JP2553581Y2 - Hydraulic cylinder cushion device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushion device for reducing an impact at a stroke end portion of a cylinder.

[0002]

2. Description of the Related Art As an apparatus of this kind, for example,
FIG. 3 is a diagram showing a main part of a device related to Japanese Patent Application Laid-Open No. 3-24409. The conventional device is configured to exert a cushioning effect when the hydraulic cylinder C reaches the stroke end on the extension side. FIG. 3 is a cross-sectional view of the stroke end portion.

[0003] A piston 2 is fixed to a piston rod 1 of a hydraulic cylinder C. By fixing the piston 2, a recess 3 is formed between the piston 2 and the piston rod 1, and the cushion ring 4 is fixed to the recess 3. Further, the cushion ring 4 has cutout grooves 5 and 6 at both ends thereof, and the cushion ring 4
A flow passage 7 is formed inside the inside. When the cushion ring 4 enters the cushion port 8 as shown in the figure, a choke passage 9 is formed outside the cushion ring 4, and the inflow / outflow port 10 and the rod-side chamber 11 of the hydraulic cylinder C communicate with the choke passage 9. They communicate with each other.

A check valve 12 is provided in the middle of the flow passage 7, and the check valve 12 is configured to allow only the flow from the inflow / outflow port 10 to the rod side chamber 11 in the state shown in the drawing. ing. And check valve 12
Is provided for the following reason. In other words, when the cushion function is exhibited, the flow passage 7 is covered so that the oil flows only to the choke passage 9 so that the cushion effect is sufficiently exhibited. On the contrary, when the hydraulic cylinder C is contracted by supplying the pressure oil from the inflow / outflow port 10, the pressure oil is supplied from both the choke passage 9 and the flow passage 7 so that the pressure oil is supplied at the time of starting. The movement is smooth.

The reason why the check valve 12 is provided in the middle of the flow passage 7 is as follows. That is, when the cushion effect is exerted, the pressure distribution acting on the cushion ring 4 is as shown by the arrow in the drawing.
That is, the pressure action gradually decreases outside the port as it approaches the inflow / outflow port 10. Further, inside the cushion ring 4, the maximum pressure of the rod side chamber 11 acts up to the position of the check valve 12. Therefore, when the check valve 12 is located at the left end in the drawing, the above-mentioned maximum pressure acts on almost the entire inside of the cushion ring 4, and the pressure balance with the outside of the cushion ring 4 is lost.

[0006] If the pressure balance between the outside and the inside of the cushion ring 4 is disturbed as described above, there is a problem that the cushion ring 4 is deformed. Therefore, the check valve 12 is conventionally provided in the middle of the flow passage 7 as described above so as to maintain the pressure balance between the outside and the inside of the cushion ring 4.

[0007]

In the conventional device as described above, in order to keep the cushion stroke long,
When the axial length of the cushion ring is increased, the pressure balance between the outside and the inside of the cushion ring is lost. For example, while the cushion ring is sufficiently long, the check valve 12
Is located in the middle of the flow passage 7, the check valve 1
Since the length from 2 is too long, the pressure balance is lost at the portion where the length is too long, and the cushion ring 4 is deformed in the direction of reducing the diameter. Further, the check valve 12 is connected to the inflow / outflow port 1 more than the middle of the flow passage 7.
If it approaches the 0 side, the pressure action on the side of the flow passage 7 will overcome this time, and it will be deformed so as to raise the outside of the cushion ring in that portion. Therefore, this conventional device has a problem in that it cannot be used as a device that requires a long cushion stroke. An object of the present invention is to provide a cushion device in which a cushion ring is not deformed even when a cushion stroke is sufficiently long.

[0008]

According to the invention, a cushion ring is attached to a piston rod, and the cushion ring penetrates into a cushion port at a stroke end portion of the cylinder, thereby increasing the pressure on the stroke end side to a high pressure. It assumes a cushion device for a hydraulic cylinder that exhibits a cushioning effect. Under the premise of the above device, the present invention attaches a first cushion ring and a second cushion ring in series in the direction of entry of the cushion port, and the first and second cushion rings have a flow passage inside thereof. A check valve is formed in the flow passage and allows only the flow from the cushion port side into the cylinder. Further, each of the outer sides of the first and second cushion rings is provided with an inner periphery when the cushion port enters the cushion port. This is characterized in that a choke passage is formed in combination with the above.

[0009]

According to the present invention, the first and second cushion rings sequentially enter the cushion port at the stroke end portion, thereby exhibiting the desired cushioning effect.

[0010]

According to the device of the present invention, the first and second cushion rings are provided in series, so that the cushion stroke can be sufficiently long. In addition, since the individual cushion rings do not have to be so long, even if the check valve is provided in the middle of the flow passage, the pressure balance between the outside and the inside of the cushion ring is not lost.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydraulic cylinder C of the embodiment shown in FIGS.
Is a piston 22 provided at the tip of the piston rod 21.
Thus, the inside of the cylinder tube 23 is partitioned into a bottom side chamber 24 and a rod side chamber 25. Then, the hydraulic oil flows into and out of the bottom side chamber 24 through the inflow / outflow port 26 and the rod side chamber 2
Reference numeral 5 indicates that the hydraulic oil flows in and out of another outflow / inflow port 27.

The distal end of the piston rod 21 has a small diameter portion 21a having a smaller diameter than the other portions, and the small diameter portion 21a has a first cushion ring 28,
After the cushion ring 29 and the piston 22 are sequentially inserted and arranged in series, finally, the nut 30 is firmly tightened and fixed.

A bearing member 31 is fitted to the tip of the cylinder tube 23. The bearing member 31 has a cushion port 32 communicating with the inflow / outflow port 27. The axial length of the cushion port 32 is equal to or longer than the sum of the axial lengths of the first and second cushion rings 28 and 29.

The first cushion member 28 has a groove 33 formed on the outside thereof. The depth of the groove 33 is set so as to gradually decrease from the front to the rear in the direction of entry into the cushion port 32. I have. And this first
When the cushion ring 28 enters the cushion port 32, the cushion port 32 and the groove 33 combine to form a choke passage. Further, the first cushion ring 28 has cutout grooves 34 at both ends thereof.
35 and the first cushion ring 2
A flow passage 36 is formed inside 8.
A check valve 37 is provided in the middle of the flow passage 36.

First cushion ring 28 and piston 22
The groove 38 is formed on the outside of the second cushion ring 29 interposed therebetween. Like the groove 33 of the first cushion ring 28, the depth of the groove 38 is gradually reduced from the front to the rear in the direction of entry into the cushion port 32. Further, notch grooves 39 and 40 are formed at both ends of the second cushion ring 29, and a flow passage 41 is formed inside the second cushion ring 29. And
A check valve 42 is provided in the middle of the flow passage 41.

Next, the operation of this embodiment will be described. Now, when pressure oil is supplied from the inflow / outflow port 26 and the inflow / outflow port 27 communicates with a tank (not shown), the piston 2
2 moves leftward in the drawing. When the piston 22 reaches the vicinity of the stroke end, first, the first cushion ring 28 enters the cushion port 32. When the first cushion ring 28 enters the cushion port 32 in this manner, the check valve 37 maintains the closed position and blocks the flow of the flow passage 36. Therefore, the outflow passage to the inflow / outflow port 27 is only the choke passage including the groove 33, and the choke effect is exerted from that point. Thereby, the rod side chamber 2 of the hydraulic cylinder C
Since the pressure in 5 increases, first, first cushion effect is exerted by first cushion ring 28.

When the piston 22 further moves from the above state, the second cushion ring 29 also enters the cushion port 32, so that the check valve 42 keeps the closed position also in this case. Therefore, the outflow / inflow port 2
The outflow passage to 7 is only the choke passage formed of the groove 38, and from that point on, the second choke effect by the second cushion ring is exhibited.

Next, when pressure oil is supplied from the inflow / outflow port 27 and the inflow / outflow port 26 is communicated with the tank,
The pressurized oil passes through the groove 33 of the first cushion ring 28 and pushes the check valve 37 open to open the flow passage 36.
Also flows. The pressure oil that has passed through the first cushion ring 28 passes through the groove 38 of the second cushion ring 29 and also flows into the flow passage 41 by opening the check valve 42 when pushed. Therefore, at this time, a sufficiently large flow passage area is secured, so that the pressure oil from the inflow / outflow port 27 is smoothly supplied into the rod side chamber 25.

According to the cushion device of this embodiment as described above, the first cushion ring 28 and the second cushion ring 29 are arranged in series, so that the cushion stroke must be kept sufficiently long. We can deal with it. Moreover, individual cushion rings 2
If the check valves 37 and 42 are provided in the middle of the flow passages 36 and 41, the pressure balance between the outside and the inside of the first cushion ring 28 can be improved. Can be kept. Therefore, the pressure balance is not lost and the cushion ring is not deformed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic cylinder.

FIG. 2 is an enlarged sectional view of a main part.

FIG. 3 is an enlarged sectional view of a conventional main part. C Hydraulic cylinder 21 Piston rod 22 Piston 28 First cushion ring 29 Second cushion ring 32 Cushion port 33 Groove forming a choke passage 36 Flow passage 37 Check valve 38 Groove forming a choke passage 41 Flow passage 42 Check valve

Claims (1)

(57) [Scope of request for utility model registration] 1. A hydraulic cylinder, wherein a cushion ring is attached to a piston rod, and the cushion ring penetrates into a cushion port at a stroke end portion of the cylinder, thereby increasing the pressure on the stroke end side to achieve a desired cushioning effect. In the cushion device, the first cushion ring and the second cushion ring are attached in series in a direction in which the cushion port enters,
These first and second cushion rings form a flow passage inside thereof, and the flow passage is provided with a check valve that allows only the flow from the cushion port side to the inside of the cylinder. A hydraulic cylinder cushion device having a configuration in which a chock passage is formed on the outside of the cushion port when it enters the cushion port, in combination with the inner periphery of the port.