JPS5838665B2 - Shaft sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft seal device, in particular a shaft seal device called a floating ring seal, which prevents fluid from leaking from a high pressure side to a low pressure side through a shaft penetrating portion of a rotating machine. Regarding a sealing device.

Generally, when the rotating shaft of a rotating machine passes through its casing to the outside and the fluid inside the casing has a higher pressure than the outside, a shaft sealing device is installed to prevent the high-pressure fluid from leaking to the outside. .

This shaft sealing device is constructed by fitting a seal ring around the outer periphery of the rotating shaft, and normally the shaft penetrating portion is completely sealed by supplying sealing liquid between the seal ring and the rotating shaft. There are many things that I did.

Here, a conventional shaft sealing device will be explained based on FIGS. 1 and 2.

That is, the seal rings 2, 2 are fitted around the outer periphery of the rotating shaft 1 with a slight gap ΔS.

The seal rings 2, 2 are held by a seal link cover 3, and the seal rings 2, 2 are held by a seal link cover 3.
In order to facilitate its assembly and disassembly, it has a divided structure as shown in FIG.

In particular, in FIG. 2, the seal ring 2 is divided into three parts, each of which is formed into an annular shape as a whole, and the outer periphery of the seal ring 2 is held together by an annular spring 5 via a ring retainer 4.

Further, a recessed portion 6 is formed on a part of the outer periphery of the seal ring 2, and a rotation stopper pin 7 is fitted into this recessed portion 6 in the axial direction.

This rotation stopper pin 7 is screwed into the seal ring cover 3.

This prevents the seal ring 2 from rotating and deforming.

Particularly in FIG. 1, the outer periphery of the seal ring 2 and the ring presser 4 are pressed against each other by the springs 5 in a tapered box, so that the seal ring 2 is brought into close contact with the low-pressure side inner wall of the seal ring cover 3. ing.

Here, in FIG. 1, the left side of the seal ring cover 3 is defined as a high pressure side A, and the right side is defined as a low pressure side B.

In this state, the seal ring 2 maintains a floating state within the seal ring cover 3 and between the rotating shaft 1 and moves along the gap ΔS between the inner circumference of the seal ring 2 and the outer circumference of the rotating shaft 1. Controls leakage of fluid such as gas from the high pressure side A to the low pressure side B.

Further, the seal ring 2 remains in a floating state even when the rotary shaft 1 is in operation, so that it follows minute fluctuations in the rotary shaft 1 during operation or assembly, and does not interfere with the rotation of the rotary shaft 1.

However, when the rotating shaft 1 is rotated at high speed and the pressure on the high pressure side A is extremely high, high pressure fluid flows into the seal ring chamber 8 between the outer periphery of the seal ring 2 and the seal ring cover 3, and the seal ring 2), high pressure acts on the seal ring 2, strongly tightening the seal ring 2 inward in the radial direction, that is, in the direction of the rotating shaft 1.

Therefore, when the seal ring 2 is made of carbon or synthetic resin such as Teflon as in the past, the elastic modulus is much smaller than that of steel, and therefore the tightening force causes The seal ring 2 may be deformed inward in the radial direction, or the dividing surfaces 9 may be misaligned, so that the gap ΔS between the rotating shaft 1 and the seal ring 2 becomes extremely small.

When the gap △S becomes extremely small in this way, the gap △S
When the sealing liquid is supplied to the engine, the flow rate of the sealing liquid flowing through the gap ΔS decreases, and the flow rate of the sealing liquid becomes smaller than the amount of heat generated by friction during high-speed rotation, resulting in a large temperature rise.

As a result, the rotary shaft 1 and the seal ring 2 are thermally deformed, the gap ΔS becomes smaller and the loss of power increases, making it impossible to operate the rotary machine itself.

In order to prevent this phenomenon, it is possible to incorporate a plurality of seal rings 2 in the axial direction to reduce the differential pressure between the inner and outer circumferences applied to each seal ring. Among them, the highest pressure side A
This occurs in the seal ring 2 that is close to , and the other seal rings 2 cannot sufficiently exhibit the effect of reducing the differential pressure.

The present invention was made to eliminate these drawbacks of the prior art, and its purpose is to control the leakage of extremely high-pressure fluid and to reduce the gap between the seal ring and the rotating shaft even when rotating at high speed. To provide a shaft sealing device which can always maintain a constant shaft sealing effect and exhibit a sufficient shaft sealing effect.

In the present invention, a through hole is provided at approximately the center of the seal ring in the width direction to communicate the outer circumferential side and the inner circumferential side of the seal ring, thereby reducing the differential pressure between the inner and outer circumferential sides of the seal ring. It is meant to be made smaller.

The present invention will be described below based on embodiments shown in the drawings.

Here, parts that are the same as or corresponding to the conventional ones are given the same reference numerals, and explanations of these parts will be omitted.

First, as shown in FIGS. 4 and 5, a pin 10 having a longitudinal direction in the axial direction is interposed in the split surface 9 of the seal ring 2 having a split structure.

That is, recesses 11 are formed facing each other in the circumferential direction on the dividing surfaces 9 of the seal rings 2 that are divided from each other.
．． The pin 10 is precisely fitted into the hollow formed by the pin 11.

In addition, an O-ring 12 is fitted into the inner wall of the seal ring cover 3 that holds the seal ring 2, especially the inner wall of the high-voltage line A, and this 01J ring 12 is fitted between the side surface of the high-pressure side A of the seal ring 2 and the seal ring cover 3. The inner wall surface of the high pressure side A is sealed.

Further, in the seal ring 2, a plurality of through holes 13 are formed at appropriate intervals in the circumferential direction of the seal ring 2, and these through holes 13 are formed at appropriate intervals in the circumferential direction of the seal ring 2, and the through holes 13 penetrate in the radial direction at a position approximately at the center in the width direction of the seal ring 2. 2 outer circumference and seal ring cover 3
The seal ring chamber 8 in the closed space between the seal ring chamber 8 and the seal ring 2
The gap ΔS between the inner periphery of the rotating shaft 1 and the rotating shaft 1 is communicated with each other.

This seal ring chamber 8 faces substantially the entire outer peripheral surface of the seal ring 2.

Further, in this embodiment, there is no ring presser 4 as in the conventional case, and the seal ring 2 is directly tightened by the annular spring 5.

Next, the operation of the shaft sealing device having the above configuration will be explained.

First, the fluid on the high pressure side A flows through the gap △ between the inner circumference of the seal ring 2 on the high pressure side A of the two seal rings 2 and the rotating shaft 1.
Through S, it reaches the space C between the sealing ring 2 on the low pressure side with a pressure drop of the desired pressure gradient.

During this time, fluid at an intermediate pressure between the high pressure side A and the pressure side C lower than the high pressure side A passes through the through hole 13 and passes through the seal ring 2.
is introduced into a seal ring chamber 8 on the outer periphery of the seal ring 2, where the seal ring 2 is pressurized radially inward.

In addition, the seal ring chamber 8 is connected to a high pressure 11 by an O-ring 12.
IA, and the seal ring chamber 8 is sealed from the low pressure side C because the inner walls of the seal ring 2 and seal ring cover 3 are in close contact with each other, so the pressure in the seal ring chamber 8 is sealed from the high pressure side A. The pressure is intermediate between the low pressure side C and the low pressure side C.

That is, the differential pressure applied to the inner and outer circumferential sides of the seal ring 2 is reduced, and this will be explained in detail based on FIG. 6.

First, the conventional case will be explained based on FIG. 6A. Since the seal ring chamber 8 on the outer circumferential side of the seal ring 2 is communicated with the high pressure side A via the gap ΔY, the seal ring 2 is inserted from the outer circumferential side. The force P1 pressing radially inward is equal to the pressure on the high pressure side A and is constant in the width direction of the seal ring 2.

Also, since the fluid on the high pressure side A passes through the gap ΔS,
The force P2 that pushes the seal ring 2 radially outward is on the low pressure side B
It gradually becomes smaller as it moves towards .

Therefore, the resultant force of the forces P1 and P2 acting on the seal ring 2 gradually increases from the high pressure side A to the low pressure side B, as shown by the symbol P3, and therefore the 7 absolute force of the differential pressure P3 acting on the seal ring 2 The value will be very large.

On the other hand, as shown in FIG. 6B, in the case of this embodiment, the force P2 that pushes the seal ring 2 outward in the radial direction is exactly the same as in the conventional case, and the force P2 that pushes the seal ring 2 radially outward from the seal ring chamber 8 is Direction inside (: The pushing force is different.

That is, first, since the through hole 13 is provided at approximately the center in the width direction of the seal ring 2, the intermediate pressure Pm of the pressure P2 is
acts on the seal ring chamber 8.

In addition, since the seal ring chamber 8 is sealed on both the high pressure side A and the low pressure side B, the force P1 pushing the seal ring 2 radially inward is equal to the pressure Pm and constant.

Therefore, the absolute value of the resultant force of Pl and P2 is Pm, as shown by the symbol P3, and pressures in opposite directions act on both ends in the width direction.
．． In the middle, the pressure changes linearly.

Therefore, the force applied to the seal ring 2 is minimized as a whole, and it is possible to prevent the gap ΔS between the seal ring 2 and the shaft 1 from changing, particularly from disappearing or becoming uneven.

In this case as well, the moment acting on the seal ring 2 is the same as in the conventional case, but since the seal ring 2 is held by the seal ring cover 3, this moment can be ignored.

The above effects are more pronounced in the case of a shaft sealing device that completely performs the shaft sealing function by supplying sealing liquid to the gap ΔS.

In addition, a pin 10 is provided in the dividing surface 9 of the seal ring 2 in the axial direction.
Since it is fitted, it is possible to prevent discrepancies at the dividing surface 9, and it is possible to maintain the function as an integral ring.

In the above embodiment, an O-ring 12 is interposed between the seal ring 2 and the inner wall of the seal ring cover 3 on the high pressure side A of the seal ring 2, so that the seal ring chamber 8
Although the O-ring 12 is isolated from the high-pressure side A, the differential pressure between the inner circumferential side and the outer circumferential side acting on the seal ring 2 becomes smaller, and the initial objective of the present invention is achieved.

As described above, according to the present invention, the differential pressure between the inner and outer circumferential sides of the seal ring can be reduced even when used for shaft sealing of high-pressure fluids and rotating shafts rotating at high circumferential speeds. It has the excellent effect of keeping the gap between the rotating shaft and the seal ring constant at all times to prevent the leakage flow rate of fluid from decreasing, thereby reducing temperature rise and power loss, and providing smooth shaft sealing function. be.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a conventional shaft sealing device, Fig. 2 is a cutaway side view of the same, Fig. 3 is an explanatory view showing the discrepancy phenomenon in the dividing plane of the seal ring, and Fig. 4 is a diagram showing the present invention. FIG. 5 is a cross-sectional view showing an embodiment of such a shaft sealing device, FIG. 5 is a cutaway side view of the same embodiment, and FIG. 6 is an explanatory diagram showing the pressure acting on the seal ring in the same embodiment and a conventional case. DESCRIPTION OF SYMBOLS 1...Rotating shaft, 2...Seal ring, 8...Seal ring chamber, 9...Dividing surface, 10...Pin, 12...
...O-ring, 13...through hole, A...high pressure side, B
...Low pressure side.

Claims (1)

[Claims] 1. An annular seal ring is fitted on the outer periphery of a rotating shaft extending from a high-pressure section to a low-pressure section with a small gap, and the seal ring allows fluid to flow from the high-pressure section to the low-pressure section. In a shaft sealing device for controlling leakage, a seal ring chamber is provided on the outer peripheral side of the seal ring as a closed space facing substantially the entire outer peripheral surface of the seal ring, and a seal ring chamber is provided as a closed space facing substantially the entire outer peripheral surface of the seal ring, and a seal ring chamber is provided along the axial direction of the gap from the high pressure part side. A through hole is provided at a substantially central position in the axial direction of the seal ring to form a pressure gradient of the fluid toward the low pressure part side, and communicates the gap with the seal ring chamber, and the through hole in the gap is formed by the through hole. A shaft sealing device characterized in that it is configured to guide fluid pressure in the opening into the seal ring chamber. 2. A shaft in which an annular seal ring is fitted with a small gap on the outer periphery of a rotating shaft extending from a high-pressure part to a low-pressure part, and the seal ring prevents leakage of fluid from the high-pressure part to the low-pressure part. In the sealing device, a seal ring chamber, which is a closed space facing substantially the entire outer peripheral surface of the seal ring, is provided on the outer circumferential side of the seal ring, and the fluid flows from the high pressure section side to the low pressure section side along the axial direction of the gap. forming a pressure gradient,
A through hole that communicates the gap and the seal ring chamber is provided at a substantially central position in the axial direction of the seal ring, and the through hole guides the fluid pressure at the opening of the through hole into the seal ring chamber. The shaft is characterized in that the seal ring has a divided structure divided by radial dividing surfaces and is formed in an annular shape as a whole, and an axial pin is fitted into each dividing surface of the seal ring. Sealing device.