JPS63170566A - Edge seal - Google Patents

Abstract

PURPOSE:To keep constant pressure at the sliding surface of a seal ring and ensure stable sealing performance by forming a fresh water supply chamber with the flange edge of the rotation main spindle of a water-turbine and the like and a seal ring, and communicating said chamber with a sealed chamber. CONSTITUTION:A circumferential groove is provided on the sliding surface of a seal ring 6 and forms a fresh water supply chamber 9 together with the sliding surface of a flange 2. And when this water supply chamber 9 is communicating with a sealed chamber 12 via a hole 13, fresh water fed from a water supply pipe 10 tends to flow in an arrow mark direction. The seal ring 6 is exposed to an arrow-marked downward load due to sealing pressure Pa and an arrow-marked upward load due to water supply pressure Pb. As the water supply chamber 9 is communicating with the sealed chamber 12, however, the suitable selection of D2 dimensions enables the water supply pressure Pb to balance approximately with the sealing pressure Pa. Consequently, sliding surface pressure working on the seal ring 6 is extremely low and can always be kept constant. Also, even if fresh water supply is interrupted, the sliding surface pressure of the seal ring 6 is free from an abnormal rise due to the sealing pressure Pa.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an end seal suitable for preventing leakage from the main shaft of a hydraulic machine such as a water turbine or a pump.

[Conventional technology]

Generally, in hydraulic machines such as water turbines and pumps, a shaft sealing device is installed near the impeller for the purpose of sealing high-pressure water on the impeller side. FIG. 4 shows an embodiment of an end seal used in a water turbine, in which a flange 2 is formed on each rotation l1Il11, and an impeller 3 is directly connected to the lower end of one rotation shaft 1.

The end seal 4 is installed on the upper part of the impeller 3 and includes a casing 5 surrounding the outer periphery of the flange 2 and a seal case 7 located inside the casing 5 and housing a seal ring 6.
It is attached to the seal case 7 and consists of a seal member formed by an O-ring 8 provided on the surface facing the casing 5 and a coil spring 11 that suppresses the seal case 7. The high pressure water on the Peller 3 side is then sealed.

However, in water turbines, etc., the high pressure water on the impeller side is high pressure water containing sediment led from the dam, so when the water containing sediment flows into the sliding surface of the seal ring 6, the sliding surface of the seal ring 6 and flange 2 As a result, the seal ring 6 is worn out and loses its water-sealing function at an early stage. For this reason, fresh water with a pressure slightly higher than the sealing pressure is supplied to the VfR moving part of the seal ring 6 to prevent water containing earth and sand from flowing into the VfR moving part.

FIG. 5 shows an embodiment of the end seal disclosed in Japanese Utility Model Application Publication No. 58-12678. In this embodiment,
A water supply chamber 9 is formed in the sliding portion of the seal ring 6 and the flange 2, and a water supply pipe 10 is attached to the seal case 7 to supply fresh water from the outside. Therefore, the fresh water supply pressure is slightly higher than that of water containing sediment.

Fresh water flows in the direction of the arrow in the figure, and water containing soil does not enter the sliding surface. In addition, with this type of end seal structure,
The sealing pressure P a acts to suppress the seal ring 6 on the flange 2, and the fresh water supply pressure pb conversely acts on the seal ring 6 to suppress the flange 2.
Since this acts to separate the surface of the flange 2 from the surface of the flange 2, this difference in load is used to set an appropriate sliding surface pressure.

However, in the case of a water turbine, the high-pressure water on the impeller side is high-pressure water led from a dam, and depending on the water turbine, the pressure at the shaft seal varies depending on the water level in a pond such as a dam, so the sealing pressure P
a is not constant. On the other hand, the fresh water pressure Pb supplied from the pump is constant.

Therefore, in the case of a water turbine, since the sliding surface pressure acting on the seal ring 6 changes, there is a drawback that the sealing performance, that is, the amount of water leakage increases as the sealing pressure decreases.

A further problem is that if the water supply pump stops for some reason, the force that was trying to separate the seal ring 6 from the surface of the flange 2 due to the fresh water supply pressure will no longer act, and the sliding surface pressure of the seal ring 6 will become abnormally high. This may lead to burnout accidents.

[Problem that the invention seeks to solve]

As described above, conventional end seals do not take into account problems such as fluctuations in sealing pressure and water supply interruptions, resulting in problems such as a reduction in sealing performance and burnout of seal rings.

An object of the present invention is to provide an end seal that can be used with stable sealing performance while keeping the sliding surface pressure of the seal ring constant at all times.

[Means for solving problems]

The above object can be achieved by communicating the fresh water supply chamber provided at the end face of the seal ring and flange with the sealed chamber so that the fresh water supply pressure is balanced with the pressure in the sealed chamber.

[Effect]

That is, in the present invention, the water supply chamber provided in the seal ring sliding portion and the sealed chamber are communicated with each other, and the end seal is configured so that the fresh water supply pressure is balanced with the sealing pressure. In this configuration, a water supply pump with a capacity commensurate with the amount of water leakage is provided in advance, the fresh water supply pressure is set slightly higher than the sealing pressure, and water is injected into the water supply chamber of the seal ring. However, since the water supply chamber and the sealed chamber are in communication, even if the fresh water pressure is set higher than the sealing pressure, the water supply pressure is balanced with the sealing pressure.

Further, when the water supply is stopped, the pressure water from the sealing side of the communication hole flows into the water supply chamber, so the seal ring always operates with a nearly constant sliding surface pressure.

Therefore, the sealing performance is stable, and the seal ring will not burn out even if the water supply is interrupted.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows the structure of the end face seal according to the present invention.
A flange 2 is formed on the flange 2.

Further, a casing 5 is installed to surround the rotating shaft 1 and the flange 2, and a seal ring 6 housed in a seal case 7 is pressed against the end face of the flange 2. The seal case 7 is supported by the casing 5 so as to be movable upward and downward, and a radial gap between the casing 5 and the seal case 7 is sealed by an O-ring 8.

A plurality of coil springs 11 are installed over the entire circumference of the upper part of the seal case 7 so that the seal ring 6 is reliably pressed against the end surface of the flange 2.

Further, a circumferential groove is provided in the sliding part of the seal ring 6, and a water supply chamber 9 is formed on the sliding surface of the flange 2. Fresh water is supplied to this water supply chamber 9 from a flexible water supply pipe 10. Water is supplied. The water supply chamber 9 and the sealed chamber 12 communicate with each other through holes 1 and 3, and the S1 water is configured to flow in the direction of the arrow in the figure. The communication holes 13 are provided at appropriate positions around the entire circumference of the water supply chamber 9.

Now, in the end seal, first connect the flexible water supply pipe from the water supply pump (not shown) to the water supply chamber 9.
When fresh water is supplied to the area, it tends to flow in the direction of the arrow in the figure. Furthermore, even if fresh water is supplied at a pressure higher than the sealing pressure, the water supply pressure pb will be low unless the water supply chamber 9 and the sealed chamber 12 are in communication with each other through the hole 13. Balance the sealing pressure Pa. Normally, the capacity of this type of water supply pump is at most twice the amount of water leakage, and in the conventional structure, the pressure in the water supply chamber 9 is maintained 1 to 2 kg/rj higher than the sealing pressure, but the present invention In the structure, since the water supply chamber 9 is in an open state through the communication hole 13, the water supply pressure Pb is almost balanced with the sealing pressure Pa. A load in the downward direction of the arrow is applied due to the sealing pressure Pa, and a load in the upward direction is applied due to the water supply pressure pb. Here, water supply room 9
The pressure distribution toward the inner peripheral side of the reseal ring 6 is assumed to be a linear pressure gradient as shown in the diagram2, the load W (load due to hydrostatic pressure) acting on the seal ring 6 is If the dimension of D2 is determined to be Papb, W=O in principle, and it is possible to provide an end seal that is not affected by fluctuations in the sealing pressure Pa. When the load due to hydrostatic pressure is balanced in this way, the load due to the weight of the coil spring 11 and the seal case 7 acts on the seal ring 6, so that the seal ring 6 can be operated with extremely low sliding surface pressure. Furthermore, even if the water supply pump stops, the sealing pressure Pa remains in the water supply chamber 9 through the communication hole 13.
The load balance must be maintained at all times as it acts through the

The reason why the pipe 14 is provided in the communication hole 13 in this embodiment is to prevent dirt particles from accumulating on the seal case 7 during long-term operation and from flowing into the water supply chamber 9. It is a provision.

Figure 3 shows another embodiment. A circumferential groove constituting the water supply chamber 9 is provided on the end face of the flange 2, and the effect is the same as in the embodiment described above. Further, the shape and position of the circumferential grooves provided in the seal ring 7 and the flange 2 are not limited, and may be set to appropriate dimensions and shapes.

〔Effect of the invention〕

According to the invention.

(]) Even if the sealing pressure fluctuates, the sliding surface pressure of the seal ring can always be kept constant, resulting in stable sealing performance.

(2) Even if the fresh water supply is stopped, the sliding surface pressure of the seal ring does not reach an abnormal value like in the past, and operates in the same state as before the water supply was stopped.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an end seal according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the load balance of the end seal, fjS
Figure 3 is a longitudinal section of another embodiment of the present invention. FIG. 4 is a longitudinal sectional view of a conventional end seal installed on a water turbine, and FIG. 5 is a longitudinal sectional view of a conventional end seal. ■... Rotating shaft, 2... Flange, 5... Casing, 6... Seal ring, 7... Seal case, 9
...Water supply room. Figure 1 Figure 2 Country Figure 3 Figure 4

Claims (1)

[Claims] 1. A seal ring and a seal case storing the seal ring are provided in a casing surrounding a rotating shaft with a flange, and the seal ring is pressed against the end face of the flange, and the seal case is configured of the seal case and the casing. A sealing member is provided in a radial gap to constitute an end seal, and a water supply chamber is provided in a sliding portion between the seal ring and the end face of the flange, and the water supply chamber is communicated with the sealed chamber to supply fresh water to the water supply chamber. An end seal characterized by being provided with a means for supplying water.