JPH1030730A - Non-contact sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the efficient sealing between a rotary shaft and a seal ring at a low cost. SOLUTION: Seal rings are mounted in a space around a rotary shaft with a small gap between the rotary shaft and the seal rings. A groove 72 to give the resistance against the flow from the high pressure side to the low pressure side of the fluid by the revolution of the rotary shaft is formed in at least one of the surfaces of the rotary shaft and the seal rings opposite to each other so as to leave at least surfaces 74, 76 opposite to the high pressure side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pump,
In a fluid machine such as a blower or a compressor, the present invention relates to a non-contact shaft sealing device used for sealing a fluid inside the machine with a shaft portion or reducing leakage of the fluid.

[0002]

2. Description of the Related Art An example of a conventional shaft sealing device is shown in FIG.
This is a shaft sealing structure of a blower that feeds gas under pressure, forms a space around the rotation shaft to accommodate the shaft sealing device, and a pair of symmetrical seal rings are axially opposed to this space. In the center of these two seal rings,
A fluid having a higher viscosity (usually a liquid) different from the fluid to be pumped is supplied as a sealed fluid at a higher pressure than the fluid to be pumped,
The purpose is to prevent the gas from flowing in the space on both sides of the shaft sealing device.

[0003] The seal ring has a protruding part at the side end on the low pressure side, which abuts against a side wall formed on the casing side, and is lightly pressed by a spring and fluid pressure arranged between the seal rings. As a result, the fluid is prevented from flowing while maintaining the floating property.

[0004]

As described above, since the sealed fluid is supplied at a higher pressure than the pressure-receiving fluid, the pressure difference between the sealed fluid and the outside becomes large, and the fluid is maintained while maintaining the floating property. In order to prevent the leakage, it is necessary to strictly control the gap between the shaft and the seal ring and the dimensions of each part, and to provide the seal rings in multiple stages, which has resulted in an increase in cost. The present invention has been made in view of the above circumstances, and has as its object to provide a non-contact shaft sealing device capable of performing efficient sealing between a rotating shaft and a seal ring at low cost.

[0005]

According to a first aspect of the present invention, there is provided a non-contact shaft sealing device in which a seal ring is mounted in a space around a rotating shaft with a small gap from the rotating shaft.
On at least one of the mutually facing surfaces of the rotating shaft and the seal ring, a groove that gives resistance to the flow of the fluid from the high pressure side to the low pressure side by rotation of the rotating shaft,
A non-contact shaft sealing device formed so as to leave the facing surface at least on a high pressure side.

[0006] Such grooves are formed on these opposing surfaces so as to be inclined at any angle with respect to a line parallel to the axis.
Typically, it is a spiral or approximate linear groove. Since this groove is formed leaving a facing surface (ridge) on the high pressure side, when the rotating shaft rotates, it gives resistance to the flow from the high pressure side to the low pressure side, and as a result, a strong fluid It forms a membrane and acts to maintain the floatability of the seal ring. Such an effect increases as the rotation shaft rotates at a high speed. Since the gap between the rotating shaft and the opposing surface of the seal ring is of such a size that inertial flow does not matter, substantially the same effect can be obtained by forming any of these. Note that the depth, inclination angle, pitch, size, and the like of the groove are appropriately selected according to the use situation.

The invention according to claim 2 is the non-contact shaft sealing device according to claim 1, wherein the seal ring is fixed to a casing. The invention according to claim 3 is characterized in that the seal ring is mounted so as to allow a slight movement in a direction intersecting the axis with respect to the rotation axis. This is a shaft sealing device, whereby the seal ring also moves in accordance with the displacement of the rotating shaft to prevent deviation of the gap at the circumferential position, but the pump action of the groove promotes this following operation.

According to a fourth aspect of the present invention, at least two seal rings are provided in the axial direction, and a sealing fluid different from the fluid is sealed in a space between the seal rings. The non-contact shaft sealing device according to claim 1, wherein: When the fluid to be sealed is a gas, the sealing fluid uses a more viscous liquid to improve the sealing performance and the floating property of the ring.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the non-contact shaft sealing device of the present invention is used for a blower.
The non-contact shaft sealing device is arranged while the bearing B is arranged on the right side. In this example, the seal rings 10 to 18 have a floating seal structure in which the seal rings 10 to 18 can be slightly moved in a direction intersecting the rotation shaft 20, and five stages of seal rings are arranged in the axial direction.

The non-contact shaft sealing device is housed in a seal housing space C formed so as to surround the rotary shaft 20 in the casing 22. That is, in this housing space C, the two fixing members 26,
28 is fixed to the casing 22 by bolts, and a plurality of retainers 30, 3 are provided in spaces inside these fixing members 26, 28.
2, 34, and further, these retainers 30,
In the space defined by 32, 34, the seal ring 10
18 are accommodated. The fixing members 26, 28 and the casing 22 and the fixing members 26, 28 and the retainer 30
An O-ring 36 for sealing is provided at a required position between the positions.

The five seal rings 10 to 18 are each formed by shrink-fitting a metal reinforcing ring 40 around the outer periphery of an inner ring 38 made of carbon in this example. By adopting such a double structure, the effect of reducing friction is obtained on the inner peripheral side, and as a result, the gap is reduced to improve the sealing performance and secure the mechanical strength. These seal rings 10 to 18
Is formed with a recess 42 extending in the radial direction at a part thereof, while a guide pin 44 slidably inserted into the recess 42 is provided on the side of the retainers 30 to 34. As a result, the seal rings 10 to 18 are prevented from rotating in the circumferential direction, and can be slightly moved in the radial direction.

The second and third seal rings 12, 14 from the impeller side are accommodated in a space in the same retainer 32 so as to face each other with a predetermined space 46 therebetween. In a space 46 between these seal rings, there are provided a guide groove 48 and a pin 50 for guiding the two in the axial direction, and a spring 52 for urging the two in a direction away from each other.

The retainer 32 has a radial passage 54 communicating with a space 46 between the seal rings 12 and 14.
One or more are provided at predetermined positions in the circumferential direction. The flow path 54 communicates with a circumferentially extending inner circumferential groove 56 formed on the inner circumferential surface of the first fixed member 26, and the inner circumferential groove 56 is formed with a flow path 58 formed on the first fixed member 26. The outer peripheral groove 60 communicates with a sealed fluid supply path 62 formed in the casing 22. The sealed fluid supply channel 62 is connected to a sealed fluid source such as water or oil that has a higher pressure than the fluid to be pumped. Drain spaces 64 and 66 communicating with the surface of the rotating shaft 20 are formed at the boundary between the shaft sealing device, the impeller side, and the bearing side, and the casing 22 communicates with these drain spaces 64 and 66. Drain channels 68 and 70 are formed.

On the inner peripheral surface of each of the seal rings 10 to 18,
As shown in FIG. 2, a plurality of grooves 72 (spiral grooves) are formed which are inclined by a predetermined angle θ with respect to the axis. This groove 72
Are set smaller than the seal rings 10 to 18, and ridges 74, 76 of a predetermined length are provided at both ends of the groove 72.
Are formed. The direction of the inclination of the groove 72 is such that when the rotary shaft 20 rotates, resistance is given to the pressure flow of the sealed fluid from the high pressure side to the low pressure side.

With the above arrangement, of the five stages of seal rings 10 to 18, two stages are provided on the inside of the machine where the differential pressure is small, and three stages are provided on the outside of the machine where the differential pressure is large. The groove 72
The first seal ring 10 is formed in the same direction as the second seal ring 12, and the fourth and fifth seal rings 16 and 18 are formed in the same direction as the third seal ring 14. When the rotating shaft 22 rotates, the sealing fluid is oriented so as to provide resistance to the pressure flow of the sealed fluid from the high pressure side to the low pressure side.

Next, the operation of the thus constructed non-contact shaft sealing device will be described. In this example, water is used as the sealing fluid, and high-pressure water is supplied from the outside to the sealing fluid supply path 62 to seal the gas inside the blower machine (impeller side). The pressure of the sealed fluid is adjusted to be slightly higher than the pressure in the blower. That is, when the blower is not operating, the pressure of the sealed fluid is adjusted to be low, and when the pressure is increased by operating the blower, the pressure on the sealed fluid side is also increased accordingly.

As a result, the sealed fluid is supplied to the space 46 through the sealed fluid supply path 62, the outer peripheral groove 60, the flow path 58, the inner peripheral groove 56, and the radial flow path 54, and is further supplied to the rotating shaft 20.
Then, the fluid flows from the drain spaces 64 and 66 to the drain channels 68 and 70 through the gap between the seal rings 10 and 18. Here, grooves 72 are formed on the inner surfaces of the seal rings 10 to 18, which provide resistance to the pressure flow of the sealed fluid from the high pressure side to the low pressure side as the rotating shaft 20 rotates.
For this reason, there is a great effect in reducing leakage.

In the high pressure side ridge 74 or 76 of the seal ring, a strong fluid film is formed between the opposing surfaces due to the pumping action of the groove. In this embodiment, since the seal rings 10 to 18 have a floating seal structure that slightly moves in a direction perpendicular to the axis, the sealing fluid film enhances the floatability of the seal rings. Such an effect increases as the rotating shaft 20 rotates at a high speed, so that the clearance of the seal portion can be reduced, and leakage can be efficiently prevented.

Further, in this embodiment, a ridge 74 or 76 is also provided on the low pressure side of the seal ring.
Since pressure is generated even when the rotating shaft 20 is reversed, a fluid film is formed, and damage due to contact between opposing surfaces is prevented. Therefore, rotation in both forward and reverse directions is possible.

The embodiment of the present invention is not limited to the above, and in the above, a floating seal structure in which the seal ring slightly moves in a direction perpendicular to the axis is used. In the above example, the seal ring is provided in multiple stages, but may be provided in a single stage, without using a sealing fluid.

[0021]

As described above, according to the present invention, when the rotating shaft rotates, resistance is imparted to the flow from the high pressure side to the low pressure side, and a strong fluid is applied to the facing surface between the rotating shaft and the seal ring. Since the film is formed to enhance the floating property, efficient sealing between the rotating shaft and the seal ring can be performed at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a non-contact shaft sealing device according to the present invention.

FIGS. 2A and 2B are a sectional view and a side view showing details of a seal ring of the non-contact shaft sealing device according to the present invention.

FIG. 3 is a longitudinal sectional view of a conventional non-contact shaft sealing device.

[Explanation of symbols]

 10-18 Seal ring 20 Rotating shaft 22 Casing 46 Sealed fluid space 72 Groove 74, 76 Ridge (opposing surface)

Claims (4)

[Claims] 1. A non-contact shaft sealing device in which a seal ring is attached to a space around a rotation shaft with a small gap from the rotation shaft, wherein at least one of the surfaces of the rotation shaft and the seal ring facing each other, A groove that gives resistance to the flow of the fluid from the high pressure side to the low pressure side by the rotation of the rotating shaft,
A non-contact shaft sealing device formed so as to leave the facing surface at least on a high pressure side. 2. The non-contact shaft sealing device according to claim 1, wherein the seal ring is fixed to a casing. 3. The non-contact shaft sealing device according to claim 1, wherein the seal ring is attached so as to allow a slight movement in a direction intersecting the axis with respect to the rotation axis. 4. The seal ring according to claim 1, wherein at least two seal rings are provided in the axial direction, and a space between these seal rings is filled with a sealing fluid different from the fluid. The non-contact shaft sealing device as described in the above.