JPS6131555Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a double-tube hydraulic shock absorber.
More specifically, the present invention relates to an improvement in a valve section that opens and closes a hydraulic fluid passage formed in an oil field defining member in a dual-tube hydraulic shock absorber.

Conventionally, the oil field defining member of a dual-tube hydraulic shock absorber, for example, the valve part of a piston, defines an oil field on the retainer side and an oil field on the piston side, and also prevents the inflow of hydraulic oil when the piston is operated. As a member forming an oil passage that allows oil to flow out, it is composed of a disc valve, a disc plate having a notch formed on its outer periphery, and a spacer. However, in this case, when the operating speed increases during the extension stroke, cavitation occurs in the fixed orifice, which causes abnormal noise and
There is a problem that the damping force also increases.

The present invention was made with the aim of solving this problem.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be explained below based on the drawings showing one embodiment thereof.

1 and 2 show cross sections of the main parts of the dual-tube hydraulic shock absorber according to the present invention.
2 is a piston rod, 2 is a retainer guide, 3 is a piston guide, and 4 is a spring that always urges the retainer 5 downward. Further, 6 indicates a disk valve, 7 indicates a disk plate having a notch formed as a fixed orifice on its outer periphery, 8 indicates a spacer, and 9 indicates a flexible leaf valve. The disk valve 6, disk plate 7, spacer 8, and leaf valve 9 constitute a valve section. 10 is a piston which is an oil field defining member, 11 is a piston ring, 12 is a nut, 13 is an inner tube, and 14 is an outer tube. Further, 15 indicates an oil chamber of the disc valve 6, 16 indicates an upper chamber of the piston 10, and 17 indicates a lower chamber of the piston 10. Reference numeral 18 indicates a notch as an oil passage formed on the outer periphery of the disc plate 7, 19 indicates an oil passage formed between the disc plate 7 and the leaf valve 9, and 20 indicates the piston 10.
The reference numeral 21 indicates the oil hole formed in the piston, and 21 indicates the piston seat surface.

The dual-tube hydraulic shock absorber of the present invention has a structure roughly as described above.
The functions and effects will be explained using diagrams.

In the double-tube hydraulic shock absorber according to the present invention, during the extension stroke shown in FIG. The piston 1 passes through an oil passage 19, which is an orifice formed between the plate 7 and the leaf valve 9, and passes through an oil hole 20.
0 flows out to the lower chamber 17 as shown by the arrow. Therefore, compared to the case where there is only the conventional oil passage 18,
Since the length of the orifice portion is increased, the pressure drop when the hydraulic oil passes through the orifice portion (oil passages 18 and 19) becomes gentler, and cavitation can be prevented.

Similarly, in the extension stroke, when the operating speed is high, the hydraulic oil in the upper chamber 16 of the piston 10 deflects the disc valve 6, passes through the oil chamber 15, passes through the oil hole 20, and enters the lower chamber 17 of the piston 10. It flows out as shown by the arrow. At that time, leaf valve 9
is provided, so the hydraulic oil in the oil chamber 15 is
Since the pressure increases, the oil chamber 15
It is possible to prevent a sudden pressure drop. Therefore, cavitation does not occur even if the operating speed increases, and the leaf valve 9
As with the disc valve 6, when the pressure in the oil chamber 15 increases, it bends accordingly and the oil passage in the orifice portion widens, so that the damping force does not increase significantly (see Fig. 5).

In the retraction stroke shown in Fig. 4, the piston 1
The hydraulic oil in the lower chamber 17 of 0 flows through the oil hole 2 of the piston 10.
At that time, the retainer 5, disc valve 6, disc plate 7, spacer 8, leaf valve 9, etc. are lifted up as one body, and the upper chamber 16 of the piston 10 is passed through the gap between the piston seat surface 21 and the leaf valve 9. It flows out as shown by the arrow. Therefore, in the retraction stroke, its action is no different from that of a conventional dual-tube hydraulic shock absorber.

In this embodiment, a piston is used as an example of the oil field defining member, but the invention is not limited to this. It may be applied to an oil field defining member that defines a chamber to improve a bottom valve.

With this invention as described above, the pressure in the oil chamber near the valve part is reduced in two stages without dropping suddenly, so cavitation can be reduced without changing the basic damping force characteristics in the extension and compression strokes. It is possible to provide a dual-tube hydraulic shock absorber that can prevent the occurrence of abnormal noise and reduce the occurrence of abnormal noise.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main parts of a dual-tube hydraulic shock absorber according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the vicinity of the valve part in FIG. FIG. 4 is a sectional view for explaining the operating state, and FIG. 5 is a graph comparing the pressure characteristics of the oil chamber and oil hole according to the present invention with those of the conventional one. 6... Disc valve, 7... Disc plate, 8
... Spacer, 9 ... Leaf valve, 10 ... Piston (oil field defining member).

Claims (1)

[Scope of utility model registration request] A disc valve that generates damping force during the extension stroke is provided on one side of the oil field defining member that defines the oil chamber in the main body of the dual-tube hydraulic shock absorber, and a fixed orifice is provided on the outer periphery adjacent to the disc valve. A flexible leaf valve is provided on the disc plate via a spacer, and the gap between the leaf valve and the disc plate is defined by an orifice following the notch. A dual-tube hydraulic shock absorber characterized by: