JPS58178036A - Cylinder device - Google Patents

Abstract

PURPOSE:To achieve the desired oil pressure resistance characteristic of a cylinder in a hydraulic shock absorber, by fixing a piston at one end of a piston rod movably in a predetermined range while making the conducting path of the piston chokable through deformation of a resilient member. CONSTITUTION:A small diameter section 21A is formed at the inner end of a piston rod 21 projecting through a rod guide 3 into a cylinder 1 and a piston 22 is fitted to said section 21A movably in the axial direction. Said movable range is limited by a rising step section 21B and a stopper 23. First orifice 24 conducting between the oil chambers B, C, a path opening to the oil chamber C side and second orifice 26 conducting between said path 25 and the oil chamber B are formed. Then discs 27, 28 are placed movably between said piston 22 and the step 21B and stopper 23 to be deformed by the differential pressure between both chambers B, C thus to choke the orifice 24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a piston-piston rod assembly consisting of a piston and a piston rod in a slidable manner within a cylinder, and generates a damping force during the extension stroke and contraction stroke of the piston-piston rod assembly. This relates to cylinder devices such as hydraulic shock absorbers and gas springs.

FIG. 1 shows a hydraulic shock absorber as a cylinder device according to the prior art.

In the figure, 1 is a cylinder, one end of which is covered with a cap 2 9, and a rod guide 3 and a seal member 4 fitted to the other end. Reference numeral 5 indicates a piston that is slidably provided within the cylinder 1, and reference numeral 6 indicates a piston rod that protrudes into the cylinder 1 through the rod 3 and the seal member 4, and the piston is provided at the tip of the piston rod 6. It is inserted and fixed.

Next, 7 is a free piston that is slidably inserted into the cap 2 side of the cylinder 1, and the space between the free piston 7 and the cap 2 compensates for the volume of the piston rod 6 entering the cylinder 1. A gas chamber A is formed for
The nuclear gas chamber A is filled with gas at a predetermined pressure. Further, oil chambers B and C are formed between the free piston 7 and the piston 5 and between the piston 5 and the seal member 4,
filled with oil. Reference numeral 8 denotes an orifice bored in the piston 5, and the orifice 8 allows the oil chambers B and C to communicate with each other at all times through a small flow path surface 8t.

Note that 9 and 10 are sealing members provided on the piston 5 and the free piston 7, respectively, and 11 and 12 are brackets attached to the base end of the piston 5 and the cap 2, respectively.

The hydraulic shock absorber according to the prior art has the above-described configuration, and when an external force is applied to the piston rod 6 in the direction of the arrow a in the figure, the piston rod 6 is displaced in a direction in which it extends together with the piston 5. Therefore, the pressure inside the oil chamber C becomes high, and the oil chamber C
The oil inside flows into the oil chamber B through the orifice 8.

The piston 5 is decelerated by the hydraulic resistance force when this oil passes through the orifice 8.

On the other hand, when an external force is applied to the piston rod 6 in the direction shown by the arrow in the figure, the piston is also displaced in the direction of contracting 1' together with the Sugago piston 5, and at this time, the oil in the oil chamber B passes through the orifice 8 and oil The hydraulic resistance force when flowing into the chamber C provides a damping effect on the piston 5.

FIG. 2 shows the relationship between the hydraulic resistance force and the speed of the piston 5. As is clear from the figure, since the flow path area of the orifice 8 provided in the piston 5 is constant, the characteristics of the hydraulic resistance force with respect to the speed of the piston 5 are constant, and are the same in both the extension stroke and the contraction stroke. Therefore, for example, piston 5
When the speed of the piston 5 is in a low speed range, only a small hydraulic resistance force is generated, but when the speed of the piston 5 is in a high speed range, it is necessary to have an extremely large hydraulic resistance force. Such control has not been possible with the hydraulic shock absorber according to the prior art described above. Therefore, the degree of freedom in setting the characteristics of the hydraulic resistance force is limited, and one drawback is that it is not possible to set all the characteristics optimally depending on the application of the hydraulic shock absorber.

The present invention aims to solve the above-mentioned drawbacks of the prior art, and is characterized in that a piston is movably inserted into a piston rod, and the piston rod has a range of movement of the piston. The piston is provided with a pair of regulating portions for regulating the oil pressure, and the piston is provided with a first oil chamber between the two oil chambers in the cylinder defined by the piston. A second orifice communicates with the piston, and an elastic member that deforms due to the differential pressure in the oil chamber and closes the first orifice is provided between each of the regulating portions and each end surface of the piston. An object of the present invention is to provide a cylinder device which can change the characteristics of hydraulic resistance force before and after the first orifice is closed by the extranuclear member.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 8.

First, in FIG. 3, the same components as those in FIG.
21 is a piston rod, and the piston rod 21 has a small diameter portion 21A formed at its tip;
1A, a piston 22 sliding along the inner wall of the cylinder 1;
is inserted into the piston rod 21 so as to be movable in the axial direction. A rising (5) shaped step part 21B is formed on the piston rod 21, and a stopon 23 is fixedly provided at the tip of the small diameter part 21A.
and the stopper 23 form a regulating portion that regulates the movement range of the piston 22.

Next, a first orifice 24 is bored through the piston 22 in the axial direction, and a passage 25 that opens toward the oil chamber C is formed separately from the first orifice 24. A second orifice 26 is bored between the oil chamber B and the oil chamber B. The first orifice 24 has a larger flow area than the second orifice 26. Further, the end face of the piston 22 facing the stopper 23 is formed with a protrusion 22A whose inner circumferential side protrudes from the outer circumferential side toward the systole 23 side, and the oil chamber B of the first orifice 24.
A recess 22B is formed around the opening. On the other hand, an annular protrusion 22C is provided at an intermediate portion and an outer peripheral portion of the end face of the piston 220 facing the stepped portion 21B, respectively.
A first projection 22D is formed between each projection 22C and 22D.
An annular groove (6) 22E that communicates the opening of the orifice 24 with the oil chamber C is formed, and an annular groove 22F that communicates the opening of the passage 25 with the oil chamber C is formed on the inner peripheral side of the protrusion 22C.
is formed. The protrusion length of the protrusion 22C is longer than the protrusion length of the protrusion 22D.

Reference numerals 27 and 28 indicate annular disks as elastic members interposed between the stopper 23 and the piston 22 and between the piston 22 and the stepped portion 21B, respectively.
7.28 is a stock horn and 'l respectively in the assembled state.
3, it has a radial length that protrudes radially outward from the annular groove 22E.

(-1, te, the disc 27 is on the protrusion 22A of the piston 22
When the disc 27 and the piston 22 come into contact with each other, a flow is formed between the oil chamber B and the oil chamber C via the first oriice 24.
A flow path 29 is formed to allow the entire oil to flow through the disk 27.
When the flow path 29 is deformed, the flow path 29 is closed. On the other hand, the disk 28 has a piston 2 that constantly communicates with the annular groove 22F.
A notch 28A having a larger diameter than the first step 21B is formed. Then, the disc 28 is connected to the protrusion 2 of the piston 22.
2C, the oil fluid flows in any direction between the oil chambers B and c through the second orifice 26, the passage 25, the annular groove 22F1, and the notch 28A.
8 comes into contact with the protrusion 22C of the piston 22, the first orifice 2 is formed between the disc 28 and the protrusion 22D.
4. A flow path 3 through which all oil flows from oil chamber C to oil chamber B.
o is formed and the disk 28 is deformed, the nuclear channel 3o is closed.

The cylinder device according to the present invention has the above-mentioned configuration, and its operation will now be explained based on FIGS. 4 to 7.

First, when an external force acts on the piston rod 21 and displaces it in the direction of the arrow a, the piston 22 and the disk 27 come into contact with the stop horns 23, and then the piston rod 22 slides in the direction of the arrow a with the piston rod 21. Dynamic displacement and start the entire extension stroke.

Due to the sliding displacement of the piston 22, the oil in the oil chamber C is in the first position. Flows into the oil chamber B 1 (il) through the second orifice 24.26'r.
．． Since the passage area 26 is small, a flow resistance is generated in the oil flowing in the northern part, and the piston 22 is decelerated by this hydraulic resistance force.

Due to the pressure generated in the oil chamber C, the disk 28 is also displaced toward the piston 22, and the piston 22 enters the state shown in FIG. 4 in which the disks 27 and 28 are in contact with both end surfaces thereof. Even in this case, since the flow passages 29.30 are formed between both end surfaces of the piston 7220 and each disk 27.28,
The flow of oil in the first orifice 24 is not hindered.

However, when the sliding displacement of the piston 22 increases at a high speed, the differential pressure between the oil chambers C and B becomes too large, and the disk 28 deforms as a fulcrum of the protrusion 22C'i under this pressure. The annular groove 22E is closed in the state shown in FIG. 5 in which its outer peripheral edge is in contact with the protrusion 22D.

As a result, the oil does not flow from the first orifice 24, and only the second orifice 26 becomes a waterfall or path from the oil chamber C to the oil chamber B, and the hydraulic resistance suddenly increases.

(9) On the other hand, when an external force acts on the piston-2 door 21 and moves in the direction shown in the figure, the stepped portion 21B comes into contact with the disk 28, and the piston rod 21 is displaced to a position where the disk 28 comes into contact with the piston 22. After that, the piston 22 slides in the b direction together with the piston rod 21, resulting in a contraction stroke. Due to this sliding displacement of the piston 22), from the oil chamber B to the first. When the oil flows into the oil chamber C through the second oriSwiss 24, 26i, the entire hydraulic resistance force is generated. In this case as well, the disk 27 comes into contact with the piston 22 due to the pressure in the oil chamber B, as shown in FIG. 6. In this state, the disks 27 and 28 come into contact with the piston 22, as in the case of FIG. This does not impede the flow of oil in the second orifice 24, 26.

Then, when the sliding displacement of piston/22 becomes high speed, the seventh
As shown in the figure, the disk 27 closes the flow path 29 and the first orifice 24, so the only flow path from the oil MB to the oil chamber C is the second orifice 26. (Hydraulic resistance/+n) Force increases rapidly.

Therefore, the relationship between the speed of the piston 22 and the hydraulic resistance force is shown in FIG. As is clear from the figure, in the low speed range of the piston 22, the flow path between the oil chambers B and C is the first. Since the second orifice is 24.26, the flow path area is relatively large.
Hydraulic resistance becomes small.

On the other hand, when the piston 22 slides at high speed, the disks 27 and 28 are deformed and the flow path is opened to the first orifice 2.
4 is closed, leaving only the second orifice 26,
The characteristics of the hydraulic resistance force will change and increase rapidly. Therefore, if the flow path areas of the first and second orifices 24, 26, the number of disks 27, 28, the spring force, etc. are all set appropriately, desired hydraulic resistance characteristics can be obtained.

In the above-mentioned embodiment, the case where the cylinder device f' according to the present invention is used as a hydraulic shock absorber has been described, but it goes without saying that it can also be used as a gas spring. In addition, although it has been described that the first orifice 24 has a larger flow path area than the second orifice 26, both orifices 24 and 26 have a larger flow path area.
4 and 26 may have the same diameter, and the second orifice 26
On the other hand, the block groove 22 does not need to be annular and may have four parts similar to the four parts 22B.

i, disks 27 and 28 are respectively stock A123,
Although the disc 27 has been described as protruding from the stepped portion 21B, the entire protruding portion of the disk 27 can be made unnecessary by, for example, providing the stopper 23 with a passage for introducing pressure. On the other hand, when the small diameter portion 21A is not entirely formed on the piston 21, a restricting portion such as a C ring may be used in place of the stepped portion 21B. Furthermore, if the bracket 12 is mounted upwardly, the free piston 7 does not necessarily need to be provided.

As described in detail above, according to the cylinder device according to the present invention, the piston is movably inserted into the piston rod,
The piston rod is provided with a pair of regulating parts that regulate the entire movement range of the piston, and the piston Kl [first oil chamber which communicates with two oil chambers in the cylinder defined by the piston] is provided on the piston rod. Second
orifice is bored, and an elastic member is interposed between each of the regulating portions and each end surface of the piston to deform due to the differential pressure in the internal oil chamber and close the first orifice. The characteristics of the hydraulic resistance force can be changed before and after the first orifice is closed by the cylinder. Depending on the application of the device, desired hydraulic resistance characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing a hydraulic shock absorber as a cylinder device according to the prior art, FIG. 2 is a diagram showing hydraulic resistance characteristics with respect to piston speed of the hydraulic shock absorber shown in FIG. 1, and FIGS. The figures show an embodiment of the present invention; FIG. 3 is a longitudinal sectional view of a hydraulic shock absorber as a cylinder device; FIGS. 4 to 7 are partially enlarged views of FIG. 3 showing different operating states; FIG. 8 is a diagram showing hydraulic resistance force characteristics with respect to piston speed. l...Cylinder, 21...Piston rod, 21B
...&i, 22... Piston, 23... Stroke amount, 24... First orifice, 26... Second orifice, 27.28... Disk, B, C... Oil room. Figure 4 Figure 5 Figure 6 Figure 7

Claims (2)

[Claims] (1) A piston rod is provided in the cylinder to protrude from the outside, and a piston defined in the t2 chamber in the cylinder is inserted into the tip of the piston rod so as to be movable in the axial direction of the piston rod, The piston has a first. Second
a pair of regulating parts for regulating the movement range of the piston are formed in the piston rod, and a pressure difference between the two chambers is formed between each regulating part and each end surface of the piston. A cylinder device in which elastic members are respectively interposed to deform and close the first orifice. (2) The cylinder device according to claim (1), wherein each of the elastic members is a disk.