JPS6317895Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the improvement of mechanical seals related to shaft sealing technology, and particularly relates to an internal flow type mechanical seal that is installed to prevent fluid from leaking from the inside of a device such as a pump to the outside.

Conventionally, as a type of mechanical seal used for this type of application, as shown in Fig. 1, an outer cylinder 2 having a half-cut approximately U-shaped cross section is fitted into the shaft hole opening of a housing 1 of a pump equipment body. , the outer cylinder 2
Inside are a bellows-type packing 3, a coil spring 4, a spring restraining ring 5, and a seal ring 6.
At the same time, an impeller 8 and a buffer rubber 9 are attached to the rotating shaft 7 which is inserted into the housing 1.
A floating seat 10 is mounted through the floating seat 1, and the floating seat 1 is rotated by the rotating shaft 7.
A mechanical seal is known in which the fluid sealed in the space A inside the device does not leak to the outside B by sliding contact between the end faces of the non-rotating seal ring 6. In order to lubricate the sealing sliding surface 11 between the floating sheet 10 and the seal ring 6, the mechanical seal requires the presence of a fluid film between the floating sheet 10 and the seal ring 6, and this fluid film prevents a small amount of fluid from leaking. There is a characteristic that must be tolerated. In addition, the leaked fluid leaks out from the drain hole (not shown) to the outside of the device in a short time and is detected, and has an adverse effect on the bearing (not shown, located on the right hand side in the diagram) that supports the rotating shaft 7. There is a risk of causing

In view of the above points, the present invention is a mechanical seal configured to reduce the amount of fluid leaking from the sealed sliding surface as much as possible, if not eliminate it, and retain the leaked fluid inside the mechanical seal. We aim to provide the following.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Fig. 2 shows a mechanical seal showing a first embodiment of the present invention, and shows an annular seal formed in the shaft hole opening of a housing 21 of a pump equipment or the like. An outer cylinder 23 having a substantially U-shaped half-cut cross section is fitted into the stepped portion with a buffer rubber 22 interposed therebetween. A seal ring 24 is fitted into the outer cylinder 23 so as to be movable in the axial direction, and a bellows-type packing 25 is interposed between the back step of the seal ring 24 and the radial part 23a of the outer cylinder 23. has been done. 26 is a coil spring, and 27 is a spring restraining ring. Due to the elasticity of the former coil spring 26, the seal ring 24 is pressed to the left in the figure, so that a predetermined surface pressure is applied to the sealing sliding surface 33, which will be described later. Become. Reference numeral 28 is a case having a substantially U-shaped half-cut section that is fitted around the outer periphery of the rotating shaft 29 via a buffer rubber 30 and driven by the rotation of the rotating shaft 29, and which holds the floating sheet 32 via the buffer rubber 31. I have it. The opposing surfaces of the floating sheet 32 and the seal ring 24 are in sliding contact with each other to form a sealing sliding surface 33. Both 32,2
Approximately symmetrical conical surfaces 32a and 24a are formed at the inner circumferential end of the sealing sliding surface 33 of No. 4. The inner diameter cylindrical portion 28a of the case 28 is extended toward the right in the figure, and its tip 28b reaches the inner peripheral position of the sealing sliding surface 33, and the tip 28b is bent diagonally outward. . The inner cylindrical portion 23a of the outer cylinder 23 also extends in the axial direction to a position where it overlaps the tip 28b of the case 28. A distal end 23b of the inner cylindrical portion 23a is bent obliquely outward. Also, the outer cylinder 2
The tip 23d bent diagonally inward of the outer diameter cylindrical portion 23c of the case 28 and the tip 28d bent diagonally outward of the outer diameter cylindrical portion 28c of the case 28 are engaged in the axial direction. Fixed side members such as the seal ring 24 and the case 28 and floating seat 32
The mechanical seal is constructed as a unit so that the rotating side members such as the

The mechanical seal with the above configuration is similar to the conventional seal shown in Fig. 1, from the inside of the device A to the outside B.
It operates as an internal flow type mechanical seal to prevent fluid leakage towards the
The fluid leaking from the sealing sliding surface 33 is first transferred to a first pipe formed on the outer circumferential surface of the inner diameter cylindrical portion 28a of the case 28.
The fluid is stored in the fluid reservoir 34 of Therefore, the fluid accumulated in the first fluid reservoir 34 is scattered toward the outer circumference due to the action of centrifugal force accompanying the rotation of the rotating shaft 29, and the floating sheet 32 and the seal ring 24 are It is concentrated at the inner peripheral end of the sealing sliding surface 33 along the conical surfaces 32a and 24a formed on the inner periphery, is pushed back into the sliding surface 33, and acts as a lubricating fluid film again, and this process is repeated thereafter. This makes it possible to reduce leakage occurring from the sliding surface 33. Further, fluid that overflows from the first fluid reservoir 34 or is scattered as described above but cannot return into the sliding surface 33 is removed from the outer cylinder 23.
The fluid is retained in a second fluid reservoir 35 formed on the outer peripheral surface of the inner diameter cylindrical portion 23a. Therefore, according to the mechanical seal having the above configuration, the flow of fluid returned from the fluid reservoir 34 to the sealing sliding surface 33 is greater than the flow of fluid flowing between the sealing sliding surfaces 33 from the outer circumferential side to the inner circumferential side. It begins to act as a counter pressure,
In addition to being able to reduce the overall amount of leakage, the fluid that has once leaked again acts as a lubricating film, so the lubrication effect on the sliding surface 33 can be increased, reducing wear and noise. can. Thirdly, the mechanical seal can keep the sliding surface 33 well lubricated even under dry atmospheric conditions, and fourthly, the floating sheet 32
and a conical surface 32 on the inner peripheral side of the seal ring 24.
a, 24a and the sealing sliding surface 33 is placed near the outer periphery.
The coil springs 26 and 26 are close to each other in the radial direction, and the strain on the sliding surface of the seal ring 24 can be reduced due to the positional relationship of the load application points.Fifth, the time it takes for equipment to detect a leak can be significantly reduced. This makes it possible to extend the life of the mechanical seal.

Next, a second embodiment of the present invention will be described with reference to FIG. 3. In the mechanical seal of this embodiment, the lower end of the cushioning rubber 31 interposed between the case 28 and the floating sheet 32 is extended. Case 2
The first fluid reservoir 34 is formed on the buffer rubber 31, and the inner diameter cylindrical part 23a of the outer cylinder 23 is bent halfway to form an annular groove on the inner circumferential surface. 23e, the fluid overflowing from the second fluid reservoir 35 is temporarily retained in the annular groove 23e, and the time required for the device to detect it as a leak is extended. be. In this case, the annular convex portion 23f protrudes toward the outer circumference along with the formation of the annular groove 23e.
If the outer diameter of the second
A large amount of fluid can be retained in the fluid reservoir 35, and the gap between the outer cylinder 23 and the rotating shaft 29 is preferably kept as small as possible.

As explained above, the mechanical seal of the present invention has a substantially symmetrical conical surface formed on the inner circumferential side of the sealing sliding surfaces of the floating seat and the seal ring, and a fluid reservoir on the inner circumferential side of the conical surface. In addition to being able to reduce the amount of fluid leakage compared to conventional seals, leaked fluid can be retained within the mechanical seal for a long period of time. Note that the sealing effect itself can be improved by providing a special spiral groove on the sealing sliding surface.

[Brief explanation of drawings]

FIG. 1 is a half-cut sectional view showing a conventional mechanical seal, and FIGS. 2 and 3 are half-cut sectional views of mechanical seals according to different embodiments of the present invention. 21...Housing, 22, 30, 31...Buffer rubber, 23...Outer tube, 23a, 28a...Inner cylinder portion, 23b, 28b...Tip, 23e...Annular groove, 24...Seal ring, 25 ...Patsukin,
26... Coil spring, 27... Spring restraining ring, 28... Case, 29... Rotating shaft, 32
... Floating sheet, 33 ... Sealing sliding surface, 34, 35 ... Fluid reservoir.

Claims (1)

[Scope of utility model registration request] A sealed sliding surface is created by a seal ring installed inside an outer cylinder with a roughly U-shaped half-cut cross section that is fitted onto the inner periphery of the housing, and a floating sheet installed inside a case with a roughly U-shaped half-cut cross section that follows the rotating shaft. In the internal flow type mechanical seal to be formed, a substantially symmetrical conical surface is formed at the inner circumferential end of the sealing sliding surface of the seal ring and the floating seat, and a conical surface is formed on one or both of the outer cylinder or the case. The tip of the inner cylindrical portion extends to the inner circumferential position of the sealing sliding surface, the tip is slightly bent approximately in the outer circumferential direction, and a fluid reservoir is provided on the outer circumferential surface of the inner cylindrical portion. Mechanical seal.