JPS59194143A - Piston structure for hydraulic damper - Google Patents

Abstract

PURPOSE:To eliminate scatter in damping force, by providing such an arrangement that the sizes and shapes of disc valves which are set on both end faces of a piston are made equal. CONSTITUTION:Annular recess parts 10, 11 are formed on the top and bottom faces of a piston 4, respectively, and therefore, concentrically circular outer and inner ring seats 12a, 12b, 13a, 13b are formed. A plurality of disc valves 14, 15 abut against the ring seats. The piston 4 is formed, in its barrel section, with a plurarity of axial oil passages each having its top end opened to the recess part 10 and its bottom end blocked, and a plurarity of axial oil passages 17 each having, in contrast with the passages 16, its top end blocked and its bottom end opened to the another recess part 11. Further, the piston 4 is formed, in its peripheral wall, with a pulling side oil hole 18 which is opened to an oil passage 16 that is therefore communicated with an operating chamber S2, a relatively small diameter common oil passage 19 which is also opened to the oil passage 16 for always communicating between an upper operating chamber S1 and the lower operating chamber S2, and a pushing side oil hole 20 opened to the oil passage 17 that is therefore communicated with the upper operating chamber S1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber suspended between a vehicle body and wheels of a two-wheeled vehicle, and more particularly to the structure of a piston that slides within a cylinder of the hydraulic shock absorber.

The piston used in this type of hydraulic shock absorber has a damping function as one of its functions in order to transmit the impact received by the wheels to the vehicle body as weakly as possible.

In other words, an oil passage (often a circular oil hole) drilled into the piston.
This oil passage is closed by means such as a disc valve with appropriate elasticity, and the damping force is reduced by the oil passing through the narrow passage opened by the deflection of the disc valve. Occur.

By the way, in the conventional piston structure, as shown in FIG. 3, the piston 104 is provided with oil passages 116 during the compression stroke.
and oil passages 117 during the extension stroke are provided separately to avoid interference with each other, and these oil passages 116..., 117.
... communicate with annular recesses 110, 111 formed on the upper and lower end surfaces of the piston 104, respectively, and the four parts 110, 111 are closed by disc valves 114, 115, respectively.

However, in such a piston structure, in order to prevent one disc valve 114 from blocking the other oil passage 116, the dimensions of the pulp 114 are inevitably smaller than those of the other valve 115. There is a problem.

This creates the problem that the damping force tends to vary widely due to errors in the valve shape, thickness, fulcrum position, etc.
As a result, the magnitude of the damping force differs depending on the product.

The present invention has been made to effectively eliminate such inconveniences, and its purpose is to equalize the size and shape of the disc valves disposed on both end faces of the piston, thereby eliminating variations in damping force. The purpose of the present invention is to provide a piston structure for a hydraulic shock absorber that can eliminate the above problems.

In order to achieve such an object, the present invention provides annular recesses on both end faces of a piston that slides inside the cylinder to form dust supply in the shape of an inner and outer rotation circle, and a disc valve is installed for each dust supply. The piston body is provided with a plurality of axial oil passages whose two ends are opened in one of the recesses and whose other ends are closed, and the piston circumferential wall is provided with a passageway through which the piston slides (thereby being compressed). The gist is that a common oil hole is bored to communicate the cylinder oil chamber on both sides of the piston, or a common oil hole that communicates with the column-side oil hole and the cylinder oil chambers on both sides of the piston. do.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway side view of a hydraulic shock absorber having a piston structure according to the present invention, and FIG. 2 is an enlarged cutaway side view of the piston portion of the shock absorber.

In the hydraulic shock absorber 1 shown in FIG. 1, 2 is a cylinder, and a piston rod 3 is inserted into the cylinder 2 from below.
A piston 4 that fits vertically and slidably is connected to the inner periphery.

A seal case 6 that holds an oil seal 5 that is in sliding contact with the outer circumference of the piston rod 3 is fitted on the lower inner circumference of the cylinder 2, and a damping force is generated on the inner circumference of the intermediate portion of the cylinder 2. A bottom piece 8 with a valve mechanism 7 is fitted. 9 in the figure is a rebound spring.

The inside of the cylinder 2 is divided by the piston 4 into an upper working chamber S1 and a lower working chamber S2, and hydraulic oil is sealed in both working chambers S1 and S2.

Incidentally, the upper and lower end surfaces of the piston 4 are provided with annular recesses 10 and 11, respectively, as shown in detail in FIG. , 12b and 13a.

13b is formed. And one dust supply 12a,
A plurality of disc valves 14 are in contact with 12b, and disc valves 15 having the same diameter as the disc valve 14 are in contact with the other dust supply 13a and 13b, respectively.

As shown in the figure, the body of the piston 4 has an axial oil passage 1 whose upper end opens into one recess 10 and whose lower end is closed.
6, and conversely, its upper end is closed and its lower end is the other recess 11.
A plurality of axial oil passages 17 are provided, respectively.

Further, a row-side oil hole 18 is provided in the peripheral wall of the piston 4, which opens into the oil passage 16 and allows the lower working chamber S2 and the oil passage 16 to communicate with each other.
A common oil hole 19 with a relatively small diameter also opens into the oil passage 16 and always allows the upper working chamber S1 and the lower working chamber S2 to communicate with each other.
and opens into the oil passage 17, and connects the upper working chamber S1 and the oil passage 17.
Extension-side oil holes 20 are respectively drilled to communicate with each other.

Therefore, in the second hydraulic shock absorber 1, for example, when the lever is used as a shock absorber for a vehicle, the upper end of the cylinder 2 is connected to the vehicle body side, the lower end of the piston rod 3 is connected to the axle side, and both are connected. Relative expansion and contraction movement. 21 in FIG. 1 is a bump rubber.

Next, the operation of this hydraulic shock absorber 1 will be described.

When the piston 4 moves upward in the cylinder 2 during the compression stroke without breaking, a portion of the oil in the upper working chamber S flows through the common oil hole 19, the oil passage 16, and the column-side oil hole as shown by the solid line arrow in FIG. 18 and flows into the lower working chamber S2, and another part of the oil passes through the expansion side oil hole 20 and the oil passage 17, as shown by the solid line arrow in the figure, and reaches the recess 11, where it comes into contact with the recess 11. The disc valve 15 is pushed open using the hydraulic pressure, and the final (lower working chamber S)
2.

In this compression stroke, a required damping force is generated within the shock absorber 1 based on the flow resistance when the hydraulic oil passes through each flow path.

Next, when the piston 4 moves downward in the sill 2 during the extension stroke, a portion of the hydraulic oil in the lower working chamber S2 passes through the row-side oil hole 18 and into the oil passage 16, as shown by the broken line arrow in FIG. A part of this working oil flows into the upper working chamber S1 through the common oil hole 19, and the remaining oil flows into the fourth part 10, and the disc pulp that comes into contact with the recess 10 14 is pushed open by the hydraulic pressure and flows into the upper working chamber S.

Also during this extension stroke, a required damping force is generated within the shock absorber 1 as described above.

The common oil passage 19 functions to allow hydraulic oil to pass in a low operating speed range where the disc pulp 14, 15 does not open at all, thereby generating a low damping force.

In the above, since the disc pulp '14.15 with the same size and shape is arranged on the upper and lower end surfaces of the piston 4, it is possible to eliminate variations in the damping force value, and the occurrence of a situation where the generated damping force differs depending on the product. can be prevented.

As is clear from the above description, according to the present invention, four annular parts are provided on both end surfaces of the piston sliding in the sill ring to form inner and outer ring pressures, and each ring pressure is Disk pulp is pressed into contact with the piston, and a plurality of axial oil passages are provided in the body of the piston, with one end of the recess ζ being open and the other end being closed, and the peripheral wall of the piston is provided with a plurality of axial oil passages that open one end of the recess ζ and close the other end. A common oil hole is provided to connect the oil chamber in the cylinder 2 to be compressed to the recess ζ via the axial oil passage, or to connect the row side oil hole and the oil chambers in the cylinder on both sides of the piston. The dimensions of the disc pulps disposed on both end faces of the piston can be made equal, thereby eliminating variations in damping force.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a hydraulic shock absorber having a piston structure according to the present invention, FIG. 2 is an enlarged cutaway side view of the piston portion of the shock absorber, and FIG. 3 is a piston according to a conventional example. It is a broken side view showing a structure. In the drawing, 1 is a hydraulic shock absorber, 2 is a sill ring, 3 is a piston rod, 4 is a piston, 10.11 is an annular recess, 12a
, 12b, 13a, 13b are ring pressure, 14.15 is disc pulp, 16.17 is axial oil passage, 18 is row side oil hole,
19 is a common oil hole, 20 is a suppression oil hole, S, , S2 is an upper part,
This is the lower working chamber. Patent Applicant Showa Seisakusho Co., Ltd. Representative Patent Attorney 1) Department Attorney Kuni Ohashi Patent Attorney Yu Koyama

Claims (1)

[Claims] Annular recesses are provided on both end surfaces of the piston that slides inside the cylinder to form an inner and outer circular dust supply, and a disc valve is pressed into contact with each dust supply, and the piston body is provided with the recess. A plurality of axial oil passages are provided in one of the pistons, one end of which is open and the other end of which is closed. A piston structure for a hydraulic shock absorber, characterized in that a restraint communicating with the recessed portion or a common oil hole that always communicates with the row-side oil hole and the oil chambers in the cylinders on both sides of the piston is provided.