JP2958333B2 - Hydraulic shock absorber valve device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber interposed between a vehicle body and an axle of a vehicle such as an automobile to attenuate vibration from a road surface, and more particularly to a pressure fluctuation of an oil chamber. The present invention relates to a valve device for a hydraulic shock absorber, which prevents a click noise caused by a vibration of a piston rod.

[Prior Art] In recent automobiles, noise has been reduced and noises such as engine noise and wind noise entering the vehicle interior have been reduced. For this reason, even the sound of the level which was not a problem in the past has come to be close-up.

The types of sounds emitted from the hydraulic shock absorber include a tapping sound (squealing sound) and a swift sound (shoe-shooting sound).

The noise is 10-30km / H on a slightly rough paved road.
This is the room noise generated when the vehicle is running at a low speed. The fluctuation in the pressure in the oil chamber generated when the hydraulic shock absorber switches between extension and pressure causes the piston rod to vibrate. Is transmitted to the vehicle body via the vehicle, and the vehicle body resonates and is generated.

On the other hand, the swoosh noise is a room sound generated when the vehicle travels at 20 to 50 km / H on a rough road having a large unevenness.
That is, when the hydraulic oil passes through the throttle portion of the valve in the hydraulic shock absorber, it becomes a high-speed jet to lower the pressure, and the gas dissolved in the oil becomes bubbles. These bubbles collapse and disappear when the ambient pressure increases downstream, but high pulse pressure and noise are generated in the process of generation and disappearance of the bubbles.

In the past, various countermeasures against squish noise have been taken for the above abnormal noise, but countermeasures against popping noise are still insufficient.

For example, a conventional hydraulic shock absorber shown in FIG. 6 has been developed.

In this configuration, a piston rod 3 is movably inserted into a cylinder 1 via a piston 2 serving as a partition member, and the piston 2 defines two upper and lower oil chambers 4 and 5 in the cylinder 1. The piston 2 is formed with an expansion port 6 and a pressure port 7 which communicate the two oil chambers 4 and 5, and a spacer 8 is provided at an outlet of the expansion port 6.
The extension side leaf valve 10 supported by the stopper 9 through the opening is provided to be openable and closable, and the check valve 11 supported by the stopper 13 through the spacer at the outlet of the pressure port 7 is provided to be openable and closable. A notch 12 is formed in the valve 11.

The piston 2 has a groove-shaped opening formed at the outlet of the expansion port 6, and each opening has the same pressure receiving area with respect to the expansion-side leaf valve 10.

A base valve 14 is provided at a lower portion of the cylinder 1, and includes a valve case 15 serving as a partition member, an expansion port 16 and a pressure port 17 formed in the valve case 15, and a check valve 21 provided at an outlet of the expansion hoat 16. And a pressure-side leaf valve 18 provided at the outlet of the pressure port 17.

A stamped orifice 22 is formed in the head of the seat supporting the check valve 21, and the check valve 21 has a pressure port 17.
And a hole 23 facing the hole 23 is formed.

The compression side leaf valve 18 is supported by a stopper 20 via a spacer 19.

The lower oil chamber 5 is opened and closed by a reservoir-side oil chamber 24 via ports 16 and 17, a check valve 21 and a pressure-side leaf valve 18.

During the extension side, the piston 2 moves to the left, the oil in the upper oil chamber 4 flows into the lower oil chamber 5, and the oil in the reservoir-side oil chamber 24 is also sucked into the lower oil chamber 5.

At this time, in the low-speed region, the oil in the upper oil chamber 4 flows from the notch 12 through the pressure port 7 to the lower oil chamber 5, and the flow resistance between the notch 12 and the pressure port 7 generates a low-speed damping force.

In the middle speed range, the expansion side leaf valve 10 is pushed open from the expansion port 6 to flow, and the leaf valve 10 bends to generate a damping force in the middle speed range.

When the speed is further increased, a flow resistance flowing through the extension port 6 is also generated, and a damping force in a high speed region is generated. On the other hand, in the base valve 14 on the extension side, the oil in the oil chamber 24 flows through the orifice 22 to the lower oil chamber 5 in the low-speed region, and when the medium-high speed region is reached, the check valve 21 is pushed open to open the lower oil chamber 5. Flows to In the compression stroke in which the piston 2 moves to the right, the oil in the lower oil chamber 5 at low speed is supplied to the oil chamber 24 through the stamping orifice and the expansion port 16.
To the oil chamber 24 through the hole 23 and the expansion port 17 through the compression side leaf valve 18 in the medium speed range, and the damping force in the medium speed range due to the bending action of the compression side leaf valve 18. Occurs, and in the high-speed region, the flow resistance of the pressure port 17 also occurs, and the damping force in the high-speed region is generated. On the other hand, on the piston 2 side, the oil in the lower oil chamber 5 flows out from the pressure port 7 through the notch 12 and pushes the check valve 11 open to the upper oil chamber 4.

[Problems to be Solved by the Invention] In the above-described hydraulic shock absorber, the extension side leaf valve 10 or the compression side leaf valve 18 opens during the extension / compression stroke, but each leaf valve 10, 18 opens uniformly from the entire circumference. For this reason, at the moment when the leaf valves 10 and 18 are opened, they overshoot and open more than necessary, and the flow passage area from the upper oil chamber 4 to the lower oil chamber 5 or from the lower oil chamber 5 to the oil chamber 24 increases for a moment. As a result, the pressure in the upper and lower oil chambers 4 and 5 changes suddenly. Then, the pressure fluctuation causes the piston rod 3 to vibrate and is transmitted to the vehicle body via a sprung-side mount (insulator) of the vehicle body, causing the vehicle body to resonate and generate abnormal noise called a normal noise.

Although the above-mentioned noise is a sound which cannot be heard unless it is concentrated too much, it is a serious problem at present, and it makes a driver uncomfortable or feels dangerous.

Therefore, an object of the present invention is to prevent overshoot when the leaf valve is opened, and to successively open the leaf valve to suppress a sudden increase in the flow path area and a pressure fluctuation in the oil chamber, thereby reducing the noise caused by the vibration of the piston rod. It is an object of the present invention to provide a hydraulic shock absorber in which occurrence of the hydraulic shock is prevented.

Means for Solving the Problems In order to achieve the above object, a means of the present invention divides two upper and lower oil chambers through a partition member in a cylinder, and connects the two oil chambers to the partition member. In a hydraulic shock absorber in which a plurality of ports are provided and a leaf valve is openably and closably provided at an outlet end of each port via a seat portion, the seat portion and a central annular seat surrounding the outlet of each port are provided. And an outer annular seat that is eccentric with respect to the leaf valve, and has a difference in pressure receiving area with respect to the leaf valve at the outlet of each port to make the deflection of the leaf valve non-uniform on the circumference. .

[Operation] The leaf valve is opened by the hydraulic pressure acting from the port during the expansion and contraction operation. However, since the pressure receiving area for the leaf valve at the outlet of each port is different, the leaf pressure valve opens in order from the larger pressure receiving area, and the leaf valve does not overshoot. In addition, the rapid expansion of the oil passage area and the fluctuation of the pressure in the oil chamber are suppressed, so that the piston rod does not vibrate.

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

The basic structure of the hydraulic shock absorber itself is the same as that of the prior art shown in FIG. 6, for example.

That is, the hydraulic shock absorber according to the present invention partitions the upper and lower two oil chambers 4 and 5 in the cylinder 1 through the partition member, and the partition member has a plurality of ports 6a that communicate the two oil chambers. 6n, 7a
−−−− 7n are provided, and leaf valves 10, 18, and a check valve 12 are provided at the outlet end of each port via a seat portion so as to be freely opened and closed. The feature of the present invention is that the above-mentioned seat portion includes a center annular sheet C surrounding the outlet of each port and an outer annular sheet A or B eccentric from the center as shown in FIGS. 1, 2 and 3. That is, the leaf valves 10, 18 and the check valve 12 have different pressure receiving areas at the outlets of the ports with respect to the leaf valves 10, 18 and the check valve 12, thereby making the deflection of the leaf valves 10, 18 and the check valve 12 non-uniform on the circumference. . This will be described in more detail below. A piston rod 3 is movably inserted into a cylinder 1 via a piston 2 'serving as a partition member, and the piston 2' is provided in the cylinder 1 with two upper and lower oil chambers 4,5.
Is partitioned. The piston 2 'has a plurality of extension ports 6a, 6b --- 6n for communicating the two oil chambers 4, 5 and a plurality of pressure ports 7a.
a, 7b --- 7n is formed, and an extension side leaf valve 10 supported by a stopper 9 via a spacer 8 is provided at the outlet of the extension port 6a, 6b-6n so as to be openable and closable, Pressure port 7a, 7b−
A check valve 11 which is a non-return valve supported by a stopper 13 via a spacer is also provided at the outlet of −7n via a spacer so that the check valve 11 has a notch 12 formed therein. Instead of the notch 12, a stamped orifice may be provided in the sheet.

A base valve 14 is provided at a lower portion of the cylinder 1, and is a valve case 15 serving as a partition member, an expansion port 16 and a pressure port 17 formed in the valve case 15, and a non-return valve provided at an outlet of the expansion port 16. It has a check valve 21 and a pressure side leaf valve 18 provided at the outlet of the pressure port 17. A stamping orifice 22 is formed in the head of the seat supporting the check valve 21, and a hole 23 facing the pressure port 17 is formed in the check valve 21.

The compression side leaf valve 18 is supported by a stopper 20 via a spacer 19.

The lower oil chamber 5 is opened and closed by a reservoir-side oil chamber 24 via ports 16 and 17, a check valve 21 and a pressure-side leaf valve 18.

FIG. 1 shows a piston 2 'according to one embodiment of the present invention.

A plurality of extension ports 6a, 6b --- 6n provided on the piston 2 '
An annular seat A which is eccentric from the center O is formed at the outlet of, and a leaf valve 18 is in contact with the seat A. Due to the eccentricity of the seat A, the pressure receiving area around the leaf valve 10 around the port 6a is the largest.
The pressure receiving area around 6b and 6d is large, and the pressure receiving area around port 6c is the smallest.

Similarly, on the upper surface of the piston 2 ', the pressure ports 7a, 7b-
-The circular sheet B eccentric from the center O is located around the exit circle of 7n.
Are formed, and the pressure receiving area around the check valve 11 as the leaf valve around the port 7b is the largest, and then the pressure receiving areas around the ports 7a and 7c and further around the port 7d are sequentially reduced.

By varying the pressure receiving area with respect to the leaf valve in this way, the deflection of the leaf valve is made non-uniform on the circumference, and the leaf valves are opened in descending order according to the pressure receiving area. The sheet need not be annular, but may be rectangular or oval.

Conversely, the seat may not be eccentric, and the leaf valve may be eccentric, rectangular, or oval.

During the extension operation, in the low speed range of the piston 2 ', the oil in the upper oil chamber 4 flows out of the notch 12 to the lower oil chamber 5 through the pressure ports 7a, 7b --- 7n. The damping force of the graph a shown in FIG.

In the middle / high speed range, first, the extension side leaf valve 10 in the vicinity of the port 6a having the largest pressure receiving area is partially pushed open, and a damping force is generated by initial leakage due to bending of this portion, and this characteristic is graphed. b.

When the speed is further increased after the opening around the port 6a, the opening around the next port 6b, 6d opens, and finally the opening around the port 6c. In other words, the leaf valve 10 is opened sequentially from the portion having the larger pressure receiving area.

The damping force characteristic due to the deflection of the leaf valve 10 is shown by a graph b, and the overall characteristic is shown by a graph c. Similarly, during the compression operation, the check valve 11 is sequentially opened from a portion having a large pressure receiving area.

As described above, when the leaf valve 10 or the check valve 11 is sequentially opened from a portion having a large pressure receiving area, the flow passage area of the oil flowing from the upper oil chamber 4 to the lower oil chamber 5 or from the lower oil chamber 5 to the upper oil chamber 4 becomes Since the pressure does not suddenly expand, the pressure fluctuations in the upper and lower oil chambers 4 and 5 do not suddenly occur, and therefore the piston rod 3 does not vibrate. Therefore, no rattling noise due to the vibration of the piston rod 3 is generated.

The configuration of the seat portions A and B of the piston 2 'may be adopted in the valve case 15 of the base valve 14, and in this case, the pressure side leaf valves 18 are sequentially opened.

FIGS. 3 and 4 relate to another embodiment of the present invention, in which the annular seat is eccentrically mounted and the leaf valve is mounted eccentrically. An eccentric annular sheet A is provided on the piston 2 ', and a sheet C is provided around a hole into which the piston rod 3 is inserted. On the other hand, the leaf valve 10 'has a hole 10a for inserting a piston rod eccentric from the center O, and a horizontal portion for preventing displacement is formed in the hole 10a. In this case, the deflection of the leaf valve becomes more uneven, and the leaf valve surely opens from a portion having a large pressure receiving area.

[Effects of the Invention] According to the present invention, since the pressure receiving area of the partition member with respect to the leaf valve at each port outlet is made different, when the leaf valve abutting on the seat portion of the hoat outlet opens,
Since the opening area, in other words, the area of the pressure receiving area is sequentially opened from a large portion, the area of the flow passage flowing between the oil chambers does not increase rapidly, so that the pressure 6 of the oil chamber does not fluctuate rapidly. For this reason, the piston rod does not vibrate, so that a rattling sound on the vehicle body side due to the vibration of the piston rod is prevented.

[Brief description of the drawings]

FIG. 1 is a right side view of a cross section of a piston of a hydraulic shock absorber according to one embodiment of the present invention, FIG. 2 is a left side view of the same cross section of the piston, and FIG. 3 is a right side view of a cross section of a piston according to another embodiment. FIG. 4 is a right side view of the leaf valve, FIG. 5 is a graph showing damping force characteristics of the hydraulic shock absorber of the present invention, and FIG. 6 is a vertical front view of a conventional hydraulic shock absorber. 1 ... Cylinder 2 '... Piston as a partition member 4,5 ... Oil chamber 6a, 6b ---- 6n, 7a, 7b ---- 7n ... Port 10,18 ... Leaf valve 11 ... Check valve 15… Valve cases A and B as partition members

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16F 9/00-9/58 B60G 13/08

Claims (1)

(57) [Claims] 1. An upper and lower two oil chambers are defined in a cylinder via a partition member. The partition member is provided with a plurality of ports communicating the two oil chambers, and an outlet end of each port is provided via a seat portion. In a hydraulic shock absorber provided with a leaf valve that can be freely opened and closed, the seat portion includes a central annular seat surrounding an outlet of each port and an outer annular seat eccentric from the center, and a leaf at an outlet of each port is provided. A valve device for a hydraulic shock absorber, wherein the leaf receiving valve has a difference in pressure receiving area with respect to the valve to make the deflection of the leaf valve non-uniform on the circumference.