JPS597853B2 - Hydraulic shock absorber damping force generator - Google Patents

Description

[Detailed description of the invention] In a hydraulic shock absorber used for suspension of a four-wheeled vehicle,
It is desirable that the damping force during compression be approximately proportional to the compression speed.

For this reason, in the past, a valve made of an elastic plate was pressed against the opening surface of the oil hole, and an orifice was provided.When the compression speed was small, the orifice generated a damping force with a square characteristic, and when the speed reached a certain speed, the valve was bent. For the first time, a device was used that produced a damping force with a square-law characteristic.

However, there is a bending point in the characteristic curve at the point where it transitions from the square characteristic to the square-third power characteristic, and before and after that it is the square characteristic or the square-third power characteristic as mentioned above, so the compression speed and There was a drawback that a good proportional relationship with the damping force could not be obtained.

Moreover, in order to make the magnitude of the damping force by the orifice dog a desired value, the diameter of the hole must be adjusted appropriately, but this adjustment is difficult and there is also the drawback that it is difficult to obtain an appropriate damping force.

The present invention eliminates the above-mentioned drawbacks by extremely simple means, and provides a device that can obtain damping force characteristics that are approximately proportional to the compression or expansion speed of the shock absorber, and whose magnitude can be easily adjusted.

FIG. 1 shows an example of a hydraulic shock absorber equipped with a damping force generating device according to an embodiment of the present invention, in which an outer cylinder 3 is coaxially mounted transparently on the outside of an inner cylinder 2 into which a piston 1 is slidably fitted. A damping force generating device 4 of the present invention is provided at the bottom of the inner tube and outer tube.

Although not shown, the piston 1 is also provided with an appropriate damping force generating mechanism.

Fig. 2 is a vertical sectional view of the damping force generating device 4, and Fig.
The figure is a cross-sectional view of the A-A section, in which a partition 7 is provided between the gap 5 between the inner cylinder 2 and the outer cylinder 3 and the inside 6 of the inner cylinder 2, and 3 Individual oil holes 8, 8...
... and 9, 9... are formed, and their opening surfaces are connected by annular grooves 10, 11 and 12, 13.

In addition, a disc valve 14 is arranged on the upper surface of the partition wall 7 to cover the grooves 10 and 12, and is pressed with a weak spring 15.
A plurality of oil holes 16 are provided in the valve 14 so as to face the oil holes 16.
is provided.

Further, on the lower surface of the partition wall 7, a plurality of grooves 18 are provided to form a recessed part 17 and to communicate the recessed part with the gap 5. A plurality of valves 19, 20, 21 are overlapped to form an inner groove 1.
1 and presses the valve with a retainer 23 via a spacer 22 to fix its center to the partition wall 7.

Note that an annular raised portion 24 is formed between the annular grooves 11 and 13, and the top of this raised portion and the valve 1
Since a step α is provided between the center portion of the valve 9 and the surface of the partition wall 7 with which it comes into contact, the peripheral edge of the bulb is pressed against the raised portion 24 with an appropriate force.

Further, a plurality of grooves 25 are formed on the periphery of the valve 19 as required.

Further, the center points of the valves 19, 20, 21 coincide with the center O of the support shaft 26, but the center point a of the annular raised portion 24 is separated from the center point 0 as shown in FIG. For example, it is biased by a minute distance δ of 0.5 to 1 mrnB degrees.

In the above-mentioned device, during the extension stroke of the shock absorber, the disc valve 14 opens and the oil in the gap 5 flows into the oil holes 9, 9, . . .
The damping force is easily absorbed into the interior 6 of the inner cylinder, and in this case, the damping force generating mechanism of the piston 1 generates a damping force with appropriate characteristics.

Further, during the compression stroke, the disc valve 14 remains closed as shown in the figure.

Therefore, when the compression speed is low, oil in the inner part 6 of the inner sleeve passes through the oil holes 16, 8 and the groove 25 of the valve 19 into the gap 5.
A damping force having a square characteristic determined by the size of the groove 25 is generated.

Also, as the compression speed increases, this damping force
When a certain value determined by the total elasticity of 0.21 is exceeded, the periphery of the valve begins to separate from the raised portion 24 and oil flows out from the gap.

In this case, when the center point 0 of the valves 19, 20, 21 and the center point α of the protrusion 24 coincide, the
A damping force having a 2/2 characteristic is generated.

However, as mentioned above, since the deviation δ is given between the points 0 and α, the distance from the center point O of the bulb to the protrusion 24 differs for each part, and in parts where the distance is small, the valve is pressed against the raised portion with a large force, and the large portion is pressed with a relatively small force.

Therefore, when the aforementioned compression speed is relatively low, the valve separates from the protrusion only in the portion where the aforementioned distance is large;
As the speed increases, the range of the separation gradually expands.

Therefore, the relationship between the compression speed of the shock absorber and the damping force becomes steeper than the above-mentioned square-law characteristic, and by selecting the deviation distance δ, it is possible to provide a substantially proportional relationship therebetween.

In addition, the compression speed is extremely high, and the entire circumference of the valve is covered with ridges 24.
In a state completely separated from the center, the damping force becomes a two-thirds power characteristic, similar to the conventional device.

As explained above with respect to the embodiments, the device of the present invention can obtain a damping force that is approximately proportional to the operating speed of the shock absorber, and for this reason, the present invention is particularly applicable to the portion that generates the damping force during compression. By doing so, the ride comfort of the vehicle can be improved.

In addition, since the characteristics are determined by the bias distance δ, the adjustment thereof is easy.

Further, since the partition wall 7 shown in the above embodiment is generally formed of sintered metal, it is extremely easy to form the annular raised portion eccentrically.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a hydraulic shock absorber equipped with a damping force generating device according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a part of FIG. 1, and FIG. -A sectional view. In the figure, 1 is a piston, 2 is an inner cylinder, 3 is an outer cylinder,
4 is a damping force generator, 5 is a gap, 6 is the inside of the inner shell, 7 is a partition wall, 8, 9 are oil holes, 10, 11, 12, 13 are grooves,
14 is a disc valve, 16 is an oil hole, 19, 20, 21
24 is an elastic valve, 24 is a raised portion, and 25 is a groove.

Claims (1)

[Claims] 1. In a hydraulic shock absorber in which a cylinder is filled with oil and a piston is slidably fitted therein, the opening of the oil hole is surrounded by a partition wall provided with an oil hole through which oil flows due to the movement of the piston. A bulb having an annular raised part formed therein and made of an elastic disk having a peripheral edge in pressure contact with the raised part is arranged so that its center point is slightly offset from the center point of the raised part,
A damping force generating device characterized in that a central portion of the valve is fixed to the partition wall.