JPH0518509Y2 - - 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.
A variable orifice swing 10 is formed in the rotary valve rotatably inserted therein, and the rotary valve is rotatably operated from the outside via a control rod 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 extension, the piston 2 moves to the left, and the oil in the oil chamber A flows from the extension port 4 to the extension valve 6.
The oil is deflected and flows into the oil chamber B, and due to the resistance at that time, a pressure difference is generated between the oil chambers A and B, and a high expansion-side damping force is generated by the expansion valve 6. At this time, piston rod 3
The amount of oil corresponding to the discharge volume 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 pressure difference 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 13 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 high damping force characteristics a are obtained when the piston speed is medium or high speed.
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 road surface or rough road, 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. To provide a damping force adjusting device for a hydraulic shock absorber which can make the characteristic relatively linear instead of a square-law characteristic, and can independently set the hard and soft characteristics on the rebound side.

<Means for solving the problems> In order to achieve the above purpose, the configuration of the present invention is as follows.
A first expansion-side leaf valve and a first compression-side leaf valve are provided at the mouth ends of the two expansion and compression ports provided on the piston, respectively, so as to be able to open and close freely, and a disk is provided above the piston, and a third valve is provided on the disk. A second expansion-side leaf valve and a second pressure-side leaf valve are provided at the upper and lower ends of the port, respectively, and a bypass is provided in the disk and piston rod to communicate the third port with the lower oil chamber. It is characterized by the provision of a valve that adjusts the area.

<Function> When the bypass is closed, a high expansion/compression damping force is generated by the first expansion side leaf valve and the first compression side leaf valve, and when the bypass is open, the flow flowing through the bypass is A passage and a flow passage through each of the first expansion/compression leaf valves are formed, and an intermediate or low damping force is obtained depending on the opening area of the bypass.

<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 outer cylinder 20 are connected to the lower cap 26 and the bracket 2.
4 to the axle side.

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 with the inner cylinder 17. A reservoir 23 is defined between the outer cylinder 20 and the upper oil chamber 21, which communicates with the reservoir 23 through a passage provided in the bearing and a check seal, and similarly, the lower hydraulic pressure 22 communicates with the reservoir 23 through a base valve. are doing.

At the lower part of the piston rod 19 are a valve stopper 27 and a spacer 28, an upper second expansion leaf valve 29 and a disk 50, a second pressure leaf valve 52 and a plate 51, a first pressure leaf valve 53 and the piston 18. Then, the first expansion-side leaf valve 31, the expansion-side main valve 54, the spring 55, and the piston nut 35 are sequentially inserted in series,
These members are held between the stepped portion of the piston rod 19 and the piston nut 35.

The piston 18 is axially bored with a growth side port 36a and a compression side port 36b which communicate the two upper and lower oil chambers 21, 22.

A first pressure side leaf valve 53 is disposed at the upper mouth end of the pressure side port 36b so as to be openable and closable, and the outer periphery of this leaf valve 53 bends upward during compression. A first growth-side leaf valve 31 is disposed at the lower mouth end of the growth-side port 36a so as to be freely openable and closable, and the outer periphery of this leaf valve 31 bends downward when it is extended. The lower part of the first expansion-side leaf valve is always urged in the closing direction by a spring 55 via the main valve 54.

A disk 50 is provided above the piston 18, and a third port 33 that opens to the upper oil chamber 21 is provided through the disk 50, and a second expansion side port is provided at the upper mouth end of the port 33. A leaf valve 29 is provided so as to be openable and closable, and a second leaf valve 29 is provided at the lower mouth end.
A pressure side leaf valve 52 is provided so as to be openable and closable.

The port 33 is opened and closed via a branch passage 37 to the lower oil chamber 22 via a bypass in the piston rod 19, as will be described later.

The second leaf valve 29 may be used only for the expansion side, but in the embodiment, it is used for both expansion and compression, and the inner periphery is bent downward during expansion, and the outer periphery is bent upward during compression.

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
A through hole 4 is formed in the piston rod 19 in the radial direction through the port 41a.
0 and can be selectively opened and closed. The through hole 40 is always open to the branch passage 37 and the port 33 in the disk 50. rotary valve 3
9 is connected to a control rod 27 which is rotatably inserted into the hole 46. 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, and the rotary valve 39 is changed. The port 41a is operated from fully open to fully closed while adjusting the opening area of the port. 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 port 37 and the passages 40 and 44 are connected to the bypass 3
6c, and this bypass 36c is opened and closed by a rotary valve 39, and when it is open, its opening area is adjusted.

The basic structure of the valve mechanism and passage in the piston section is shown in the circuit diagram of FIG. 3 when the piston is expanded, and is shown in the circuit diagram of FIG. 4 when it is compressed.

Next, we will discuss the operation.

The port 41a of the rotary valve 39 is the passage 40
Suppose that it is fully open for .

When the extension operation is performed in this state, the cracking pressure of the first leaf valve 31 is increased by the spring 55, so in the low and medium speed range, the second extension side leaf valve 29 is pushed open and the lower oil chamber 22 is supplied from the bypass 36c. flows. When the piston speed becomes high and the differential pressure generated in the first leaf valve 29 becomes large, the first expansion-side leaf valve 31 opens. Therefore, in the low and medium speed range, the damping force is determined only by the second rebound leaf valve 29, and in the high speed range, the damping force is determined by the second rebound leaf valve 29, and in the high speed range, the damping force is determined by the damping force shown in FIG. The damping force characteristic becomes Fr2. At this time, oil corresponding to the volume discharged from 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 baize valve, and the oil in the lower oil chamber 22 flows in the opposite direction to the above.

That is, the cracking pressure of the first pressure-side leaf valve 53 is set high, and in the low-medium speed range, the oil in the lower oil chamber 22 flows from the bypass 36c to the port 33 via the passage 37, and the cracking pressure of the first compression-side leaf valve 53 is high. 29
The oil is divided into the upper oil chamber 21 from the second pressure side leaf valve 52. When the piston speed increases, the differential pressure generated between the second expansion side leaf valve 29 and the second pressure side leaf valve 52 increases, and when it becomes greater than the cracking pressure of the first pressure side leaf valve 53, it opens and the port 36b is opened. It also flows into the upper oil chamber 21. Therefore, in the low and medium speed range, damping force is generated by the base valve, the second growth side leaf valve 29, and the second pressure side leaf valve 52, and in the high speed range, the second pressure side leaf valve 53 is further combined in parallel. The low damping force characteristic Fc2 shown in FIG.

On the other hand, oil corresponding to the volume of the intrusion of the piston rod flows out into the reservoir 23 via the base valve.

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 passage 40, oil does not flow into the bypass 36c.

Therefore, during expansion, the oil in the upper oil chamber 21 bends the outer periphery of the first expansion-side leaf valve 31 through the port 36a, and 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 first
A high damping force is generated only by the growth side leaf valve 31, and the damping force characteristics on the growth side are shown in graph Fr1 in Fig. 5.
becomes.

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 Baize valve. On the other hand, part of the oil in the lower oil chamber 22 is transferred from the port 36b to the first oil chamber 22.
It acts only on the pressure side leaf valve 53, and this first
bending the outer periphery of the pressure side leaf valve 53 upward,
It flows out into the upper oil chamber 21. At this time, a high damping force is generated by the first pressure side leaf valve 53 and the base valve, and the compression side damping force characteristic is graph Fc1 in FIG.
It will be shown as follows.

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. In this case, the oil flow is exactly the same as when the damping force is low when the port 41a is fully opened. However, since the port 41a is constricted, the characteristic is that square resistance is added due to the constriction of the variable port 41a, and the first expansion side leaf valve 31
The cracking pressure is reached. As a result, the rebound intermediate damping force characteristic is shown by graph Fr3 in FIG.

Incidentally, oil corresponding to the discharge volume of the piston rod is supplied from the reservoir 23 to the lower oil chamber 22.

On the other hand, during compression operation, the flow is the same as when the port 41a is fully opened. In this case, since the bypass 36a is throttled, a square resistance due to the throttle of the variable port 41a is added, and as a result, the intermediate damping force characteristic on the compression side becomes the intermediate damping force characteristic as shown by characteristic Fc3 in FIG. becomes.

Oil corresponding to the amount of oil that has entered the piston rod flows out into the reservoir 23 from the base valve.

As mentioned above, if the practical range is up to the medium speed range, the high damping force on the rebound side is due to the characteristics of the first rebound side leaf valve 31, and the high damping force on the compression side is due to the characteristics of the first compression side leaf valve 53. The low rebound damping force is determined solely by the characteristics of the second rebound leaf valve 29. Although the damping force of the compression side low damping force is also determined by the combination of the second expansion side leaf valve 29 and the second compression side leaf valve 52, the combined characteristics can be adjusted by appropriately selecting the characteristics of the second compression side leaf valve 52. Can be set arbitrarily. In addition, the range of change in damping force can be set to a wide range by a single valve for high damping force and low damping force, and moreover, it is possible to obtain a substantially linear characteristic for low damping force.

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

B. As is clear from the damping force characteristics in Figure 5, the high damping force characteristics Fr1 and Fc1 and the low damping force characteristics Fr
2 and Fc2, 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 Fc3 are obtained not as square characteristics but as relatively linear characteristics.

C Hard and soft damping force characteristics on the rebound and compression sides can be set independently.

D. A disk is provided above the piston, a bypass is provided on this disk, and a second side leaf valve and a second pressure side leaf valve are provided at each of the upper and lower mouth ends of the port opening into the upper oil chamber.
The position of the piston is lowered due to the provision of the disk, and as a result, the fitting length from the bearing becomes longer, reducing piston friction.
The piston can be moved up and down smoothly.

[Brief explanation of the drawing]

Fig. 1 is a partial longitudinal sectional 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, and Fig. 3 is a circuit diagram of the valve section when extended. , Fig. 4 is a circuit diagram of the valve section during compression, 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 conventional damping force characteristic. This is a graph showing. 17...Cylinder, 18...Piston, 19...
...Piston rod, 21, 22...Oil chamber, 33...
...Third port, 36a... Extension port, 36b...
...Pressure port, 29...Second expansion side leaf valve,
31...First expansion side leaf valve, 36c...Bypass, 39...Rotary valve, 50...Disc, 53...First pressure side leaf valve, 52
...Second pressure side leaf 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. Two expansion ports and a pressure port are formed, a first expansion side leaf valve is provided at the lower mouth end of the expansion port so as to be openable and closable, and a first compression side leaf valve is provided at the upper mouth end of the pressure port so as to be openable and closable. Further, the piston rod is provided with a disk above the piston, a third port opening into the upper oil chamber is formed in this disk, and a second expansion side leaf valve and a third expansion side leaf valve are provided at the upper and lower mouth ends of the third port. The second pressure side leaf valve is provided to open and close freely, a bypass is provided on the disk and the piston rod to communicate the third port with the lower oil chamber, and a valve is provided in the bypass to adjust the opening area of the bypass. Damping force adjustment device for hydraulic shock absorbers. (2) The damping force adjusting device for a hydraulic shock absorber according to claim 1, wherein the valve for adjusting the opening area is a rotary valve provided with a variable port. (3) The damping force adjusting device for a hydraulic shock absorber according to claim 1, wherein the first extension leaf valve is always biased in the closing direction by a spring.