JP2707282B2 - Hydraulic shock absorber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber optimized for a swift noise suppression in a medium to high piston speed range.

[Prior art and its problems] When the hydraulic oil from the high-pressure side oil chamber suddenly flows out to the low-pressure side oil chamber when the hydraulic oil passes through the piston part or the base valve part in the cylinder, a squish sound is generated. The squish noise may be generated, and causes a so-called noise in a vehicle or work equipment equipped with the hydraulic shock absorber.

Therefore, the applicant of the present application has previously made respective proposals relating to Japanese Utility Model Application Nos. 62-15460 and 62-92390 for measures against swift noise.
The configuration is optimal when the piston speed is in the low speed range.

Therefore, in the above-mentioned prior art proposal, it was not possible to eliminate the inconvenience of swift sound generation in the medium to high speed range of the piston speed.

The present invention has been made in view of the above circumstances, and a purpose thereof is to newly provide a hydraulic shock absorber which is optimal for a swift noise countermeasure in a medium to high speed region of a piston speed. To be.

[Means for solving the problem]

In order to achieve the above object, the configuration of the hydraulic shock absorber according to the present invention includes a seat portion protruding from an end surface of a valve seat member, and a pressure receiving portion formed inside the seat portion and opposed to a pressure receiving surface of a damping valve. And a pressure-reducing portion in which the bottom is positioned at a position higher than the bottom of the pressure-receiving portion while being lowered from the top of the seat, inside the seat. The pressure reducing section is connected to the pressure receiving section, and a port opened to the pressure receiving section is used for circulation of hydraulic oil in a medium to high speed range of a piston speed. .

The valve seat member is a piston body in the piston portion or a valve case in the base valve portion, and the port opened in the valve seat member is an extension port in the piston body or a compression port in the valve case, and , Damping valve,
The expansion valve in the piston portion or the compression valve in the base valve portion.

Also, while the seat portion is formed in an annular shape, the pressure receiving portion is formed in an annular groove shape, and the pressure reducing portion is formed in an annular groove shape or between the pressure receiving surface of the opposed damping valve. It is formed in the shape of an annular gap that appears.

(Operation)

When the piston speed is in the middle and high speed range when the piston slides in the inner cylinder, the hydraulic oil from the high pressure side oil chamber flows into the port opened in the valve seat member.

The hydraulic oil that has flowed into the port flows into a pressure receiving portion formed such that the port opens and faces the pressure receiving surface of the damping valve.

The hydraulic oil that has flowed into the pressure receiving section continuously flows into the pressure reducing section that communicates with the pressure receiving section.

The hydraulic oil that has flowed into the pressure reducing section opens the damping valve and flows out into the low-pressure side oil chamber. At this time, the opening of the damping valve exerts a predetermined damping action.

Further, in the above-described hydraulic oil flow process, the high oil pressure of the hydraulic oil flowing into the pressure receiving portion via the port is once reduced when flowing into the pressure receiving portion, and is further flowed into the pressure reducing portion to further reduce the pressure. Then, under the reduced pressure state, the hydraulic oil flows out to the low-pressure side oil chamber, so that the hydraulic oil from the high-pressure side oil chamber does not flow out to the low-pressure side oil chamber at a high pressure.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

As shown in FIG. 1, a hydraulic shock absorber according to one embodiment of the present invention is formed in a so-called double-cylinder type,
, An inner cylinder 2, a rod 3, a piston part 4, and a base valve part 5.

In this embodiment, the outer cylinder 1 is, for example, a lower end member, the lower end of which is closed by a bottom member 1a.
It is assumed that the upper end is closed by a bearing member or the like (not shown) in a hermetically sealed structure, and the rod 3 is slidably inserted through the shaft core or the like of the bearing member or the like.

The inner cylinder 2 is disposed concentrically inside the outer cylinder 1 and defines a reservoir chamber C between its outer periphery and the inner periphery of the outer cylinder. 4, a rod-side oil chamber A and a piston-side oil chamber B are formed.

That is, the lower end of the inner cylinder 2 is closed by a base valve portion 5 described later, and the upper end is closed by the bearing member or the like.

The rod-side oil chamber A and the piston-side oil chamber B communicate with each other via a piston part 4, and the piston-side oil chamber B and the reservoir chamber C communicate with each other via a base valve part 5 described later. It is going to be.

In this embodiment, the rod 3 is used as an upper end member while the outer cylinder 1 is used as a lower end member, and the tip (lower end in the figure) of the rod 3 is freely retractable into the inner cylinder 2. It is inserted through.

The piston 3 is connected to the tip of the rod 3.

The piston portion 4 is slidably housed in the front inner cylinder 2, and separates the rod-side oil chamber A and the piston-side oil chamber B within the inner cylinder 2 as described above. The rod-side oil chamber A and the piston-side oil chamber B communicate with each other.

That is, the piston section 4 includes a piston body 40, a damping valve 41, and a check valve 42.

The piston body 40 has a piston ring 43
And a seal ring 44, and each of the rings 43, 44
Is in sliding contact with the inner periphery of the inner cylinder 2, thereby defining a rod-side oil chamber A and a piston-side oil chamber B within the inner cylinder 2.

The piston body 40 is the valve seat member according to the present invention, and is interposed in the front end spigot portion 3a of the rod 3, and is drilled so as to penetrate its thickness in the axial direction. And an inner port 40a and an outer port 40b.

The inner port 40a is the main and extension port in the present invention, and the damping valve 41 is adjacent to the extension port so as to close the lower end of the extension port.

The outer port 40b is a so-called suction port, and the check valve 42 is provided adjacent to the suction port so as to close the upper end side of the suction port.

By the way, the piston body 40 is provided with the damping valve 41 adjacent thereto, and as shown in FIG. 2, a seat portion 40c formed to protrude from an end surface which is a lower end in the drawing, and the seat portion 40c It has a pressure receiving part 40d formed inside and facing the pressure receiving surface of the damping valve 41, and a pressure reducing part 40e formed inside the seat part 40c so as to communicate with the pressure receiving part 40d.

The pressure receiving section 40d and the pressure reducing section 40e face the pressure receiving surface of the damping valve 41.

The pressure reducing section 40e is formed so that the bottom thereof is positioned at a position (down in the figure) above the bottom of the pressure receiving section 40d while descending (upward in the figure) from the top of the sheet section 40c. ing.

And, the inner port 40a opening to the pressure receiving portion 40d,
It is used for the distribution of hydraulic oil in the middle and high speed range of the piston speed.

In this embodiment, the pressure receiving section 40d and the pressure reducing section 4
0e are each formed in an annular groove shape.

In the present embodiment, the damping valve 41 is formed of an annular leaf valve, and is disposed so that the inner peripheral end is fixed and the outer peripheral end is free, and a valve body 45 is adjacent to the lower end surface on the outer peripheral side. Has been established.

The lower end of the valve body 45 has a piston nut 46.
The upper end of the spring 47 locked to the seat portion 40 is brought into contact with the seat portion 40 in the ascending direction, that is, the outer peripheral end of the leaf valve.
It is urged in the direction of pressing against c.

A shim 46a is interposed between the upper end of the piston nut 46 and the inner peripheral end of the leaf valve.

In this embodiment, the check valve 42 is composed of two laminated annular leaf valves, and is fixed to the inner peripheral end at the upper end surface of the piston body 40 in the drawing so that the outer peripheral end is free. The outer peripheral side closes the upper end side of the outer port 40b, and the cutout hole 42a on the inner peripheral side is aimed at the upper end side of the inner port 40a.

The check valve 42 has a notch orifice 42b on the lower surface on the outer peripheral side thereof.
According to 2b, it is expected that damping force will be generated in the low-speed range of piston speed.

The check valve 42 is applied with an initial load by a non-return spring 48 on its outer peripheral side, and the lift amount is regulated by a valve stopper 49.

The above non-return spring 48 and valve stopper
In the 49, the inner port 40a is formed on the inner peripheral side, that is, notch holes 48a and 49a are formed on the inner peripheral side of the check valve 42 to aim at the notch hole 42a.

The base valve portion 5 is disposed so as to be positioned inside the lower end of the inner cylinder 2, and the piston side oil chamber B
And the reservoir chamber C (see FIG. 1).

That is, the base valve portion 5 has a valve case 50 serving as a valve seat member in the present invention, has a damping valve 51 on a lower end surface side of the valve case 50, and A check valve 52 is provided on the upper end surface side of the.

The outer periphery of the valve case 50 is clamped between the lower end of the inner cylinder 2 and the upper surface of the bottom member 1a.
A notch hole 50a is provided at the lower end thereof to allow communication between the inside of the valve case 50 and the reservoir chamber C.

The valve case 50 is basically configured in the same manner as the piston body 40, and has an inner port 50 that is opened so as to penetrate its thickness in the axial direction.
b and an outer port 50c, the inner port 50b
Is the main pressure side port in the present invention, and the damping valve 51 is disposed adjacent to the pressure side port so as to close the lower end side of the pressure side port.

Further, the outer port 50c is a so-called suction port, and the check valve 52 is provided adjacent to the suction port so as to close the upper end side of the suction port.

By the way, the valve case 50 has the damping valve 51 adjacent thereto and is configured similarly to the piston main body 40. As shown in FIG. 3, the valve case 50 has a protruding end formed at the lower end in the figure. A pressure receiving portion 50e formed inside the seat portion 50d and facing the pressure receiving surface of the damping valve 51; and a pressure receiving portion 50e inside the seat portion 50d.
And a pressure reducing section 50f formed so as to communicate with.

The pressure receiving portion 50e and the pressure reducing portion 50f face the pressure receiving surface of the damping valve 51.

The positional relationship of the pressure reducing portion 50f with respect to the seat portion 50d and the pressure receiving portion 50e is the same as that in the piston body 40.

The inner port 50b opening to the pressure receiving portion 50e is used for flowing hydraulic oil in a medium to high speed region of the piston speed.

In this embodiment, it is assumed that the pressure receiving portion 50e is formed in an annular groove shape, but the pressure reducing portion 50f is formed in an annular gap having a different shape from this.

In this embodiment, the damping valve 51 is composed of a plurality of stacked annular leaf valves, and is disposed so that the inner peripheral end is fixed and the outer peripheral end is free.

The base end side of the annular leaf valve is maintained in a fixed state by abutting a valve stopper 54 with a washer 53 therebetween, and the valve stopper 54, the washer 53 and the leaf valve are connected to the valve case. It is held at the lower end of a set nut 55 that penetrates the 50 shaft core.

In this embodiment, the check valve 52 is formed of a single annular leaf valve, and is mounted on the upper end of the set nut 55 on the end face of the valve case 50 which is the upper end in the drawing. Is held in.

The check valve 52 is arranged so that the outer peripheral side closes the upper end side of the outer port 50c, and the cutout hole 52a on the inner peripheral side is aimed at the inner port 50b.

A stamping orifice 50g is formed on the outer peripheral side seat portion at the upper end surface of the valve case 50 adjacent to the outer peripheral lower surface of the check valve 52, and the piston speed is reduced by the stamping orifice 50g. The generation of damping force in the region is guaranteed.

The check valve 52 is applied with an initial load by a non-return spring 56 on its outer peripheral side.

Therefore, in the hydraulic shock absorber formed as described above, the piston portion 4 increases its speed in a medium to high speed range, for example, in a pressure side stroke in which the piston portion 4 descends in the inner cylinder 2.
Hydraulic fluid flows into the rod-side oil chamber A via the outer port 40b and the check valve 42 in the piston portion 4, and an amount of hydraulic oil corresponding to the integral of the rod 3 entering the piston-side oil chamber B is obtained. The oil flows from the piston side oil chamber B into the reservoir chamber C via the inside port 50b of the base valve section 5 and the damping valve 51.

On the contrary, in the extension stroke in which the piston portion 4 moves out of the inner cylinder 2 in the middle and high speed range, the operating oil in the rod side oil chamber A causes the inner port 40a of the piston portion 4 and the damping valve 41 to move. The hydraulic oil flows into the piston-side oil chamber B through the piston-side oil chamber B, and an amount of hydraulic oil corresponding to the rejected volume integral of the rod 3 deficient in the piston-side oil chamber B is supplied from the reservoir chamber C to the outer port 50c of the base valve portion 5 and the check valve. Replenished via 52.

Therefore, a predetermined compression damping force is generated by the compression valve 51 of the base valve section 5 during the compression stroke of the hydraulic shock absorber, and a predetermined compression damping force is generated by the extension valve 41 of the piston section 4 during the compression stroke of the hydraulic shock absorber. Is generated.

In the low piston speed range, the piston portion 4
Then, the notch orifice 42b of the check valve 42,
In the base valve part 5, the stamped orifice of the valve case 50
When hydraulic oil passes through 50 g, a predetermined damping force can be generated.

By the way, according to the present invention, when the piston speed is in the middle and high speed range, the generation of the swift sound is prevented as follows.

That is, for example, during the extension stroke of the hydraulic shock absorber,
The hydraulic oil from the rod-side oil chamber A flows into the inner port 40a of the piston body 40, and then the inner port 40a is opened and a pressure receiving portion 40d formed so as to face the pressure receiving surface of the expansion valve 41. And further flows into a pressure reducing section 40e communicating with the pressure receiving section 40d.

Then, the hydraulic oil flowing into the pressure reducing section 40e is supplied to the damping valve 4e.
1 is opened to flow into the piston-side oil chamber B, which is a low-pressure-side oil chamber. At this time, a predetermined damping action is exhibited by opening the damping valve 41.

Therefore, the inner port 40
The high oil pressure of the hydraulic fluid flowing into the pressure receiving part 40d through a
The pressure is once reduced when flowing into the pressure receiving portion 40d, and further flows into the pressure reducing portion 40e to be further reduced in pressure, and flows out to the low pressure side oil chamber under the reduced pressure state.

Therefore, the hydraulic oil from the rod-side oil chamber A does not flow out to the piston-side oil chamber B at a high pressure, and the danger of generating a squish noise is eliminated.

When the hydraulic shock absorber is on the compression stroke,
When the hydraulic oil from the piston-side oil chamber B flows into the low-pressure-side reservoir chamber C when the piston-side oil chamber B is set as the high-pressure-side oil chamber, the base valve portion 5 generates a swift sound in the same state. Of course is eliminated.

As described above, the damping portion 40e in the piston portion 4
Is formed in the shape of an annular groove, whereas the pressure reducing portion 50f of the base valve portion 5 is formed in the shape of an annular gap having a different shape.
It is a matter of course that both 40e and the pressure reducing portion 50f of the base valve portion 5 may be formed in the same shape of annular groove (or annular gap shape).

〔The invention's effect〕

As described above, according to the present invention, it is possible to prevent in advance the generation of a squish sound in a medium-to-high speed range of the piston speed, so that a so-called noise is generated in the automobile or work equipment equipped with the hydraulic shock absorber. In addition, there is an advantage that the generation of the noise can be eliminated in advance, and in particular, when the vehicle is a passenger, the prevention of the squishing sound in the medium to high speed region of the piston speed is more effective.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a hydraulic shock absorber according to an embodiment of the present invention partially cut away, and FIGS. 2 and 3 are partial longitudinal sectional views showing a part of each of them in an enlarged manner. [Description of Symbols] 1 ... Outer cylinder 2 ... Inner cylinder 3 ... Rod 4 ... Piston section 5 ... Base valve section 40 ... Piston body 50 as a valve seat member 50 ... Valve case 40a as a valve seat member … Extension side port 50b as a port Compressor side port 40c, 50d as a port Seat section 40d, 50e… Pressure receiving section 40e, 50f… Decompression section 41… Extension side valve 51 as a damping valve Valve A: Rod-side oil chamber B: Piston-side oil chamber C: Reservoir chamber

Claims (1)

(57) [Claims] 1. A hydraulic shock absorber comprising: a seat portion protruding from an end surface of a valve seat member; and a pressure receiving portion formed inside the seat portion and facing a pressure receiving surface of a damping valve. Inside the sheet portion, a pressure reducing portion is formed in which the bottom is positioned at a position above the bottom of the pressure receiving portion while being lowered from the top of the sheet portion, and the pressure reducing portion is communicated with the pressure receiving portion. And a port opening to the pressure receiving portion is used for circulation of hydraulic oil in a medium to high speed region of a piston speed.