JPH0413461Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a shot absorber, and in particular,
The present invention relates to an improvement in a shock absorber that can effectively prevent cavitation and swishing noise during expansion and contraction.

[Conventional technology]

In general, a shock absorber is designed so that when the piston moves up and down in the cylinder, a damping force is generated on either or both expansion sides by a predetermined damping valve, and the damping force at that time is In the medium to high piston speed range, the damping force is generated by the valve characteristics and port characteristics, and in the low piston speed range, the damping force is generated by the orifice characteristics.

For example, a structure as shown in FIG. 4 has been proposed as a structure that allows generation of a damping force with orifice characteristics in a low piston speed range.

That is, FIG. 4 shows the piston part 2 in the cylinder 1.
This structure has a damping valve 2c disposed to close the upper end of the port 2b of the piston body 2a.

The damping valve 2c is formed by stacking a plurality of annular leaf valves, and the lowermost annular leaf valve has an orifice O formed of a notch at its outer peripheral end.

Therefore, by appropriately setting the flow path area of the orifice O in the damping valve 2c described above, it is possible to generate a damping force with orifice characteristics in a desired low piston speed range.

[Problem that the invention attempts to solve]

However, in the above proposal, when a damping force with desired orifice characteristics is generated,
There is a disadvantage that cavitation is generated and also a swishing sound is generated.

That is, when the upstream side of the orifice O in the damping valve 2c becomes the high pressure side, the high pressure oil flows into the downstream side via the orifice O, but the high pressure oil flows out all at once to the low pressure side, which is the downstream side. If this happens, a so-called injection state of the hydraulic oil will occur, which will cause cavitation and a swiss noise.

Therefore, the purpose of the present invention is to provide a new shock absorber having a valve structure that eliminates the risk of cavitation or swishing noise when generating damping force in the low piston speed range using orifice characteristics. .

[Means for solving problems]

In order to solve the above-mentioned problems, the structure of the shock absorber according to the present invention is such that an inner seat is provided with an opening groove in which the upper end of the port bored in the valve seat member is opened, and an inner seat is provided protruding from the upper end surface of the valve seat member. The valve seat member has a damping valve disposed so as to block the opening groove from above, and a damping valve is provided on the upper end surface of the valve seat member on the outer periphery of the inner seat part and is perforated concentrically with the inner seat part. The damping valve has an orifice on the lower surface of its outer peripheral end, and an annular seat between the upper surface of the outer seat and the lower surface of the outer peripheral end of the damping valve. is disposed, and an annular gap is formed between the lower end surface of the damping valve and the upper surface of the lower inner seat portion inside the annular seat.

[Effect]

When the upper oil chamber becomes the high pressure side, the hydraulic oil from the high pressure side oil chamber flows into the pressure reducing groove through the orifice formed in the damping valve and is once depressurized in the pressure reducing groove. The reduced pressure hydraulic oil does not flow into the opening groove through the annular gap formed between the upper end surface of the inner seat part and the lower end surface of the upper damping valve inside the ring seat, causing an injection state. This will cause the oil to leak into the low-pressure side oil chamber.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

FIG. 1 shows a shock absorber according to an embodiment of the present invention, in which a piston portion 2 in a cylinder 1 is disposed at a lower end spigot portion 3a of a piston rod 3 inserted into the cylinder 1. and the lower end threaded portion 3b of the piston rod 3.
It is formed so as to be fixed by a piston nut 30 threaded onto the piston nut 30.

The inside of the cylinder 1 is divided into an upper oil chamber A and a lower oil chamber B by the piston part 2, and a base valve part 4 is disposed inside the lower end of the cylinder 1. It is assumed that an outer tube 10 is provided on the outside of the reservoir chamber C to form a reservoir chamber C.

Note that the reservoir chamber C and the lower oil chamber B in the cylinder are communicated with each other via the base valve portion 4.

The piston portion 2 has a port 20a in a piston body 20, which is a valve seat member, that allows communication between the upper oil chamber A and the lower oil chamber B, and the piston body has an upper end open at the upper end of the port 20a. As shown in FIG. 2, the upper end surface of the port 20 has an annular opening groove 2 in which the upper end of the port 20a opens.
0b, and a pressure reducing groove 20c formed annularly around the outer periphery of the opening groove 20b.

The pressure reducing groove 20c is formed concentrically with the opening groove 20b, and is formed by an annular outer seat portion 20d and an annular inner seat portion 20e protruding from the upper end surface of the piston body 20. Groove 2
Sections 0b and 20c are formed.

The upper end surface of the outer seat section 20d is set to be at the same height as the upper end surface of the inner seat section 20e, so that there is no difference in height between the two.

A damping valve 21 is disposed at the upper end of the piston body 20, and the damping valve 21 is
In this embodiment, it is an expansion side valve.

The damping valve 21 is formed by stacking a plurality of annular leaf valves, and is capable of generating a damping force having a predetermined valve characteristic by bending the inner peripheral end of the valve. Adjacent to the upper surface of the inner peripheral end is the lower surface of the inner peripheral end of a valve stopper 23, which is biased downward by contacting the lower end of the spring 22 whose upper end is locked.

The valve stopper 23 has a port 23a formed to penetrate through its wall thickness in the axial direction, and a lower end opening of the port 23a faces the upper surface of the damping valve 21.

The damping valve 21 has an orifice O on the lower surface of the outer peripheral end, and the orifice O has a third
As shown in the figure, it consists of a notch formed at the outer peripheral end of the annular leaf valve 21a at the bottom layer.

The orifice O is connected to the pressure reducing groove 20.
c, so that hydraulic oil from above the damping valve 21 can flow into the pressure reducing groove 20c.

A ring seat 24 formed concentrically with the damping valve 21 is adjacent to the lower surface of the outer peripheral end of the damping valve 21 (see the broken line diagram in FIG. 3), and the lower surface of the ring seat 24 is located on the lower outer side. It is adjacent to the upper surface of the seat portion 20d.

Since the width of the thick wall portion of the ring seat 24 is approximately half the length of the notch forming the orifice O of the damping valve 21, the ring seat 24 of the orifice O Therefore, the hydraulic oil passes through a portion on the plane that is not blocked (indicated by diagonal lines in FIG. 3).

The inside of the ring seat 24 is a space,
The lower surface of the damping valve 21 is located above the space, and the upper surface of the annular seat portion 20e formed on the upper end surface of the piston body 20 is located below the space.

Therefore, an annular gap S is formed inside the annular seat 24 between the lower surface of the damping valve 21 and the upper surface of the inner seat portion 20e. The pressure reducing groove 20c and the opening groove 20b are brought into communication.

Note that the damping valve 21, the spring 22,
The valve stopper 23 and the ring seat 24 fit the upper end of the outer periphery of the piston body 20 into the lower end thereof,
The piston rod 3 is housed in a cap 25 with a cutout hole inserted in the piston rod 3 so that its upper end is engaged with the stepped portion 3c of the piston rod 3.

Therefore, when the piston part 2 moves up inside the cylinder 1 at low speed, the upper oil chamber A, which is the oil chamber on the high pressure side,
The hydraulic oil from inside flows into the pressure reducing groove 20c through the orifice O of the damping valve 21, and the hydraulic oil flowing into the pressure reducing groove 20c flows inside the ring seat 24 between the lower surface of the damping valve 21 and the lower side. It flows into the opening groove 20b via the annular gap S formed between the inner sheet portion 20e and the upper surface.

When the high pressure oil flows into the pressure reducing groove 20c, it is once reduced to a low pressure, and the reduced pressure oil continues to flow into the opening groove 20c and further reduced in pressure, and then the lower pressure oil on the low pressure side Room B
Since the high-pressure oil will flow out to the side, a situation will not occur in which the high-pressure oil suddenly flows out to the low-pressure side, and therefore, a so-called injection state of hydraulic oil will not occur.

Furthermore, as the hydraulic oil passes through the orifice O and the annular gap S, a rebound damping force characteristic of the orifice is generated.

Note that when the piston part 2 moves up inside the cylinder 1 at medium to high speed, the hydraulic oil from the upper oil chamber A, which is the high pressure side, flows into the opening groove 20b and the port 20a through the inner peripheral end of the damping valve 21. and flows into the lower oil chamber B.

At that time, a rebound damping force having predetermined valve characteristics and port characteristics is generated.

The feature of the present invention described above is that in this embodiment, the base valve portion 4 in the cylinder 1
It is also embodied in

That is, as shown in FIG.
A valve case 40 serving as a valve seat member has a port 40a, similarly to the piston body 20 serving as a valve seat member in the piston portion 2, and a valve case 40 serving as a valve seat member has a port 40a. The upper end surface of the port 40 has an opening groove 40b in which the upper end of the port 40a opens, and a pressure reducing groove 40c formed on the outer periphery of the opening groove 40b. A damping valve 41 as a pressure side valve is disposed at the upper end of the valve case 40.

The opening groove 40b is defined by an inner seat portion 40e that protrudes from the upper end surface of the valve case 40, and the pressure reducing groove 40c is defined by the inner seat portion 40e.
The outer seat portion 40d is arranged concentrically around the outer periphery of the outer seat portion 40d.
It is divided by.

The damping valve 41 is composed of stacked annular leaf valves, and has an orifice O formed of a notch at the lower surface of its outer peripheral end, that is, at the outer peripheral end of the lowest leaf valve 41a.

Then, the orifice O is connected to the pressure reducing groove 40c.
They are now facing each other.

The lower surface of the outer peripheral end of the damping valve 41 is adjacent to the upper surface of the ring seat 44 whose lower surface is adjacent to the upper surface of the outer seat portion 40d.

That is, the exposed portion of the orifice O facing the pressure reducing groove 40c is narrowed by the area where the ring seat 44 is adjacent to the orifice O (see the hatched portion in FIG. 3).

Further, the inside of the ring seat 44 is a space, and above the space is the damping valve 41.
The lower surface of the inner sheet portion 40e is located below the space, and the upper surface of the inner sheet portion 40e is located below the space.

Therefore, an annular gap S is formed inside the annular seat 44 between the lower surface of the damping valve 41 and the upper surface of the inner seat portion 40e. The pressure reducing groove 40c and the opening groove 40b are brought into communication.

A valve stopper 43 , which is biased downward by a spring 42 , is adjacent to the upper surface of the damping valve 41 .
1, the spring 42, the valve stopper 43, and the ring seat 44 fit the upper end of the outer periphery of the valve case 40 into the lower end thereof, and the upper end thereof is connected to the cylinder 1.
The cap 45 is housed in a cap 45 with a cutout hole, which is disposed so as to be locked to the lower end crimped portion 1a of the cap.

Therefore, even in the above-mentioned base valve part 4, when the piston part 2 moves down inside the cylinder 1 at low speed, the hydraulic oil from the lower oil chamber B passes through the orifice O of the damping valve 41 and enters the pressure reducing groove. 40c
At the same time, it flows from the pressure reducing groove 40c through the annular gap S into the opening groove 40b and into the port 40.
It flows into the reservoir chamber C side.

Since the pressure oil from the high-pressure side flows out to the low-pressure side via the pressure reducing groove 40c, the outflow does not occur in a so-called injection state.

Furthermore, a damping force having a predetermined orifice characteristic is generated by passing through the orifice O, and when the piston speed is medium to high, the inner circumferential end of the damping valve 41 is bent to absorb pressure oil from the high pressure side. flows out to the low pressure side, and a damping force with predetermined valve characteristics is generated.

[Effect of idea]

As described above, according to the present invention, when the damping force is generated in the low speed range of the piston due to the orifice characteristics, the hydraulic oil from the high pressure side is not suddenly leaked to the low pressure side, so the hydraulic oil on the low pressure side This has the advantage that the injection state of the hydraulic oil is not caused in the event of a spill, and there is no risk of cavitation or swishing noise.

Further, according to the present invention, it is sufficient that the upper surface of the seat portion formed on the upper end surface of the valve seat member is flush with the upper surface of the valve seat member, and an annular seat is interposed between it and the lower surface of the upper damping valve. Since it is sufficient to use only the above-described structure, there is no inconvenience such as having to drastically change the basic form of the piston part or the base valve part, which is advantageous in terms of implementation.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view partially showing a shock absorber according to an embodiment of the present invention, Fig. 2 is a top end view of the piston body which is a valve seat member, and Fig. 3 is a view of the bottom layer constituting the damping valve. FIG. 4, which is a plan view of the leaf valve, is a longitudinal sectional view partially showing a conventional shock absorber. 1... Cylinder, 2... Piston part, 3... Piston rod, 4... Base valve part, 20...
Piston body, 20a... Port, 20b... Opening groove, 20c... Pressure reducing groove, 20d... Outer seat portion, 20e... Inner seat portion, 21... Damping valve, 24... Ring seat, 40... Valve case, 40
a...Outside port, 40b...Opening groove, 40c...
...Decompression groove, 40d...Outer seat part, 40e...
Inner seat portion, 41...damping valve, 44...ring seat, A...upper chamber, B...lower chamber, C...reservoir chamber, O...orifice, S...annular gap.

Claims (1)

[Claims for Utility Model Registration] (1) An opening groove in which the upper end of a port formed in the valve seat member opens is defined by an inner seat portion protruding from the upper end surface of the valve seat member, and In a shock absorber having a damping valve disposed to close a groove from above, an outer seat is provided on the upper end surface of the valve seat member and protrudes from the outer periphery of the inner seat part concentrically with the inner seat part. The damping valve has an orifice on the lower surface of the outer peripheral end thereof, and an annular seat is disposed between the upper surface of the outer seat part and the lower surface of the outer peripheral end of the damping valve. A shock absorber characterized in that an annular gap is formed between the lower end surface of the damping valve and the upper surface of the lower inner seat part inside the annular seat. (2) The shock absorber according to claim 1, wherein the valve seat member is a piston body in a piston portion within the cylinder. (3) The shock absorber according to claim 1, wherein the valve seat member is a valve case in a cylinder base valve section.