JPH09287668A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a clearance between a seal ring and a shaft properly by fitting a pressing plate outer periphery part for supporting a floating seal ring between a cylinder inner periphery part and a bearing outer periphery part, forming the cross section of a pressing plate into an L shape, and protruding its outer periphery part in the axial direction along the inner periphery surface of the cylinder. SOLUTION: The outer periphery part 7b-1 of a pressing plate 7b whose cross section is of L shape is protruded in the axial direction along the inner periphery surface of a cylinder, and an area between the outer periphery part 7b-1 and a hydraulic cylinder is sealed with an O-ring or the like fitted into a seal groove 7b-3. When hydraulic fluid flows into the chamber 9b and applies pressure, the hydraulic pressure works upon the outer periphery part 7b-1 outwards in the diametrical direction, so that a clockwise moment occurs at the pressing plate 7b. As a result, the deformation of the pressing plate 7b facing the ring, which is pressed and generated by a floating seal ring 6b, is returned to its original condition, and this part is not inclined, so that the ring 6b is not also inclined. It is thus possible to keep a clearance between the ring 6b and a piston rod 1 properly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device applied to hydraulic cylinders, compressors and the like.

[0002]

2. Description of the Related Art A conventional seal device will be described with reference to FIG. 5. Reference numeral 1 is a piston rod (or rotary shaft) corresponding to a reciprocating shaft, and 1a is a flange provided on the outer end of the piston rod 1b. Is a piston integrated with the piston rod 1, 2 is a hydraulic cylinder surrounding the piston rod 1, 3a and 3b are oil holes for letting hydraulic oil into and out of the hydraulic chambers 9a and 9b, and 4a and 4b are piston rods. Outer ring 5a, 5b of the spherical bearing supporting 1 and inner ring 6a, 6b of the spherical bearing supporting the piston rod 1.
Is a floating seal ring, 7a and 7b are holding plates for supporting the floating seal rings 6a and 6b, and 8
Is a sleeve on the inner peripheral surface of the hydraulic cylinder 2.

10a and 10b are lids on both ends, 11a and 11
b is a bolt, and by fastening the bolts 11a and 11b to fix the lids 10a and 10b at both ends to the hydraulic cylinder 2, the outer rings 4a and 4b of the spherical bearing and the holding plates 7a and 7b.
And the sleeve 8 are fixed to the hydraulic cylinder 2. High-pressure oil is alternately supplied to the hydraulic chambers 9a and 9b, an axial force is applied to the piston rod 1 through the piston 1b to reciprocate the piston rod 1, and this movement is engaged with the flange 1a. (Not shown) to reciprocate the object.

The above floating seal rings 6a, 6
b represents the high pressure oil in the hydraulic chambers 9a and 9b, the bearing 4a,
5a or bearings 4b, 5b is a seal for preventing leakage. These floating seal rings 6a, 6
b is attached to the outer peripheral surface of the piston rod 1 with a minute gap, and in order to properly maintain this gap,
It is necessary to firmly support the floating seal rings 6a and 6b by the pressing plates 7a and 7b so as not to tilt them.

[0005]

The conventional sealing device shown in FIG. 5 has the following problems. FIG. 6 shows the pressing plate 7.
It is an expansion vertical side view of the vicinity of b. The holding plate 7b is sandwiched and supported by the outer ring 4b of the spherical bearing and the sleeve 8. When the hydraulic oil flows into the hydraulic chamber 9b, the hydraulic pressure acts in the direction of the arrow in FIG. Since only the outer peripheral portion of the holding plate 7b is supported, the holding plate 7b is pushed by the floating seal ring 6b that receives hydraulic pressure and bends as shown in FIG. Then, the floating seal ring 6b becomes
By deforming along the surface of the holding plate 7b and tilting as shown in FIG. 6, the gap between the floating seal ring 6b and the piston rod 1 becomes narrow, and an appropriate gap cannot be maintained. When driving in such a state, in some cases,
The floating seal ring 6b may cling to the piston rod 1 and damage such as seizure may occur.

In order to prevent the floating seal ring 6b from tilting, the pressing plate 7b may be thickened, but a very thick plate is required, and the hydraulic cylinder 2
However, it becomes longer and the cost becomes higher. The present invention is proposed in view of the above problems, and an object of the present invention is to provide a seal device capable of appropriately maintaining a gap between a floating seal ring and a shaft.

[0007]

To achieve the above object, the present invention provides a bearing inside a reciprocating or rotatable shaft and a cylinder surrounding the reciprocating or rotating shaft in a cylinder inside the bearing. A floating seal ring that forms a chamber and prevents the hydraulic oil in the chamber from leaking to the bearing side is attached to the outer peripheral surface of the shaft with a minute gap, and the outer peripheral portion of the holding plate that supports the floating seal ring is In a sealing device interposed between an inner peripheral portion of a cylinder and an outer peripheral portion of the bearing, the pressing plate is formed in an L-shaped cross section, and the outer peripheral portion of the pressing plate is formed along the inner peripheral surface of the cylinder. It is projected in the axial direction (claim 1).

According to the present invention, a bearing is interposed between a shaft capable of reciprocating or rotating and a cylinder surrounding the shaft to form a chamber in the cylinder inside the bearing, and the working oil in the chamber is transferred to the bearing side. A floating seal ring to prevent leakage to the outer peripheral surface of the shaft with a small gap, and the outer peripheral portion of the holding plate supporting the floating seal ring between the inner peripheral portion of the cylinder and the outer peripheral portion of the bearing. In the sealing device interposed in the above, the thickness of the pressing plate is increased inward in the radial direction (claim 2).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Next, a sealing device of the present invention will be described with reference to FIGS.
1, a reciprocating piston rod (or rotating shaft), 4b is an outer ring of a spherical bearing that supports the piston rod 1, 6b is a floating seal ring, and 7b is the same floating seal ring 6b. Is a presser plate for supporting the sleeve, 8 is a sleeve on the inner peripheral surface of the hydraulic cylinder (see 2 in FIG. 5), and 9b is a chamber formed in the hydraulic cylinder inside the spherical bearing.

The pressing plate 7b is formed in an L-shaped cross section, and an outer peripheral portion 7b-1 of the L-shaped pressing plate 7b has an axially protruding shape along the inner peripheral surface of the cylinder. Reference numeral 7b-2 is a portion facing the floating seal ring of the L-shaped pressing plate 7b having the same cross section, and 7b-3 is a seal groove provided on the tip outer peripheral surface of the outer peripheral portion 7b-1. The space between the cylinder and the cylinder is sealed by a seal member such as an O-ring fitted in the seal groove 7b-2.

Next, the operation of the sealing device shown in FIGS. 1 and 2 will be specifically described. When hydraulic oil flows into the chamber 9b and hydraulic pressure is applied, the hydraulic pressure is applied to the pressing plate 7 having an L-shaped cross section.
It acts radially outward with respect to the outer peripheral portion 7b-1 of b, and a clockwise moment is generated in the L-shaped pressing plate 7b in cross section, which causes the floating seal ring 6b.
Since the deformation of the floating seal ring facing portion 7b-2 of the pressing plate 7b caused by being pushed by is returned to the original state and this portion does not tilt, the floating seal ring 6b also does not tilt and the floating seal ring 6b does not tilt.
The gap between b and the piston rod 1 is properly maintained.

(Second Embodiment) Next, a sealing device of the present invention will be described with reference to a second embodiment shown in FIGS.
Reciprocating piston rod (or rotating shaft), 4b
Is a spherical bearing outer ring that supports the piston rod 1, 6b is a floating seal ring, 7b is a holding plate that supports the floating seal ring 6b, 8 is a sleeve on the inner peripheral surface of the hydraulic cylinder (see 2 in FIG. 5), and 9b Is a chamber formed in the hydraulic cylinder inside the spherical bearing.

The pressing plate 7b has a wall thickness that increases inward in the radial direction. Next, the operation of the sealing device shown in FIGS. 3 and 4 will be specifically described. When hydraulic oil flows into the chamber 9b and hydraulic pressure is applied, the floating seal ring 6b is pressed against the pressing plate 7b by the hydraulic pressure, and the pressing plate 7b bends and tilts. Since the amount of tilt at this time can be predicted by calculation in advance, if the thickness of the holding plate 7b is increased inward in the radial direction by the amount corresponding to the amount of tilt, the floating seal ring 6b will hold the holding plate 7b. When pressed against the high pressure side (chamber 9
Since the surface (b side) is held in a state of being orthogonal to the axis of the piston rod 1 and does not tilt, the floating seal ring 6b also does not tilt, and the clearance between the floating seal ring 6b and the piston rod 1 is appropriate. Held in.

[0014]

According to the sealing device of the present invention (claim 1), the pressing plate is formed in an L-shaped cross section as described above, and the outer peripheral portion of the pressing plate is projected in the axial direction along the inner peripheral surface of the cylinder. When hydraulic oil flows into the chamber and hydraulic pressure is applied,
This hydraulic pressure acts radially outward on the outer peripheral portion of the L-shaped holding plate, and a clockwise moment is generated in the L-shaped holding plate, and the holding plate is pressed by the floating seal ring. Since the deformation of the portion facing the floating seal ring is returned to the original state and does not tilt, the floating seal ring also does not tilt and the gap between the floating seal ring and the shaft can be properly maintained.

Further, in the sealing device of the present invention (claim 2), the wall thickness of the holding plate is made thicker inward in the radial direction as described above, and the working oil flows into the chamber, the hydraulic pressure is applied, and it floats. When the seal ring is pressed against the holding plate, the high-pressure side (chamber side) surface of the holding plate is held in a state orthogonal to the axis of the shaft and does not tilt, so the floating seal ring also does not tilt. , The gap between the floating seal ring and the shaft can be properly maintained.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of a sealing device of the present invention.

FIG. 2 is a vertical cross-sectional side view showing an L-shaped pressing plate in section of the sealing device.

FIG. 3 is a vertical sectional side view showing a second embodiment of the sealing device of the present invention.

FIG. 4 is a vertical cross-sectional side view showing a holding plate of the sealing device.

FIG. 5 is a vertical cross-sectional side view showing a conventional sealing device.

FIG. 6 is an operation explanatory view of the sealing device.

[Explanation of symbols]

1 Reciprocating shaft or rotating shaft 4b Spherical bearing outer ring supporting shaft 1 6b Floating seal ring 7b Holding plate 7b-1 Outer peripheral part of holding plate 7b 7b-2 Floating seal ring facing part of holding plate 7b 8 Hydraulic cylinder Sleeve 9b chamber

Claims (2)

[Claims] 1. A bearing is interposed between a reciprocating or rotatable shaft and a cylinder surrounding the shaft to form a chamber in the cylinder inside the bearing, and the working oil in the chamber is prevented from leaking to the bearing side. Is mounted on the outer peripheral surface of the shaft with a small gap, and the outer peripheral portion of the holding plate that supports the floating seal ring is interposed between the inner peripheral portion of the cylinder and the outer peripheral portion of the bearing. In the sealing device described above, the pressing plate is formed in an L-shaped cross section, and an outer peripheral portion of the pressing plate is axially projected along an inner peripheral surface of the cylinder. 2. A chamber is formed in a cylinder inside the bearing by interposing a bearing between a reciprocating or rotatable shaft and a cylinder surrounding the shaft, and the working oil in the chamber is prevented from leaking to the bearing side. Is mounted on the outer peripheral surface of the shaft with a small gap, and the outer peripheral portion of the holding plate that supports the floating seal ring is interposed between the inner peripheral portion of the cylinder and the outer peripheral portion of the bearing. In the sealing device described above, the thickness of the pressing plate is increased inward in the radial direction.