JPS59194170A - Mechanical seal - Google Patents

Abstract

PURPOSE:To quickly cope with a sharp pressure reverse phenomenon to maintain a sealed state, by fitting movable rings on both the sides of a secondary seal. CONSTITUTION:A driven ring 4, which constitutes sealing surfaces 5 together with a seat ring 3 secured on a rotary shaft 2, is supported on the inside by a guide 6 so that the ring can be moved in the axial direction and pushes the seat ring 3 under the force of a spring 7. A secondary seal 8 and movable rings 9, 10 are provided in a space defined between the steps 4a, 6a of the inside of the driven ring 4 and the outside of the guide 6, so that the movable rings are placed on both the sides of the secondary seal and they can be moved. The pressure of a first fluid A on the outside of the driven ring 4 and that of a second fluid B on the inside of the driven ring act to the sides of the movable rings 9, 10 located opposite the secondary seal 8.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a mechanical seal that prevents the internal fluid from flowing out of a rotating machine, and more specifically, to a compressor or a pump in which the differential pressure between the internal fluid pressure and the external fluid pressure is positive or negative. This relates to a mechanical tar that exhibits sealing performance even when it is reversed.

[Background of the invention]

Conventionally, in compressors and pumps, the magnitude relationship between internal fluid pressure and external fluid pressure is not determined, and the differential pressure therebetween may be reversed in polarity. A mechanical seal capable of properly sealing the shaft seal even under such pressure fluctuation conditions is disclosed in Japanese Patent Publication No. 58-3149. This mechanical seal maintains sealing performance by moving the secondary seal in the axial direction to apply increased pressure to the back surface of the driven ring, applying force to press the driven ring against the seat ring.

In this mechanical cooling, the movement of the secondary seal described above may not be sufficient as it follows pressure fluctuations. In particular, when the reversal action between internal fluid pressure and external fluid pressure is rapid, the secondary seal will not move in response to this fluctuating pressure.
It was sometimes impossible to apply a fluctuating pressure fluid to the driven ring.

[Purpose of the invention]

The present invention has been made based on the above-mentioned problems, and provides a mechanical seal that can maintain normal sealing performance in response to pressure fluctuations even when the internal and external fluids have a rapid pressure reversal action. The purpose is to

[Summary of the invention]

In order to achieve the above object, the present invention forms a sealing surface that seals a first fluid on the outer peripheral surface side of the driven ring and a second fluid on the inner peripheral surface side by the seat ring and the driven ring, In a mechanical seal that includes a secondary seal between the curved surface of the driven ring and a guide member that guides the axial movement of the driven ring opposing thereto, the peripheral surface of the driven ring on the secondary seal side and the internal material of the driven ring A step is provided in each of the steps to form a space in which the secondary seal can move in the axial direction, and within the space formed by the step, a secondary seal and a movable ring on both sides of the secondary seal are provided with a movable O-T function. The first fluid and the second flow/JX body are inserted into the movable ring on the side opposite to the secondary seal surface, respectively.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an actual example of the mechanical seal of the present invention. In the figure, 1 is a casing, 2 is a rotating shaft, 3 is a seat ring fixed to the rotating shaft 2, and 4 is a sealing surface 5 together with the seat ring 3. This driven ring 4 is held movably in the axial direction by a guide member 6 on its inner peripheral surface. Reference numeral 7 denotes a spring provided on the rear end surface of the driven ring 4, and this spring 7 functions to press the driven ring 4 against the seat ring 3. The driven ring 4 is prevented from rotating by a rotation locking pin (not shown). 8 is a secondary seal provided between the inner peripheral surface of the driven ring 4 and the outer peripheral surface of the guide member 6.

The inner circumferential surface of the driven ring 4 and the outer circumferential surface of the guide member 6 each have a stepped portion 4a for forming an annular space.

6a is formed. In the space formed by the stepped portions 4a and 6a, the above-described secondary seal 8 and movable rings 9 and 10 located on both sides thereof are movably inserted. The secondary seal 8 has seal portions formed at two locations: a contact portion between its outer circumference and the inner circumferential surface of the driven gear 4, and a contact portion between the inner circumference and the outer circumferential surface of the guide member 6. On the rear surface of the movable ring 9 and 10 on the side opposite to the secondary seal, there is a first ring on the outer peripheral side of the driven ring 4, as shown in FIGS.
Circumferential grooves 9A, 10A that serve as pressure acting parts for the fluid man and the second fluid B on the inner peripheral side of the surface motion ring 4, and radial grooves that introduce the fluid man and B into these circumferential grooves 9A, IOA, respectively. Grooves 9B and IOB are provided. As shown in FIG. 2, the radial groove 9B of the moving ring 9 is provided on the outer peripheral end surface of the moving ring 9 in order to quickly introduce the first fluid into the circumferential groove 9A. Further, the radial groove 10B of the moving ring 10 directs the second fluid B to the circumferential groove 1 as shown in FIG.
It is provided on the inner circumferential end surface of the moving ring 10 in order to quickly introduce it into the 0A.

Next, the operation of one embodiment of the mechanical seal of the present invention described above will be explained.

Usually, the pressure between the first fluid A and the second fluid B? M, P
The relationship with i+ is 2 people〉Ps.

In this state, the secondary seal 8 is pressed rightward in the drawing by the pressure PA of the first fluid A, as shown in FIG. 1.Protrusion into the gap G is prevented.

On the other hand, if a sudden pressure reversal phenomenon occurs in this state, that is, a relationship between PA and PB occurs, the second fluid B passes through the gap G and flows into the circumferential groove 10 via the radial groove 10B of the moving ring 10.
Flows into A. As a result, the moving ring 10 moves the secondary seal 8 to the left in the drawing, as shown in FIG.

Next, when the pressures of the first fluid A and the second fluid B are reversed again and become PA>PII, the first fluid A is placed on the side opposite to the secondary sealing surface of the moving ring 90 as described above. pressure PA is applied, and the secondary seal 8 returns to the state shown in FIG. In this way, even if a magnitude relationship 75 occurs between the pressure PA of fluid A and the pressure Pa of fluid B, each fluid A is always present on the side surface of the secondary seal 8.

B's pressure Two people can exert legitimate force by Pg.

The pressure and pressure sealing and land functions of each fluid A and B will be explained using FIGS. 6 and 7.

FIG. 6 shows the pressure action relationship when PA>pH shown in FIG. 4 (normal usage state). In order for the mechanical seal to function properly, the sealing surface 5 must be in constant contact. In the present invention, fluid pressure due to the pressure difference Po between the pressure PA of fluid A and the pressure Pa of fluid B acts around the driven ring 4 and also acts on the side of the secondary seal 8 opposite to the sealing surface. As a result, the axial force acting on the driven ring 4 is FA in the relationship between the force FA trying to close the sealing surface 5 and the force Fo trying to open the sealing surface 5, as shown in FIG. )F.

Therefore, the driven ring 4 is pressed against the seat ring 3 and maintains good sealing performance of the sealing surface 5.

Also, contrary to the above, the pressure PAIPm of fluids A and B is PA
In this case, the pressure PR of fluid B and the flow I
The differential pressure Px between the pressure A and the pressure PA acts on the stepped portion 4a of the driven ring 40, as shown in FIG. Accordingly, the force relationship acting on the driven/g 4 is such that Fm, l>Fo between the force FIl that attempts to close the sealing surface 5 and the force Fo that attempts to open the sealing surface 5. As a result, the slave 1+J ring 4 is pressed against the seat ring 3. As a result, even if the pressure reversal described above occurs, the sealing surface 5 maintains good sealing performance.

Even if such a pressure reversal phenomenon occurs, the moving ring 9.1
0, the secondary seal 8 can quickly move in the axial direction within the space formed by the stepped portions 4a and 6a.

Although the above-described embodiment is applied to a stationary mechanical seal in which the driven ring 5 is supported by the guide member 6, it can also be applied to a rotating mechanical seal in which the driven ring 4 is provided on the rotating shaft side. Furthermore, the present invention can also be applied to a case where the secondary seal is arranged on the outer peripheral side of the driven ring 4. However, the shapes of the pressure acting portions and fluid introduction grooves formed in the moving rings 9, 10 are limited to those in the above-described embodiments (9).For example, it is also possible to form only radial grooves.

〔Effect of the invention〕

As described above, according to the present invention, when the pressure relationship between the first fluid and the second fluid to be sealed suddenly reverses, the secondary seal can be quickly moved in the axial direction by inserting the moving ring. The differential pressure l can be applied to the driven ring to maintain the seal. As a result, it is possible to provide a mechanical seal that can quickly respond to the above-mentioned sudden pressure reversal phenomenon and maintain sealing performance.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing the upper half of an embodiment of the mechanical seal of the present invention, and FIGS. 2 and 3 are side views of an example of a moving ring used in the mechanical seal of the present invention.
FIGS. 4 and 5 are explanatory diagrams showing the operating state of the mechanical seal of the present invention when the pressure is reversed in the secondary coolant, and FIGS. 6 and 7 are respective pressure effects when the pressure is reversed in the mechanical seal of the present invention. It is an explanatory diagram showing a state. (10) 1... Casing, 2... Rotating shaft, 3... Seat ring, 4... Driven ring, 4a... Step portion, 5...
... Sealing surface, 6... Guide member, 6a... Step portion, 7
・・・Spring, 8...Secondary seal, 9.10...Movement ring, 9A, IOA...f33 FA

Claims (1)

[Claims] 1. The seat ring and the driven ring form a sealing surface that tightly contacts the first fluid on the outer peripheral surface side of the driven ring and the second fluid on the inner peripheral surface side, and In a mechanical seal that includes a secondary seal between the secondary seal and the guide member that guides the axial movement of the opposing driven ring, the peripheral surface of the driven IJ song secondary seal side and the guide member of the driven ring each have a A step is provided to form a space in which the secondary seal can move in the direction, and a secondary seal and a moving ring are movably inserted on both sides of the secondary seal into the space formed by the step. A mechanical seal characterized in that a first fluid and a second fluid acting portion are formed on the side opposite to the secondary seal surface of the moving ring. 2. In the mechanical seal according to claim 1, the first
A mechanical seal characterized in that the fluid 2 and the second fluid acting portion are constituted by a fluid pressure acting portion provided on the back surface of the moving ring and a groove for introducing fluid into the fluid pressure acting portion. 3. The mechanical seal according to claim 2, wherein the fluid pressure acting portion is a circumferential groove, and the fluid introduction groove is a circumferential, backwardly curved radial groove. 4. The mechanical seal according to claim 2, wherein the fluid pressure acting part and the fluid introduction groove are radial (backward). 5. The mechanical seal according to claim 2 A mechanical seal characterized in that the fluid pressure acting part and the fluid introduction groove are circumferential grooves.