JPS626135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A hydraulic shock absorber for suspending a vehicle body, such as an automobile or a motorcycle, must have appropriate damping force characteristics in each of the compression stroke and extension stroke. Therefore, for example, a check valve is provided in the oil hole of the piston, an orifice for generating a damping force is formed in the check valve, and a thin elastic plate is superimposed on the check valve to generate a damping force by blocking the orifice. A device is used. In such a device, when the piston moves in the direction in which the check valve closes, hydraulic pressure is applied to the elastic plate through the orifice, and the elastic plate bends and oil flows through the orifice, creating an appropriate damping force. occurs.
However, when the elastic plate bends and oil begins to flow,
The oil pressure applied to the elastic plate changes to close the orifice again. For this reason, when the moving speed of the piston reaches a certain value, the damping force pulsates violently before and after the movement speed, which impairs the ride comfort of the vehicle and generates abnormal noise. An object of the present invention is to provide a damping force generating device for a hydraulic shock absorber which eliminates the above-mentioned drawbacks.According to the present invention, a cylinder is filled with oil and a piston is slidably fitted into the cylinder. In a hydraulic shock absorber, two relatively thick plate-shaped valves are stacked and arranged on the opening surface of a concave groove in an oil passage through which oil flows as the piston moves, and the two valves are pressed together by a spring. An orifice is provided in the outer valve, and a sufficiently large oil hole is formed in the inner valve so as to face the orifice, and a plurality of thin elastic plates arranged inside the groove are attached to the inner valve. The gist is that the oil hole is blocked by polymerization, and one edge of the elastic plate is sandwiched between the edge of the groove and the inner valve, and the damping force pulsates violently when the orifice is opened and closed. This prevents this, thereby improving riding comfort and preventing the generation of abnormal noise.

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, and Fig. 2 is a sectional view taken along line AA in Fig. 1, showing a cylinder 1 filled with oil.
A piston 2 is slidably fitted into the cylinder, and an outer cylinder 3 is coaxially disposed outside the cylinder. A piston ring 4 is fitted to the piston 2 and attached to the lower end of a piston rod 5. This piston is provided with a plurality of oil holes 6 that communicate between the upper and lower parts of the piston, and the upper end is connected to an annular groove 7. It is connected with. In addition, relatively thick plate-shaped valves 8 and 9 are placed overlappingly on the upper opening surface of the oil passage consisting of the oil hole 6 and the groove 7, and are pressed by a spring 10 to form a check valve. . The outer valve 8 is provided with a plurality of orifices 11, 11, . . . , and the inner valve 9 is provided with sufficiently large arc-shaped oil holes 12, 12, . A plurality of thin annular elastic plates 13, 13 disposed inside the groove 7 are overlapped with the lower surface of the inner valve 9 to close the oil hole 12, and the inner peripheral edge of the elastic plate is overlapped with the lower surface of the inner valve 9. It is inserted between the edge of the groove 7 and the valve 9. Furthermore, a small notched groove 14 is provided on the outer peripheral edge of the groove 7, and the damping force during the extension stroke of the shock absorber, that is, when the piston 2 moves upward, is reduced by this notched groove, the valve, and the elastic plate. A generator is configured. Although not shown, the piston rod 5 is pulled out through a rod guide and an oil seal provided at the upper ends of the cylinder 1 and outer cylinder 3, and a valve as disclosed in Japanese Utility Model Publication No. 41-2171 is installed at the lower ends of the cylinder and outer cylinder. structure or
A structure similar to the present invention is provided. That is, an oil passage communicating between the gap between the cylinder 1 and the outer cylinder 3 and the inside of the cylinder 1 is provided in the valve structure, and this oil passage is used during the compression stroke of the shock absorber, that is, when the piston 2 is moved downward. A check valve is provided that closes during the stroke and opens during the extension stroke, that is, the stroke in which the piston moves upward.
An orifice is provided to flow oil into the gap between the two.

In the above-mentioned hydraulic shock absorber, when an automobile or the like runs onto a high place on the road surface, the piston 2 first moves downward and then moves upward. When the piston descends, the spring 10 shown in FIG. The oil passage will be opened. However, as mentioned above, during the compression stroke in which the piston 2 descends, the check valve of the valve structure provided at the lower end of the cylinder 1 is closed and sealed by the rod guide of the cylinder 1. The oil enters the gap between the cylinder 1 and the outer cylinder 3 through the orifice of the valve structure at the lower end of the cylinder, and at this time, the flow resistance at the orifice causes a damping force as shown by the broken line in FIG. Generate F. In addition, during the extension stroke in which the piston 2 rises, the check valve consisting of valves 8 and 9 closes and the notched groove 1
4 or the oil passing through the orifice 11 generates a damping force +F as shown by the solid line in FIG. That is, since oil flows only through the notched groove 14 when the piston is moving at a low speed, the damping force increases rapidly as the speed increases. As the damping force increases, the hydraulic pressure applied to the upper surface of the elastic plate 13 via the orifice 11 and the oil hole 12 increases.
When the rising speed of the piston exceeds a certain value, the elastic plate 1
The peripheral edges of the valves 3 and 13 are bent downward in FIG. 1, creating a gap between the elastic plate and the lower surface of the valve 9. Therefore, oil flows through the orifice 11, and the damping force increases slowly as the piston speed increases.

As in the above embodiment, the present invention arranges two relatively thick plate-shaped valves 8 and 9 overlappingly on the opening surface of the oil passage through which oil flows as the piston 2 moves, and the outer valve 8 An orifice 11 is provided in the inner valve 9, an oil hole 12 is formed opposite to the orifice and is sufficiently larger than the orifice, and a valve made of an elastic plate 13 is arranged to close the oil hole 12. be. For this reason, when the above-mentioned check valve is in a closed state, when the oil pressure in the upper part of the check valve increases due to the upward movement of the piston, for example, this oil pressure is transmitted to the oil hole 12 of the valve 9 via the orifice 11. Therefore, the hydraulic pressure is applied to the elastic plate 13 over an extremely wide area corresponding to the size of the oil hole 12, and the elastic plate is bent by a force corresponding to the product of this hydraulic pressure and the area. Oil begins to flow through the orifice 11. When oil starts to flow through the orifice 11 in this manner, hydraulic pressure is applied to almost the entire surface of the elastic plate 13. However, as mentioned above, oil hole 1
Since orifice 2 is formed sufficiently large, orifice 1
When the oil that is squeezed in 1 and generates a damping force enters the oil hole 12, its volume expands and the pressure decreases.
The difference in the force applied to the elastic body plate 13 before and after the oil flows can be made relatively small (in other words, if the oil hole 12 is made as small as the diameter of the orifice 11 or smaller, the oil hole 12 Since a damping force is generated in the elastic plate 13, and the pressure of the squeezed oil is directly applied to the elastic plate 13, the difference in the force applied to the elastic plate 13 before and after the oil flows becomes large.For this reason, the elastic plate 13 13 is bent once and oil begins to flow through the orifice 11, the elastic plate stably maintains the bent state and there is no possibility that it will vibrate.Therefore, the damping force is reduced. This eliminates drawbacks such as fluctuations that impair the riding comfort of the vehicle or generate abnormal noises.In other words, the conventional device does not have a valve 9, and the orifice 1
Since the elastic plate 13 was in close contact with the elastic plate 13, before the elastic plate was bent, hydraulic pressure was applied only to a very small area, and when the elastic plate 13 was bent and oil started flowing through the orifice, the pressure receiving area of the elastic plate increased. , which suddenly and significantly increases, bends further, recovers due to reaction, and performs an oscillating operation such as closing the orifice again.
Therefore, as shown by the dotted line in FIG. 3, the damping force pulsates violently when the orifice opens and closes, resulting in poor riding comfort and the production of abnormal noise.

In this way, the present invention achieves extremely simple installation and productivity by simply interposing another plate-shaped valve having an oil hole larger than the orifice between the plate-shaped valve having the orifice and the elastic plate. The damping force is prevented from pulsating violently when the orifice is opened and closed by means that do not damage the orifice, thereby improving riding comfort and preventing the generation of abnormal noise.
Further, the present invention can also be applied to an oil passage of a valve structure provided at the bottom of the cylinder.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a characteristic curve of the apparatus shown in FIGS. 1, 2, and 3. In the figure, 1 is a cylinder, 2 is a piston, 3 is an outer cylinder, 4 is a piston ring, 5 is a piston rod, 6 is an oil hole, 7 is a groove, 8 and 9 are plate-shaped valves, 10 is a spring, and 11 is an orifice, 12 is an oil hole, 13 is an elastic plate, 14
is a notched groove.

Claims (1)

[Claims] 1. In a hydraulic shock absorber in which a cylinder is filled with oil and a piston is slidably fitted, two thick plate-shaped valves are superimposed on the opening surface of the groove in the oil passage through which oil flows as the piston moves. The outer valve of the two valves is provided with an orifice, and the inner valve is formed with a large oil hole facing the orifice, and is placed inside the groove. The oil hole is closed by superimposing a plurality of thin elastic plates on the inner valve, and one edge of the elastic plate is sandwiched between the edge of the groove and the inner valve. Features a damping force generator.