JPH08312790A - Mechanical seal - Google Patents

Abstract

PURPOSE: To provide a mechanical seal to reduce an amount of lubrication oil leaking to the outside of a casing and to prevent the occurrence of seizure and blister of a slide end face between a fixed ring and a rotary ring. CONSTITUTION: In a mechanical seal which is fixed to a casing 1 and in which a rotary shaft 2 is inserted and which comprises a fixed ring 8 brought into rotatable slide contact with the outer peripheral surface of the rotary shaft 2; and a rotary ring 9 positioned in the casing 1 and fixed on the outer peripheral surface of the rotary shaft 2, and is formed in such a manner that one end face 9a of the rotary ring 9 is slidably pressed against one end face 8a of the fixed ring 8, a plurality of grooves 10 positioned approximately on a concentric circle are formed in either the end face 9a of the slidably pressed rotary ring 9 or the end face 8a of the fixed ring 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical seal for preventing a lubricating oil in a casing from leaking out of the casing in a device having a rotary shaft penetrating the casing.

[0002]

2. Description of the Related Art The structure of a conventional mechanical seal is shown in FIG.
It will be described based on. First, a rotary shaft 2 that penetrates the casing 1 is provided. The outer peripheral surface side of the seat ring 3 is fitted and fixed to the casing 1, the rotary shaft 2 is inserted into the seat ring 3, and the outer peripheral surface of the rotary shaft 2 is rotatably slidably contacted with the inner peripheral surface of the seat ring 3. Has been done. An O-ring 4 is interposed between the outer peripheral surface of the seat ring 3 and the casing 1.

Next, a carbon ring 5 is formed on a portion of the outer peripheral surface of the rotary shaft 2 located inside the casing 1.
Are fitted and fixed, and the inner peripheral surface of the carbon ring 5 and the rotating shaft 2
An O-ring 6 is interposed between the outer peripheral surface and the outer peripheral surface. Further, the carbon ring 5 is provided on the outer peripheral portion of the rotary shaft 2.
One end surface 5a of the seat ring 3
A spring 7 for urging the carbon ring 5 so as to press it against a is arranged.

Here, the rotating shaft 2 rotates integrally with the carbon ring 5, and the outer peripheral surface of the rotating shaft 2 is seat ring 3.
The end surface 5a of the carbon ring 5 and the end surface 3a of the seat ring 3 are slidably pressed by the urging force of the spring 7 so as to slidably contact the inner peripheral surface of the seat ring 3. This prevents the lubricating oil in the casing 1 from leaking out of the casing 1 after passing between the end surfaces 3a and 5a and between the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the seat ring 3. are doing.

In order to effectively prevent the lubricating oil from leaking out of the casing 1, it is necessary to increase the pressing force between the end faces 3a and 5a to reduce the gap between the end faces 3a and 5a. However, if the gap between the end surfaces 3a and 5a becomes too narrow because the pressing force between the end surfaces 3a and 5a is too strong, the end surface 3
The oil film of the lubricating oil between a and 5a is broken, and seizure easily occurs between the end faces 3a and 5a. On the other hand, end face 3
If the gap between the end faces 3a and 5a becomes too wide because the pressing force between a and 5a is too weak, the amount of lubricant that leaks out of the casing 1 increases because the lubricant easily passes through this gap. . Therefore, it is necessary to adjust the biasing force of the spring 7 so that the gap between the end surfaces 3a and 5a has an optimum value.

If the seat ring 3 and the carbon ring 5 that press the end faces 3a and 5a are made of the same material, seizure easily occurs. Therefore, the seat ring 3 is made of a stainless material and the carbon ring 5 is formed. It is made of carbon material. Furthermore, in order to enhance the sealing effect between the end faces 3a and 5a, the end faces 3a and 5a are mirror-finished.

[0007]

However, in a device in which the pressure in the casing 1 fluctuates, such as a screw compressor, the fluctuating pressure in the casing 1 also affects the gap between the end faces 3a, 5a. That is, the fluctuating pressure in the casing 1 causes the end face 5 a of the carbon ring 5 to move toward the end face 3 a of the seat ring 3 together with the urging force of the spring 7.
It acts as a force to press. Therefore, the biasing force of the spring 7 is weakened so that the pressure between the end faces 3a and 5a does not become too strong even when the pressure in the casing 1 becomes maximum. Therefore, the gap between the end surfaces 3a and 5a tends to be wider than the optimum value, and the amount of lubricating oil leaking out of the casing 1 is large.

Further, in order to enhance the sealing effect, the end face 3
When a and 5a are mirror-finished, the viscous resistance of the oil film between the end surfaces 3a and 5a is significantly increased due to the increase in pressure in the casing 1 and the increase in the viscosity of the lubricating oil, and the surface of the end surface 5a of the carbon ring 5 is fired. Blister-like blister may occur. When such a blister occurs,
The gap between the end faces 3a, 5a becomes large, and the lubricating oil easily leaks out, and when the blister is broken, the amount of lubricating oil leaking out sharply increases. The life of the mechanical seal is greatly reduced by the repeated occurrence and destruction of the blister. Therefore, research on the material of the carbon ring 5 in which blisters are less likely to occur is under way.

[0009]

According to the present invention, there is provided a fixed ring fixed to a casing and having a rotary shaft inserted therethrough, and an outer peripheral surface of the rotary shaft slidably slidably in contact with the fixed ring. A mechanical seal having a rotary ring fixed to the outer peripheral surface of the rotary shaft, wherein one end surface of the rotary ring is slidably pressed against the one end surface of the fixed ring. Further, a plurality of grooves located substantially concentrically are formed on either one of the end surface of the rotating ring and the end surface of the fixed ring.

[0010]

In the present invention, since the lubricating oil is contained in the groove formed on one of the end surface of the rotating ring and the end surface of the fixed ring, the pressing force for pressing the end surface of the rotating ring against the end surface of the fixed ring is large. Even if set to a value, the oil film of the lubricating oil does not run out between these end faces, and seizure due to the oil film running out of the lubricating oil is prevented. Further, since the groove is formed on the end faces, the viscous resistance of the oil film between the end faces does not significantly increase, and the occurrence of blisters due to the large increase of the viscous resistance of the oil film between the end faces is prevented. .
Further, since the pressing force between the end faces can be set to a large value, the amount of lubricating oil leaked out is reduced. Further, since the groove is formed substantially concentric with the end face, the lubricating oil that has entered the groove is suppressed from moving in the axial direction due to the labyrinth effect, and leakage of the lubricating oil is further reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same parts as those described in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. A seat ring 8 which is a fixed ring is provided in the casing 1 through which the rotary shaft 2 penetrates.
The outer peripheral surface side is fitted and fixed, and the rotating shaft 2 is inserted through the seat ring 8 and the outer peripheral surface of the rotating shaft 2 is rotatably slidably contacted with the inner peripheral surface of the seat ring 8. An O-ring 4 is provided between the outer peripheral surface of the seat ring 8 and the casing 1. The seat ring 8 is made of stainless steel.

Next, a carbon ring 9, which is a rotating ring made of carbon material, is fitted and fixed to a portion of the outer peripheral surface of the rotary shaft 2 located inside the casing 1, and the inner peripheral surface of the carbon ring 9 is fixed. An O-ring 6 is interposed between and the outer peripheral surface of the rotary shaft 2. Further, a spring 7 for urging the carbon ring 9 so as to press the one end surface 9a of the carbon ring 9 against the one end surface 8a of the seat ring 8 is arranged on the outer peripheral portion of the rotary shaft 2. . Further, a plurality of ring-shaped grooves 10 located concentrically are formed on the end surface of the seat ring 8.

In such a structure, when the rotary shaft 2 is driven to rotate, the carbon ring 9 rotates integrally with the rotary shaft 2 and the outer peripheral surface of the rotary shaft 2 slidably contacts the inner peripheral surface of the seat ring 8. . Further, due to the biasing force of the spring 7, the end surface 9a of the carbon ring 9 is moved to the seat ring 8
The end surfaces 8a and 9a are slidably pressed against each other.

Here, since a plurality of ring-shaped grooves 10 are formed on the end surface 8a of the seat ring 8, the lubricating oil in the casing 1 has entered the grooves 10. Therefore, even if the biasing force of the spring 7 is set so that the pressing force between the end surfaces 8a and 9a has a large value,
Between these end surfaces 8a and 9a, the oil film of the lubricating oil does not run out, and the occurrence of seizure due to the running out of the oil film is prevented. Further, due to the existence of this groove 10, the end faces 8a, 9a
It is prevented that the viscous resistance of the oil film of the lubricating oil between the two greatly increases, and thus the end surface 9 of the carbon ring 9 is prevented.
Generation of blisters in a is prevented.

By preventing the occurrence of blisters on the end surface 9a of the carbon ring 9, there is no restriction that the carbon ring 9 is made of a material which is less likely to cause blisters, and the selection range of the material of the carbon ring 9 is wide. In addition, the manufacturing cost can be reduced.

Further, even if the pressing force between the end faces 8a and 9a is increased, it is possible to prevent the oil film of the lubricating oil between the end faces 8a and 9a from running out and the occurrence of blisters on the end face 9a, so that the urging force of the spring 7 is increased and By increasing the pressing force between the end surfaces 8a and 9a, the amount of lubricating oil leaking out of the casing 1 can be reduced. In particular,
In a device in which the pressure inside the casing 1 changes, such as a screw compressor, it is possible to set a large pressing force between the end surfaces 8a and 9a without considering the pressure change inside the casing 1, and to the outside of the casing 1. This greatly contributes to the reduction of the amount of lubricating oil leaked. further,
Since the groove 10 is formed substantially on the concentric circle of the end surface 8a, the lubricating oil that has entered the groove 10 is prevented from moving in the axial direction by the labyrinth effect, and leakage of the lubricating oil is further reduced. .

In the present embodiment, the seat ring 8 having the groove 10 formed on the end surface 8a has been described as an example, but such a groove 10 is formed on the end surface 8a of the seat ring 8.
Instead, it may be formed on the end surface 9a of the carbon ring 9.

The shape of the groove 10 has been described as an example of a ring shape in which the start end and the end are continuous, but an arc-shaped groove in which the start end and the end are not continuous is formed on substantially concentric circles. May be.

[0019]

According to the present invention, in the mechanical seal for preventing the leakage of the lubricating oil from the inside of the casing,
Since a plurality of grooves that are located substantially concentrically are formed on either one of the end surface of the fixed ring that is slidably pressed and the end surface of the rotating ring, the lubricating oil inside the casing has entered these grooves. Therefore, even if the pressing force that presses the end face of the rotating ring against the end face of the fixed ring is set to a large value, the oil film of the lubricating oil does not run out between these end faces,
It is possible to prevent the occurrence of seizure due to the oil film running out of the lubricating oil.Moreover, since the groove is formed on the end faces, the viscous resistance of the oil film between the end faces does not increase significantly. It is possible to prevent the occurrence of blister due to a large increase in resistance, and to prevent the occurrence of blister, it is possible to widen the selection range of the material of the fixed ring and the rotating ring and reduce the manufacturing cost. Moreover, since the pressing force between the end faces can be set to a large value, the amount of lubricating oil leaked out can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a seat ring, in which (a) is a vertical sectional front view and (b) is a side view.

FIG. 3 is a vertical sectional front view showing a conventional example.

[Explanation of reference numerals] 1 casing 2 rotating shaft 8 fixed ring 8a end face 9 rotating ring 9a end face 10 groove

Claims (1)

[Claims] 1. A fixing ring fixed to a casing, through which a rotary shaft is inserted, and an outer peripheral surface of the rotary shaft slidably slidably contacted, and fixed to the outer peripheral surface of the rotary shaft located inside the casing. In the mechanical seal having an end face of the rotary ring slidably pressed to one end face of the fixed ring, the end face of the rotary ring slidably pressed and the end face of the rotary ring A mechanical seal characterized in that a plurality of grooves located substantially concentrically are formed on either one of the end faces of the fixing ring.