JPS583151B2 - mechanical seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in mechanical seals used in pumps, compressors, and the like.

Generally, as shown in FIG. 1, a mechanical seal is rotated by a rotating ring 4 fixed to a rotating shaft 3 and a holder 11 removably attached to a casing body 10 via a flange 9 via a spring 8. A stationary ring 2 supported to press against the ring 4 forms a sealed end face 5 which is adapted to seal against fluids in the premises 6.

However, as shown in FIG. 1, the conventional mechanical seal has the following drawbacks because it is not provided with any means for regulating the movement of the stationary ring 2 in the axial direction.

In other words, since the mechanical seal built into the device cannot be visually recognized from the outside, the only way to determine when to replace the mechanical seal is to detect fluid leaking from the sealed end face 5. Because the axial movement of the ring 2, that is, the movement toward the rotating ring 4, is not regulated, the user does not notice even after the amount of wear on the sealing end face 5 exceeds the allowable range, and when fluid leakage is detected,
There is a risk that the entire mechanical seal may have already been damaged, or in extreme cases, the equipment itself may be damaged, and it is often the case that it is incorrect to judge when to replace the mechanical seal.

In addition, in the conventional mechanical seal, the rotating shaft 3 is fitted and fixed with the rotating shaft 3, and the stationary ring 2 is supported by the holder 11, and the holder opening is connected to the casing via the flange 9. The mechanical seal is assembled by attaching it to the main body 10, but during this assembly, the movement of the stationary ring 2 in the axial direction is not restricted, so the stationary ring 2 is pushed out by the spring 8 and detached from the holder 11. Therefore, in extreme cases, the stationary ring 2 is easily removed from the holder 1.
There is a risk that the device may be installed in a position that is deviated from 1 or at an angle.

When a mechanical seal is assembled in such a defective state, it goes without saying that not only will it fail to exhibit a good sealing function, but it will also be damaged.

It goes without saying that it is not easy to replace the mechanical seal.

Furthermore, even if a mechanical seal is installed in a device in which the positional relationship between the casing 1 and the rotating shaft 3 is precisely adjusted, in reality there are few such devices, so the mechanical seal installed in the device is Due to the relative displacement in the axial direction between the casing 1 and the rotary shaft 3, a certain amount of displacement and vibration is often experienced in the axial direction, but in this case, the movement of the stationary ring 2 in the axial direction is not restricted.
The above-mentioned vibrations and the like are often amplified, leading to unexpected situations.

Conventional mechanical seals have the above-mentioned drawbacks due to the fact that the axial movement of the stationary member 2 is not regulated, but they also have the following drawbacks.

That is, in the conventional type, since the sealed end surface 5 generates frictional heat due to relative sliding rotation between the stationary ring 2 and the rotating ring 4,
As shown in FIG. 1, a cooling liquid is injected into the sealed end surface 5 from an injection hole 7 provided in the casing 1.

However, in this conventional device, when the rotary shaft 3 is in a rotating state, the fluid inside the machine 6 forms a laminar flow on the outer circumference of the machine interior 6, that is, on the inner circumferential surface side of the casing.

For this reason, the cooling water flowing in through the injection hole 7 flows while being pressed against the outer periphery of the interior 6 and is not injected into the sealed end surface 5, which is a drawback.

In addition, in FIG. 1, if particulates or the like are contained in the sealed fluid, the portion to the left of the sealed end surface 5 in FIG.
Since there is no flow of sealing fluid in the space b1 between the holder 11 and the stationary ring 2 and the spring retaining hole C provided in the holder 11, fine particles accumulate, causing minute particles to move toward the shaft 3 in the direction of the arrow f in FIG. The smooth movement of the stationary ring 2 in the direction of the arrow e in FIG. 1 may be impaired due to excessive movement or wear of the sealing end surface 5.

The present invention provides an improved mechanical seal that eliminates all of the above-mentioned drawbacks.

That is, the mechanical seal of the present invention maintains constant axial movement of the stationary ring by engaging a pin protruding from the outer peripheral surface of the stationary tube with an axially elongated hole provided in a cylindrical guide connected to the holder. This ensures that the wear on the sealing end face does not exceed the allowable range, and also controls and absorbs axial displacement and vibration as much as possible.Furthermore, the stationary side assembly is made into a unit to ensure accurate assembly and assembly of the mechanical seal. The cylindrical guide is designed to facilitate replacement work, and the cylindrical guide is extended to the sealed end face to form a cooling passage between the cylindrical guide and the stationary ring. This is intended to improve the cooling function and prevent the accumulation of fine particles.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In the figure, reference numeral 21 denotes a casing main body 22, a flange 23 removably attached to the rear end of the main body 22, and a holder 24 attached to the front end of the inner peripheral surface of the flange 23 via an O-ring 25. It is a casing consisting of.

Then, the holder 24 is inserted into the spring chamber 2 from the center of the front end surface.
6, and an inner cylindrical portion 27 is formed forward from the inside of the front end surface.

Furthermore, 28 is a stationary ring formed by attaching a joint body 30 to the front end surface of a stationary ring main body 29, and this stationary ring main body 29 has its rear end surface pressed and supported by the tip of a spring 31 housed in the spring chamber 26. At the same time, it is slidably supported in the axial direction, that is, in the front-rear direction, on the outer circumferential surface of the inner cylinder portion 27 via the O-ring 35a.

Further, 32 is a rotating ring that is fitted and attached to the rotating shaft 33 via an O-ring 35 and fixed by a sleeve 34.

The front end surface of the joined body 30 of the stationary ring 28 is in liquid-tight contact with the rear end surface of the rotating ring 32, forming a sealed end surface 36.

Therefore, the sealing end surface 36 provides a seal between the inside 42 and the outside 43 of the machine.

Further, 38 is a cylindrical guide integrally connected to the holding body 24, which surrounds the outer peripheral surface of the stationary ring 28 and seals the sealed end surface 3.
It has been extended to 6.

This cylindrical guide 38 forms a cooling passage 37 between it and the outer peripheral surface of the stationary ring 28 , and flows from an inflow hole 41 formed through the flange 23 and the holder 24 to the rear part of the cooling passage 37 . A cooling medium such as a cooling liquid is allowed to flow in.

Further, the cylindrical guide 38 is provided with a plurality of elongated holes 39 (only one shown) extending in the front-rear direction, which is the axial direction, and each pin 40 has its head located in each elongated hole 39. is tightened and fixed to the outer periphery of the stationary ring body 29,
Due to the engagement of each elongated hole 39 with the pin 40, the stationary ring 28
The stationary ring 2
8 is prevented from rotating around the axis.

The longitudinal length of the elongated hole 39 is such that when the pin 40 is locked at the front end 39a, the stationary ring 28 can be pulled out from the holder 24, that is, the inner cylindrical part 27 despite the pressure from the spring 31. The maximum amount of forward movement of the stationary ring 28 is regulated so that the stationary side assembly is unitized without any damage, and within a range where the amount of wear on the sealed end surface 36 does not exceed a predetermined allowable amount of wear (for example, about several mm). is set to be

Next, the operation of the above embodiment will be explained.

Coolant is caused to flow into the passage 37 from the inlet hole 41 at the same time as the rotating shaft 33 starts rotating.

At this time, since the passage 37 is formed between the stationary ring 28 on the stationary side and the cylindrical guide 38 and reaches the sealed end surface 36, the coolant flowing in from the inlet hole 41 flows into the inside of the machine.
The fluid flows forward in the passage 37 from the rear end side of the stationary ring 28 without being affected by the fluid of No. 2.

Therefore, due to the flow action of this coolant, the holding body 2
It is reliably prevented that fine particles such as slurry are deposited in the stationary side portion such as the space between the stationary ring 28 and the stationary ring 28.

Since the front end edge of the cylindrical guide 38 is formed to a position opposite to the sealed end surface 36, the cooling liquid easily and reliably reaches the sealed end surface 36, and therefore the seal is sealed which generates frictional heat due to the rotation of the rotating shaft 33. The end face 36 can be cooled sufficiently and efficiently.

Incidentally, the front end surface of the joined body 30 gradually wears out due to sliding contact with the rotating ring 32, but as the stationary ring 28 gradually moves forward due to the pressing force of the spring 31, the sealed end surface 36 always remains kept in good condition.

However, when the stationary ring 28 slides forward by a predetermined amount, the pin 4
0 comes into contact with the front end 39a of the elongated hole 39, and the stationary ring 28
prevents it from sliding forward.

Therefore, by appropriately setting the length of the elongated hole 39 in the longitudinal direction as described above, excessive wear on the front end surface of the joined body 30 can be prevented.

That is, although the joined body 30 is usually formed from a soft material and held by the stationary ring body 29 made of metal,
Even if the joined body 30 is worn out, the rotating ring 32 made of a hard material
The rotating ring 32 does not come into sliding contact with the stationary ring body 29, so the rotating ring 32 will not be damaged to the extent that it cannot be reused even if it is repaired, and moreover, the fluid that has the risk of ignition or explosion will be sealed. metal (stationary ring body 29)
Abnormal heat generation due to sliding contact between the sealing fluid and the hard material (rotating ring 32) does not occur, and therefore, ignition and explosion of the sealed fluid can be prevented.

Further, when the pin 40 comes into contact with the front end 39a of the elongated hole 39, the stationary ring 28 is prevented from sliding forward, so the length of the elongated hole 39 in the front and rear direction is set appropriately as described above. This allows the stationary ring 28 to be removed during installation and removal.
It is possible to prevent problems such as detachment of the inner cylinder part 27 of the holding body 24.

Therefore, attachment and detachment operations can be easily performed without damaging the stationary ring 28 or other parts, and therefore, the sealing function will not deteriorate.

As described in detail above, in the mechanical seal of the present invention, the stationary ring 28 is inserted into the elongated hole 39 in the axial direction provided in the cylindrical guide 38.
A pin 40 protruding from the outer peripheral surface of the ring is engaged, and the movement of the stationary ring 28 in the axial direction is restricted within a certain range, so it has the following important and excellent functions in terms of mechanical seals. It is.

First, it has a function of regulating the maximum amount of axial movement of the stationary ring 28 in the direction toward the rotating ring 32 .

This prevents damage to the mechanical seal (and further damage to the device itself).

In other words, it functions as a safety valve.

That is, when the wear on the sealed end surface 36 reaches a predetermined allowable wear amount, the pin 40 abuts against the front end 39a of the elongated hole 39, and the axial movement of the stationary ring 28 by the spring 31 is stopped. The wear does not progress beyond the allowable wear amount, and only a phenomenon in which fluid leaks from between the stationary ring 28 and the rotating ring 32 occurs.

Therefore, by detecting this fluid leakage, it is possible to accurately determine when to replace the mechanical seal.

In other words, by the time a fluid leak is detected, allowable wear has already been exceeded and parts of the mechanical seal have been damaged to the point where they cannot be replaced, or even worse, the equipment in which the mechanical seal is installed has been damaged. This prevents unforeseen situations such as accidents from occurring.

Second, when a mechanical seal program is inserted into a device in which the positional relationship between the casing 21 and the rotating shaft 33 has not been properly adjusted, the function of regulating and absorbing the axial displacement and vibration that each part of the mechanical seal receives is provided. have

In other words, the axial displacement and vibration that the mechanical seal part receives due to the relative displacement between the casing 21 and the rotating shaft 33 are suppressed more than necessary because the axial movement of the stationary ring 28 is restricted within a certain range. The vibrations are not amplified, but are regulated and absorbed, thereby reliably preventing the occurrence of unexpected situations caused by amplification of the vibrations and the like.

Thirdly, it has a function of unitizing the stationary side assembly.

This is an extremely important feature in the structure of mechanical seals that require accurate assembly.

That is, even when the stationary ring 2B is not in contact with the rotating element 32, the pin 40 is locked to the front end 39a of the elongated hole 39, so that the stationary ring 2B can be moved away from the holder 24 against the pressing force of the spring 31. Since it will not come off and will be held in good condition by the holder 24, the stationary side assembly can be installed and removed very easily, and the stationary ring 28 will not come off from the holder 24 or be tilted. There is no risk of a mechanical seal being assembled in a defective state.

Being able to easily install and remove them and assemble them accurately is an immeasurable advantage for on-site workers, and is also important for achieving good sealing performance.

Fourthly, it has a function of preventing rotation of the stationary ring 28 around its axis due to relative sliding rotation with the rotating ring 32.

This is naturally provided in conventional devices, but the fourth function can be achieved by the engagement between the elongated hole 39 and the pin 40 to have the first to third functions described above. It is significant that it also has a

That is, there is no need to provide any special means for preventing rotation of the stationary ring 28, so the structure of the mechanical seal does not become unnecessarily complicated.

Furthermore, according to the present invention, the cylindrical guide 38 on the stationary side
Since the cooling passage 37 reaching the sealed end face 36 is provided between the stationary ring 28 and the stationary ring 28, the cooling medium is guided into the passage 37 and reaches the sealed end face 36 well and reliably. It can be efficiently cooled and can reliably prevent fine particles such as slurry from accumulating on the stationary side portion.

Moreover, since the cylindrical guide 38 for forming the cooling passage 37 is also used as a member for forming the elongated hole 39 which is a part of the means for regulating the movement of the stationary ring 28 in the axial direction, the cooling By providing the passage 37, the structure of the mechanical seal does not become unnecessarily complicated.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view showing a conventional example, FIGS. 2 and 3 show an embodiment of the present invention, FIG. 2 is a schematic longitudinal sectional view, and FIG. 3 is a long hole in a cylindrical guide. FIG. 24... Holding body, 28... Stationary ring, 3
2... Rotating ring, 33... Rotating shaft, 36
... Sealed end surface, 37 ... Cooling passage, 3
8...Cylindrical guide, 39...Long hole, 4
0...Pin.

Claims (1)

[Claims] 1 The rotating ring 32 provided on the rotating shaft 33 and the holder 24
In a mechanical seal in which a stationary ring 28 is supported to press against a rotating ring 32 and a sealed end face 36 is formed, the holder 24 has a cylindrical guide 38 that surrounds the stationary ring 28 and extends to the sealed end face 36. Connected to the cylindrical guide 3
A cooling passage 37 is formed between the stationary ring 28 and the cylindrical guide 38, and a pin 40 protruding from the outer peripheral surface of the stationary ring 28 is engaged with a long hole 39 in the axial direction provided in the cylindrical guide 38. A mechanical seal characterized in that the axial movement of 28 is restricted within a certain range.