JPS62141373A - Sealing device for rod of hydraulic cylinder - Google Patents

Abstract

PURPOSE:To prevent the abnormal rise of the hydraulic pressure in an intermediate chamber by forming the groove part into which the O-ring of a buffer device is accommodated so that the O-ring does not shift in the direction of the groove width. CONSTITUTION:The bottom width of a groove 60 into which an O-ring 51 and a buffer ring 50 are accommodated is represented by the interval between the straight lines 61 and 65, and is made a little narrower than the width dimension of the sectional surface of the deformed O-ring 51. When the hydraulic pressure in a hydraulic chamber 8 increases during the operation of a hydraulic cylinder, also the hydraulic pressure in the left side chamber 70 for the O-ring increases, and the O-ring 51 is pressed rightward by the hydraulic pressure. Therefore, though the oil in the right side chamber for the O-ring is pushed into an intermediate chamber 55, the intermediate chamber 55 can be kept in a low pressure, since the quantity of the pushed-out oil is enough small to be absorbed by the deflection of a U-packing 5c.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sealing device for a rod of a hydraulic cylinder.

<Prior art> As shown in FIG. 2, a conventional hydraulic cylinder 1 has an inner hole 1
A piston 2 fixed to a rod 3 is slidably inserted into the piston a, and by supplying and discharging pressure oil to the pressure chamber 8 or 7, the rod 3 moves left and right as shown by arrow A. . A bearing 5a1, a buffer device 5b, and a SU gasket 5C are arranged on the rod cover 5 of the hydraulic cylinder 1 in order from the pressure chamber 8 side, and the buffer device 5b and the U gasket 5C constitute a seal device S. The buffer device 5b has a configuration in which a buffer ring 50 is pressed by an O-ring 51, as shown in FIG. The buffer ring 50 has a base 52 that contacts the O-ring 51 and an inner portion 54 that has a protrusion 53 that contacts the surface of the rod 3.
Consisting of When the buffer ring 5° is rotated about the protrusion 53, the inner circumferential surface of the portion 54 reduces the gap between it and the surface of the rod 3, thereby enhancing the buffering effect. Note that the buffer ring 50 is made of hard synthetic resin.

In this conventional hydraulic cylinder 1, when pressure oil is supplied to the pressure chamber 7, the rod 3 moves to the right. At this time, the oil located along the surface of the rod 3 passes through the bearing 5a, and when it reaches the buffer device 5b, it is scraped off by the protrusion 53 of the buffer ring 50, and the oil is removed from the buffer device 5b and U.
Entry into the intermediate chamber 55 between the gasket 5C and the gasket 5C is cut off.

In addition, during the operation of the hydraulic cylinder 1, pressure oil is supplied to the pressure chamber 8, or pressure oil is supplied to the pressure chamber 7 and while the rod 3 is moving to the right, the exhaust pressure increases and the pressure chamber When the oil pressure at 8 increases, the oil pressure causes the buffer ring 50 to roll around the protrusion 53 to increase the buffering effect.

<Problem that the invention seeks to solve>

In the conventional rod sealing device of the hydraulic cylinder 1 described above, the oil pressure in the intermediate chamber 55 increases during the operation of the hydraulic cylinder.
There is a problem of oil leakage. That is, the buffer ring 50 is placed in the groove 56 in which the buffer ring 50 is accommodated.
An O-ring 51 is provided to press the rod 3 from the outer periphery, and since the cross-sectional diameter of the O-ring 51 is smaller than the width of the groove 56, it can be moved in the direction of the axis of the rod 3. Because the O-ring 51 can move within the groove 56, an abnormally high pressure is generated in the intermediate chamber 55 as follows. The buffer ring 50 of the buffer device 5b
When the rod 3 moves in the direction shown in the figure while the pressure in the hydraulic chamber 8 is low, the oil on the surface of the rod 3 is scraped off, so dynamic pressure is generated at the protrusion 53 (partial pressure generated when scraping).
acts. When the pressure in the intermediate chamber 55 is lower than this dynamic pressure, the pressure in the intermediate chamber 55 increases until it approaches the value of the dynamic pressure. In this case, since high pressure is not acting on the hydraulic chamber 8, the buffering effect of the buffer link 50 is small.
Even after being scraped off by the protrusion 53 of the buffer ring 50, oil remains and the remaining oil flows into the intermediate chamber 55. As a result, the amount of oil in the intermediate chamber 55 increases. Therefore, the oil in the intermediate chamber 55 flows into the chamber 57 on the right side of the O-ring 51 shown in the figure, and moves the O-ring 51 to the left in the figure. Eventually, after the volume of the chamber 57 increases, the intermediate chamber 5
5 reaches the dynamic pressure, the flow of oil into the intermediate chamber 55 is stopped. In this state, that is, when the volume of the chamber 57 is increased, when high pressure such as pump pressure or high pressure due to increased back pressure for some reason acts on the pressure chamber 8, the O-ring 51 will move as shown in FIG. As a result, the intermediate chamber 55 becomes abnormally high pressure and the U
The lip portion 58 of the gasket 5C is damaged and oil leaks.

This invention solves the above problem by fixing the volume of the intermediate chamber 55.

<Means for Solving the Problems> The means of the present invention is provided in a rod cover portion of a hydraulic cylinder, and includes an O-ring that presses a buffer ring, through which a rod is inserted into an inner hole, from the outer periphery of the rod cover. A rod seal of a hydraulic cylinder consisting of a buffer device housed in a groove formed on the inner peripheral surface of a rod insertion hole, and a U-packet provided between the rod and the rod cover on the downstream side of the buffer device. In the device,
The shape of the O-ring accommodating portion of the groove is determined to prevent movement of the O-ring in the groove width direction.

<Operation> According to the above means, since the O-ring is restricted from moving in the groove width direction and does not move, even if the O-ring is pushed by the pressure on the pressure chamber side of the hydraulic cylinder, the buffer device and The oil pressure in the intermediate chamber between the U and the gasket will not rise abnormally.

<Embodiment> FIG. 1 shows an embodiment of the present invention, which differs from the conventional seal device shown in FIG. Since the other parts are the same as those shown in FIG. 3, they will be designated by the same reference numerals and their explanation will be omitted.

The groove 60, as shown in an enlarged view in FIG. 1st
It is represented by a straight line 67, a second straight line 67, and a curved line 66 that smoothly connects the straight line 65.67. Arc 62 indicating the bottom of the groove.
64 and the straight line 63 are the cross-sectional shapes of the deformed O-ring 51, taking into consideration the deformation that occurs when the O-ring 51 is compressed from the outer peripheral surface to a state where the necessary pressing force is obtained against the buffer ring 50. This corresponds to the outer periphery of the . The groove bottom width is indicated by the distance between the straight line 61 and the first straight line 65, and is slightly narrower than the width of the cross-sectional shape of the deformed O-ring 51. The groove width of the portion indicated by the distance between the straight line 61 and the second straight line 67 is a predetermined width that prevents the buffer ring 50 from rotating significantly, and is the same as the conventional one.

Also, the dimension from the surface of the rod 3 to the straight line 6'5 indicating the groove bottom is that the O-ring 51 and the buffer ring 50 are in the groove 6'.
The rod 3 is housed in the performance wire ring 50.
It is determined that the compressor is compressed by a predetermined value when inserted into the inner hole of the compressor. Therefore, the buffer ring 50 receives a pressing force from the outer periphery caused by the O-ring 51 being compressed.

Note that a chamber 69 is connected to the bosom 68 of the buffer ring 50.

This hydraulic cylinder rod sealing device is configured such that when the hydraulic pressure in the hydraulic chamber 8 increases while the hydraulic cylinder 1 is in operation, the chamber 69,
The oil pressure in the pocket 68 and the chamber 70 on the left side of the O-ring in the figure also rises, and the O-ring 51 is pushed to the right by the oil pressure. For this reason, the oil in the chamber 71 on the right side of the O-ring in the figure is pushed out to the intermediate chamber 55, but since this amount of oil is a small amount that can be absorbed by the U-packet 5C by its deflection, the intermediate chamber 55 is kept at a low pressure. can be kept.

<Effects of the Invention> According to the present invention, the groove portion in which the O-ring of the buffer mounting device is accommodated is formed so that the O-ring does not move in the width direction of the groove.
Since it is possible to prevent an abnormal rise in the hydraulic pressure in the intermediate chamber between the seal and the seal, it is possible to maintain the pressure at a low level regardless of the pressure in the pressure chamber of the hydraulic cylinder, which has the effect of preventing damage to the U seal. can get.

[Brief explanation of drawings]

Fig. 1(a) is a partial longitudinal sectional view of the main part showing an embodiment of this hydraulic cylinder, Fig. 1(c) is a partially enlarged view of Fig. 1(a), and Fig. 2 is a part of a conventional hydraulic cylinder. FIG. 3 is a partially enlarged view of FIG. 2, and FIG. 4 is a partially enlarged view of FIG. 3. l... Hydraulic cylinder, 2... Piston, 3... Rod, 5... Rod cover, 5C... U packing,
50...buffer ring, 51...0 ring, 6
0...Groove. Patent applicant Representative of Coal Open-pit Mining Machinery Technology Research Association Satoshi Shimizu and 2 others Figure 1 (a) Figure 1 (b)

Claims (1)

[Claims] (1) The buffer ring, which is provided on the rod cover of the hydraulic cylinder and has the rod inserted through its inner hole, is housed in the groove formed on the inner circumferential surface of the rod insertion hole of the rod cover together with the O-ring that presses from the outer periphery of the buffer ring. In a hydraulic cylinder rod sealing device comprising a buffer device formed by a buffer device and a U packing provided between the rod and the rod cover on the downstream side of the buffer device, the shape of the O-ring accommodating portion of the groove is A sealing device for a rod of a hydraulic cylinder, which is configured to prevent movement of the O-ring in the groove width direction.