JPH07243536A - Floating ring seal - Google Patents

Abstract

PURPOSE:To reduce the contact load of a rotary shaft with seal rings and prevent generation of scratches by furnishing circumferentially stretching grooves at the contact surfaces of the seal rings with retainers, and cutting holes for putting these grooves in communication to the low pressure side at the internal circumferences of the seal rings. CONSTITUTION:A plurality of retainers 8 are fitted in a cylindrical case 2 as stretching in the axial direction, wherein the case 2 is penetrated by a rotary shaft 1, and between the shaft 1 and the retainers 8, seal rings 9 in the same number as retainers 8 are held capable of floating by loosely fitting pins 10... protruded at one surface of seal ring in holes 11... provided at the inner side faces of the retainers 8. Grooves B stretching in the circumferential directions are formed at the contacting surfaces of the seal rings 9 with retainers 8 and are punt in communication to the low pressure side at the inner side faces of the seal rings 9 through holes C and to the high pressure side about the seal rings 9 through capillaery tubes D. Thereby the pressure in the grooves B is raised when the rotary shaft 1 is in contact with the seal rings 9 so that the pressing force of the seal rings 9 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating ring seal used as a shaft sealing device for a high pressure pump such as a reactor water supply pump or a boiler water supply pump according to the present invention. It relates to a floating ring seal suitable for reduction.

[0002]

2. Description of the Related Art For example, in a conventional floating ring seal, as described in Japanese Patent Application No. 56-115634, the contact surface between the seal ring and the retainer is a single plane.
The seal ring is pressed against the retainer by the differential pressure of the seal, and the pressing load is constant regardless of the approach distance between the rotating shaft and the seal ring, and when the rotating shaft and the seal ring contact, the contact surface of the seal ring The load, which is the pressing force multiplied by the friction coefficient of the contact surface between the seal ring and the retainer, acts in the direction perpendicular to the axis.

[0003]

In the above-mentioned prior art, a water film is formed between the rotary shaft and the seal ring when the pump is operated, and the pump is operated in a non-contact manner. However, a water film is formed during start-up, stop and low-speed operation. Since the seal ring and the rotating shaft come into contact with each other, and a load is applied to the contact surface, sliding scratches occur at the contact portion, which increases the gap between the rotating shaft and the seal ring and increases the amount of seal leakage. There was a problem.

An object of the present invention is to reduce the contact load between the seal ring and the rotary shaft by reducing the pressing force of the seal ring at the time of contact between the seal ring and the rotary shaft, and prevent the occurrence of sliding scratches on the contact portion. This is to prevent an increase in the amount of seal leakage due to an increase in the gap between the rotary shaft and the seal ring.

[0005]

To achieve the above object, the floating ring seal of the present invention is provided with a circumferential groove on the contact surface of the seal ring with the retainer or the contact surface of the retainer with the seal ring. A hole for connecting the circumferential groove to the low pressure side of the inner circumference of the seal ring is provided, and the circumferential groove is connected to the high pressure side of the seal ring by a hole having a throttle mechanism such as a capillary tube or an orifice. I chose

[0006]

In the floating ring seal constituted by the above means, when the seal ring and the rotating shaft come into contact with each other, a hole connected to the circumferential groove provided on the contact surface of the seal ring with the retainer is connected to the rotating shaft. As a result, the pressure in the circumferential groove communicating with the high pressure side of the seal ring through the hole having the throttle mechanism increases, and the pressing force of the seal ring decreases.

As a result, the contact load between the seal ring and the rotary shaft is reduced, so that it is possible to prevent the occurrence of sliding scratches on the contact portion, and to prevent an increase in the amount of seal leakage due to an increase in the gap between the rotary shaft and the seal ring. be able to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a floating ring seal according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a rotary shaft, 2 is a cylindrical case provided in the rotary shaft penetrating portion of the pump body 3, and is formed coaxially with the rotary shaft 1 penetrating therethrough.
Is fixed by. An O-ring 5 for preventing liquid leakage from the fitting surface is provided on the fitting surface with the pump body 3, and a sealing liquid supply port 6 is provided at a position corresponding to the sealing liquid inlet A of the pump body 3. An inwardly facing annular protrusion 7 is formed at the rear end. Reference numeral 8 denotes a plurality of retainers that are fitted in and arranged in the axial direction of the inner surface of the tubular case 2. Between each retainer and the rotary shaft 1, a plurality of seal rings 9 as many as the retainer are provided, and a plurality of pins 1 projectingly provided on one surface thereof.
0 is loosely held by loosely fitting 0 into a hole 11 provided on the inner surface of each retainer 8. A circumferential groove B is provided on the contact surface of the seal ring 9 with the retainer 8, and the circumferential groove B is connected to the inner circumferential low pressure side of the seal ring 9 by a hole C. Further, the groove B in the circumferential direction is a capillary tube D.
Is connected to the high pressure side of the seal ring 9. 1
Reference numeral 2 denotes a lantern ring for sealing liquid, which is arranged in parallel with the retainer 8 at the position of the sealing liquid supply port 6 on the inner surface of the cylindrical case 2. A sealing liquid reservoir groove 12b is formed, and a plurality of through holes 12c are formed between both grooves. Reference numeral 13 denotes a side retainer, and one side surface thereof is in close contact with one side surface of the seal rings 9 at both ends. Reference numeral 14 is a case cover having an annular projection 15 formed therein, and 16 is a fastening bolt. Fastening bolt 1
By fastening the case cover 14 to the tubular case 2 at 6, the retainer 8, the lantern ring 12, and the side retainer 13 arranged side by side in the axial direction of the inner surface of the case 2 together with the seal ring 9 form the inner annular projection 7 of the case 2. And the inner annular protrusion 15 of the case cover 14 are sandwiched and fixed, and integrated with the case 2.

In the floating ring seal thus constructed, the clearance e between the inner surface of the seal ring 9 and the outer surface of the rotary shaft 1 is set to a minute clearance of 0.1 to 0.2 mm, and the sealing liquid inlet is introduced into this minute clearance. The sealing liquid is caused to flow from A through the sealing liquid supply port 6 and the supply groove 12a of the lantern ring 12, the through hole 12c, and the reservoir groove 12b, and the liquid inside the pump is sealed by the liquid film in the minute gap e.

The rotary shaft 1 will be described below with reference to FIGS. 2, 3 and 4.
The contact load of the seal ring 9 will be described.

2 is a detailed explanatory view of the seal ring portion of FIG. 1, FIG. 3 is a pressure distribution diagram before and after the seal ring of FIG. 2, and FIG.
FIG. 4 is a cross-sectional view of the contact surface of the seal ring 9 with the retainer 8 in the direction perpendicular to the axis.

In FIG. 2, D1 is the inner diameter of the contact surface of the seal ring 9 with the retainer 8, D2 is the inner diameter of the circumferential groove B, D3 is the outer diameter of the circumferential groove B, and D4 is the outer surface of the contact surface. Is the diameter. Before and after the seal ring 9, the pressure P2 of the fluid on the upstream side passes through the gap e, and therefore P due to the pressure loss in the gap.
The pressure is reduced to 1. Further, since the upstream end surface 9a and the outer diameter 9b of the seal ring 9 are provided with a clearance for floating with respect to the retainer 8, the upstream pressure P2 is also applied to the seal ring upstream end surface 9a and the outer diameter 9b. It is working.
Further, 1a is a rotary shaft in contact with the seal ring 9.

When a gap is formed between the outer surface of the rotary shaft 1 and the inner surface of the seal ring 9, the groove B in the circumferential direction is connected to the low pressure side by the hole C, so that the groove B in the circumferential direction is The pressure becomes P1. The pressure distribution before and after the seal ring 9 at this time is shown in FIG. In FIG. 3, X is the pressure distribution on the upstream side, Y is the pressure distribution on the downstream side, and ΔP is the pressure loss in the gap e. On the other hand, when the outer surface of the rotary shaft 1 and the inner surface of the seal ring 9 contact each other, the hole C is blocked by the rotary shaft 1, so that the inside of the circumferential groove B communicated with the seal ring high pressure side by the capillary tube. The pressure becomes P2. At this time, the pressure on the downstream side of the seal ring has a distribution indicated by Y ′ in FIG. 3, and the pressure difference before and after the seal ring is smaller than that when the outer surface of the rotary shaft 1 and the inner surface of the seal ring 9 are not in contact with each other.

In FIG. 4, A1 is the area of the inner contact surface of the seal ring 9 with the retainer 8, A2 is the area of the circumferential groove, and A3 is the area of the outer contact surface of the seal ring 9 with the retainer 8.

From the above pressure and area relationship, the pressing force F due to the fluid pressure of the seal ring 9 is

[0017]

## EQU00001 ## F = .DELTA.P.times. (A1 + A2 + (A3) / 2) (Equation 1) In the conventional floating ring seal, the pressing force is always applied regardless of the contact between the rotating shaft and the seal ring. there were.

When the rotating shaft contacts

[0019]

F = ΔP × (A1) / 2 (Equation 2) Further, the contact load f in the direction perpendicular to the axis when the rotating shaft 1 and the seal ring 9 are in contact with each other is as follows. When the friction coefficient is μ, it is expressed by the following equation.

[0020]

[Equation 3] f = μ × F (Equation 3) According to the present embodiment, the load at the time of contact between the rotary shaft 1 and the seal ring 9 is compared to that of the conventional floating ring seal according to Equations 1, 2 and 3. It is possible to significantly reduce it.

[0021]

According to the present invention, the contact load between the seal ring and the rotating shaft is reduced by reducing the pressing force of the seal ring at the time of contact between the seal ring and the rotating shaft, and the occurrence of sliding scratches at the contact portion is prevented. However, it is possible to provide a floating ring seal that can prevent an increase in the amount of seal leakage due to an increase in the gap between the rotary shaft and the seal ring.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a floating ring seal of the present invention.

FIG. 2 is an explanatory view of a seal ring portion of FIG.

FIG. 3 is a pressure distribution diagram before and after the seal ring of FIG.

FIG. 4 is a cross-sectional view of the contact surface of the seal ring with the retainer in a direction perpendicular to the axis.

[Explanation of symbols]

1 ... Rotating shaft, 8 ... Retainer, 9 ... Seal ring, B ... Circumferential groove, C ... Hole, D ... Capillary tube, e ... Gap between rotating shaft and seal ring.

Claims (1)

[Claims] 1. An inner surface of a stationary body, which penetrates a rotary shaft, and one or a plurality of retainers arranged in parallel in an axial direction of the stationary body, and the retainer, which is in contact with the retainer in an axial surface, between the retainers and the rotary shaft. , A floating ring seal including a seal ring that is held so as to be capable of floating in a direction perpendicular to the axis through a pin, in a circumferential direction on a contact surface of the seal ring with the retainer or a contact surface of the retainer with the seal ring. And a hole for connecting the circumferential groove to the inner circumference low pressure side of the seal ring is provided, and the circumferential groove is connected to the high pressure side of the seal ring by a hole having a throttle mechanism. A characteristic floating ring seal.