JPH0247315Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a static mechanical seal in a centrifugal pump, etc., and is a static mechanical seal applied to a centrifugal pump, etc. that requires movement and adjustment of the rotating shaft in the axial direction. It's about stickers.

<Prior Art> In a pump such as a centrifugal pump that rotates an impeller, it is necessary to adjust the gap between the impeller and the casing in order to adjust the discharge pressure. In addition, in cases where slurry liquid is the target, auxiliary blades or back blades are provided to provide a pressure reducing effect to the shaft seal, and in this case as well, the gap between the blade and the casing must be adjusted to adjust the pressure reducing effect. There is a need. These clearance adjustments are performed by moving the rotating shaft in the axial direction.

Conventionally, gland packings, lip seals, and the like have been mainly used as shaft sealing devices for such rotating equipment. However, in recent years, there has been a demand for improved sealing performance, and the application of mechanical seals is being considered as a response to this demand.

However, when mechanical seals are used in these pumps whose rotating shafts are moved and adjusted, there is a problem in that the surface pressure on the sealing surface of the mechanical seal changes due to the adjustment. In addition, in these conventional pumps, if a mechanical seal is installed in addition to the auxiliary vanes for leak prevention, the sealing performance can be greatly improved, but on the other hand, there is a problem in that the length of the shaft seal portion becomes extremely long.

Figure 3 shows a configuration in which these pumps are equipped with the most common rotary mechanical seal, which includes an auxiliary vane 52 for the purpose of reducing pressure inside the seal box and discharging fluid, and a mechanical seal installed on the atmospheric side of the auxiliary vane 52. A seal is attached. In this mechanical seal, a rotating ring 61 mounted on a rotation axis is configured to do so. In such a configuration, when the rotating shaft X is moved in the axial direction to adjust the gap between the impeller 51 and the casing 50, only the spring receiver 62 moves, and the installation length L of the mechanical seal changes. It is expected that leakage will occur in a short period of time due to the surface pressure becoming too high or too low. That is, as the mounting length L becomes longer, the contact pressure decreases, and as it becomes shorter, the contact pressure increases. Therefore, in order to keep this contact pressure constant, it is necessary to keep the mounting length L constant. Therefore, once the position of the impeller has been determined, it is necessary to attach it to the L dimension of the mechanical seal at that position, which is very time consuming.

Furthermore, although the auxiliary vane 52 provides very high sealing performance, the auxiliary vane 52 and the mechanical seal are aligned in the axial direction, so there is a drawback that the installation length of the seal portion becomes long.

<Summary of the invention> This invention was made in view of the above points.
First, a static structure was adopted as a mechanical seal, and a non-rotating ring was fitted on the casing side so as to be movable in the axial direction, a rotating ring was fixed to the inside of the machine from the non-rotating ring on the rotating shaft, and the rotating ring a screw formed to generate a force toward the inside of the machine on the outer peripheral surface of the machine;
A position at a predetermined distance in the axial direction from the rotating ring,
a non-rotating ring positioning groove provided on the rotating shaft;
A set plate that is removably inserted into the groove and comes into contact with the non-rotating ring to regulate the axial position of the non-rotating ring, and a fixture that fixes the non-rotating ring at the position regulated by the set plate. It is characterized by:

In addition, in the above, "fixed on the rotating shaft" or "installed on the rotating shaft" is not limited to the meaning directly on the rotating shaft, but refers to the case where it is fixed or provided indirectly through a sleeve, etc. is naturally included.

According to this configuration, when the rotating shaft is moved, the non-rotating ring is also regulated in its axial position by the set plate and is automatically moved by the same amount as the shaft movement, so the installation length of the mechanical seal is always constant. is maintained. As a result, the surface pressure on the sealing surface becomes constant, and good sealing performance can be maintained.

Further, the screw pump action of the screw formed on the rotating shaft can generate a pressing force toward the impeller 51, and the sealing performance can be further improved. As a result, without using the auxiliary vanes, it is possible to obtain substantially the same sealing performance as with the provision of the auxiliary vanes, and moreover, it is possible to shorten the installation length of the seal portion.

Furthermore, the reason why a stationary mechanical seal was adopted in this invention is as follows.

In other words, with ordinary rotary mechanical seals, the sealing surface of the non-rotating ring is required to have high perpendicularity accuracy when installed, so when the non-rotating ring is made movable in the axial direction as in the present invention, each time it is moved, This requires precise orthogonal alignment work, and axial movement work is extremely time-consuming. On the other hand, in the case of a stationary mechanical seal, the perpendicular precision of the non-rotating ring does not need to be so high, and it is easy to move the seal in the axial direction.

<Example> The present invention will be described below based on one example.

The embodiment shown in FIGS. 1 and 2 is an example in which the present invention is applied to a centrifugal pump. In the figure, 50 is a casing, and 51 is an impeller. Since it is necessary to adjust the position of the impeller 51 within the casing 50 without disassembling the casing, the rotating shaft X is moved and adjusted in the axial direction. A rotating ring 2 is fitted and fixed on the rotating axis X. On the other hand, the non-rotating ring 1 is fitted into the casing 50 side. The non-rotating ring 1 consists of a non-rotating sealing ring 10 and a ground cover 11, with a spring 12 interposed between them to press the non-rotating sealing ring 10 toward the rotating ring 2 to form a sliding sealing surface. It's summery. There are screws 2 on the outer circumferential surface of the rotating ring 2.
0 is formed. The threading direction of the screw 20 differs depending on the rotational direction of the rotation axis X, but it is set in a direction that causes a force to be generated in the fluid around the screw in the direction of the inside of the machine (in the direction of the impeller 51) as shown by the arrow. The screw 20 pushes back fluid that would otherwise leak out of the machine, improving sealing performance. Furthermore, since solid matter such as slurry is also pushed back, any adverse effects on the mechanical seal are also eliminated. Note that the screw pump effect is greater when the gap between the screw 20 and the casing 50 is made as small as possible.

Both the non-rotating sealing ring 10 and the ground cover 11 are configured to be movable in the axial direction. Furthermore, an O-ring 13 is interposed between the non-rotating sealing ring 10 and the casing 50, and an oil seal 14 is interposed between the ground cover 11 and the rotating shaft X.

A groove 3 is formed on the rotation axis X in order to keep the length L of the mechanical seal, which is composed of the rotating ring 2, the non-rotating seal ring 10, the spring 12, the ground cover 11, etc., constant. A set plate 4 is suitably installed in this groove 3 and comes into contact with the rear end of the ground cover 11 to position the ground cover 11 and keep the installation length L at a constant value. The set plate 4 is fitted into the groove 3 only when adjusting the movement of the rotation axis X, and is attached to the ground cover 11 with bolts 40, and is kept raised during normal use. FIG. 2 shows a state in which the set plate 4 is raised. This can be done by making a long hole in the set plate 4 so that it can be slid in the vertical direction. Further, the set plate 4 may be made removable from the ground cover 11.

The ground cover 11 whose position is regulated by the set plate 4 is fixed by a fixture, in this embodiment a set screw 5.

In the above embodiment, the mechanical seal unit is mounted directly on the rotating shaft X, but it is of course possible to install it through a sleeve or the like. In this case, the groove 3 will naturally be formed on the sleeve.
Naturally, the non-rotating sealing ring 10 and the ground cover 11 are also mounted on the sleeve.

Next, we will explain how to use it. When adjusting the movement of the rotation axis X in the axial direction, first loosen the set screw 5 to make the ground cover 11 freely movable. Then, the lower end of the set plate 4 is inserted into the groove 3 and fixed to the rear end of the ground cover 11 with bolts 40. In this state, if the rotation axis It is not affected by and always remains constant. After completing the movement adjustment of the rotation axis
to secure the ground cover 11, and then tighten the bolts 4.
0, raise the set plate 4, and set the second
Set the state as shown in the figure. As described above, it is possible to adjust the movement of the rotation axis X while keeping the surface pressure of the sealing surfaces formed by the non-rotating sealing ring 10 and the rotating ring 2 constant.

After adjusting the movement, rotate the pump and the rotating ring 2
The rotation of the screw 20 causes the screw 20 to exert a screw pump action, thereby preliminarily preventing fluid leakage, and furthermore, the sealing surface with the non-rotating ring 10 completely prevents leakage. Therefore, the sealing performance is extremely high, there is no need to use auxiliary blades, etc., and the total length of the seal portion can be shortened. Furthermore, this screw 20 allows solids to be pushed back into the machine by the screw pump action, so even when pumping fluid containing slurry, the mechanical seal will not be clogged with solids. , does not impede the function of the mechanical seal.

<Effects of the invention> As explained above, according to the stationary mechanical seal of the invention, extremely high sealing performance can be obtained without the need for auxiliary vanes, etc., and as a result, the installation length of the seal part can be shortened. I can do it. It also becomes possible to seal the slurry liquid. In addition, when adjusting the movement of the rotating shaft, the installation length of the mechanical seal does not change, and the surface pressure on the sliding sealing surface does not change, so good sealing performance can be maintained. There are big advantages.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing an embodiment of the present invention, FIG. 2 is a half-sectional view showing a state with a set plate removed, and FIG. 3 is a half-sectional view showing a conventional technique. 1: Non-rotating ring, 2: Rotating ring, 3: Groove, 4: Set plate, 5: Set screw, 10: Non-rotating sealing ring, 11: Ground cover, 12: Spring, 13: O-ring, 14: Oil Seal, 2
0: Screw, 40: Bolt, 50: Casing, 5
1: Impeller, 52: Auxiliary blade, 60: Non-rotating sealing ring, 61: Rotating ring, 62: Spring receiver, 6
3: Ground cover, 64: Casing, 65:
spring.

Claims (1)

[Scope of Claim for Utility Model Registration] A non-rotating ring fitted on the casing side so as to be movable in the axial direction, a rotating ring fixed to the inside of the machine from the non-rotating ring on the rotating shaft, and a rotating ring on the outer peripheral surface of the rotating ring. a screw formed to generate an inward force; a groove for positioning the non-rotating ring provided on the rotating shaft at a predetermined distance in the axial direction from the rotating ring; and a groove capable of being inserted into and removed from the groove. A set plate that is inserted into the set plate and comes into contact with the non-rotating ring to regulate the axial position of the non-rotating ring; and a fixture that fixes the non-rotating ring at a position regulated by the set plate. Stationary mechanical seal for centrifugal pumps, etc.