JPH0516423Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a damping force adjustment device for a hydraulic shock absorber in a two-wheeled vehicle, a four-wheeled vehicle, etc., which absorbs and alleviates impact energy from a road surface.

<Prior Art> As a conventional hydraulic shock absorber of this type, one having a structure shown in FIG. 6 is known.

A piston rod 3 is movably inserted into the cylinder 1 via a piston 2. The piston 2 divides the cylinder 1 into two upper and lower oil chambers A and B, and a reservoir chamber C is formed on the outer periphery of the cylinder 1. It is sectioned.

The piston 2 is provided with an expansion port 4 and a pressure port 5 that communicate the two oil chambers A and B, and an expansion valve 6 that is biased by a spring is provided at the outlet end of the expansion port 4 so as to be openable and closable. Similarly, a pressure valve 7 is provided at the mouth end of the pressure port 5.

A communication hole 13 and a passage 14 are formed in the piston rod 3 to communicate the oil chambers A and B, and a variable orifice 10 is formed in the rotary valve rotatably inserted into the piston rod 3. Rotation operation is performed via the door 15.

A piston nut 16 is provided at the lower end of the piston rod 3 for tightening and holding a piston, etc., and this piston nut has an expansion orifice facing the passage 14 and a check valve incorporated therein.

A base valve is provided at the bottom of the cylinder 1. In the above hydraulic shock absorber, variable orifice 10
is closed, and during expansion, the piston 2 moves to the left, bends the expansion valve 6 from the expansion port 4 of the oil chamber A, and flows into the oil chamber B. Due to the resistance at that time, a differential pressure is created between the oil chambers A and B. occurs, and a high expansion-side damping force is generated by the expansion valve 6. At this time, an amount of oil corresponding to the discharge volume of the piston rod 3 is supplied from the reservoir chamber C to the oil chamber B via the base valve.

On the other hand, during compression, piston 2 moves to the right and oil chamber B
The oil flows from the pressure port 5 into the oil chamber A by deflecting the pressure valve 7, and at this time, a differential pressure is generated between the oil chambers A and B, resulting in a high damping force during compression. At this time, the oil corresponding to the intrusion volume of the piston rod 3 returns the oil in the oil chamber B to the reservoir chamber C from the base valve, but the pressure in the oil chamber B increases due to the resistance of the base valve, and a damping force due to the base valve is also generated. .

When the control rod is further rotated and the variable orifice 10 is opened to the communication hole 13, in addition to the flow path through the expansion valve 4 during expansion, the flow from the variable orifice 10 passes through the passage 14 and from the expansion orifice in the piston nut 16. Oil flows into oil chamber B.
Therefore, the resistance is smaller than in the above case,
The differential pressure between oil chambers A and B also becomes smaller, and a lower damping force is generated. In this case, the extension orifice in the piston nut is usually set smaller than the variable orifice, and the low damping force during the extension stroke is controlled by this extension orifice.

Next, during the compression stroke, in addition to the flow path through the pressure valve 7, a flow is generated through the passage 14 and the variable orifice 10, and as a result, the resistance becomes smaller than the high damping force described above, and the oil chambers A, B The differential pressure between them is also small, and a low damping force is generated. The damping force at this time is mainly controlled by the variable orifice 10.

<Problems to be solved by the invention> The damping force characteristics of the above hydraulic shock absorber are shown in FIG. 7, and the high damping force characteristics when the variable orifice 10 is closed are shown in graphs a1 and a2. Graph b shows the low damping force characteristics when 10 is opened.
1, b2. That is, in the low speed range of the piston, the area of the orifice that bypasses the expansion valve 6 and the pressure valve 7 is changed, and the generated damping force of the square characteristic can be changed relatively widely. Since the set pressure is constant and does not change regardless of pressure or flow rate, expansion valve 6 and pressure valve 7 are
Even though the damping force (or differential pressure between oil chambers A and B) has a square characteristic with respect to the piston speed (or oil flow rate) until valve 6 or 7 opens, the valve characteristics after valve 6 or 7 open are The graphs are b1 and b2, and when the piston speed is medium or high speed, the damping force characteristic a is high.
There is not that much difference compared to 1 and a2. Therefore, there is a problem in that the desired low damping force cannot be obtained in situations where a high piston speed occurs, such as on a rough or rough road surface, even on the riding surface of an automobile.

Therefore, the purpose of the present invention is to obtain a large change in damping force from a low speed range to a high speed range of piston speed, and to obtain a large difference between high damping force and low damping force, and also to obtain a large difference in damping force between high and low damping forces. It is an object of the present invention to provide a damping force adjusting device for a hydraulic shock absorber which can have a relatively linear characteristic instead of a square-law characteristic, and can also provide a difference in low-speed characteristics of intermediate damping force.

<Means for solving the problem> In order to achieve the above purpose, the structure of the present invention is as follows.
A piston rod is movably inserted into the cylinder via a piston, and the piston divides the cylinder into two upper and lower oil chambers, and the piston has a first port and a second port that communicate with the two oil chambers. The first port, which is commonly used for expansion and compression, is located at the upper mouth end of the first port.
A second leaf valve for common expansion and compression is provided at the lower mouth end of the second port so as to be openable and closable, and a through hole opens into the lower oil chamber of the second leaf valve. is always urged in the closing direction by a spring through a hollow valve provided with a piston rod, and the piston rod is provided with a branch passage that communicates the first port and the upper oil chamber with the lower oil chamber;
This branch passage is characterized by being provided with a valve for adjusting the opening area of the branch passage.

<Function> When the branch passage is closed, a high damping force is generated due to expansion by the second leaf valve, and when the branch passage is open, the flow path flowing through the first port and the branch passage is , a flow path that flows from the upper oil chamber through the branch passage, and a flow path that flows through the second port and the second leaf valve are formed. Damping force can be obtained.

<Example> An example of the present invention will be described below based on FIGS. 1 to 5.

A piston rod 19 is movably inserted into the inner cylinder 17 via a piston 18, and the piston rod 19 penetrates the bearing and packing and projects to the outside.

The upper end of the piston rod 19 is connected to the vehicle body, and the inner cylinder 17 and the outer cylinder 20 outside thereof are connected to the axle via a lower cap 26 and a bracket 24.

The piston rod 19 has a cover 2 extending downward.
5 are connected.

Inside the inner cylinder 17, two upper and lower oil chambers 21 and 22 are partitioned by a piston 18, and an outer cylinder 20 is provided on the outside of the inner cylinder 17 and is arranged concentrically therewith. A reservoir 23 is defined between the cylinder 20, and the upper oil chamber 21 communicates with the reservoir 23 via a passage provided in the bearing and a check seal, and the lower oil chamber 22 communicates with the reservoir 23 via a base valve. are doing.

At the bottom of the piston rod 19 are a valve stopper 27, a spacer 28, an upper first leaf valve 29, a piston 18, a spacer 33, a lower second leaf valve 31, a valve seat 32, a hollow valve 45, a spring 34, and a piston nut. 35 are successively inserted in series, and these members are held between the stepped portion of the piston rod 19 and the piston nut 35.

The piston 18 has a plurality of first ports 36a and second ports 36b for expansion and compression, which communicate the two upper and lower oil chambers 21 and 22 in the axial direction.

A first leaf valve 29 for both expansion and compression is arranged at the upper mouth end of the first port 36a so as to be openable and closable.
The inner circumference of this leaf valve 29 bends downward when it is expanded, and its outer circumference bends upward when it is compressed.

A second leaf valve 31 for both expansion and compression is arranged at the lower mouth end of the second port 36b so as to be openable and closable.
The outer periphery of this leaf valve 31 bends downward when it is expanded, and the inner periphery bends upward when it is compressed.

The valve 45 is in contact with the lower surface of the second leaf valve 31, and a spring 34 is interposed between the valve 45 and the spring seat 35a of the piston nut 35, and the spring 34 is always connected to the second leaf valve via the valve 45. 31 in the closing direction.

The valve 45 is bent to have an L-shaped cross section and has a chamber 42 inside.
A through hole 43 is formed in the body, and the chamber 42 communicates with the lower oil chamber 22 via the through hole 43.

A passage 44 and a hole 46 that open to the lower oil chamber 22 are formed in the piston rod 19, and a hollow cylindrical stopper 47 and a cylindrical rotary valve 39 are inserted into the passage 44. A passage 41 communicating with the variable port 41a
and a plurality of variable orifices 51 having different diameters are formed, and this passage 41 is selectively opened and closed via a port 41a to a through hole 40 bored in the piston rod 19 in the radial direction, and is also connected to the piston rod via the variable orifice 51. A through hole 50 provided therein is selectively opened and closed, and the through hole 50 is always open to the upper oil chamber 21. That is, the rotary valve 39 is connected to the control rod 27 rotatably inserted into the hole 46, and when the control rod 27 is rotated from outside the upper end of the piston rod 19, the rotary valve 39 rotates in the same direction. The port 41a, which is a variable port of the rotary valve 39, and the variable orifice 51 are operated from fully open to fully closed while adjusting the opening area of the variable orifice 51.

The port 41a is composed of a plurality of ports having different inner diameters, and an arbitrary port may be selected and opened as a passage by rotating a rotary valve.

The piston 18 is integrally formed with an annular chamber 38 branching inward from the middle of the port 36a, and the first port 36a and the chamber 38 are connected to the piston rod 19.
It communicates with the passageway 40 of.

The through hole 40 and the passage 44 constitute the first branch passage 36c, and the through hole 50 and the passage 44 constitute the first branch passage 36c.
constitutes a second branch passage 36d, and these branch passages 36c and 36d are opened and closed by a rotary valve 39, and when open, the opening area thereof is adjusted.

The basic structure of the valve mechanism and passage in the piston section is shown in the circuit diagram of FIG.

Next, we will discuss the operation.

It is assumed that the port 41a of the rotary valve 39 and the variable orifice 51 are fully opened to the through holes 40 and 50.

When the extension is operated in this state, the oil in the upper oil chamber 21 bends the inner circumference of the first leaf valve 29 and flows out from the first port 36a to the lower oil chamber 22 via the first branch passage 36c. . Similarly, the second leaf valve 31 is bent through the second port 36b, and the oil flows out into the lower oil chamber 22, and further flows out into the lower oil chamber 22 from the variable orifice 51 through the second branch passage 36d. At this time, the pressure-flow characteristic that combines the flows of the first leaf valve 29 and the variable orifice 51 is shown by PBR1 in FIG.
The pressure-flow characteristics of the leaf valve 31 are shown by Pr1, and the pressure-flow characteristics of the entire piston part are
As a result, the rebound damping force characteristic at that time is shown as Pr2, which is a composite of PBR1 and Pr1, and the Fr
2, resulting in a relatively linear and low damping force.
At this time, oil corresponding to the discharge volume of the piston rod 19 is refilled from the reservoir 23 into the lower oil chamber 22 without resistance by opening a check valve provided in the base valve.

Furthermore, during compression operation, pressure builds up due to the resistance of the base valve, and the oil in the lower oil chamber 22 flows in the opposite direction to that described above.

On the other hand, the oil corresponding to the intrusion volume of the piston rod flows out into the reservoir 23 via the base valve. At this time, the combined pressure-flow characteristics of the first leaf valve 29 and the variable orifice 51 are as shown in FIG.
The pressure-flow characteristics of the second leaf valve 31 are shown as PBC1 in FIG. The damping force characteristic becomes a relatively linear low damping force characteristic shown by graph Fc2 in FIG.

Next, rotate the rotary valve 39 and
When 1a is fully closed, high damping force can be obtained.

That is, when the port 41a is blocked from the through hole 40 and the variable orifice 51 is blocked from the through hole 50, oil does not flow into the first and second branch passages 36c and 36d.

Therefore, during expansion, oil in the upper oil chamber 21 acts on the second leaf valve 31 through the second port 36b. At this time, the second leaf valve 31 uses the valve seat 32 as a fulcrum and its outer periphery is bent downward against the valve 45 and the spring 34, and the oil in the second port 36b flows out into the lower oil chamber 22.

On the other hand, the oil equivalent to the volume discharged from the piston rod 21 is replenished from the reservoir 23 into the lower oil chamber 22 via the check valve of the base valve. In this case, the second
The pressure-flow rate characteristic of the leaf valve 31 is shown by the graph Pr1 in FIG. 4, and as a result, the damping force characteristic on the expansion side becomes the graph Fr1 in FIG.

Further, during the compression operation, oil corresponding to the volume of the piston rod intrusion first flows out from the lower oil chamber 22 through the base valve to the reservoir 23, and the pressure in the lower oil chamber 22 increases due to the resistance of the base valve. On the other hand, some of the oil in the lower oil chamber 22 is drained through the through hole 43 of the valve 45.
The oil acts on the second leaf valve 31 through the chamber 42, bends the inner circumference of the leaf valve 31 upward, and further flows out into the upper oil chamber 21 from the second port 36b. At this time, the pressure-flow characteristics of the second leaf valve 31 are shown by graph Pc1 in FIG.
As a result, the compression side damping force characteristics are as shown in the graph in Figure 5.
It is shown as Fc1.

Next, when the port 41a of the rotary valve 39 is half-opened, or when a small port is selected from a plurality of ports, an intermediate damping force is generated depending on the opening amount of the port 41a.

The operation during extension is exactly the same as when the damping force is low.
However, since the variable port 41a is narrowed and the variable orifice 51 is also small, the pressure-flow characteristic that combines the flows of the first leaf valve 29 and the variable orifice 51 is shown by PBR2 in FIG. 4, and the small flow rate However, the differential pressure generated increases. Therefore, the pressure-flow characteristics of the entire piston section are Pr1 in Fig. 4.
The characteristics of Pr3 are synthesized with PBR2, and as a result, the damping force becomes Fr3 in Fig. 5, which is an intermediate damping force with a difference from the low damping force in the low speed range compared to the case without the variable orifice shown by the broken line a. characteristics are obtained.

Compression operation is exactly the same as at low damping force. However, the variable port 41a is narrowed and the variable orifice 51
The first leaf valve 2 is also smaller.
9 and the combined pressure of the flow of variable orifice 51 -
The flow rate characteristics are shown by PBC2 in Fig. 4, and the differential pressure generated becomes large even with a small flow rate. Therefore, the pressure-flow characteristics of the entire piston section are Pc1 in Fig. 4.
The characteristics of Pc3 are synthesized with PBC2, and as a result, the damping force becomes as shown in Fc3 in Figure 5, which has a lower damping force in the low speed range compared to the case without the variable orifice shown by the broken line b. intermediate damping force characteristics can be obtained.

Oil corresponding to the volume of piston rod penetration flows out into the reservoir 23 via the base valve.

<Effect of invention> According to the present invention, the following effects can be obtained.

B. As is clear from the damping force characteristics in Figure 5, the low damping force characteristics Fr2 and Fc2 and the high damping force characteristics Fr
1 and Fc1, a large difference in damping force is obtained from the low speed range to the high speed range, and as a result, the ride comfort of cars, etc. is improved in situations where high piston speeds occur, such as on rough or rough roads. do.

(b) Similarly, as can be seen from FIG. 5, the low damping force characteristics Fr2 and Fc2 are obtained not as square characteristics but as relatively linear characteristics.

C. The characteristics of the intermediate damping force in the low speed range have a large difference compared to the low damping force.

D. Since the first and second leaf valves are used for expansion and compression, there is no need to provide separate leaf valves for expansion and compression sides, and the overall length of the piston can be shortened.

E. During compression, the oil in the lower oil chamber can be made to act on the second leaf valve through the through hole.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal front view of a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the piston section of Fig. 1, Fig. 3 is a circuit diagram of the valve section, and Fig. 4 is a graph showing pressure-flow characteristics, Fig. 5 is a graph showing damping force characteristics, Fig. 6 is a partially longitudinal front view of a conventional hydraulic shock absorber, and Fig. 7 is a graph showing conventional damping force characteristics. . 17...Cylinder, 18...Piston, 19...
...Piston rod, 21, 22...Oil chamber, 36a
...First port, 36b...Second port, 2
9...first leaf valve, 31...second leaf valve, 36c, 36d...branch passage, 39...
...Rotary valve.

Claims (1)

[Claims for Utility Model Registration] (1) A piston rod is movably inserted into the cylinder via a piston, the piston defines two upper and lower oil chambers in the cylinder, and the two oil chambers communicate with the piston. A first port and a second port are formed, and a first leaf valve for expansion and compression is provided at the upper mouth end of the first port so as to be openable and closable, and a first leaf valve for expansion and compression is provided at the lower mouth end of the second port. A second leaf valve for shared pressure is provided so that it can be opened and closed freely.
The leaf valve is always biased in the closing direction by a spring through a hollow valve with a through hole that opens into the lower oil chamber, and the piston rod has the first port and the upper oil chamber connected to the lower oil chamber. 1. A damping force adjustment device for a hydraulic shock absorber, characterized in that a branch passage communicating with the hydraulic shock absorber is provided, and a valve for adjusting an opening area of the branch passage is provided in the branch passage. (2) The hydraulic pressure according to claim 1 of the utility model registration claim, wherein the valve for adjusting the opening area is a rotary valve provided with a variable port that opens and closes in the first port and a variable orifice that opens and closes in the upper oil chamber. Shock absorber damping force adjustment device.