JPH0531284Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is installed inside a hydraulic cylinder and used to prevent damage to the sliding parts of the hydraulic cylinder due to dirt mixed in oil.

<Prior Art> As shown in FIG. 2, a hydraulic cylinder has pressure oil supplied to and discharged from pressure chambers 7 and 8 formed by a cylinder tube 1, a piston 2, a head cover 4, and a rod cover 5. The rod 3 is configured to operate as shown by arrow A.

In this hydraulic cylinder, a piston 2 is held on an inner surface 1a of a cylinder tube 1 by a bearing 2b, and a member 2 that seals between pressure chambers 7 and 8
A is provided. The rod 3 is supported by a bush 5a on a rod cover 5, and there is a buffer ring 5b and a seal member 5c between the pressure chamber 8 and the outside.
It is sealed by a sealing device S formed by.

The pressure oil supplied to the hydraulic cylinders is contaminated with dust such as scale in piping or metal powder generated by wear of equipment. This debris flows into the pressure chamber together with the pressure oil during the operation of the hydraulic cylinder, damaging the inner surface 1a of the cylinder tube 1 and the surface of the rod 3, resulting in oil leakage, i.e., between the pressure chambers 7 and 8. This may cause oil leakage or oil leakage from the pressure chamber 8 to the outside. In order to prevent this damage, there is a structure in which a dust ring 2c is provided outside the bearing 2b, as shown in FIG.
This dust ring 2c prevents dust flowing into the pressure chambers 7, 8 from being caught between the piston 2 and the inner surface 1a of the cylinder tube 1.

<Problems to be solved by the invention> In FIG. 3, the dust ring 2c is endless and is formed so that its outer circumferential surface reliably follows the inner surface 1a of the cylinder tube 1, and its inner circumferential surface is formed along the piston 2. It is designed so that it touches the bottom of the groove.
In a hydraulic cylinder having such a configuration, the piston 2 may vibrate due to the operation of the hydraulic cylinder, or the piston 2 may be pushed to one side in the diametrical direction against the inner peripheral surface of the cylinder tube 1 depending on the load condition. When subjected to such an acting force, the dust ring 2c is compressed on one diametrical side, and a gap is created between the outer surface of the dust ring 2c and the inner surface 1a of the cylinder tube 1 on the opposite side. There was a problem that dirt entered this gap and caused damage to the inner surface of the cylinder tube.

Further, when one of the pressure chambers 7 or 8 becomes high pressure, a horizontal pressing force is applied to the dust ring 2c due to the pressure difference between the pressure chambers 7 and 8, causing the problem that the dust ring 2c may fall off.

In addition, the pressure chamber 7 or 8 of the dust ring 2c
The side is the inner surface 1a of the cylinder tube 1 and the piston 2
Since there is a small gap formed between the outer surface of the cylinder and the outer surface of the cylinder, there is a risk that dirt will get caught in this small gap, which may cause damage to the inner surface of the cylinder.

<Means for solving the problem> The means according to the present invention is a hydraulic cylinder in which a dust seal is provided either between the sealing member of the piston of the hydraulic cylinder and the pressure chamber or between the bush of the rod cover and the pressure chamber. In the dust seal device, when the dust seal is provided between the sealing member of the piston of the hydraulic cylinder and the pressure chamber, the dust seal is connected to a large inner diameter portion having a large inner peripheral surface and this large inner diameter portion. and a small inner diameter portion having an inner peripheral surface smaller in diameter than the large inner diameter portion, the small diameter side of the small inner diameter portion is accommodated in a groove provided in the piston and abuts against the groove side, and the end surface of the large inner diameter portion is A passage provided approximately in line with the end surface of the piston, providing a gap between the inner circumferential surfaces of the large inner diameter portion and the small inner diameter portion and the piston, and communicating the pressure chamber side of the dust seal with the sealing member side. When the dust seal is provided between the bush of the rod cover and the pressure chamber, the dust seal is connected to a large outer diameter portion having a large outer peripheral surface and a large outer diameter portion. a small outer diameter portion having an outer circumferential surface smaller in diameter than the outer diameter portion; The dust seal is provided so that its end face substantially coincides with the end face of the rod cover on the pressure chamber side, and a gap is provided between the outer peripheral surfaces of each of the large outer diameter portion and the small outer diameter portion and the rod cover, and the dust seal is provided on the pressure chamber side and The present invention is characterized in that a passage is provided that communicates with the bushing side.

<Function> In the present invention having the above means, the end face of the dust seal on the pressure chamber side is substantially aligned with the end face of the piston on the pressure chamber side in the case of the dust seal provided on the piston, and the dust seal provided on the rod cover Since the end face of the rod cover on the pressure chamber side is generally aligned, no small gap is formed between the piston and the inner surface of the cylinder tube or between the rod cover and the rod on the pressure chamber side of the dust seal. Therefore, the danger of biting into dirt is eliminated.

In addition, the dust seal provided on the piston provides a gap between the piston and the inner circumferential surface of each of the large inner diameter portion and small inner diameter portion, so the piston is pressed diametrically to one side with respect to the inner circumferential surface of the cylinder tube. When such an acting force is applied, the piston is allowed to displace in the direction perpendicular to the axis of the cylinder tube by the amount of the gap, and no force acting on the dust seal deforms it, so the outer peripheral surface of the dust seal and the cylinder tube The state of close contact with the inner circumferential surface of is maintained.

Since the dust seal provided on the rod cover provides a gap between the outer circumferential surfaces of the large and small outer diameter portions and the rod cover, the piston rod is pressed to one side in the diametrical direction against the inner circumferential surface of the rod cover. When such an acting force is applied, the piston rod and dust seal are allowed to be displaced in the direction perpendicular to the axis relative to the rod cover by the amount of the gap, and since no force acting on the dust seal deforms it, the inner peripheral surface of the dust seal and The state of close contact with the outer peripheral surface of the piston rod is maintained.
Therefore, even when such an acting force is applied, the risk of getting caught in dirt is prevented.

This configuration of the dust seal is more likely to fall off when subjected to a lateral pressing force, compared to a conventional configuration in which most of the dust seal is accommodated in the groove. However, the hydraulic pressure acting on the pressure chamber acts on both sides of the dust seal due to the presence of the passage. Therefore, the pressure on both sides of the dust seal becomes equal, and the lateral pressing force due to the pressure difference does not act on the dust seal, so that the dust seal can be prevented from falling off.

<Example> FIG. 1a shows the present invention implemented on the rod cover 5 side. In the same figure, rod cover 5
A rod 3 passes through the side, and this rod 3
is supported by the bushing 5a, and the bushing ring 5
A sealing device S formed by a sealing member b and a sealing member 5c is provided in the same manner as in FIG. Additionally, a dust ring 10a is provided between the bush 5a and the pressure chamber 8. This dust ring 10
A is formed of a large outer diameter part and a small outer diameter part, and the large diameter side of the large outer diameter part is inserted into the groove 15a provided in the rod cover 5 and brought into contact with the groove side surface, and the groove bottom There is a gap 1 between the outer peripheral surface of the large outer diameter part on the side.
6b, and a gap 16a is provided between the small outer diameter portion and the outer peripheral surface. Therefore, the dust ring 10a can follow the movement of the rod 3 in a direction perpendicular to its axis. Further, as shown in the figure, the dust ring 10a and the rod cover 5 are provided so that their end surfaces on the pressure chamber 8 side coincide with each other. A chamber 20a formed between the dust ring 10a and the bush 5a includes a passage 21 having a filter 22a.
It is connected to the pressure chamber 8 via a.

With the above structure, there is no small gap between the end face of the rod cover 5 on the pressure chamber 8 side and the rod 3, so that no dust is trapped even when the rod 3 moves in the direction of arrow B.

Furthermore, when the piston rod 3 receives a force that causes a small displacement in the direction perpendicular to the axis relative to the rod cover 5, the dust ring 10a is deformed while remaining in close contact with the outer peripheral surface of the piston rod 3 due to the presence of the gaps 16a and 16b. Displace without. Therefore, there is no gap between the dust ring 10a and the outer peripheral surface of the piston rod 3, so there is no risk of dust getting caught.

Any hydraulic pressure acting on the pressure chamber 8 is transferred to the chamber 20 through a passage 21a having a filter 22a.
a, so no hydraulic pressing force acts on the dust ring 10a. Therefore, the dust ring 10a does not fall off during the operation of the hydraulic cylinder. In addition, in the passage 21a, only pressure is transmitted, and the flow of oil is approximately equal to 0, so dirt in the pressure chamber is removed from the chamber 2.
It does not flow into 0a.

FIG. 1b is an enlarged view similar to the enlarged view of the piston portion shown in FIG. 3, in which the present invention is applied to a piston portion, and the differences from FIG. 3 are as follows. The dust rings 10c, 10c' are formed of a large inner diameter part and a small inner diameter part, as shown in the figure.
The small diameter side of the small inner diameter portion is inserted into the grooves 15c, 15c' on both sides of the piston 2 so as to abut on the side surfaces of the grooves, in substantially the same way as the dust ring 10a shown in FIG. 1a. The inner peripheral surface of each small inner diameter portion of 10c' and grooves 15c, 15
Clearances 16d and 16d' are provided between the bottom surface of c' and gaps 16c and 16c' are provided between the inner peripheral surface of the large inner diameter portion and the piston side. The rings 10c, 10c' are designed to be able to freely move in a direction perpendicular to the axis.
In addition, as shown in the figure, dust rings 10c, 10
It is provided so that c' and the end surface of each side of the piston 2 on which it is provided coincide. moreover,
Dust rings 10c, 10c' and bearing 2b,
The chambers 20c, 20c' provided between the pressure chambers 7, 2b' communicate with the pressure chambers 7, 8 via passages 21c, 21c' having filters 22c, 22c'.

The embodiment shown in FIG.
Since c, 10c' and the end faces of the piston 2 on the pressure chambers 7 and 8 side coincide with each other, there is no small gap between the outer circumference of the end face of the piston 2 and the inner circumference of the cylinder 1. 2. Even when moving, it is difficult for dust to get caught. Furthermore, even if the piston 2 receives a force that causes a small displacement in the direction perpendicular to the axis of the cylinder tube 1, the gaps 16c, 16d, 16c', 1
6d' allows the dust rings 10c and 10c' to be displaced in the direction perpendicular to the axis of the piston 2 while maintaining close contact with the inner circumferential surface of the cylinder tube 1 without being deformed. For this reason, dust ring 10
Since no gaps are formed between c, 10c' and the inner circumferential surface of the cylinder tube 1, there is no risk of dirt getting caught. Even if oil pressure acts on the pressure chamber 7, the dust ring 10c acts on the chamber 20c through the passage 21c, so the dust ring 10c
No falling off due to hydraulic pressure. dust ring 10
Similarly to the dust ring 10c, c' does not fall off due to hydraulic pressure.

Note that the passage 30 shown in FIG.
This is for releasing the high pressure acting on the front chamber S1 of the buffer ring 5b to the pressure chamber 8 when the pressure is applied in the direction of arrow B. In the front chamber S1, rod 3
When it operates in the direction of arrow B, the oil adhering to its surface is scraped off by the buffer ring, creating a high pressure. If the generation of this high pressure is prevented, no unreasonable force will be applied to the sealing device S, and
A stable sealing effect can be obtained.

<Effects of the invention> The present invention is provided so that the pressure chamber side end surface of the rod cover or piston on which the dust ring is provided is substantially aligned with the pressure chamber side end surface of the dust ring. Since there are no small gaps between the rod cover and the rod or between the inner surface of the cylinder and the piston, there is an excellent effect of preventing dirt from getting caught. When subjected to a force that causes displacement, the dust ring does not deform due to the gap between the rod cover and the outer circumferential surface of the dust ring, or the gap between the piston and the inner circumferential surface of the dust ring, and the outer circumferential surface of the piston rod It maintains a close contact with the cylinder tube or the inner circumferential surface of the cylinder tube, and has an excellent effect that there is no risk of dust getting caught during this time. In this way, by combining the weak point of the construction, which is that the dust ring tends to fall off due to the pressing force, with the construction in which the front and rear pressure of the dust ring is always kept the same by the passage, it has an excellent effect of preventing dust from getting caught. It can be improved to prevent the dust ring from falling off even if sudden hydraulic pressure is applied to the pressure chamber without causing any damage. Therefore, it is possible to reliably maintain the function of protecting the rod surface or the surface without the cylinder tube from damage caused by dirt.

Furthermore, since no hydraulic pressing force is applied to the dust ring, it is possible to use a soft material, and in this way, even if dirt enters between the dust ring and the sliding surface, it will remain in the dust ring. It is in a state where it is buried, and the sliding surface prevents scratches from occurring at any time.

[Brief explanation of the drawing]

Figure 1a is a partially enlarged longitudinal side view of an example in which this invention is implemented on the rod cover side, Figure 1b is a partially enlarged longitudinal side view of an example in which this invention is implemented in the piston part, and Figure 2 is a conventional hydraulic cylinder. FIG. 3 is a vertical sectional side view showing one example of the conventional example, and FIG. 3 is a partially enlarged vertical lateral side view showing another conventional example. 1...Cylinder tube, 2...Piston, 2
a... Seal member, 2b, 2b'... Bearing,
S...Seal device, 3...Piston rod, 4...
...Head cover, 5...Rod cover, 5a...
Pressure chamber, 7, 8...pressure chamber, 10a, 10c,
10c'...Dust ring (dust seal), 16
a, 16b, 16c, 16d, 16c', 16d'...
...Gap, 21a, 21c...passage.

Claims (1)

[Scope of utility model registration request] A dust seal device for a hydraulic cylinder in which a dust seal is provided either between a sealing member of a piston of a hydraulic cylinder and a pressure chamber or between a bush of a rod cover and a pressure chamber, wherein the dust seal is connected to a sealing member of a piston of the hydraulic cylinder. When installed between a pressure chamber, the dust seal is made of a large inner diameter portion having a large inner circumferential surface and a small inner diameter portion connected to the large inner diameter portion and having an inner circumferential surface smaller than that of the large inner diameter portion. The small diameter side of the small inner diameter portion is accommodated in a groove provided in the piston and brought into contact with the side surface of the groove, and the end surface of the large inner diameter portion is provided so as to substantially match the end surface of the piston, and the large inner diameter portion and the small inner diameter A gap is provided between the inner peripheral surface of each part and the piston, and a passage is provided that communicates the pressure chamber side of the dust seal with the seal member side, and the dust seal is connected to the bush of the rod cover and the pressure chamber. When the dust seal is installed between a large outer diameter portion having a large outer circumferential surface and a small outer diameter portion connected to the large outer diameter portion and having an outer circumferential surface smaller than the large outer diameter portion. the large diameter side of the large outer diameter portion is accommodated in a groove provided in the rod cover and brought into contact with the side surface of the groove, and the end surface of the small outer diameter portion is made substantially coincident with the end surface of the rod cover on the pressure chamber side. A hydraulic cylinder having a structure in which a gap is provided between the outer circumferential surface of each of the large outer diameter portion and the small outer diameter portion and the rod cover, and a passage is provided that communicates the pressure chamber side and the bush side of the dust seal. dust seal device.