JPH0121251Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of a mechanical seal related to the shaft sealing technology, and is particularly useful for sealing fluid that tends to leak from the inner periphery of the sliding surface toward the outer periphery in equipment such as horizontal pumps. This invention relates to an external flow type mechanical seal that is installed in a.

Conventionally, as a type of mechanical seal used for this type of application, as shown in FIG. The seat 3 and the O-ring 4 are attached, and the fixed seal ring 5 is attached to the floating seat 3, and the rotating shaft 6 is inserted into the housing 1 through the O-ring 4'. A floating seat 3' that rotates as a result is mounted, a rotating seal ring 7 is mounted on the floating seat 3', and the rotating seal ring 7 and the non-rotating stationary seal ring are brought into sliding contact. Each sliding contact surface 7 related to sliding contact
A mechanical seal is known that is configured to prevent fluid sealed in a space A on the inner circumferential side of a, 5a from leaking into a space B on the outer circumferential side. However, as is clear from FIG. 1, such conventional mechanical seals have a structure in which the inner diameter of the floating seat 3 is smaller than the inner diameter of the sliding surface 5a of the fixed seal ring 5, so that the following problems arise. There is.

(1) When pump equipment is filled with liquid, the air near the sliding surface is not completely evacuated and remains in the area, and as a result, if the rotating shaft is driven with the sliding surface not in contact with liquid, the sliding material Seizing or damage may occur.

(2) When a slurry liquid is used as the sealing fluid, there is a risk that the slurry in the liquid may accumulate on the lower inner circumference of the stationary seal ring, which forms a concave area, and may get caught in the sliding surface.

In view of the above points, the present invention aims to provide a mechanical seal that eliminates the drawbacks of the prior art described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a half-cut sectional view showing the attached state of the mechanical seal according to the first embodiment of the present invention. In the figure, reference numeral 31 denotes a housing in which an O-ring 34 is housed along with a floating seat 33 that is elastically biased by a coil spring 32 in its shaft hole opening.
A fixed seal ring 35 is attached to the fixed seal ring member to constitute a fixed seal ring member. A floating seat 33' rotates as a result of a rotating shaft 36 inserted into the housing 31 via an O-ring 34'.
, and further the floating sheet 33'
A rotary seal ring member is constructed by attaching a rotary seal ring 37 to the rotary seal ring 37. Here, the inner diameter of the sliding surface 35a of the fixed seal ring 35 is formed to be equal to the inner diameter of the sliding surface 37a of the rotary seal ring 37, and the inner circumferential surface of the fixed seal ring member is The sliding surface 35a is formed in a tapered shape that gradually becomes larger in diameter toward the rear from the inner end.

Further, referring to FIG. 3, a second embodiment of the present invention will be described. This embodiment has the same structure as the first embodiment except for the following points. That is, the fixed seal ring 45 of this embodiment constitutes a fixed seal ring member by itself, and is directly fitted and fixed to the shaft hole opening of the housing 41 together with the O-rings 44, 44, and is also in sliding contact with the fixed seal ring 45. The rotating shaft 4 is inserted into the housing 41.
A driven rotary seal ring 47 is directly attached to the rotary seal ring 6 via an O-ring 44' to form a rotary seal ring member. Therefore, the features of this embodiment are also the same as those of the first embodiment.

As explained above, in the mechanical seal of the present invention, there is no step near the sliding contact surface on the inner circumferential surface of the fixed seal ring member, so there is less possibility of air accumulating near the sliding contact surface, and a large amount of solid content in the slurry is eliminated. There is no risk of accumulation.

In addition, the inner circumferential surface of the fixed seal ring member is formed in a tapered shape that gradually increases in diameter from the inner end of the sliding surface toward the rear, completely preventing air from accumulating near the sliding surface when the liquid is filled. can be prevented. and,
The sealing fluid flowing in the circumferential direction due to the rotation of the rotary seal ring member flows rearward along the inner circumferential surface of the stationary seal ring member, thereby preventing solid content of the slurry from accumulating near the sliding surface. .

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view showing the attached state of a conventional mechanical seal, and FIGS. 2 and 3 are half-cut sectional views showing the attached state of the mechanical seal according to the first embodiment and the second embodiment. FIG. 3 is a half-cut sectional view showing the attached state of the mechanical seal. 31, 41... Housing, 32... Coil spring, 33, 33'... Floating seat, 34, 34', 44, 44'... O ring, 3
5, 45...Fixed seal ring, 35a, 45a
... Fixed seal ring sliding surface, 36, 46 ... Rotating shaft, 37, 47 ... Rotating seal ring, 37
a, 47a...Rotary seal ring sliding surface.

Claims (1)

[Scope of utility model registration request] In an external flow type mechanical seal consisting of a fixed seal ring member fixed to the housing side and a rotating seal ring member fixed to the rotating shaft side,
The inner diameter of the sliding surface of the fixed seal ring member is not smaller than the inner diameter of the sliding surface of the rotating seal ring member, and the inner peripheral surface of the fixed seal ring member gradually extends rearward from the inner end of the sliding surface. A mechanical seal formed in a tapered shape with a large diameter.