JPH0571830B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a shaft seal device, and in particular to a non-contact type shaft seal device in which the sealing mechanism is improved by imparting flexibility to the shaft seal element, which is a fixed system. Regarding.

[Prior Art] As shown in FIG. 17, a conventional cylindrical shaft seal device forms a seal gap C between the seal ring 2 and the rotary shaft 1 in a plane parallel to the rotary shaft 1.
The structure includes a buffer mechanism that brings a vertical plane into pressure contact with the plane of the casing 3 and seals the rotating portion by this contact pressure. In addition, the end face type shaft seal device has a buffer mechanism that seals the rotating part by forming a seal gap between the plane of the seal ring 5 parallel to the rotating shaft runner 4 and the runner 4, as shown in FIG. It is configured to have Therefore, the conventional shaft sealing device is
In either case, both the rotating system and the fixed system are composed of rigid surfaces.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional shaft seal, both the rotary system and the stationary system are composed of rigid surfaces, and therefore the following problems occur.

(1) In the case of a cylindrical seal, when rotating at high speed, the seal gap C tends to become smaller due to the shear heat of the bearing fluid and the centrifugal expansion of the shaft 1, but if it becomes significant, C=O and seizure occurs.

Furthermore, carbon graphite or the like is often used for the seal ring 2, which is a fixed system, in order to improve slidability, but it has a small coefficient of linear expansion, making it difficult to manage gaps.

(2) In the case of end-face seals, as shown by the two-dot chain line in Figure 18, deformation occurs due to the shear heat of the fluid between the seal surfaces, and this deformation reduces the joint bearing function and causes contact problems. .

(3) In either case, self-alignment performance is poor because there is not sufficient springiness in the radial or axial direction.

As described above, in the conventional sealing surfaces, both of the sealing surfaces are rigid, making it difficult to maintain a stable seal gap at high speeds and high temperatures.

[Purpose of the invention]

An object of the present invention is to provide a shaft seal device that can stably maintain a narrow seal gap even under high-speed and high-temperature conditions by providing a sealing surface fixing system with spring properties and damping properties. It is.

[Summary of the Invention] The structure of the present invention in accordance with the above object is to provide an elastic sealing oil that faces the rotating shaft and generates a fluid film pressure therebetween to form a sealing gap, and then An elastic damp oil is layered on the opposite side of the rotating shaft to dampen the vibrations of the seal oil.
Furthermore, it has an elastic foil laminated structure in which an elastic spring foil for elastically supporting the dump foil on the fixed system support surface is layered. As a result, the spring properties and damping properties in the thickness direction of the elastic foil are distributed and act in the circumferential direction of the rotating shaft.
This prevents the seal gap from disappearing and seizure from occurring at high speeds and high temperatures.

In addition, the seal oil, dump oil, and spring oil described above are continuously formed integrally, and this integrally formed single piece of elastic oil is wound and incorporated between the rotating shaft and the fixed system support surface. It has an elastic foil laminated structure. As a result, in order to obtain a laminated structure of foils, instead of stacking individual foils, it is possible to stack them by simply winding a single sheet of elastic foil, and by using an elastic body for the seal element, the number of parts can be reduced. This prevents the size from increasing and the assembly work from becoming complicated.

[Example] An example of the present invention will be described below based on FIGS. 1 to 16.

1 to 4 show an embodiment of a cylindrical seal structure that also has a bearing function, which is a non-contact type shaft seal structure that uses gas, steam, oil, etc. as a process fluid. As shown in FIG. 1, the seal structure according to the present embodiment includes a spring oil 1 which is suspended by a spacer 9 on a support surface 8 of a case 7 which is a fixed system.
0.Basically, three flexible thin plates (elastic foils) are stacked, a dump oil 11 also floated by a spacer 9, and a seal oil 12 brought into close contact, and one end is locked and fixed with a key 13. Rotation is caused by both the spring and damping function of the fluid film pressure formed in the seal gap C between the sealing oil 12 of the inner shell and the rotating shaft 14, and the springing and damping function of the laminated oil structure. It is designed to seal the parts.

Each elastic foil, including the spacer 9, is a separate film-shaped structure as shown in FIG. 2, and is inserted into the case 7 to cover the bearing surface 8 in a ring shape. That is, spring oil 1
0 is made of flat elastic foil on both the upper and lower surfaces, and the rudder oil 15 fulfills the function of the spacer 9 to partially float it from the bearing surface 8. The ladder oil 15 has rectangular windows 17 with a length L ₀ ' that are bored in the width direction of the elastic oil leaving both end portions 16, 16, and are arranged in parallel in the length direction. The vertical lattice becomes the spacer 9 of the spring oil 10.

Although the dump oil 11 has a flat lower surface, pockets 18 of any shape capable of being locally filled with fluid are machined on the upper surface at predetermined intervals in the length direction at a depth of about half the plate thickness. In the illustrated example, the pocket 18 is cross-shaped. The function of the spacer 9 to partially float the dump oil 11 from the spring oil 10 is performed by the rudder oil 15 having the same shape as that used for the spring oil 10. 2 rudder oils 15,1
As can be seen from FIG. 1, the difference between the spacers 9 and 9 is that the pitch of the spacer 9 is shifted by half when it is inserted into the case 7, that is, the pitch between the spacers 9 supporting the spring oil 10 is changed. The point is that the dump oil 11 is stacked in a shifted manner so that the spacer 9 is aligned with the spacer 9. The reason why the spring oil 10 is interposed between the two rudder oils 15, 15 with the vertical lattice spacers 9, 9 shifted is that the spring oil 10 is given wave-like deformability and has a spring function. This is to make it possible. The region having this spring function is not the entire width L of the foil, but the length L ₀ ' of the rectangular window 17 excluding both end portions 16 and 17. Both end portions 16,
The length L-L ₀ ' of 17 has no spring properties and has the function of keeping the foils in close contact with each other to maintain airtightness.

The sealing oil 12 has a flat lower surface but a convex upper surface having a sealing area of L ₀ (<L ₀ '). Since this seal is a non-contact type clearance seal, the surface of the seal area, which is a convex portion, is appropriately subjected to surface treatment in consideration of slidability and wear resistance. In the illustrated example, the sealing oil 12 is of a plain type, but this shape may be arbitrary, such as a spiral groove or a herringbone pocket type. Further, a plurality of orifices 19 are provided at the center thereof at predetermined intervals in the length direction, and the seal oil 12 is placed in the dump oil 1 so that the pocket 18 of the dump oil 11 is directly below the orifice 19.
Lay it on top of 1. The reason why the orifice 19 is stacked so that it communicates with the pocket 18 is that the fluid film pressure formed in the sealing area is released to the pocket 18 through the orifice 19, thereby creating a local gap between the upper surface of the dump oil 11 and the lower surface of the seal oil 12. This is to provide the damp oil 11 with a squeeze film damper function by effectively forming a fluid film. The orifice 19 and the pocket 18 are located between the spacers 9, which support the dump oil 11, so that elastic deformation of the dump oil 11 in the radial direction outward is allowed when fluid film pressure is applied to the pocket 18. Further, the distance between adjacent orifices 19 and pockets 18 is set to be twice the pitch between spacers in the illustrated example of FIG.

In this way, in the foil element, in addition to the fluid film pressure spring/damping element formed by the seal gap C, the spring/damping element formed between the foils is distributed and arranged in the circumferential direction of the bearing surface 8. become.

Note that the window portion 17, pocket 18, orifice 19, convex portion, etc. of the foil element are processed and formed by known photo etching techniques.

Figures 3 and 4 show a mating part of a foil element wound into a cylindrical shape to be inserted into the case 7, and a convex part 20 is formed on one of the mating ends, and this convex part is formed on the other end. A recessed portion 21 is formed to engage with the portion 2, and these are fitted together, thereby maintaining sealing performance between the foil elements.

FIGS. 5 to 7 show the foil shaft seal element 22 composed of the case 7 and the foil element constructed in this manner actually applied to a shaft seal device. FIG. 5 shows a floating ring type having a buffer mechanism, and FIG. 7 shows a fixed ring type.

Now, in the above configuration, the rotating shaft 14
When high-speed rotation starts or the ambient temperature becomes high, the seal gap C becomes smaller due to the shear heat of the fluid and the expansion of the rotating shaft. This fluid film pressure pushes the sealing oil 12 radially outward. Therefore,
A spring oil 10 and a dump oil 1 are stacked and supported on the bearing surface 8 so that elastic deformation is allowed by the spacer 9 of the ladder oil 15.
One of the spring oils 10 is elastically deformed in a wave-like manner. In addition, part of the increased fluid film pressure generated in the seal gap C due to self-excited vibration of the rotary shaft 14 due to high-speed rotation is transferred to a pocket formed on the upper surface of the dump oil 11 through an orifice 19 bored in the seal oil 12. Guided by 18. The fluid film pressure guided to the pocket 18 on the upper surface of the dump oil 11 reduces the high pressure fluid film pressure formed in the seal gap C since the pocket 18 has a larger flow path area than the orifice 19. Therefore, the flexible dump oil 11 is locally displaced radially outward, and the displaced portion is locally filled with fluid.

By the way, in order for the shaft seal device to operate stably at high speeds and high temperatures, it is necessary to have appropriate external springs and damping elements placed along the sealing surface in addition to the springs and damping elements based on fluid film pressure. be.

However, in this embodiment, the appropriate external spring and damping functions are constructed by a laminated five foil structure. That is, as a spring element,
Since the spring oil 10 is deformed in a wave-like manner along the circumferential direction of the bearing surface 8 by the action of the fluid film pressure generated in the seal gap C, the springs are distributed and arranged in the circumferential direction. In addition, the dump oil 11 is locally displaced by the action of the pressurized fluid film pressure generated in the seal gap C as an external damping element, and the fluid is locally filled along the circumferential direction.
This filled portion functions as a squeeze film damper, and this function is distributed and arranged in the circumferential direction. Therefore, the shaft seal structure according to this embodiment can effectively absorb or suppress disturbances and self-excited vibrations that occur at high speeds, and can also reduce the seal gap C, which tends to become smaller at high speeds and high temperatures, to zero. It can be held stably and extremely small without causing any damage.

Also, seal oil 12 and dump oil 1
Most of the surfaces with 1 are in close contact, and the dump oil 11 and spring oil 10 are also in close contact with both end portions 16, 17 of the rudder oil 15, 15, and the mating ends of the oil elements are also fitted. Since the gap is also made smaller, it is possible to improve the sealing performance.

In addition, not only floating type shaft seal devices which have the original self-aligning effect, but also fixed type shaft seal devices, the seal element is spring-loaded.
Since a foil laminated structure having damping properties is adopted, this structure itself provides self-aligning properties, and contact with the rotating shaft 14 can be effectively avoided.

That is, according to this embodiment, the heat of the rotating shaft 14
Its ability to function in response to deformation and expansion caused by centrifugal force far exceeds that of conventional rigid seal devices. Therefore, it is advantageous to apply it to turbomachines in general that rotate at high speed, particularly turbocompressors, turboexpanders, turbochargers, turbo refrigerators, etc. that use high-temperature or low-temperature fluids as process fluids.

FIG. 8 shows a modification of the embodiment shown in FIG. 1, and the difference from FIG. 1 is that the spring oil 3
0. Dump oil 31 and seal oil 32 are continuously processed into one piece, and are wrapped three times around the bearing surface 34 of case 33 and connected to case 33 by key 35 provided at the end of spring oil 30. This is a fixed point. Integrated elastic foil 3
6, as shown in FIG. 9, a spring oil portion S, a damp oil portion D, and a seal oil portion E are successive in this order from the left. The rectangular recesses 37, 37 formed in the spring oil portion S and the dump oil portion D are not windows with holes as in the case of the ladder oil 15 described above, but are recesses with a bottom thickness t ₁ remaining. A plurality of rectangular recesses 37 are formed in the length direction with a pitch b, and the boundary between the spring oil portion S and the damp oil portion D is particularly large with a pitch of 1.5b. If formed in this way, when triple-wound and assembled in the case 33, the spacer 3 of the spring oil portion S
Spacer 38 of dump oil part D between 8 and 38
The springs can be distributed and arranged in the circumferential direction. Therefore, by providing a rectangular recess 37 in the spring oil portion S and the dump oil portion D that does not pass through the front and back sides, the ladder oil 15 that is required when using separate foils is no longer necessary, and the spring oil 30 and dump oil 31 itself has a spacer 38. On the other hand, the orifice 39 formed in the convex portion of the seal oil portion E has a pocket 40 integrally connected thereto. Therefore, a pocket 40 is separately provided on the surface of the dump oil 31 where the seal oil 32 overlaps.
There is no need to form.

In this way, in this modified example, the seal element can be constructed with one foil instead of the five foils that were required, and the number of parts is reduced, making molding, assembly, and processing of the shaft seal structure easier, resulting in lower costs. This has the advantage of being able to be quantified.

Next, an embodiment in which the present invention is applied to a non-contact type end face sealing device will be described.

As shown in FIG. 10, the construction principle of the end seal structure is basically the same as that of the cylindrical seal structure, and includes a spring oil 42 having a shaft hole in the center, a dump oil 43 having almost the same shape, and a seal oil 44. Consisting of three disc-shaped elastic foils, the dump oil 43 and the spring oil 42 have a plurality of door-shaped recesses 4 arranged radially on their lower surfaces.
5. As shown in FIG. 11, the door-shaped concave portion 45 is closed on the outer circumferential side to maintain airtightness on the outer circumferential side of the disk-top oil and to leave a mounting ring 47 for providing a plurality of mounting holes 46, and is closed on the inner circumferential side. The inner circumferential side is open to allow large elastic deformation. The difference between the spring oil 42 and the dump oil 43 is that there is a difference in the machining position of a plurality of door-shaped recesses 45 equally distributed in the circumferential direction with respect to the circumferential position of the mounting hole 46. That is, as shown in FIG. 10, the door-shaped recesses 45 are processed to be shifted from each other by 1/2 of the pitch angle θ,
As a result, the springiness in the thickness direction of the foil is distributed in the circumferential direction. On the other hand, the seal oil 44 is illustrated as having a plurality of spiral groups 48 engraved on its upper surface, and a plurality of mounting holes 46 are formed on the outer circumferential side of the spiral group 48.
A mounting ring 47 is provided with a land portion 49 on the inner circumferential side that largely controls sealing performance. The spiral group 48 has a depth of about one-half the thickness of the foil shown in FIG. 12, and its width gradually becomes narrower in the direction of the arrow indicating the direction of rotation of the runner.

FIG. 13 shows an embodiment of a non-contact type end face sealing device equipped with such three foil elements. Oil element mounting ring 4
7, 47, and 47 parts are overlapped and placed on the mounting plate 50,
By aligning the mounting holes 46, overlapping the clamping plates 51, and tightening the mounting bolts 52, the sealing performance in the radial direction between the three foil elements is improved. An elastic member 54 such as an airtight bellows connected to the holder 53 is connected to one end of the mounting plate 50 on the opposite side to the runner 56 side where the foil element is tightened, and the elastic member 54 is connected to the holder 53 while maintaining airtightness between the holders 53 and the holder 53. The oil shaft seal element 55 is elastically supported.

The cylindrical seal device described above functions as a perfectly circular plain bearing and stably maintains the narrow seal gap C to exert its sealing function.
The spiral group type end face sealing device exhibits a bearing function and a sealing function particularly by the pressure increasing action of the group 48. That is, in the end face type seal structure, a pump-in type spiral group 48 as shown in FIG. 10 is machined on the upper surface of the seal oil 44, and as shown in _FIG . It is designed to pump in toward the high pressure side (inner peripheral side P ₁ ). Therefore, the spiral group 48 not only has a bearing function but also functions to raise the pressure of the low-pressure side fluid P ₂ to the group end and prevent the high-pressure fluid P ₁ from flowing outward, thereby enhancing the sealing performance. . It should be noted that the sealing performance largely depends on the size of the seal gap C between the land portion 49 of the seal oil 44, and how the seal gap C between the land portion 49 can be stably kept small governs the overall seal performance. do.

By the way, due to the design of the non-contact end seal structure,
Pressure balance is important. As shown in FIG. 14, P ₂ ~ acting on the upper surface of the seal oil 44
The integral value of P′ ~ P ₁ and P ₂ acting on the mounting plate 50,
The pressure balance is determined so that the sum of P ₁ and the offset F ₀ of the elastic member 54 etc. is equal in a steady state. Here, P' is the pressure generated at the group end of the spiral group 48, and P ₂ and P ₁ are:
It is a function of rotational speed and working clearance.

In addition, a pump-out type can also be considered as a spiral group type. This is a structure in which the group is provided on the inner circumferential side and the land portion is provided on the outer circumferential side.
The pressure balance will be as shown in the figure. That is,
The pumping function of the group has the effect of increasing the pressure of the low-pressure side fluid of _P2 outward and providing a bearing function, and restricting the high-pressure side fluid of _P1 from flowing into the inner peripheral side. The above-mentioned sealing function is not a characteristic of the foil structure, since a normal rigid face seal has a similar effect.

In particular, end face seals with a foil structure exhibit superior functionality compared to rigid face seals in high-speed ranges. That is, since the non-contact type end seal is operated with a very narrow operating clearance, in-plane heat generation occurs due to fluid shear heat in a high-speed region, and the sealing surface is thermally deformed and its flatness is reduced. However, the non-contact end seal having a foil structure according to the present invention has a function that can cope with the above-mentioned thermal denaturation. As shown in FIG. 16, even if the runner 56 is deformed, the sealing surface backed up by the spring oil 42 and dump oil 43 having the door-shaped recess 45 has flexibility, so the runner 56
6, and can maintain non-contact property. As a result, it is possible to prevent the use limit of the high-speed seal from decreasing due to thermal deformation of the sealing surface, and the cause of this type of trouble can be eliminated. Furthermore, the flexibility of the foil element extends not only to thermal deformation but also to improved tolerance against centrifugal deformation, intrusion of foreign matter, etc., and can greatly expand practicality.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(1) Since it has an elastic oil laminated structure consisting of seal oil, dump oil, and spring oil, even if the seal surfaces are deformed due to shear heat of the fluid that occurs at high speeds and high temperatures, and thermal and centrifugal expansion, the elastic oil remains intact. Due to the springiness and damping properties of the oil, the seal gap never becomes zero or there is no contact, so problems such as seizing or clinging do not occur, and a small gap can be stably maintained. .

(2) Furthermore, the spring and damping properties of the elastic foil provide a large self-aligning effect, making assembly easy.

(3) Furthermore, since the seal oil, dump oil, and spring oil are integrally molded continuously rather than separately, the number of parts is small, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of essential parts showing a preferred embodiment of the present invention, FIG. 2 is an exploded perspective view of the foil element in FIG. 1, and FIG. 3 is a spring foil,
Fig. 4 is a perspective view illustrating the fitted state of the mating ends of the dump oil or seal oil, Fig. 4 is a perspective view illustrating the fitted state of the mating ends of the rudder oil, and Fig. 5 shows the oil shaft seal element incorporated. Side sectional view of floating ring type shaft seal device,
6 is a front sectional view of the foil shaft seal element shown in FIG. 5, FIG. 7 is a side sectional view of a fixed ring type shaft seal device incorporating the foil shaft seal element, and FIG. 8 is a modification of FIG. 1. 9 is a developed view of the foil element shown in FIG. 8, FIG. 10 is an exploded plan view of the foil element showing another embodiment of the present invention, and FIG. 11 is a exploded view of the foil element shown in FIG. FIG. 12 is a perspective view of the main parts of the spring oil or damp oil, FIG. 13 is a side sectional view of an end seal device incorporating the oil element of FIG. 10, and FIG.
Figure 4 is a state diagram of the pump-in type pressure balance of the spiral group type end seal, Figure 15 is a state diagram of the same pump-out type pressure balance, and Figure 16 is the oil diagram when the runner is deformed in Figure 13. Fig. 17 is a cross-sectional view showing the correspondence of elements, and Fig. 17 is a schematic configuration diagram of a conventional cylindrical seal.
FIG. 8 is also a schematic diagram of the end face type seal. In the figure, 8 is a fixed system bearing surface, 10 is a spring oil, 11 is a dump oil, 12 is a seal oil, 14 is a rotating shaft, 30 is a spring oil, 31 is a dump oil, 32 is a seal oil, and 34 is a fixed oil. In the system bearing surface, 36 is a continuously integrated elastic foil, 42 is a spring foil, 43 is a damp oil, 44 is a seal oil, and 56 is a shaft runner.

Claims (1)

[Scope of Claims] 1. A sealing oil that generates a fluid film pressure to form a seal gap between a rotating shaft and a fixed system bearing surface, a damping oil that dampens vibrations of the sealing oil, and a damping oil that dampens the damping oil. A shaft seal device characterized in that it has an elastic foil laminated structure comprising a spring foil elastically supported on the fixed system support surface. 2 Seal oil that generates a liquid film pressure to form a seal gap with the rotating shaft, a damp oil that dampens vibrations of the seal oil, and a spring oil that elastically supports the damp oil on a fixed system support surface. are continuously integrated to form an elastic foil, and the elastic foil is laminated between the rotating shaft and the fixed system support surface so as to be wrapped around the rotating shaft. Shaft seal device.