JPH0240353Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a sealing device for a rotating machine such as a centrifugal compressor where the internal pressure is high.

(Prior Art) Oil film seals are often used as shaft seals for high-pressure compressors. The oil film seal has a metal seal ring attached to the shaft to be sealed through a small gap, and seal oil with a pressure slightly higher than the internal pressure of the compressor shaft seal is supplied to the gap to create a pressure oil film. This pressure oil film prevents the high pressure gas inside the compressor from leaking.

There are two types of conventional ring-shaped seal members, one of which has a uniform inner peripheral surface facing the axis of the ring-shaped seal member over the entire circumference, and the other has a ring The inner surface facing the axis of the sealing member having a shape similar to the arcuate surface 11 shown in FIG. 2 was formed.

(Problems to be solved by the invention) In the shaft seal using a ring-shaped seal member whose inner peripheral surface is uniform over the entire circumference, there is a pressure oil film between the shaft and the seal annular member, the shaft and the seal. There is a problem that self-excited vibrations called oil whip are likely to occur in the component system, and even in shaft seals that use seal members whose inner peripheral surface has multiple arcuate surfaces, changes in the oil film cross section may occur. However, even though a vibration damping effect is provided, there is a problem in that it is not sufficient to damp the self-excited vibration called oil whip.

(Means for Solving the Problems) The present invention addresses the above problems, and provides an oil film formed between the shaft hole provided in the housing of a rotating machine and the rotating shaft passing through the coaxial hole. In a sealing device for a rotating machine, a cross-sectional annular case is housed in an annular groove provided in the shaft hole, a first annular seal member is placed on the outside of the annular case, and a first annular seal member is placed on the outside of the annular case. A second annular seal member is accommodated on the inner side, and a first annular protrusion that contacts the outer side surface of the annular groove is provided on the outer peripheral side of the outer surface of the annular case, and the first annular seal member A second annular protruding portion that contacts the annular case is provided on the inner peripheral side of the inner surface of the annular case, and a plurality of circular arc surfaces continuous in the circumferential direction are formed on the inner peripheral surface of the first annular seal member. An object of the present invention is to provide a sealing device for a rotating machine that can prevent the generation of self-excited vibrations called oil whip.

(Example) Next, the shaft seal of the compressor of the present invention was
To explain with an embodiment shown in Figures 1 to 3, 1 is a shaft, 2 is a compressor housing, and a cross-sectional annular case 3 is accommodated in an annular groove 2a provided in the shaft hole of the compressor housing 2. A first annular protrusion 3a is provided on the outer peripheral side of the side surface on the atmosphere side of the case 3, and an O-ring 3b is fitted into the O-ring groove on the outer surface on the gas side. There is a large-diameter annular groove and a small-diameter annular groove on the gas side of the case 3. The first annular seal member 4 is inserted into the large-diameter annular groove, and the second annular seal member 4 is inserted into the small-diameter annular groove. The annular seal member 5 is inserted, and the second annular protrusion 3c on the inner periphery of the side surface of the case 3 faces the first annular seal member 4, and the O-ring groove of the second annular seal member 5 is inserted. A ring 5a is provided, and the same O
The ring 5a abuts the case 3, and a coil spring 6 is interposed between the first annular seal member 4 and the second annular seal member 5.

Further, an oil hole 7 is provided in the center of the compressor housing 2, and an oil hole 8 passing through the case 3 is provided at a position facing the coil spring 6 of the case 3. Further, a plurality of grooves 9 are provided along the axial direction on the outer circumferential surface of the first annular seal member 4, and a leaf spring 10 inserted into the grooves 9 is inserted into the protrusion 1 at the center.
0a is in contact with the first seal member 4, and the protrusions 10b, 10b at both ends are in contact with the case 3,
A minute gap c is formed between the first seal member 4 and the case 3. Also, the first seal member 4
A plurality of arcuate surfaces 11 are formed on the surface facing the axis 1 .

(Function) Next, to explain the function of the rotary machine seal device, the seal oil, which has been adjusted to a pressure slightly higher than the pressure inside the compressor shaft seal device by an automatic pressure regulator (not shown), is pumped into the oil hole 7. →The space between the compressor housing 2 and the case 3→The oil flows into the inside of the case 3 through the oil hole 8, and the gap c between the first annular seal member 4 and the case 3 and the second annular seal member 5 The first annular seal member 4 and the second annular seal member 5 fill the gap between the first annular seal member 4 and the case 3.
and flows into the gap between the second annular seal member 5 and the shaft 1 and the gap between the first annular seal member 4 and the shaft 1. and shaft 1 are sealed.

At this time, although the pressure difference between the pressure of the seal oil and the pressure on the atmospheric side is large, the pressure exerted by the seal oil around the first annular seal member 4 is balanced, and the pressure of the seal oil around the first annular seal member 4 is balanced. The first annular seal member 4 is pressed against the case 3 by the pressure acting on the gas-side side surface of the seal member 4, but the protrusion 3c is located at the minimum radius of the first seal member 4 and the protrusion is Since the contact width of the strip 3c is small, the force with which the first seal member 4 is pressed against the protrusion 3c is small.
When the shaft 1 vibrates, the first seal member 4 can sufficiently follow the vibration. Furthermore, when the compressor enters the operating state, the difference between the pressure of the seal oil and the opposing internal pressure of the compressor is small, so the force exerted by the second seal member 5 on the shaft 1 is small. In other words, the shaft 1 of the compressor is supported by two bearings (not shown) and is also supported by two sets of the first seal member 4 and the second seal member 5, resulting in an unsteady support structure. As mentioned above, the unstatic reaction force exerted on the shaft 1 is extremely small. Also case 3
is pressed by the pressure of the seal oil against the protrusion 3a having a relatively large area, so when the compressor is operated and seal oil is supplied, it is placed in an appropriate relative position with respect to the shaft 1 (the first seal member 4. The second seal member 5 is almost fixed at a position where a larger clearance is maintained from the shaft than the second seal member 5. In the groove of the case 3 which is almost fixed to the compressor housing 2, the case 3 is
A first sealing member 4 elastically supported by the shaft 1
It vibrates following the vibration of. That is, the first seal member 4 is surrounded by viscous damping oil (seal oil).
It vibrates as a vibration damper in the shaft 1, and damps the vibration energy injected from the shaft 1. Furthermore, the contact surface between the first seal member 4 and the protrusion 3c of the case 3 and the second seal member 5 also provide an additional vibration damping effect. In this way, the shaft vibration is reduced, self-excited vibration caused by oil whip does not occur, and the first seal member 4 and the second seal member 5 function as a quiet compressor sealing device.

(Effect of the invention) The present invention provides a sealing device for a rotating machine that seals between an axial hole provided in a housing of a rotating machine and a rotating shaft passing through the coaxial hole by an oil film formed in that part. A cross-sectional annular case is housed in an annular groove provided in the shaft hole, a first annular seal member is housed on the outside of the annular case, and a second annular seal member is housed on the inside of the annular case. A first annular protrusion that contacts the outer side surface of the annular groove is provided on the outer peripheral side of the outer surface of the annular case, and a second annular protrusion that contacts the first annular seal member. The first annular seal member is provided on the inner peripheral side of the inner surface of the annular case, and a plurality of circular arc surfaces continuous in the circumferential direction are formed on the inner peripheral surface of the first annular seal member, thereby preventing the generation of self-excited vibration called oil whip. It has a preventive effect.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view showing an embodiment of the sealing device for a rotating machine of the present invention, and Fig. 2 is a cross-sectional view taken along the line X-X in Fig. 1.
The cross-sectional view, FIG. 3, is a YY cross-sectional view of FIG. 2. 1... shaft, 2... housing, 2a... annular groove, 3... annular case, 3a... first annular protrusion, 3c... second annular protrusion, 4... first annular protrusion Annular seal member, 5...Second annular seal member, 1
1... Arc surface.

Claims (1)

[Scope of utility model registration request] In a sealing device for a rotating machine that seals between an axial hole provided in a housing of a rotating machine and a rotating shaft passing through a coaxial hole by an oil film formed in that part, a cross-sectional shaped groove is provided in an annular groove formed in the axial hole. The annular case is housed, and a first
A second annular seal member is housed inside the annular case, and a first annular protrusion that contacts the external side surface of the annular groove is placed on the outer periphery of the outer surface of the annular case. A second annular protrusion that contacts the first annular seal member is provided on the inner peripheral side of the inner surface of the annular case, and a plurality of circular arc surfaces continuous in the circumferential direction are connected to the first annular seal member. A sealing device for a rotating machine, characterized in that the sealing device is formed on the inner peripheral surface of an annular sealing member.