JPH0315055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber capable of adjusting damping force.

Hydraulic shock absorbers absorb the natural vibrations generated by shocks received by suspension springs while a car is running.
To quickly damp vibrations and improve riding comfort,
It is interposed between the vehicle body and the axle.

In addition, in order to damp vibrations as mentioned above, a damping valve is installed on the piston that divides the inside of the cylinder, which is sealed at both ends, into two oil chambers. At times, oil is configured to flow from one side of the oil chamber to the other through the damping valve while generating a predetermined flow resistance to generate a desired damping force.

Furthermore, due to the difference in operating type, such hydraulic shock absorbers include single-effect damping valves that generate damping force only when the piston rod moves in or out, and double-effect valves that generate damping force during both operations. Hydraulic shock absorbers with double-acting damping valves have come to be widely used to improve running performance and stability when turning vehicles at high speeds.

Incidentally, in recent years, hydraulic shock absorbers have been provided that allow occupants to arbitrarily adjust the damping force according to the load applied to the vehicle body. If the damping valve is to be implemented in the stroke, it is necessary to separately attach damping force variable means, such as an externally operated rotary valve, to both the rebound damping valve and the compression damping valve.

As a result, the structure becomes complicated, the damping force adjustment operation becomes troublesome, and when the operation is performed while the vehicle is driving, there arises a problem that the steering stability deteriorates.

This invention solves these conventional problems, and by rotating a single rotary valve by externally operating a control rod, the damping force on the rebound side and the damping force on the compression side can be adjusted separately and simultaneously. The purpose is to make the

Therefore, the present invention provides a cylinder whose both ends are sealed, a hollow piston rod which is freely inserted from one sealed end of the cylinder and has a gas chamber and an oil reservoir chamber inside, and an axial direction of the hollow piston rod end. a first oil hole and a second oil hole drilled at two locations; a cylindrical rotary valve with open ends that rotatably slides on the inner periphery of the hollow piston rod end;
a third oil hole and a fourth oil hole that communicate with the first oil hole and the second oil hole and are provided in the rotary valve; and a control rod that rotates the rotary valve from outside the hollow piston rod. a piston valve provided on the end side of the hollow rod so as to close the lower open end of the rotary valve; a compression side damping valve and a rebound suction check valve provided on the piston valve; and the first oil hole. and a piston attached to the outer periphery of the hollow piston rod between the second oil hole and slidingly in contact with the inner circumferential surface of the cylinder, and a rebound damping valve and a compression side suction check valve provided on the piston. It is something.

An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows one embodiment in detail. Reference numeral 1 denotes a cylinder whose both ends are sealed, and a hollow piston rod 2 is inserted into one sealed end of the cylinder. The hollow piston rod 2 is sealed at one end thereof with a sealing material 3, and is supported by a bearing 4 so as to be freely slidable in the axial direction. The upper end of the hollow piston rod 2 is sealed with a sealing material 5,
The lower end is open downward. On the outer circumference of the lower end of this hollow piston rod 2, first piston rods are provided at two locations in the axial direction.
An oil hole 6 and a second oil hole 7 are bored.

A control rod 8 is inserted into the hollow piston rod 2 and supported in a liquid-tight manner by the sealing material 5, and is driven manually or by a motor as required. A cylindrical rotary valve 9 with open ends is rotatably inscribed in the lower end of the control rod 8, and a third oil hole 10 and a fourth oil hole are provided at two locations in the axial direction of the rotary valve 9. The oil hole 11 is configured to communicate with the first oil hole 6 and the second oil hole 7, respectively.
12 is an open oil hole provided at the upper end of the rotary valve 9.

A piston 13 is inserted into the outer periphery of the hollow piston rod 2 between the first oil hole 6 and the second oil hole 7.
It is fixed by a piston nut 14 screwed into the outer periphery of the end. Reference numeral 15 denotes a communication hole drilled in the piston nut 14 for constant communication with the oil hole 7. Further, the piston 12 is provided with a rebound damping valve 16 and a compression side suction check valve 1.
7 is provided.

18 is provided at the end of the piston nut 14,
It is a piston valve that closes the lower open ends of the hollow piston rod 2 and the rotary valve 9, and the piston valve 18 includes a compression side damping valve 19.
and an extension side suction check valve 20.

The piston 13 divides the inside of the cylinder 1 into an oil chamber 21 and an oil chamber 22. The inside of the hollow piston rod 2 is divided into an oil reservoir chamber 23 and an air chamber 24 as a gas chamber above the oil reservoir chamber 23. It is divided at the interface. Note that the air chamber 24 is located in the cylinder 1.
It is compressed and expanded to compensate for the volume entered by the hollow piston rod 2, and can be made into a gas chamber if necessary.

Next, the operation of the embodiment having such a configuration will be explained.

(a) When the hollow piston rod 2 moves in the direction of extension relative to the cylinder 1.

First, when the third and fourth oil holes 10 and 11 of the rotary valve 9 are not communicating with the first and second oil holes 6 and 7 of the hollow piston rod 2, the upper part of the piston 13 is Due to the movement, the oil pressure in the oil chamber 21 increases, and the oil pressure in the oil chamber 22 tends to decrease to negative pressure. Therefore, in order to maintain the hydraulic balance between these two oil chambers 21 and 22, the oil in the oil chamber 21 is transferred to the expansion side damping valve 1.
It flows into the oil chamber 22 only through the oil chamber 6. This oil flow is throttled in the damping valve 16, creating a high flow resistance and generating a large vibration damping force.

On the other hand, in order to lower the damping force, the rotary valve 9 is rotated by operating the control rod 8, and thereby each oil hole 1
When 0 and 11 are connected to oil holes 6 and 7,
The oil in the oil chamber 21 passes through the expansion damping valve 16 and flows into the oil chamber 22, and also flows into the oil chamber through the first oil hole 6, the third oil hole 10, and the expansion side suction check valve 20. The oil that flows into 22 and further passes through the oil holes 6 and 10 is
The oil is passed through the open oil hole 12 provided in the upper part of the rotary valve 9 to the oil reservoir chamber 23 in the hollow piston rod 2.
It also flows inside. Note that the air in the air chamber 24 is compressed by the oil flowing into the oil reservoir chamber 23.

By the way, in this case, the other oil holes 7,
11 is also in communication, but during the extension stroke, the extension side suction check valve 20 opens immediately and widely, so that the oil introduced into the hollow of the rotary valve 9 does not pass through the oil holes 7 and 11. Instead, it flows into the oil chamber 22 via this extension side suction check valve 20. As a result, the oil flows into the oil chamber 22 through the extension side suction check valves other than the extension damping valve 16 in the oil chamber 23, so that the damping force can be reduced.

Therefore, the oil in the oil chamber 22 is
The oil passes through the pressure side damping valve 20 of No. 8 and flows into the oil reservoir chamber 23 from the hollow of the rotary valve 9 .
Therefore, the compression side damping valve 20 generates a predetermined vibration damping force. On the other hand, when the piston 13 acts on the pressure side, the pressure side suction check valve 17 provided thereon is immediately opened, so oil flows quickly from the oil chamber 22 to the oil chamber 21, and both oil chambers 21 , 22 come to be balanced. Therefore, the vibration damping force on the compression side does not become as large as the vibration damping force on the extension side.

On the other hand, in order to reduce the vibration damping force on the pressure side, the control rod 8 was operated to rotate the rotary valve 9, thereby communicating the oil holes 10 and 11 with the oil holes 6 and 7, respectively. In this case, the oil in the oil chamber 22 flows into the oil reservoir chamber 23 through the pressure side damping valve 19, and
Oil flowing into the oil chamber 21 through the pressure side suction check valve 17 goes around the outer periphery of the hollow piston rod 2, passes through the oil holes 6 and 10, and flows into the oil reservoir chamber 23. Furthermore, the oil in the oil chamber 22 flows through the oil holes 7 and 11, into the hollow of the rotary valve 9, and through the oil hole 12 into the oil reservoir chamber 23. For this reason, the oil hole 6,
10 and the oil holes 7, 11, the damping force is reduced by the amount that flows through the oil holes 6, 11.
The oil that has entered the oil reservoir chamber 23 through the oil holes 7 and 11 compresses the air in the air chamber 24 and acts to compensate for the volume of the hollow piston rod 2 entering the cylinder 1.

In other words, when reducing the damping force by communicating the oil holes 6 and 10 and communicating the oil holes 7 and 11, on the extension side, oil passes through one of the oil holes 6 and 10. On the compression side, by allowing oil to pass through both the oil holes 6 and 10 and oil holes 7 and 11, the damping force can be reduced. ing. In this case, by arbitrarily selecting the sizes of the oil holes 10 and 11 provided in the rotary valve 9, the magnitude of the damping force on the extension side and the compression side can be arbitrarily selected.

FIGS. 2a and 2b are cross-sectional views of the structure of the rotary valve 9 in which the rotation of the rotary valve 9 changes only the damping force on the compression side without changing the damping force on the extension side. In the same figure, 10
a, 10b and 11a, 11b are oil holes provided at two opposite locations on the upper and lower sides of the rotary valve 9, and although the opening diameters of the oil holes 10a, 10b are equal, the opening diameter is larger than that of the oil hole 11a. It's summery.

Such oil holes 10a, 10b, 11a, 11b
In the rotary valve 9 with the rotary valve 9, the oil holes 10a and 11a are connected to the oil holes 6 and 7 of the hollow piston rod by rotating it, and the oil holes 10b and 11b are connected to the oil holes 6 and 7 of the hollow piston rod. The flow rate of oil flowing through the oil hole 7 via the oil holes 11a and 11b during the pressure stroke differs between the cases where they are communicated with each other. Therefore, by rotating the rotary valve 9, the damping force on the extension side does not change, but the damping force on the compression side can be changed. In addition, the oil holes 10a, 10b, 11a,
By arbitrarily selecting the size and number of 11b, it is possible to adjust the damping force only on the extension side or on both the extension side and the compression side at the same time. In addition,
In order to obtain the same effect, the hollow piston rod 2 is provided with a plurality of oil holes with different opening diameters, and the rotary valve 9 is provided with one oil hole at the top and one at the bottom. It is also possible to selectively communicate each oil hole with one of the plurality of oil holes of the hollow piston rod 2.

As explained in detail above, according to this invention,
The rotary valve rotatably fitted into the hollow piston rod is rotated by an external operation, and the oil hole provided in the hollow piston rod and the oil passage provided in the rotary valve are communicated or disconnected. Between the separated oil chambers and between these and the oil sump chamber in the hollow piston rod,
By allowing oil to flow in parallel with the damping valve, vibration damping force can be adjusted arbitrarily according to the size of the load on the vehicle, and a dual-effect valve for damping force can be used. Even in this case, the advantage is that the damping force adjustment on the rebound side and the compression side can be performed individually and simultaneously with only a single operation of the control rod.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a hydraulic shock absorber according to the present invention, FIG. 2 a is a cross-sectional view taken along the line A-A in FIG.
is also a sectional view taken along line B-B. 1...Cylinder, 2...Hollow piston rod,
6, 7...Oil hole, 8...Control rod, 9
... Rotary valve, 10, 11, 12 ... Oil hole, 13 ... Piston, 16 ... Rebound damping valve, 17 ... Compression side suction check valve, 18 ...
Piston valve, 19... Compression side damping valve, 20
...Rebound side suction check valve, 21, 22...
Oil chamber, 23... oil reservoir chamber, 24... gas chamber.

Claims (1)

[Claims] 1. A cylinder sealed at both ends; a hollow piston rod inserted into and out of one sealed end of the cylinder and having a gas chamber and an oil reservoir chamber inside;
A first oil hole and a second oil hole bored at two locations in the axial direction of the hollow piston rod end; a cylindrical rotary valve with open ends that rotatably slides on the inner periphery of the hollow piston rod end; a third oil hole and a fourth oil hole provided in the rotary valve and communicating with the first oil hole and the second oil hole, respectively; and a control rod that rotates the rotary valve from outside the hollow piston rod. , a piston valve provided on the hollow rod end side so as to close the lower open end of the rotary valve, a compression side damping valve and a rebound side suction check valve provided on the piston valve, and the first oil hole and the first oil hole. A hydraulic shock absorber comprising a piston attached to the outer periphery of a hollow piston rod between two oil holes and slidingly in contact with the inner circumferential surface of the cylinder, and an extension side damping valve and a compression side suction check valve provided on the piston. 2. The hydraulic shock absorber according to claim 1, wherein a plurality of first oil holes and a plurality of second oil holes are provided in the hollow piston rod. 3. The hydraulic shock absorber according to claim 1, wherein the rotary valve is provided with a plurality of third oil holes and a plurality of fourth oil holes. 4. The hydraulic shock absorber according to claim 1, wherein the control rod is driven by a motor.