JPS6135427B2 - - 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 type, 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, 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.

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.

Figure 1 shows the conventionally considered cooling liquid guide for a liquid-cooled rotor.
1 is a diagram showing an inlet/outlet device, and 1 is an inlet pipe to which a cooling liquid, 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 the 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, the second
In the figure, 2c is a plurality of protruding pieces (the figure shows a case of 6 pieces) formed integrally with the outer periphery of the inflow pipe 2, and these protruding pieces 2C serve as spacers between the inflow pipe 3 and the outflow pipe 3. This serves to integrally connect the inflow pipe 2 and the outflow pipe 3, and also serves to reinforce both pipes 2 and 3. The inflow pipe 2 and the outflow pipe 3 having the protruding piece 2c are firmly connected together by shrink fitting, for example, to form 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, the rotor shaft 5 is provided with an inflow path 5b and an outflow path 5c, which 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 cooling liquid, and after the rotor coil is circulated and cooled as described above, it is discharged from the opening 3a of the outflow pipe 3 via the outflow passages 5c and 3b. . 61 is this opening 3a
This is the first outlet chamber for receiving the liquid discharged from the tank, and is configured to always remain full of coolant to prevent the coolant (pure water) from coming into contact with the atmosphere and becoming contaminated. . 71 is a first outlet pipe for leading out the cooling liquid from this first outlet chamber;
The coolant drawn out from this first outlet pipe does not come into contact with the atmosphere and is not contaminated as described above, so after lowering the temperature with a heat exchanger (not shown), etc. ) to the inlet pipe 1 and subjected to recirculation. Reference numeral 81 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 fixed 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. Reference numeral 82 denotes a second outlet chamber for suppressing leakage between the first outlet chamber 61 and the rotating supply/discharge pipe 4.
The labyrinth seal 62 is a second outlet chamber that receives leakage from the first outlet chamber 61 that has passed through the second labyrinth seal. This second outlet chamber 62 is different from the first outlet chamber 61 described above and is not filled with cooling liquid, so there is a risk that the cooling liquid (pure water) may come into contact with the atmosphere and be contaminated. Reference numeral 9 denotes an air supply pipe to prevent this, and by constantly supplying a cool gas such as nitrogen or hydrogen to the second outlet chamber 62 through this air supply pipe,
The pressure within the second outlet chamber 62 is always kept slightly higher than atmospheric pressure to prevent atmospheric air from entering the second outlet chamber. Therefore, this second
Since the leakage liquid from the outlet chamber 62 does not come into contact with the atmosphere and is not contaminated, the coolant drawn out from the second outlet pipe 72 is not used in the heat exchanger or the pump in the same way as the coolant drawn out from the first outlet chamber 61. It is provided for recirculation via a feed pump (none of which is 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 this area will be contaminated by the atmosphere.
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 a direction opposite to the rotational direction, and during high-speed rotation, the pumping effect created by the opposing stationary surface 85 minimizes the amount of sealing fluid leaking into the third outlet chamber 63. It can be kept to a small value.

In the seal of the conventional configuration described above, the water supply pipe 4
When the water supply pipe 4 is at rest, or when the rotational speed of the water supply pipe 4 is low and the pumping effect by the screw is not sufficient, a large amount of sealing liquid leaks into the third outlet chamber containing the atmosphere. However, since the capacity of the sealing fluid supply device is determined by the amount of leakage when the seal is at rest or when rotating at low speed, leakage when the seal is at rest or when rotating at low speed is a fatal flaw in conventional seals.

Not limited to the screws mentioned here as an example, but with structures in which sealing is achieved by the pumping effect of rotation, a common drawback is that the sealing effect disappears or deteriorates when the screw is stationary or rotates at low speed.

In this way, seals that utilize the pump effect of rotation are non-contact and can exhibit performance even at high circumferential speeds and under vibration, but they have the major drawback that the sealing effect becomes extremely poor when stationary or when rotating at low speeds. had.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by combining a seal that uses a rotating pump effect and a rubber seal whose clearance can be controlled by a control device, it is possible to It is an object of the present invention to provide a shaft sealing device that can suppress the amount of leakage to a low level over the entire rotational speed range from 1 to 4.

Hereinafter, as an embodiment of the present invention, a case where the present invention is applied to a liquid-cooled rotor type rotating electric machine will be described based on the drawings.

In FIG. 3, the second outlet chamber 62 is connected to the air supply pipe 9.
The chamber is filled with a humid gas that is slightly more pressurized than the atmosphere introduced from the air. Reference numeral 84 is a sealing liquid supply pipe for supplying sealing liquid, and the sealing liquid is supplied at a pressure slightly higher than that of the cold gas. Reference numeral 4b denotes a screw machined on the outer periphery of the supply/discharge pipe 4 in a direction opposite to the direction of rotation, and seals the sealing liquid between it and the stationary surface 85 by the pumping effect produced by rotation. Reference numeral 86 is an annular rubber provided so as to surround the supply/discharge pipe 4, and is contracted by pressurized gas introduced from the supply/discharge pipe 87, so that the gap with the supply/discharge pipe can be adjusted. 87a and 87b are valves for adjusting the pressure of gas supplied to the annular rubber 86; for example, 87a is connected to a compressed gas supply device, and 87b is opened to the atmosphere.

88 is a control device for the valves 87a, 87b, which operates the valves 87a, 87b according to a predetermined program based on a signal from the rotation speed detection device 89.
Controls the opening degree.

As shown in FIG. 4, the seal between the screw 4b and the stationary surface 85 due to the pump effect (hereinafter referred to as a screw seal) begins to exhibit its sealing effect when the number of revolutions exceeds a certain level. An annular rubber 86 (hereinafter referred to as a "rubber seal") is pressed onto the outer periphery of the supply/discharge pipe 4 when it is at rest, creating a sealed state with zero leakage. However, during rotation, in order to prevent seizure and wear of the annular rubber 86, a gap between the outer circumferential surface of the supply/discharge pipe 4 and the annular rubber 86 is maintained at least a minimum gap determined depending on the rotation speed.
must be provided between. In other words, as shown in Figure 4, as the rotation speed increases, the rubber seal
Leakage must be increased to prevent seizure and wear.

Looking at FIG. 4, it can be seen that the characteristic curve of the screw seal and the characteristic curve of the rubber seal intersect at a certain rotation speed. That is, below a certain rotational speed, a screw seal does not exhibit sufficient sealing effect, but within that rotational speed range, a rubber seal exhibits sufficient sealing effect.

The control device 88 uses both the rubber seal and the screw seal in the rotation speed range where the sealing performance of the screw seal is insufficient according to the signal from the rotation speed detection device 89.
At higher rotational speeds, the opening degrees of the valves 87a and 87b are controlled, for example, in accordance with a program as described below, so that only the screw seals are used.

In FIG. 5, the opening degree of valves 87a and 87b is controlled by the control device 88 so that the rubber seal is pressed against the outer periphery of the supply/discharge pipe 4 and the amount of leakage becomes zero when the system is stationary. In addition, the control device 88 controls the opening degree of the valves 87a and 87b according to the rotational speed so that the amount of leakage is the minimum that does not cause seizure or wear on the rubber seal up to the rotational speed n _c , and the compression supplied to the rubber seal is Adjust gas pressure. At rotational speeds n _c or higher, screw seals are applied.
Since this is sufficiently effective, the opening degree of the valves 87a and 87b is controlled by the control device 88 so that the pressure of the compressed gas supplied to the rubber seal becomes zero. That is, in this example, the control device 88 controls the valves 87a and 87 in accordance with the rotation speed so that the compressed gas pressure supplied to the rubber seal becomes as shown in the lower half of FIG.
7b.

FIG. 6 shows an example in which the pressure of the compressed gas supplied to the rubber seal is kept constant during low-speed rotation below the rotational speed n _c . In this case, the pressure of the compressed gas supplied to the rubber seal is determined so that the rubber seal does not seize or wear out at the rotational speed n _c , so leakage occurs during low speed rotation compared to the example shown in Figure 5. Although the amount increases, there is an advantage that the structure of the control device 88 can be simple.

In the above embodiment, a threaded seal is used as the seal that utilizes the pumping effect due to rotation, but any seal that utilizes the pumping effect due to rotation may be used. FIG. 7 shows an example in which something other than a threaded seal is used as a seal that utilizes the pump effect due to rotation. That is,
4c is a wing provided on the outer periphery of the supply/discharge pipe 4, which produces a pumping effect during rotation and performs sealing. 86 is an annular rubber, 87 is an air supply pipe, 87a, 87b are valves, 88
89 is a control device, and 89 is a rotational speed detection device, and their functions are the same as those explained in FIG. 3.

Further, in the above embodiment, the case where the control device 88 receives a signal from the rotation speed detection device 89 is explained, but the control device 88 also receives a signal from a leakage detection device (not shown) provided in the outlet chamber 63. Good too.

Further, in the above embodiment, a case where the present invention is applied to a coolant lead-in/out part of a rotating electrical machine has been described, 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, a seal that utilizes the pump effect of rotation and a rubber seal are combined, and the pressure of compressed gas supplied to the rubber seal is controlled by inputting the rotation speed or leakage amount. It is possible to provide a seal structure that suppresses leakage in the entire range from static to high-speed rotation.

[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 embodiment of the present invention, FIGS.
Figure 6 is a diagram showing the characteristic curve of the seal, Figure 7 is a diagram showing the characteristic curve of the seal.
The figure is a diagram for explaining another example of application of the present invention. 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 its flange, 4b is a screw provided on its outer periphery in the opposite direction to the rotation direction, 4c
is a blade, 5 is a rotor shaft, 5a is its flange, 5
b is an inflow path, 5c is an outflow path, 61, 62, 63 are outlet chambers, 71, 72, 73 are outlet pipes, 81, 8
2, 83 is a labyrinth seal, 9 is an air supply pipe, 84
85 is a sealed air supply pipe, 85 is a stationary surface, 86 is an annular rubber, 87 is an air supply pipe, 87a, 87b are valves, 88 is a control device, and 89 is a rotation speed detection device. 〓〓〓〓〓

Claims (1)

[Claims] 1. A first seal provided on the outer periphery of the rotating shaft to prevent leakage of the cooling liquid by the pump effect generated by the rotation of the rotating shaft, and a first seal made of an elastic material provided surrounding the rotating shaft. 2 stickers and
A shaft sealing device comprising: a control device that adjusts a gap between the rotating shaft and the second seal according to the rotational speed of the rotating shaft or the amount of leakage of the cooling liquid.