JPS6150183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a liquid seal for a rotating shaft.

Hereinafter, as an example of a conventional device of this kind, a case where it is applied to a liquid-cooled rotor type rotating electric machine will be described.

As is well known, increasing the capacity of a rotating electric machine depends on how to suppress temperature rise, that is, how to achieve effective cooling. In other words, it is no exaggeration to say that the capacity of a rotating electric machine is determined by its temperature rise suppression, that is, its cooling performance. On the other hand, it is becoming increasingly necessary to increase the single machine capacity of generators among rotating electric machines, especially turbine generators, from the standpoint of improving the efficiency of power plant construction. By the way, a cooling method that circulates hydrogen gas has been used to cool turbine generators so far, and an increase in the capacity of a single unit has been achieved, but this has already reached its limit. A significant increase in capacity cannot be expected. Therefore, there is a strong desire to put another cooling method into practical use.

To meet this demand, it is conceivable to use a cooling fluid with good cooling efficiency, such as water, instead of hydrogen gas as the cooling medium. Based on this idea, it has already been proposed and realized to cool the stator by circulating the coolant, but if we can develop this and successfully circulate the coolant to the rotor. , the cooling effect can be dramatically increased.

However, if we take a turbine generator as an example,
The rotor normally rotates at a high speed of 3,600 revolutions per minute (60Hz), and the biggest problem in realizing this is how to introduce and extract the coolant into such a high-speed rotating body. This has hindered the spread of liquid-cooled rotor-type rotating electric machines.

FIG. 1 is a diagram showing a conventionally considered coolant inlet/output device for a liquid-cooled rotor, and 1 is an inlet pipe to which coolant, such as pure water, is supplied via a feed pump (not shown). . The reason why pure water is used as a cooling liquid is as follows. The coolant is circulated within each tube and the rotor coil as described below, so if water containing impurities is used as the coolant, the impurities may cause corrosion of the tubes and rotor coil. Therefore, it is desirable to use pure water that does not contain any impurities. Reference numeral 2 denotes a circular inflow pipe which has an opening 2a and receives the cooling liquid from the inlet pipe 1 through this opening, and its hollow interior 2b serves as an inflow path for the cooling liquid. 3 is a circular outflow pipe provided around the inflow pipe 2 with a predetermined gap;
The gap 3b between the inflow pipe 2 and the inflow pipe 2 becomes an outflow path for the coolant. 3a is an opening provided at one end of this outflow pipe 3, and the cooling liquid is discharged through this opening. Incidentally, the outflow pipe 3 and the inflow pipe 2 are integrally connected to form a supply/discharge pipe 4 as shown in FIG. That is, in FIG. 2, 2c is a plurality of protruding pieces (the figure shows a case of six pieces) that are integrally formed on the outer periphery of the inflow pipe 2, and these protruding pieces 2c are attached to the outflow pipe 3.
It serves as a spacer between the inflow pipe 2 and the outflow pipe 3 to integrally connect them, and also serves to reinforce both pipes 2 and 3. Inflow pipe 2 having this protruding piece 2c
and the outflow pipe 3 are firmly and integrally connected, for example, by shrink fitting or the like, and constitute a supply/discharge pipe 4. 4a is a flange formed at the end of this supply/discharge pipe 4, and 5 is a rotor shaft of a rotating electric machine having a flange 5a that is in close contact with this flange and connected with, for example, a bolt (not shown). Needless to say, a rotor coil (not shown) is attached to the child shaft. Further, as is clear from the figure, this rotor shaft 5 is provided with an inflow path 5b and an outflow path 5c that communicate with the inflow path 2b and the outflow path 3b of the supply/discharge pipe 4, respectively, and the supply/discharge pipe 4 is provided with an inflow path 5b and an outflow path 5c. After the coolant is circulated through the rotor coil, it is discharged into the outflow passage 5c. Note that the arrows in the figure indicate the flow of the coolant, and as described above, after the coolant circulates and cools the rotor coil, it flows from the opening 3a of the outlet pipe 3 via the outlet channels 5c and 3b. It is discharged. 6
Reference numeral 1 denotes a first outlet chamber for receiving the liquid discharged from the opening 3a, and the chamber is always kept full of the cooling liquid to prevent the cooling liquid (pure water) from coming into contact with the atmosphere and being contaminated. It is configured as follows. 71
is the first outlet pipe for leading out the coolant from this first outlet chamber, and the coolant led out from this first outlet pipe does not come into contact with the atmosphere and is not contaminated as described above. , the temperature is lowered by a heat exchanger (not shown), etc., and then sent to the inlet pipe 1 again via a feed pump (not shown), where it is subjected to recirculation. 8
Reference numeral 1 denotes a first labyrinth seal for preventing the coolant from leaking from inside the inlet pipe 1 to the first outlet chamber 61, and it is impossible to completely eliminate leakage between the rotating part and the stationary part. Therefore, efforts are made to minimize leakage. This leakage is not a big problem because it is circulated again via the first outlet pipe 71 as described above, but if the leakage amount is too large, the efficiency will deteriorate, so it goes without saying that it is better to have a smaller amount. Nor. 82 is a second labyrinth seal for suppressing leakage between the first outlet chamber 61 and the rotating supply/discharge pipe 4, and 62 is a seal from the first outlet chamber 61 that has passed through the second labyrinth seal. A second outlet chamber for receiving leakage liquid. Unlike the first outlet chamber 61, this second outlet chamber 62 is not filled with cooling liquid;
Therefore, there is a risk that the coolant (pure water) may come into contact with the atmosphere and be contaminated. Reference numeral 9 denotes an air supply pipe for preventing this, and by constantly supplying a clean gas such as nitrogen or hydrogen to the second outlet chamber 62 through this air supply pipe, the inside of the second outlet chamber 62 is The pressure is always kept slightly higher than atmospheric pressure to prevent atmospheric air from entering the second outlet chamber. Therefore, since the liquid leaking from the second outlet chamber 62 does not come into contact with the atmosphere and is not contaminated, the second outlet pipe 72
Similar to the cooling liquid drawn out from the first outlet chamber 61, the coolant drawn out from the first outlet chamber 61 is recirculated via a heat exchanger and a feed pump (none of which are shown).

In order to seal off the damp gas in the second outlet chamber 62, a sealing fluid having a pressure slightly higher than that of the damp gas in the outlet chamber 62 is supplied from the sealing fluid supply pipe 84. The sealing liquid passes through the labyrinth seal 83 and leaks into the second outlet chamber 62, but as described above, the coolant drawn out from the second outlet chamber 62 is not purified and is provided for recirculation. Therefore, the sealing fluid, like the cooling fluid, must be pure water. On the other hand, since the third outlet chamber 63 contains the atmosphere,
The sealing fluid that leaks into the tank 63 becomes contaminated with the atmosphere and must be disposed of. Of course, water can be purified and reused, but whether it is discarded or reused, in order to prevent the size of the water purification device or water purification treatment device from becoming large, a third outlet for the sealing liquid is required. It is necessary to suppress leakage into the chamber 63 as much as possible. 4b
is a screw machined on the outer periphery of the supply/discharge pipe in the opposite direction to the rotating direction, and during high-speed rotation, the pumping effect created by the opposing stationary surfaces causes the third outlet chamber 63 of the sealing liquid to flow.
It is possible to suppress the amount of leakage to an extremely small value. Further, reference numeral 86 is an annular elastic material, that is, an annular rubber, provided to surround the supply/discharge pipe 4, that is, the rotating shaft. When the supply/discharge pipe 4 is at rest, compressed gas is supplied from the supply pipe 87 to move the annular rubber 86 into the supply/discharge pipe. By crimping the outer peripheral surface, leakage of the sealing liquid to the third outlet chamber 63 can be prevented.

In the seal configuration described above, during low-speed rotation when the pumping effect produced by the thread is not sufficient, the air pressure supplied from the air supply pipe 87 must be adjusted to suppress leakage of sealing liquid to the third outlet chamber 63. Therefore, it was necessary to create a small gap between the annular rubber 86 and the outer periphery of the supply/discharge pipe.

However, since the rotor shaft 5 to which the supply/discharge pipe 4 is directly connected is supported by a sliding bearing (not shown), the supply/discharge pipe 4 may float up as the rotation increases, or the supply/discharge pipe 4 may Because it overhangs from the rotor shaft 5, it vibrates relatively large when the resonance rotation speed passes, so the annular rubber 86 has a function to follow the movement of the supply and discharge pipe while maintaining a small gap with the outer circumference of the supply and discharge pipe. is required.

The previously used annular rubber 86 could not be expected to have a function such as following the movement of the supply/discharge pipe as described above, so the annular rubber 86 was designed to maintain a small gap with the outer periphery of the supply/discharge pipe. When the supply and exhaust pipes were rotated to a certain point, the rubber seizes up or wears out.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and by changing the shape of the annular rubber 86, the annular rubber 86 has a function of following the movement of the supply/discharge pipe. Additionally, it is an object of the present invention to provide a device in which there is little risk of the annular rubber 86 seizing or wearing out even if the supply/discharge pipe rotates while maintaining a small gap between the annular rubber 86 and the outer periphery of the supply/discharge pipe. It is said that

An embodiment of the present invention will be described with reference to the drawings. In FIG. 4, the annular rubber 86 has a large width-to-thickness ratio. This will be obvious when compared with the conventional product shown in FIG. The reason for increasing the width and thickness of the rubber will be explained below.

FIG. 5 shows a state in which pressure is applied to the annular rubber 86 of FIG. 4. In the figure, P _G is the pressure due to compressed gas, P _W is the pressure of the liquid to be sealed, and P _L
is the pressure of the liquid on the annular rubber surface 86a. P _G is distributed evenly around the outer circumference of the rubber, but since P _W is applied to only half of the inner surface of the rubber, the rubber is inclined as shown in FIG. Due to this inclination, the pressure P _L on the annular rubber surface 86a becomes a curved line that bulges above the straight line connecting P _W and 0, as shown in FIG.

FIG. 6 shows a state where the supply/discharge pipe 4 is eccentric by e.

As a result of the eccentricity of the supply/discharge pipe 4, the gap between the annular rubber surface 86a and the supply/discharge pipe 4 becomes narrow in the upper half of FIG. 6, but becomes wider in the lower half.

As a result, the upper and lower halves have an annular rubber surface 86.
The pressures PL ₁ and PL ₂ at a have different distributions as shown in FIG. 7, and the pressure PL 1 in the upper half _{where the gap is narrower exceeds the pressure PL 2 in} the lower half where the gap is wider.

In other words, uneven pressure occurs between the upper and lower halves,
The force indicated by the horizontal line in FIG. 7 pushes the annular rubber 86 in a direction that equalizes the gap.

Therefore, the annular rubber 86 shown in FIG.
It has a function of following the movement of the supply/discharge pipe 4.

According to the teachings of fluid mechanics, when there is a relationship h ₂ /h ₁ ≈2.2 between the gaps h ₁ and h ₂ shown in FIG. 5, the integral value of PL becomes maximum.

Therefore, at the maximum rotation speed at which the annular rubber 86 is used for sealing, the minimum clearance at which the annular rubber 86 starts to wear out is taken as h ₁ , and depending on P _G and P _W at that time, h ₂ = 2.2h ₁ . It is most effective if the dimensions of the annular rubber are determined so that it is inclined.

In the above description, an example has been given in which the present invention is applied to a coolant inlet/output device for a cooling rotor type rotating electric machine, but it goes without saying that the present invention is effective for all liquid seals of rotating shafts.

As described above, according to the present invention, by increasing the width-to-thickness ratio of the annular rubber, the annular rubber has the ability to follow the movement of the shaft.
Therefore, even if the shaft rotates while maintaining a small gap between the annular rubber and the shaft, it is possible to provide an apparatus in which there is little risk of the annular rubber being seized or worn out.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional coolant inlet/output device, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a diagram showing an example of the conventional device, and Fig. 4 is an axis of the present invention. FIG. 5 is a diagram showing an embodiment of the sealing device, FIG. 5 is a diagram showing the shaft sealing device of the present invention in a state where pressure is applied, FIG. 6 is a diagram showing the shaft sealing device of the present invention when the shaft is eccentric, and FIG. Figure 7 is a diagram showing the pressure distribution when the shaft is eccentric. In addition, the same reference numerals in each figure indicate the same or equivalent parts, 1 is the inlet pipe, 2 is the inflow pipe, 2a
is its opening, 2b is an inflow path, 2c is a protruding piece, 3
is an outflow pipe, 3a is its opening, 3b is an outflow path,
4 is a supply/discharge pipe, 4a is a flange thereof, 4b is a screw provided on its outer peripheral surface in the opposite direction of rotation, 5
is the rotor shaft, 5a is its flange, 5b is an inflow path, 5c is an outflow path, 61, 62, 63 are outlet chambers,
71, 72, 73 are outlet pipes, 81, 82, 83 are labyrinth seals, 9, 87 are air supply pipes, 84 is a sealing liquid supply pipe, 85 is a stationary surface, 86 is an annular rubber,
86a is the surface facing the shaft, 86 is 86
It is a retainer.

Claims (1)

[Claims] 1. An annular elastic member having a surface facing the outer periphery of the rotating shaft through a small gap on the inner periphery at the center of the width in the axial direction, and having both ends in the width direction fixed so as to surround the rotating shaft. , an air supply pipe for supplying compressed gas so as to apply pressure to the outer circumferential surface of the elastic member, and a shaft sealing device for sealing a liquid to be supplied around the outer circumference of the rotating shaft, wherein the elastic member is connected to the opposite side of the rotating shaft. A shaft sealing device characterized in that the surface is inclined in the axial direction so that the ratio of the width to the thickness thereof is increased so as to be able to follow the radial movement of the rotating shaft.