk valve 29-...Compression side sub-disk valve 38, 40... ...Bypass passage (first embodiment) 61,
62...Bypass passage (second embodiment) 72, 73-
... Bypass passage (3rd embodiment) Patent applicant Tokiko Co., Ltd. (2 idiots) Fig. 3 32 Fig. 4 Fig. 7 Fig. 8 Fig. 11

Claims (1)

[Claims] (1) The inside of the cylinder is divided into two cylinder chambers by a partition member, and the partition member includes a communication passage that communicates the two cylinder chambers, and a disk that opens and closes using hydraulic pressure in the communication passage to generate a damping force. A back pressure chamber is provided on the opposite side of the disc valve from the partition member, and a cylinder chamber on the side where the disc valve provided with the back pressure chamber generates the hydraulic pressure received from the communication passage, and the back pressure A bypass passage communicating with the chamber is provided, and a sub-disc valve is provided which opens and closes by hydraulic pressure in the back pressure chamber to generate a damping force, and the opening pressure of the sub-disk valve is adjusted to the pressure when the disk valve opens. A hydraulic shock absorber characterized by being set higher than the pressure.