JPS5872744A - Device for adjusting damping force of plural-cylinder hydraulic buffer - Google Patents

Abstract

PURPOSE:To always obtain an optimal damping force under various operating conditions, by providing a damping force adjusting means having various orifices in series with damping valves, so that the width of adjustment of the damping force can be made large. CONSTITUTION:A piston 4 is fitted with damping valves 12, 13 which are placed in parallel with each other so that the valves are opened for one direction at elongation and contraction respectively. Working oil flows through a damping force adjusting means 15 and the damping valves 12, 13. In the adjusting means 15, a disc 18 having plural orifices 17 different in diameter is fitted on the tip of an operating rod 16 which extends through a piston rod 5 and can be rotated. The effective passing diameter (orifice diameter) of passages 19, 20 communicating with the damping valves 12, 13 is increased or decreased by the rotation of the rod 16. Since all the working oil is caused to flow through the variable orifices in series with the damping valves 12, 13 at any of the elongation and contraction, the damping force can be adjusted in a wide range.

Description

[Detailed description of the invention]

The present invention allows adjustment of damping force in a dual-tube hydraulic shock absorber for vehicles! ! : Concerning the improvement of profanity. A hydraulic shock absorber that makes it possible to adjust the damping force according to the operating condition fl is used, for example, in JP-A-54-117=
What was disclosed in the No. 186 publication is that a variable orifice is installed in parallel with a damping valve in the screw valve.

[ ], the attenuation resistance is adjusted by increasing or decreasing the distance between the orifices by external operation. However, in this case, even if the variable orifice is fully closed, there is an oil flow from the damping valve, so the damping force cannot be increased that much while the orifice is fully closed and fully opened. It was not always possible to obtain optimal damping characteristics depending on the operating conditions. An object of the present invention is to enable the damping force to be adjusted to a large extent so that an appropriate damping force can be maintained at all times in response to a wide range of operating conditions. In the present invention, a cylinder is housed in a cylinder so as to be freely slidable, and an oil chamber is defined above and below the oil chamber, and a reservoir chamber is formed between the oil chamber and the oil chamber on the outside of the cylinder. , A base valve is installed at the bottom of the cylinder. It is composed of a spool that opens a communication side passage between the upper oil chamber and the reservoir chamber in response to hydraulic pressure, and the piston is equipped with expansion side and compression side damping valves in parallel ('j1 A variable orifice is installed in series with both of these damping valves. Therefore, in the compression side stroke, the upper oil chamber communicates with the reservoir chamber via the spool, and the check valve is closed, so that all the hydraulic oil in the lower oil chamber is compressed. It flows from the upper oil chamber to the reservoir chamber through the piston damping adjustment means and the compression side damping valve, and in the rebound stroke, communication between the upper oil chamber and the reservoir chamber is cut off.
All of the hydraulic oil flows from the rebound damping valve to the lower oil chamber via the damping force adjusting means, and in both cases, the entire amount of the moving hydraulic oil flows to the damping force adjusting means, so that the damping force adjusting means The damping characteristics can be greatly changed in response to changes in the wear. Embodiments of the present invention will be described below based on the drawings. In FIG. 1, an outer cylinder 2 and an inner cylinder 3 are disposed concentrically inside an outer shell 1, and a piston 4 can be freely slid on the inner cylinder 3.
will be installed. The piston rod 5 of the piston 4 extends outside through the bearing 6 and is connected to the vehicle body via a bracket (not shown). A bracket 8 is fixed to the lower part of the outer shell 1,
An axle (not shown) is connected thereto, and a base valve 9 is located at the bottom of the outer and inner cylinders 2.3. Oil chambers Δ and B are formed below −F of the piston 4, and an oil chamber C is formed between the inner cylinder 3 and the outer cylinder 2, and the oil chambers A and C communicate with each other through a passage 10 of the bearing 6. do. A reservoir chamber whose upper portion is a gas chamber E is formed between the outer cylinder 2 and the outer shell 1, and this reservoir chamber is always in communication with the valve chamber E of the base valve 9 via a passage 11. Screw! Damping valves 12.13 that open in one direction on the expansion side and compression side are arranged in parallel in the damping valves 12.13 on the expansion side and compression side, respectively, and hydraulic oil is supplied to these damping valves 12.13 via the damping force adjustment stage 15. circulate. This adjustment means 15 is operated by rotating through the piston rod 5.A circle 1118 having a plurality of orifices 17 of different diameters is attached to the tip of the rod 16, and rotation of the rod 16 causes each damping valve 12. The effective passage diameters (orifice diameters) of the passage ports 19 and 20 communicating with 13 are increased or decreased. Note that 21 is a case that houses the openings 19 and 20 and the disk 18, and is screwed onto the piston rod 5. On the other hand, in the base valve 9, a spool 24 is slidably housed in an inner hole 23 of a valve case 22 fixed to the inner and outer cylinders 3.2. . The spool 24 is urged upward by a spring 25 and moves to a position where the pressure in the oil chamber B and the pressure in the valve chamber F are balanced. A port 26 connecting the oil chamber B and the valve chamber is provided at the center of the spool 24, and this port 26 is pushed by a spring 28 during the compression stroke to close the valve 27-5-. Reference numeral 29 is a support frame for the check valve 27. The spool 2/I has a side passage 30 that communicates with the passage 26 and the outer circumference.
This side passage 30 communicates with an oil chamber C formed in the valve case 22 and selectively connects with a through hole 31 as the spool 24 is displaced. A dashpot chamber 34 is formed between the spool 24 and the spool 24 to prevent sudden upward movement of the spool 24. The device is configured as described above, and its operation will be explained next. In the extension stroke of the piston rod 5, the upper oil chamber A contracts.
The pressure in the oil chamber 8 increases, and the pressure in the expanding oil chamber 8 tends to decrease. Therefore, the spool 24 of the base valve 9 is moved upward by the spring 25 and the oil pressure in the valve chamber F, and
While cutting off the communication between 0 and the through hole 31, the enlarged oil chamber B
When the valve 27 opens, the passage 11 is opened from the reservoir chamber.
, hydraulic oil is introduced via the valve chamber F. -6- On the other hand, the hydraulic oil in the partial oil chamber Δ is the same as the normal oil chamber C.
As described above, the oil flows through the expansion side damping valve 12 and flows into the lower oil chamber B in order to cut off communication through the through hole 31, seal it, and increase the pressure. Now, since the vent 19 is placed in series with the damping valve 12, all of the hydraulic fluid passes from the vent 19 through the variable orifice 17. Therefore, the opening degree of the Δ refit 17 can be adjusted by turning the disk 18. As shown in FIG.
The actual damping force can be adjusted to a large value according to the orifice diameter. Note that FIG. 2 shows control states in two positions: when the orifice 17 is open (solid line) and when it is closed (solid line). (However, when the orifice 17 is closed, a high damping force is generated due to the leakage flow rate.) Next, in the pressure side stroke where the piston rod 5 enters, the pressure in the lower oil chamber B increases, contrary to the above, and the pressure in the upper oil chamber △ increases. Pressure decreases. Therefore, the check valve 27 of the base valve 9 closes, and the spool 24 moves downward while deflecting the spring 25 by -7-, connecting the side passage 30 with the through hole 31 as shown in the figure. Therefore, all of the hydraulic oil in the shrinking oil chamber B is
The upper oil chamber A passes through the pressure side damping valve 13 from the vent 20 of the engine 4.
The oil chamber C communicates from the valve chamber F to the reservoir chamber through the through hole 31 and the side passage 30 as described above. Therefore, it flows from the passage 10 to the reservoir room. Therefore, even on this pressure side, all the hydraulic oil in the oil chamber B passes through the orifice 17, and the damping force can be changed significantly by changing the diameter of the orifice as on the expansion side. Next, the embodiment shown in FIG. 3 will be explained. In this case, the outer cylinder 2 of FIG.
It communicates with the through hole 31 of No. 2. Therefore, as shown in the figure, the spool 24 of the base valve 9
In the pressure side stroke in which the oil moves downward, the excess oil in the upper oil chamber Δ flows out from the passage 10 through the pipe 40 to the through hole 31, the side passage 30, and the valve chamber F1 reservoir chamber. The structure can be simplified by omitting the outer cylinder. As described above, according to the present invention, all the hydraulic oil is made to flow through the damping force adjustment means (variable orifice) in series with the damping valve in both the expansion and compression strokes, so that the orifice diameter By selecting , the damping force can be adjusted to 11], which has the effect of providing the optimum damping characteristic according to the operating condition 1!1. In addition, the check valve of the base valve is lnl on the expansion side stroke.
Therefore, insufficient suction will not occur, and the occurrence of cavitella and foreign products can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing damping force characteristics, and FIG. 3 is a sectional view of a second embodiment. 1... Outer shell, 2... Inner cylinder,
4... Piston, 5... Piston rod, 9...
Base valve, 10... Passage, 12.13... Damping valve, 15...-9- damping force adjustment stage 1, 16... Operating rod, 17... Orifice, 18... Disc, 19.20... Entrance, 2
2...Valve case, 24...Spool, 25...
・Spring, 26...Port, 27...Check valve, 30...Side channel, 31...Through hole, 40...Pipe, Δ, B, G,...Oil chamber, 1 ]...Reservoir room, F
...Valve chamber, patent applicant Kayaba Kogyo Co., Ltd. -10- Figure 2 Figure 3

Claims (1)

[Claims] A piston is housed inside the cylinder so that it can freely slide, and an oil chamber is defined above and below the piston.
A base valve is installed at the bottom of the cylinder to form a reservoir chamber between the cylinder and the pressure side. In response to the rising oil pressure in the lower oil chamber, the communication side passage between the lower oil chamber and the reservoir chamber is opened (
The piston is composed of a spool, a compression side damping valve, and a damping force adjusting means with a variable orifice is arranged in series with both damping valves. Damping force adjustment device for hydraulic shock absorbers.