JPS6135816Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shaft sealing device that allows the sealing pressure to be changed arbitrarily, and is particularly suitable for use when sealing gas against a rotating shaft that rotates at high speed. It is.

A shaft sealing device such as a mechanical seal used to prevent sealed fluid such as gas from leaking from between the rotating shaft attached to the casing of a gas compressor, etc., and the casing. The shaft sealing liquid chamber is formed adjacent to the sealing part, and the pressure of the shaft sealing liquid in the shaft sealing liquid chamber is higher than the pressure of the sealing fluid in the casing, so that the shaft is sealed when the rotating shaft is rotating and when it is stopped. Designed to prevent fluid leakage.

However, in the conventional type, when the rotary shaft rotates at high speed, there is a large power loss due to the seal pressure, and the seal portion is severely worn, requiring frequent replacement work.

From this perspective, the present invention aims to improve the conventional shaft sealing device to increase its applicability to rotating shafts that rotate at high speed, and to provide a shaft sealing device that can arbitrarily change the sealing pressure even during operation. The aim is to reduce power loss and extend the life of the seal by reducing wear on the seal.

The configuration of the shaft sealing device of the present invention that achieves this purpose is such that a rotating shaft having a rotating seal ring formed on its outer circumferential surface is rotatably attached to a casing, and the sealing surface that slides in sliding contact with the end surface of the rotating seal ring is placed on one end. and an external stationary seal ring and an internal stationary seal ring that face each other with the rotating seal ring in between are fitted into the casing so as to be movable in a direction parallel to the axis of the rotating shaft, and Annular locking portions are provided on the peripheral surfaces of the outer stationary seal ring and the inner stationary seal ring to face the small-diameter thin-walled portions, respectively, and are opposed to the small-diameter thin-walled portions of the outer stationary seal ring. A first sealing material is interposed between one of the locking portions, and a second sealing material is interposed between the small diameter thin wall portion of the internal stationary seal ring and the other locking portion facing thereto. furthermore, a third sealing material is interposed between the casing and the other end side of the external stationary seal ring, and the inner peripheral surface of the casing is partitioned by the third sealing material and the second sealing material. and outer peripheral surfaces of the rotary seal ring, the outer stationary seal ring, and the inner stationary seal ring, respectively, to form a constant pressure chamber, which is partitioned by the first seal material and the third seal material, and is defined by the first seal material and the third seal material, and is A variable pressure chamber is formed surrounded by an inner peripheral surface and an outer peripheral surface of the external stationary seal ring, and a differential pressure flow path communicating with the variable pressure chamber is connected to a shaft sealing liquid circulation flow path passing through the constant pressure chamber, and a flow rate adjustment valve is provided. and the differential pressure flow path located between the flow rate adjustment valve and the variable pressure chamber is connected to the constant pressure chamber via a throttle flow path equipped with a throttle mechanism. be.

Hereinafter, one embodiment of the shaft sealing device according to the present invention will be described in detail with reference to the drawings showing its principle structure. The drive is rotatably mounted inside. On the inner circumferential surface of the casing 13, there is an annular locking part 1 that sandwiches the rotary seal ring 11 and faces in a direction parallel to the axis of the rotary shaft 12 (left-right direction in the figure).
The inner stationary seal ring 16 and the outer stationary seal ring 17, each of which has a sealing surface in sliding contact with the rotary seal ring 11 on one end thereof, sandwich the rotary seal ring 11 and are attached to the rotary shaft 12. They are fitted into the casing 13 so as to face each other in a direction parallel to the axis of the casing 13.
Between these internal static seal ring 16 and external static seal ring 17 and each of the locking parts 14 and 15, there is a compression coil spring 18 that presses the seal surface against the end surface of the rotary seal ring 11, and a connecting pin 19 for preventing rotation. are interposed at equal intervals, and between the tips of the locking portions 14 and 15 and the outer circumferential surface of the small diameter thin wall portion 20 formed on the inner stationary seal ring 16 and the outer stationary seal ring 17, O-rings 21 and 36 are interposed as a first sealing material and a second sealing material, respectively. or,
The outer peripheral surface of the external stationary sealing 17 and the casing 1
An O-ring 22 is also interposed as a third sealing material between the inner circumferential surface of A variable pressure chamber 23 is defined by the outer circumferential surface of the external stationary seal ring 17 and the inner circumferential surface of the casing 13. Similarly, the O-ring 36 which is the second sealing material on the side of the O-ring 22 and the internal stationary seal ring 16
The constant pressure chamber 24, which is partitioned by the rotary seal ring 11, the inner stationary seal ring 16, and the outer stationary seal ring 17, and is surrounded by the inner circumferential surface of the casing 13, is a storage tank in which the shaft sealing liquid 25 is stored. 26, a fluid pump 27 that sends the shaft sealing liquid 25 to the constant pressure chamber 24, and a shaft sealing liquid 2 in the constant pressure chamber 24.
5 and a cooler 29 that lowers the temperature of the shaft sealing liquid 25 that has risen due to the frictional heat of the seal portion. ing. Therefore, by making the pressure of the shaft sealing liquid 25 filling the constant pressure chamber 24 higher than the pressure of the gas inside the machine to be sealed, leakage of this gas can be prevented. On the other hand, a differential pressure flow path 32 equipped with a flow rate adjustment valve 31 is connected between the shaft sealing fluid circulation flow path 30 and the variable pressure chamber 23, and a differential pressure flow path 32 equipped with a flow rate adjustment valve 31 is connected between the variable pressure chamber 23 and the flow rate adjustment valve 31. The differential pressure flow path 32 between is connected to the constant pressure chamber 24 and has a fixed throttle (throttle mechanism) 33 in the middle.
4 is connected. Therefore, the variable pressure chamber 23 is also filled with the shaft sealing liquid 25, and the shaft sealing liquid 25 in the constant pressure chamber 24 is filled with the shaft sealing liquid 25.
5 is indirectly prevented from leaking to the outside.
That is, the external stationary seal ring 17 is connected to the constant pressure chamber 24.
The contact pressure between the external stationary seal ring 17 and the rotating seal ring 11, that is, the sealing pressure, can be set to an arbitrary value by changing the pressure of the shaft sealing liquid 25 in the variable pressure chamber 23. . For example, when the flow rate adjustment valve 31 is fully closed, the inside of the variable pressure chamber 23 can be made to have the same pressure as the inside of the constant pressure chamber 24, and functions as a very general mechanical seal. However, when the flow rate adjustment valve 31 begins to open, the shaft sealing liquid 25 flows from the throttle channel 34 through the differential pressure channel 32 and reaches the shaft sealing fluid circulation channel 30.
Since the pressure of the shaft sealing liquid 25 on the downstream side of the fixed throttle 33 is reduced, the pressure inside the variable pressure chamber 23 is reduced, and the pressing force of the external stationary seal ring 17 against the rotary seal ring 11 is reduced. This becomes more noticeable as the flow rate adjustment valve 31 is opened, so a differential pressure detector 35 is provided between the throttle channel 34 and the differential pressure channel 32, and by reading the value of this differential pressure detector 35, the external stationary seal The pressing force of the ring 17 can be confirmed. Therefore, the differential pressure detector 35 and the flow rate adjustment valve 31
By connecting these via a control device (not shown), it is possible to automatically maintain a constant pressing force at all times. In this embodiment, a fixed throttle 33 is incorporated in the throttle channel 34 as a throttle mechanism, but a throttle valve may be inserted instead and the magnitude of the differential pressure may be further adjusted by operating the throttle valve.

In the present embodiment, the variable pressure chamber 23 is provided on the external stationary seal ring 17 side, but it goes without saying that it may be provided on the internal stationary seal ring 16 side or on both sides.

In this way, according to the shaft sealing device of the present invention, the sealing pressure can be changed arbitrarily regardless of the operating condition of the rotating shaft, so the sealing pressure that best suits the operating condition can be easily set, and the sealing pressure can be changed at will. It is possible to avoid unnecessary wear and heat generation, and the life of the seal portion can be extended even for a rotating shaft that rotates at high speed.

[Brief description of the drawings]

The drawing is a circuit sectional view showing the principle structure of an embodiment of the shaft sealing device according to the present invention, and the reference numerals in the drawing are: 11 is a rotary seal ring, 12 is a rotary shaft, 13 is a
is the casing, 16 is the internal stationary seal ring, 1
7 is an external stationary seal ring, 21 is an O-ring (first sealing material), 22 is an O-ring (third sealing material),
23 is a variable pressure chamber, 24 is a constant pressure chamber, 30 is a shaft sealing liquid circulation flow path, 31 is a flow rate adjustment valve, 32 is a differential pressure flow path,
33 is a fixed throttle, 34 is a throttle channel, and 36 is an O-ring (second sealing material).

Claims (1)

[Scope of utility model registration request] A rotary shaft having a rotary seal ring formed on its outer circumferential surface is rotatably attached to a casing, and an external stationary seal has a seal surface on one end side that slides into contact with the end surface of the rotary seal ring, and faces the rotary seal ring with the rotary seal ring in between. A ring and an internal stationary seal ring are respectively fitted into the casing so as to be movable in a direction parallel to the axis of the rotating shaft, and the external stationary seal ring and the internal stationary seal ring are respectively fitted on the inner peripheral surface of the casing. Annular locking portions facing the formed small-diameter thin-walled portions are respectively provided protrudingly, and a first sealing material is interposed between the small-diameter thin-walled portion of the external stationary seal ring and one of the locking portions opposing the small-diameter thin-walled portion. a second sealing material is interposed between the small-diameter thin-walled portion of the internal stationary seal ring and the other opposing locking portion, and further between the casing and the other end of the external stationary seal ring A third sealing material is interposed between the third sealing material and the second sealing material, and the inner peripheral surface of the casing, the rotating seal ring, the external stationary seal ring, and the internal stationary seal are separated from each other by the third sealing material and the second sealing material. A constant pressure chamber is formed surrounded by the outer circumferential surfaces of the rings, and is partitioned by the first sealing material and the third sealing material, and is surrounded by the inner circumferential surface of the casing and the outer circumferential surface of the external stationary seal ring. A variable pressure chamber is formed, and a differential pressure flow path communicating with the variable pressure chamber is connected to a shaft sealing liquid circulation flow path passing through the constant pressure chamber via a flow rate adjustment valve, and a flow rate adjustment valve and the variable pressure chamber are connected to each other. A shaft sealing device characterized in that the differential pressure flow path and the constant pressure chamber located therebetween are connected via a throttle flow path provided with a throttle mechanism.