JPH0118927Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a stern tube shaft sealing device, and in particular, in a pressurized fluid feeding type stern tube shaft sealing device, the amount of pressurized fluid fed when the shaft is stopped is zero, and the shaft rotation is It is an object of the present invention to provide a stern tube shaft sealing device that can sometimes obtain an appropriate flow rate of pressurized fluid and consumes a small amount of pressurized fluid.

Conventional pressurized fluid feed type stern tube shaft sealing devices prevent seawater and slurry in seawater from entering the ship;
In order to prevent premature wear of the seawater side lip seal, it is necessary to constantly supply pressurized fluid with a pressure higher than seawater pressure both when the shaft is rotating and when it is stopped. However, while the shaft is stopped, the seawater side lip seal does not wear out, and such excessive supply of pressurized fluid goes against energy conservation.

The present invention was developed in view of the above problems, and is a stern tube that stops the supply of pressurized fluid when the shaft is stopped, and allows an appropriate amount of pressurized fluid to flow out depending on the rotation speed even when the shaft is rotating. This constitutes a shaft sealing device. In other words, the stern tube shaft sealing device of the present invention has two pairs of mechanical seals disposed back to back in the pressurized fluid inlet, and the pressurized fluid flow control mechanism is configured only on the sliding surface of the seawater side mechanical seal. This is what I did. The pressurized fluid flow control mechanism has a plurality of grooves that do not penetrate the sliding surface, and the grooves have a shape such that they are inclined in the direction of rotation, and the pressurized fluid flows through the rotation of the mechanical seal. This acts to forcibly draw the fluid into the inside of the sliding surface, which works together with the viscous effect of the pressurized fluid to create a force that opens the sliding surface. As a result, when the shaft is stopped, the pressurized fluid is sealed by the sliding surfaces being in close contact with each other, and when the shaft is rotating, an appropriate amount of the pressurized fluid is allowed to flow out through the minute gap created between the sliding surfaces.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a half-cut sectional view of a stern tube shaft sealing portion showing the first embodiment. Reference numeral 1 denotes a shaft sleeve that penetrates the shaft seal portion, and the shaft sleeve 1 includes a seawater-resistant lip seal 2 supported between a first case 11 and a second case 12, a fourth case 14, and a fifth case 15. Lip seals 3 for in-machine oil carried between them are respectively slidably connected and extrapolated. The third case 13 has a larger inner diameter than the second case 12 and the fourth case 14, and is assembled in an airtight manner so that an annular recess 18 is formed on the inner circumferential side, and the annular recess 18 has a double seal structure. A mechanical seal is constructed. Reference numerals 4 and 5 indicate rotary side seal rings which are provided to face the side sliding surfaces of the second case 12 and the fourth case 14, respectively, and between the two rotary side seal rings 4 and 5. is provided with a fixing ring 6 that is externally inserted and fixed to the shaft sleeve 1, and both rotating side seal rings 4, 5
Knock pins 7 and 8 protruding from the back of the fixing ring 6 are loosely fitted into the engagement hole 6b formed in the fixing ring 6 to prevent rotation, and the coil spring 10 inserted into the through hole 6a is inserted into the seal ring on both rotating sides. 4 and 5, and each sliding surface 4a, 5a of the rotating side seal rings 4, 5 is mounted between the second case 12 and the fourth case 14.
The O-ring 19 is pressed against the sliding surface of the shaft sleeve 1 with an appropriate pressing force, and between the shaft sleeve 1 and the O-ring 19,
20 is interposed and externally inserted in an airtight manner. Furthermore, a plurality of radial grooves 4b as shown in FIG. It constitutes a pressure fluid flow control mechanism, and the groove 4b has a rotation direction (arrow) and an inclination angle θ (0<θ<
90°) and starts from the outer peripheral side of the sliding surface 4a and does not cross the sliding surface.

In the figure, 16 is a pressurized fluid feed line communicating with the annular recess 18, and the pressurized fluid is fed into the annular recess 18 by a feed device (not shown). Reference numeral 17 denotes a leakage recovery line that communicates with the main body side of the hull, and is opened between the inner rotary side seal ring 5 and the lip seal 3 to leak fluid and seawater leaked through the mechanical seal, as well as in-flight oil leaked through the lip seal 3. be recovered on board.

In the shaft sealing device configured as described above, when the shaft is stopped, the pressurized fluid fed into the annular recess 18 from the feed line 16 slides between the rotating side seal rings 4, 5, the second case 12, and the fourth case 14. Completely sealed by surfaces and O-rings 19,20. In this case, the lip seal 2 acts as a first seal to prevent leakage of seawater, and the rotating side seal ring 4 and O-ring 19 act as a second sealing device.

Further, when the shaft rotates, the pressurized fluid is forcibly drawn into the sliding surface 4a by the groove 4b provided in the sliding surface 4a of the rotating side seal ring 4, and the pressure and viscosity of the pressurized fluid are reduced. As a result, the sliding surface 4a expands, and the pressurized fluid flows out in a limited manner toward the back side of the lip seal 2 through the minute gap, and the pressurized fluid leaking to the outer lip seal 2 side is prevented. The fluid pressurizes the back surface 2a of the lip seal 2, keeping the lip in balance and providing a very low-load sliding action to prevent premature wear of the lip. Even if the supply of pressurized fluid is stopped for some reason during shaft rotation, the lip seal 2 operates as a seawater seal due to seawater pressure. However, in this state, it is expected that the lip seal 2 will wear out prematurely, and in this case, when the pressurized fluid feed line 16 is closed, the pressure of the seawater leaking through the lip seal 2 will cause the back pressure on the rotating side seal ring 5 to increase. 4th case 14
A second seal is formed by strongly pressing against the seawater, and seawater is prevented from entering.

Next, FIG. 3 shows another structure of the sliding surface 4a of the rotating side seal ring 4 of the shaft sealing device of the present invention. That is, 4c is a deep groove formed with a plurality of radial grooves extending from the annular groove to the outer periphery, and concave grooves 4d each extending in the opposite direction to the rotation direction (arrow) from the radial grooves of the deep groove 4c.
These grooves 4c and 4d are formed so as not to cross the sliding surface 4a, and pressurized fluid is forcibly drawn into the concave groove 4d during rotation.

Furthermore, FIGS. 4 and 5 show other embodiments of the pressurized fluid flow control mechanism, and FIG. was formed,
In addition, FIG. 5 shows the sliding surfaces 4 of the rotating side seal ring 4 and the stationary side seal ring formed on the second case 12.
Grooves 4b and 12b are formed in a and 12a.

As described above, the present invention provides a pressurized fluid flow control device consisting of a rotating side seal ring, a stationary side seal ring, etc. in the pressurized fluid circulation section.
It maintains an appropriate flow rate of pressurized fluid when the shaft rotates, prevents premature wear of the seawater side lip seal, and also reduces the flow rate of pressurized fluid to zero when the shaft is stopped, reducing the amount of pressurized fluid consumed as much as possible. It has extremely great practical effects.

[Brief explanation of drawings]

Fig. 1 is a half-cut cross-sectional view of the shaft sealing part of the stern tube showing one embodiment of the stern tube shaft sealing device of the present invention, Fig. 2 is a front view of the rotary side seal ring, and Fig. 3 shows another embodiment. The front view of the rotating side seal ring shown in FIG. 4, and FIG. 5 are front sectional views of main parts showing other embodiments of the pressurized fluid flow control mechanism, respectively. 1... Shaft sleeve, 2, 3... Lip seal, 4, 5... Rotating side seal ring, 4b, 1
2b...Groove, 10...Coil spring, 12,
14... Case, 16... Pressurized fluid feed line,
17...Leakage recovery line, 19,20...O ring.

Claims (1)

[Scope of utility model registration request] A seawater lip seal and an in-machine oil lip seal are provided between the shaft and the case member, and an annular recess is formed between the seawater lip seal and the in-machine oil lip seal through which pressurized fluid is sent to the case member. , a seawater side mechanical seal for sealing the pressurized fluid against the seawater lip seal side, and an in-machine oil seal for sealing the pressurized fluid against the in-machine oil lip seal side, between the annular recess and the shaft. A side mechanical seal is configured, and the sliding surface of only the seawater side mechanical seal has a shape for forcibly drawing the pressurized fluid inside the sliding surface by rotation of the seawater side mechanical seal. A stern tube shaft sealing device, characterized in that a groove is formed, and the groove does not cross the sliding surface.