JPH0138367Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a mechanical seal for slurry liquid.

When a slurry liquid such as pulp slurry is used as the sealing liquid, it is known that solid matter gets caught in the sealing surface or clogs the spring, etc., resulting in wear of the sealing surface and poor tracking of the driven ring.

For this reason, conventional methods have been used such as injecting clean liquid from the outside and creating a double mechanical seal.

Although the above-mentioned drawbacks can be overcome by injecting a cleaning fluid, a new problem arises in that the sealing fluid is diluted by the cleaning fluid. On the other hand, if the amount of cleaning liquid to be injected is reduced in order to avoid this, there is a problem in that the above-mentioned drawbacks cannot be solved satisfactorily.

Further, in the case of a double mechanical seal, although there is no problem such as dilution of the sealing liquid, there is a drawback that the structure is complicated and the cost is high.

The present invention has been made to improve the above-mentioned conventional drawbacks, and is intended to prevent clogging due to solids in the slurry liquid with a relatively simple structure.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a half-sectional view showing an example in which the present invention is applied to a mechanical seal for a slurry pump.
is the rotating shaft, A is the casing, 1 is the fixed ring, 2 and 3
are rotating rings, 2 is a driven ring, 3 is a collar, and 4 is a pressing spring, which are mounted so as to fit around the rotating shaft X from the outside.

The spring 4 is exposed without covering its outside and is in direct contact with the sealing fluid. The cross-sectional shape of the spring 4 is not round but rectangular as shown in FIGS. 2 and 3. In this embodiment, the shape is approximately square, but shapes such as rectangles and trapezoids are also possible. The winding direction of the spring 4 varies depending on the direction of rotation of the rotary ring, and is set to cause a flow in the sealing liquid in the direction of the arrow in FIG. 1. That is, the winding direction of the spring 4 is determined so as to generate a force in the direction away from the sealing surface S formed by the fixed ring 1 and the driven ring 2. However, in this winding direction, if the spring 4 transmits the rotational force from the collar 3 to the driven ring 2, the spring 4 will receive a force in the opening direction, which is not preferable.

Therefore, in this embodiment, a plurality of protrusions 20 and 30 extending in the axial direction are formed at the bases of the driven ring 2 and the collar 3, and rotational force is transmitted by meshing the protrusions 20 and 30 with each other.

If the pitch of the spring 4 is too wide or too narrow, the screw pumping effect will be reduced, so the pitch is chosen so that the pumping effect is maximized.

In this embodiment, the following configuration is added to further enhance the pulp slurry discharge effect.

That is, an annular protrusion 10 is provided on the casing side corresponding to the collar 3, and a constricted portion 11 is formed between the protrusion 10 and the collar 3. In this embodiment, the protrusion 10 is formed by attaching an annular bush to the casing A, but if there is a neck bush B exactly at the collar 3 position, it may be used.

A thread 12 is formed on the outer peripheral surface of the collar 3 so that a flow in the direction of the arrow is formed in the constricted portion 11. This thread 12 is the axis
It may be formed so as to cause a flow in the direction of the arrow in the same manner depending on the direction of rotation.

Note that a blade or the like may be formed instead of this thread 12.

Further, in this embodiment, a thread 12 is also formed on the outer periphery of the driven ring 2 to discharge solid matter from the vicinity of the sealing surface S. Further, in this case as well, blades may be used instead of the threads 12.

In the above configuration, the spring 4 is exposed in the sealing liquid and has a rectangular cross section.
A large screw pump action is generated to generate a force in the direction of arrow P to discharge solid matter such as pulp near the sealing surface S and spring 4. This prevents solid objects from getting caught in the sealing surface S, clogging the spring 4, and the like.

Furthermore, in this embodiment, a constriction part 11 is provided, and the collar 3 and the rotating ring 2 are provided with threads 12 or blades, so that the discharge of solid matter is facilitated.

As explained above, the mechanical seal of the present invention has a spring fitted on the outside of the rotating shaft, exposed in the sealing liquid, and has a rectangular cross-section, and further seals the winding direction of the spring. Since the force is generated in the sealing liquid in the direction away from the surface, this creates a pumping action that allows solids to be discharged from the vicinity of the sealing surface, thereby suppressing troubles caused by solids. There are advantages such as Furthermore, since the spring, which is a component of the mechanical seal, is used as is, there is an advantage that there is no need to add any new parts.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view showing an embodiment of the mechanical seal of the present invention, FIG. 2 is a front view of the collar, spring, and rotating ring, and FIG. 3 is a perspective view of the spring. In the figure, 1 is a fixed ring, 2 is a driven ring, 3 is a collar,
4 represents a spring, 11 represents a constriction portion, and 12 represents a thread.

Claims (1)

[Scope of utility model registration request] In a mechanical seal for slurry liquid having a fixed ring, a driven ring, and a spring that presses the driven ring toward the fixed ring, the spring is attached so as to fit around the rotating shaft from the outside, and the spring is inserted into the sealing liquid. A slurry liquid characterized in that the cross-sectional shape is square and the spring is wound in a direction that causes a force in the sealing liquid to move away from the sealing surface formed by the fixed ring and the driven ring. mechanical seal.