JPH0743454Y2 - Cushion device for hydraulic cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cushion device for a hydraulic cylinder, and particularly to prevent the piston from suddenly colliding with the cylinder head or the cylinder bottom when the piston is extended or compressed most. The present invention relates to a cushion device for a hydraulic cylinder.

[Conventional technology]

A shock absorber for a lift cylinder that decelerates the piston slightly before the rising end of the piston to mitigate the impact at the rising end and, on the contrary, quickly reaches a constant lowering speed when descending from the rising end is a real example. It is started in Japanese Patent Publication No. 61-23683.

In this lift cylinder shock absorber, a piston rod is movably inserted into the cylinder via a piston, and the piston defines two upper and lower oil chambers in the cylinder, and the two oil chambers are provided in the piston rod and the piston. A check valve made of a ball valve is provided on the valve seat in the passage of the piston so as to be openable and closable.

Near the maximum extension of the piston, the passage of the piston rod is gradually narrowed to act as a cushion, and when descending from the maximum extension state, the check valve opens and the oil in the lower oil chamber flows out to the upper oil chamber through the passage of the piston. You can do it.

[Problems to be solved by the invention]

In the above-mentioned shock absorber for lift cylinder, a passage is provided in the piston, and the check valve is housed in the passage so that the check valve can be opened and closed freely. A lot of seat processing accuracy is required, the processing is difficult, and a long processing time is required. Further, a ball valve as a check valve is required, the number of parts is large, and the cost is high. Further, since the piston is provided with a check valve, the diameter of the piston is inevitably large, and the hydraulic cylinder itself is large in diameter, which is disadvantageous in terms of weight.

Therefore, an object of the present invention is to provide a cushioning device for a hydraulic cylinder which has a reduced number of processing steps, a small number of parts, a small diameter and a light weight, and is excellent in economic efficiency.

[Means for solving problems]

In order to achieve the above object, the structure of the present invention is such that a bearing is provided at the end of the cylinder and a piston is provided at the outer periphery of the end of the piston rod, and the piston rod is movable in the cylinder through the piston and the bearing. The piston part is composed of a piston and a bearing seal that is movably provided on the outer circumference of the piston and is in sliding contact with the inner circumference of the cylinder.The piston part further includes a rod-side oil chamber and a non-rod-side oil chamber inside the cylinder. These two oil chambers are connected to each other through a passage formed in the piston rod and a gap between the piston and the cylinder to form an annular groove in the outer periphery of the piston. An annular bearing seal that communicates or blocks the gap is inserted into the annular groove so as to be movable in the axial direction, and a notch passage in the axial direction is formed in the inner periphery of the bearing seal, and the rod side oil chamber is formed. Radial cutout passages are formed on the opposing end faces, the bearing seal blocks the gap near the stroke end of the piston rod, and the bearing gradually narrows the mouth end of the passage formed in the piston rod. It is what

[Action]

The bearing seal blocks the gap near the stroke end of the piston, the passage opening end of the piston rod is gradually narrowed by the bearing to create a cushion, and when the piston rod moves in the opposite direction from the stroke end state, the bearing seal is closed. By lifting and communicating the gap, the oil in the oil chamber opposite to the rod flows out into the oil chamber on the rod side through the notch passages in the axial direction and the radial direction of the bearing seal.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

A cylinder head 2 is screwed into one end of the cylinder 1, and a bearing 3 and a dust seal 4 are housed in the cylinder head 2.
A packing 5 as an oil seal and a packing retainer 6 are provided in the bearing 3.

A piston rod 8 is movably inserted into the cylinder 1 via a piston portion 7 and a bearing 3, and the piston portion 7 has an upper oil chamber 9 serving as a rod-side oil chamber in the cylinder 1 and an opposite rod opposite to the piston rod. The lower oil chamber 10, which is a side oil chamber, is partitioned.

The piston part 7 is a piston screwed onto a piston rod 8.
Bearing seal 12 movably mounted on the outer circumference of 11 and piston 11
It consists of and.

The piston rod 8 has a T having a horizontal passage 16 and a vertical passage 17.
A V-shaped passage is formed, and these passages 16 and 17 connect the upper and lower oil chambers 9 and 10 to each other.

An annular groove 15 is formed on the outer circumference of the piston 11, and this annular groove
An annular bearing seal that slides against the inner circumference of the cylinder 1 in 15
An upper end 12 of the bearing seal 12 facing the oil chamber 9 on the piston rod side is formed with one or a plurality of notch passages 13 in the radial direction. Further, as shown in FIG. 4, one or a plurality of notch passages 19 are formed on the inner circumference of the bearing seal 12 to form an oil passage for oil.

Between the annular groove 15 and the bearing seal 12, oil is allowed to flow and an arbitrary gap 14 is provided so that the bearing seal 12 can move up and down.
And a slight gap 18 is formed between the outer circumference of the piston 11 and the inner circumference of the cylinder 1 along the longitudinal direction to allow oil to flow.

As shown in FIG. 1, for example, when the piston 11 is extended,
As shown in FIG. 2, the upper oil chamber 9 is compressed to a high pressure, and the internal pressure of the oil chamber 9 causes the bearing seal 12 to descend to block the annular gap 18 between the piston 11 and the cylinder 1, 9
The oil in the lower oil chamber 1 passes through the passages 16 and 17 of the piston rod 8.
Spill to 0. In the vicinity of the maximum extension of the stroke end of the piston 11, the mouth end of the passage 16 is gradually narrowed by the bearing 3,
The flow velocity resistance of 16 reduces the piston speed to prevent the piston 11 from abruptly colliding with the bearing 3 and to act as a so-called cushion.

When the piston moves in the compression direction from the time of maximum extension, as shown in FIG. 3, the lower oil chamber 10 is compressed to a high pressure, and the internal pressure lifts the bearing seal 12 to open the annular gap 18, so that the lower portion The oil in the oil chamber 10 is introduced into the upper oil chamber 9 through the annular gap 18-the gap 14 and the notch passage 19-the notch passage 13-the annular gap 18, and the piston 11 descends smoothly without generating negative pressure. To do.

[Effects of the Invention] The present invention has the following effects.

1) In the vicinity of the stroke end, the passage provided in the piston rod is gradually narrowed by the bearing, and the bearing seal blocks the communication between the two oil chambers, so that the cushion is effective due to the flow resistance of the passage of the piston rod.

2) Since the piston is provided with an annular groove and the bearing seal is movably inserted into this annular groove, the number of parts is small, and complicated hole processing and seat processing that requires precision are not required, so processing is possible. It is easy and economical.

3) Since the bearing seal is formed with the notch passages in the axial direction and the radial direction, when the bearing seal is lifted, the oil can smoothly flow.

4) Since the bearing seal has a cutout passage in the axial direction in the inner circumference, it can also have a check valve function without losing the bearing function.

5) Since the bearing seal has a check valve function, it is not necessary to provide each check valve separately, and accordingly, the number of parts is small, the diameter of the piston can be reduced, and the weight can be reduced.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a hydraulic cylinder according to an embodiment of the present invention, FIGS. 2 and 3 are enlarged sectional views showing the operation of a bearing seal, and FIG. 4 is a schematic plan view of the bearing seal. Is. DESCRIPTION OF SYMBOLS 1 ... Cylinder, 3 ... Bearing, 7 ... Piston part, 8 ... Piston rod, 9 ... Rod side oil chamber, upper oil chamber, 10 ... Anti-rod side oil chamber, lower oil chamber, 11 ... Piston, 12 ... Bearing seal, 13 … Notched passage, 14… Gap, 15… Annular groove, 16,17…
Passage, 18 ... Gap, 19 ... Notched passage.

 ─────────────────────────────────────────────────── ───Continued from the front page (56) References JP 62-17406 (JP, A) Actual development 57-178098 (JP, U) Actual public Sho 54-32150 (JP, Y2) Actual public 61- 28086 (JP, Y2) Actual public Sho 61-41441 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A bearing is provided at an end of a cylinder, and a piston is provided at an outer periphery of an end of a piston rod. A piston rod is movably inserted into the cylinder through the piston and the bearing. The piston is composed of a bearing seal that is movably provided on the outer circumference of the piston and slidably contacts the inner circumference of the cylinder.Furthermore, the piston section defines a rod-side oil chamber and an anti-rod-side oil chamber inside the cylinder. Is a hydraulic cylinder in which a passage formed in the piston rod and a gap between the piston and the cylinder communicate with each other, and an annular groove is formed on the outer periphery of the piston. An annular bearing seal for blocking is inserted movably in the axial direction to form a notch passage in the axial direction on the inner periphery of the bearing seal and a notch in the radial direction on the end face facing the rod side oil chamber. Forming a passageway, bearing seal shuts off the gap at the stroke end near the piston rod, also, the cushion device of the hydraulic cylinder, characterized in that gradual throttling mouth end of the passage where the bearing is formed in the piston rod.