JPH0227251Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shaft seal structure, and particularly to a shaft seal structure equipped with a flushing mechanism.

[Background Art and Problems] Conventionally, when handling highly viscous fluids, especially liquids that generally have a wide range of viscosities such as resins such as polybutene, polyethylene, linear low-density polyethylene, and polystyrene, with equipment such as pumps, , a mechanical seal, an oil seal, a float bushing, etc. are used, and in order to further ensure a complete seal, it is already known that such a seal structure is combined with a flushing mechanism.

FIG. 10 shows an example of a pump with a conventional structure equipped with a flushing mechanism. In the figure, a high viscosity liquid 1
1 is included. A rotating shaft 12 passes through the casing 10, and the rotating shaft 12 is rotatably supported by the casing 10 via a bearing 13. Further, the rotating shaft 12 is inserted into the insertion hole 14 of the neck portion 10A of the casing 10 and inserted into the casing 1.
It is derived outside of 0.

A housing 16 having a cavity 15 inside is provided on the outside of the neck portion 10A, and the housing 16 has a cavity 15 inside.
The rotating shaft 12 led out from the housing 1 passes through the cavity 15 and is guided through the lead-out hole 17 of the housing 16.
6. Further, in the cavity 15, a mechanical seal 18 is disposed on the outlet hole 17 side, and a float bushing 19 is disposed on the insertion hole 14 side by being pressed by a spring 20. It is sealed.

Furthermore, flushing liquid 22 is flowed into the cavity 15 from a flushing liquid tank (not shown) through a flushing liquid inlet 21 provided in the housing 16 by a flushing liquid pump (also not shown), and the flushing liquid 22 After passing through the gap 23 between the insertion hole 14 and the rotating shaft 12, the high viscosity fluid flows out from the flushing liquid return port 24 provided in the neck portion 10A, passes through a return pipe (not shown), and exits the pump inlet (not shown). It is designed to be refluxed into 11. By providing such a flushing mechanism, it is intended to prevent seepage of the highly viscous liquid 11, remove sliding wear scales on the bearings 13, etc., and maintain an appropriate temperature by preventing heat generation.

In addition, in Fig. 10, the float bush 19
Instead, an oil seal with a lip may be used. Further, the flushing liquid is a liquid that does not affect the high viscosity liquid 11, such as oil.

By the way, since the conventional shaft seal structure equipped with a flushing mechanism was used for a small rotating machine, there were no major problems. However, in a relatively large device, the diameter D of the rotating shaft 12 is large and the length L of the gap 23 is long, so that the high viscosity liquid 11 that has entered the insertion hole 14 is
The high viscosity liquid 11 is forced to flow in the direction of rotation, and the shear velocity of the high viscosity liquid 11 increases relative to the speed of the rotating shaft 12, and pressure buildup occurs in the high viscosity liquid 11, resulting in a large flow of the flushing liquid 22 through the insertion hole 14, that is, reflux. This created resistance, making it difficult to inject the flushing liquid 22 from the inlet 21, and sometimes damaging the shaft seal.

Therefore, there were cases in which the flushing mechanism could not perform the above-mentioned function. Furthermore, the flushing liquid 22 is a handling liquid (high viscosity liquid 1
1) The types are limited from the point of entry into the body,
Although it is necessary to control the material balance of the liquid to be handled and the amount of injection (recirculation amount), it has been difficult to manage this.

[Purpose of the invention] The purpose of the invention is to provide an enclosure structure in which the flushing liquid can be circulated sufficiently smoothly, so that the function of the flushing mechanism can be fully exhibited, and the amount of reflux can be easily controlled. There is a particular thing.

[Means and effects for solving the problem] Therefore, the present invention provides at least one of a plurality of convex portions and concave portions separated in the circumferential direction on the inner peripheral surface of the insertion hole through which the rotating shaft is inserted. , the high viscosity liquid that has entered the gap between the rotating shaft and the insertion hole is stirred and mixed so that it is not forced to flow only in the rotational direction of the rotating shaft, and the resistance of the flushing liquid flowing back through the gap is reduced. The purpose is to achieve the above objective by making it possible to reduce the

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings, and parts whose explanations are the same as or similar to those of the conventional structure will be designated by the same reference numerals, and the explanation will be omitted or simplified.

FIG. 1 shows a first embodiment of the shaft seal structure according to the present invention, and FIG. 2 shows an enlarged view of the main parts thereof. In this embodiment, a plurality of protrusions 32 are provided as convex portions on the inner peripheral surface of the insertion hole 31 of the rotating shaft 12 in the neck portion 10A of the casing 10. The arrangement state of the protrusions 32 is, for example, the rotation shaft 12.
They are arranged at regular intervals along the circumferential direction at predetermined equal intervals along the axial direction. In addition, the protrusion 32
The height h is 0.01 to 0.1 times the diameter D of the rotating shaft 12, preferably 0.02 to 0.08 parts, and more preferably 0.03 to 0.08 parts.
More preferably, it is 0.07 times. When the height h is less than 0.01 times the diameter D, the stirring effect by the protrusion 32 is small, and when it exceeds 0.1 times, the gap 33 has to be enlarged to an extent that is actually inconvenient.

The protrusions 32 may be formed by cutting directly on the inner circumferential surface of the insertion hole 31, but as shown in FIG. Prepare the insertion tube 34 and insert this tube 3
Insert the stepped pin 36 into the hole 35 drilled at the predetermined position of 4.
is press-fitted so that its distal end side protrudes from the insertion hole 31 side, and then the insertion tube 34 is attached to the neck portion 10A. According to this method, the protrusions 32 can be easily manufactured no matter how they are arranged.

Note that the size of the gap 33 provided between the rotating shaft 12 and the protrusion 32 is larger than that of the conventional structure because the protrusion 32 is provided.

According to such an embodiment, the following effects can be obtained.

Even if the high viscosity liquid 11 enters the gap 33 and wraps around the rotating shaft 12 and attempts to block the passage of the flushing liquid in the gap 33, the protrusion 32 is provided to protrude into the gap 33. Since the high viscosity liquid 11 is forcibly rotated together with the rotating shaft 12, the high viscosity liquid 11 is forcibly stirred and mixed with the flushing liquid 22. Therefore, the resistance to the flow of the flushing liquid 22 can be reduced, and the gap 33
Even when the length L is long, the pressure buildup here is eliminated, and the flushing pressure for refluxing the flushing liquid 22 can be stabilized.
Therefore, the amount of reflux of the flushing liquid 22 can be easily controlled.

Figure 3 shows the change in flushing pressure over time in this example (solid line) compared to when the gap was widened to the same extent as in this example but no protrusions were provided (dashed line). has been done. As can be seen from this figure, according to this example, the flushing liquid is smoothly refluxed. Furthermore, it can be seen that the same effect cannot be obtained simply by increasing the size of the gap 33.

As described above, in this embodiment, since there is no flushing failure, the function of the flushing mechanism can be fully exhibited. Therefore, if applied to a pump, the pump capacity will be improved and it will be possible to handle high viscosity liquids with a viscosity of 10,000p.

Furthermore, even after the high viscosity liquid 11 solidifies while the rotating shaft 12 is stopped, it can be easily restored to its original fluid and agitated state by reheating, which prevents the protrusions 32 from becoming clogged. There is no.

A second embodiment is shown in FIGS. 4 and 5. In this second embodiment, a plurality of protrusions 32 are arranged along the same circumferential line at predetermined equal intervals along the axial direction of the rotating shaft 12, and a plurality of protrusions 32 are arranged in the circumferential direction. The arrangement angles along the axis are staggered for each position along the axial direction. That is, the protrusion 32 corresponds to A in FIG.
At each position B, C, and D, three protrusions are provided at equal 120 degree positions, and each protrusion 3 is adjacent to each other in the axial direction.
No. 2 has different angles of 30 degrees in the circumferential direction.

Such a second embodiment can also produce the same effects as the first embodiment.

Here, a specific example of a pump to which the second embodiment is applied is as follows.

Rotation speed: 12 to 119 rpm Discharge flow rate: 40 m ³ /h Discharge pressure: 62 Kg/cm ² Suction pressure: 8 to 20 Kg/cm ² Handling fluid (high viscosity liquid): Polybutene viscosity 600p Flushing liquid: Daphne manufactured by Idemitsu Kosan Co., Ltd. Under operating conditions where the turbine oil viscosity is 40 cp or more, the diameter D of the rotating shaft 12 is 175 mm, the size of the gap 33 is 10 mm, the diameter of the protrusion 32 is 10 mm, and the height is 9 mm (therefore, the diameter of the protrusion 32 is 10 mm). The distance between the top and the rotating shaft 12 is 1 mm), and the protrusions 32 are arranged at four positions at equal intervals of 33 mm along the axial direction of the rotating shaft 12, and the protrusions 32 are placed at each position along the circumferential direction. Protrusions 3 arranged at 120 degree intervals and adjacent in the axial direction
3 was placed at a position rotationally shifted by 30 degrees in the circumferential direction. Furthermore, the distance from the left end surface of the insertion tube 34 to the center of the protrusion 33 at position A is 19 mm, and the distance from the right end surface to the center of the protrusion 33 at position D is 11 mm.
mm, therefore the total length of the insertion tube 34 is 129 mm,
In addition, the outer diameter was 215 mm.

As a result, no flashing failure occurred at all.

A third embodiment is shown in FIGS. 6 and 7,
More protrusions 32 than in the first and second embodiments
are arranged rather densely, making it particularly suitable for handling high-viscosity liquids.

A fourth embodiment is shown in FIG.
In the fifth embodiment shown in FIG. 9, only an axial groove 41 is provided. In these fourth and fifth embodiments, a plurality of axial grooves 41 are provided separated in the circumferential direction. In these fourth and fifth embodiments, the protrusion 3
2 is not provided, and it can be manufactured only by relatively easy grinding, but on the other hand, it is slightly inferior to the first to third embodiments in terms of performance.

In each of the above embodiments, only one of the protrusion (protrusion 32) or the recess (groove 41, 42) was provided, but the protrusion and the recess may be provided together. Furthermore, although the protrusion or recess may be provided directly on the neck portion 10A without using the insertion tube 34, there is a disadvantage in that it is difficult to process. Further, an oil seal may be used instead of the float bush, or none of these may be used.

[Effects of the Invention] As described above, according to the present invention, the flushing liquid is refluxed sufficiently smoothly, so that the function of the flushing mechanism is fully exhibited, and a shaft sealing structure can be provided in which the reflux amount can be easily controlled.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the overall configuration of a first embodiment of the shaft seal structure according to the present invention, Fig. 2 is a cross-sectional view showing an enlarged main part of the first embodiment, and Fig. 3 is a cross-sectional view showing the first embodiment. A diagram showing how the flushing pressure changes over time in an example,
4 and 5 are a sectional view and a side view showing the main parts of the second embodiment, respectively, and FIGS. 6 and 7 are a partially cutaway perspective view and an exploded view showing the main parts of the third embodiment, respectively. 8 and 9 are partially cutaway perspective views showing essential parts of the fourth and fifth embodiments, respectively, and FIG. 10 is a sectional view of the conventional example. 10...Casing, 10A...Network part, 1
DESCRIPTION OF SYMBOLS 1...High viscosity liquid, 12...Rotating shaft, 21...Inflow hole, 22...Flushing liquid, 24...Recirculation hole, 31...Insertion hole, 32...Protrusion as a convex part, 33... Gap portion, 34... Insertion tube, 36...
Stepped pin, 41, 42...Axial groove and circumferential groove as recesses.

Claims (1)

[Claims for Utility Model Registration] (1) A housing is provided in a casing that contains a liquid and rotatably supports a rotating shaft with a bearing, and a mechanical seal is provided inside the housing into which the rotating shaft is inserted, In the shaft sealing structure in which a flushing liquid is passed through a gap between the rotating shaft and an insertion hole for inserting the rotating shaft inside the casing between the bearing and the mechanical seal, A shaft seal structure characterized in that a peripheral surface is provided with at least one of a plurality of convex portions and a plurality of concave portions separated in the circumferential direction. (2) The shaft sealing structure according to claim 1 of the utility model registration, characterized in that only a protrusion as a convex portion is provided on the inner circumferential surface. (3) In claim 2 of the utility model registration, the height of the protrusion is 0.01 of the diameter of the rotating shaft.
A shaft sealing structure characterized by ~0.1 times.