JPH0640325Y2 - Hydraulic cylinder cushion device - 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 abruptly 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, for example, a real shock absorber. It is disclosed 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. It's ready.

[Problems to be solved by the invention]

In the above-described shock absorber for lift cylinder, the piston is provided with the passage, and the check valve is accommodated in the passage so that the check valve can be opened and closed. Therefore, the piston becomes thick in the radial direction. For this reason, there is a problem that the cross-sectional area of the piston rod into which the piston is fitted becomes small and the tensile strength is reduced. In addition to lathe processing, the piston requires drilling holes for passages, seating of check valves, etc., resulting in a large number of processing man-hours and it is difficult to machine when lathing from lathe processing. It is difficult and requires a lot of processing time.

Therefore, an object of the present invention is to provide a cushioning device for a hydraulic cylinder that is excellent in strength, can reduce the number of processing steps, and is excellent in economy.

[Means for solving problems]

In order to achieve the above-mentioned object, the structure of the present invention is such that a piston rod is movably inserted into a cylinder through a piston part, and the piston part defines an upper oil chamber and a lower oil chamber in the cylinder, and The oil chamber communicates with the main passage formed in the piston rod.In the hydraulic cylinder, a bypass branched from the main passage is provided in the piston rod to allow the two oil chambers to pass through, and a check valve is provided in the bypass. And a piston main body in which an opening for the upper oil chamber of the bypass is formed closer to the piston than the opening for the upper oil chamber of the main passage, and the piston is further engraved with a screw on the inner circumference. It is configured by a cylindrical body standing upright from the piston body, and the opening of the bypass is regulated by the cylindrical body to prevent the check valve from falling off. It is intended.

[Action]

In the vicinity of the maximum extension of the piston, the main passage of the piston rod is gradually squeezed to act as a cushion, and when transitioning from the maximum extension state to the compression state, the oil in the lower oil chamber opens the check valve, and the upper part via the bypass. Spills into the oil chamber.

〔Example〕

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

The hydraulic cylinder cushion device has the following configuration.

Piston rod 8 in cylinder 1 via piston 7
Is movably inserted, the piston section defines an upper oil chamber 9 and a lower oil chamber 10 in the cylinder, and the two oil chambers 9 and 10 communicate with each other through a main passage formed in the piston rod 8, Is composed of a horizontal passage 16 opening to the upper oil chamber 9 and a vertical passage 17 opening to the lower oil chamber 10. Further, a bypass 18 is provided in the piston rod 8 in addition to the main passage to provide the two oil chambers 9 and 10. Check plate inside this bypass 18
14 is provided so as to be openable and closable, and the opening end for the upper oil chamber 9 in the bypass 18 is defined as the upper oil chamber 9 of the lateral passage 16.
Is formed on the lower side of the mouth end, which is the opening portion for the.

The piston part 7 is a piston main body 1 in which a screw 11b is engraved on the inner circumference.
1 and a guide portion 11a which is a cylindrical body standing upward from the piston body 11. Piston body 11 has screw 1
The guide rod 11a is screwed onto the piston rod 8 via 1b. At this time, the guide portion 11a regulates the alignment of the piston body 11 and the mouth end of the bypass 18 to prevent the check valve 14 from falling off. This will be described in more detail.

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 through a piston portion 7 and a bearing 3, and the piston portion 7 is arranged in the cylinder 1 such that an upper oil chamber 9 on the piston rod side and a lower oil chamber on the opposite side of the piston rod. Separates the room 10.

The piston portion 7 is provided with a bearing 12 provided on the outer circumference of a piston body 11 screwed onto a piston rod 8.

When the piston rod 8 is screwed into the piston body 11,
A guide portion 11a is provided so that the axial centers of the piston rod 8 and the piston body 11 are assembled on the same axis, and a spigot portion a is formed between the guide portion 11a and the piston rod 8.

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

A check valve consisting of a ball valve is formed at a valve seat 14 in the bypass 18 by branching from a vertical passage 17 to the piston 11 side of the end of the horizontal passage 16 of the piston rod 8 and opening above the piston 11. 13 are housed so that they can be opened and closed.

Since the bypass 18 is provided in the piston rod 8, the piston
Since 11 can be thinned in the radial direction, and the cross section of the threaded portion of the piston rod 8 can be increased accordingly, the tensile strength can be increased.

The check valve 13 is held by the guide portion 11a of the piston 11 so as not to fall off. That is, the guide portion 11a is the bypass 1
The opening area of the mouth end that is the opening of 8 is regulated so that the check valve 13 does not come out from this mouth end.

Therefore, the guide portion 11a provided on the piston body 11 has both the centering function and the function of holding the check valve 13.

When the piston rod 8 extends, the upper oil chamber 9 contracts, and the oil in the upper oil chamber 9 flows into the lower oil chamber 10 through the main passage including the horizontal passage 16 and the vertical passage 17 and the bypass 18. However, if the extension speed is high and the differential pressure between the upper oil chamber 9 and the lower oil chamber 10 is large, the check valve 13 may close.

When the piston rod 8 is further extended and the mouth end of the lateral passage 16 is closed by the bearing 3, the pressure in the upper oil chamber 9 rises, and the check valve 13 is closed by this pressure, whereby the oil in the upper oil chamber 9 is transferred to the piston rod. 8 and the bearing 3 flow out into the lower oil chamber 10 through the passages 16 and 17 from a slight annular gap formed between the bearing 8 and the bearing 3.
Therefore, the piston speed is reduced and the bearing 3 of the piston 11
Prevents a sudden collision against the so-called cushion.

When the piston moves in the compression direction from the time of maximum extension, the lower oil chamber
10 is compressed to a high pressure, and the internal pressure thereof causes the check valve 13 to separate from the valve seat 14 to open the bypass 18, so that the oil in the lower oil chamber 10 is introduced into the upper oil chamber 9 via this bypass 18, The piston 11 descends smoothly without generating pressure.

[Effect of device]

 The present invention has the following effects.

1) In the vicinity of the maximum extension, the main passage provided in the piston rod is gradually throttled and the check valve blocks the communication between the two oil chambers, so that the cushion is effective due to the flow resistance of the main passage of the piston rod.

2) The piston rod is provided with a bypass branched from the main passage, and the check valve is housed in this bypass so that it can be opened and closed freely. Therefore, the piston body is made thinner in the radial direction compared to the conventional product in which the piston is provided with a bypass. It is possible to increase the diameter of the threaded portion of the piston rod with which the piston body is screwed, and to increase the tensile strength.

3) Since the opening of the bypass is restricted by the cylindrical body to prevent the check valve from falling off, there is no need for special parts for holding the check valve, the structure can be simplified and the number of parts can be reduced. The stickiness is improved.

4) Since no bypass is formed in the piston body, complicated piston processing and seat processing requiring precision are not required in the piston body, and the processing is easy and economical.

[Brief description of drawings]

The attached drawing is a partially longitudinal front view of a hydraulic cylinder according to an embodiment of the present invention. 1 ... Cylinder, 7 ... Piston part, 8 ... Piston rod,
9, 10 ... Oil chamber, 11 ... Piston body, 11a ... Guide part, 11b ...
Screws, 16, 17 ... Main passage.

Front page continued (72) Creator Ryosuke Koga 505 Tsuchida, Kani City, Gifu Prefecture Kayaba Industrial Co., Ltd. Gifu Minami Factory (72) Creator Hironori Takagi 505, Tsuchida, Kani City Gifu Prefecture Kayaba Industrial Co., Ltd. Gifu Minami Factory (56) References 47-33588 (JP, U) 58-40211 (JP, U) 61-23683 (JP, Y2) JP 3213972 (US, A)

Claims (1)

[Scope of utility model registration request] 1. A piston rod is movably inserted into a cylinder via a piston portion, and the piston portion defines an upper oil chamber and a lower oil chamber in the cylinder, and two oil chambers are formed on a piston rod. In a hydraulic cylinder communicating via a passage, a bypass branched from the main passage is provided in the piston rod to allow the two oil chambers to pass through,
A check valve is openably and closably provided in this bypass, and an opening for the upper oil chamber of the bypass is formed closer to the piston than the opening for the upper oil chamber of the main passage. A cushion device for a hydraulic cylinder, which is composed of a carved piston body and a cylindrical body standing upward from the piston body, and which restricts the opening of the bypass by the cylindrical body to prevent the check valve from falling off.