JPH0147756B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a wet motor type internal pump for circulating reactor cooling water, which operates only when the pump is disassembled and reassembled to prevent leakage of the reactor cooling water. This invention relates to a secondary seal device for an internal pump.

[Prior Art] A conventional internal pump is a wet motor type pump installed at the bottom of a reactor pressure vessel 1, as shown in FIG. a differential user 5, a shaft 4 housed in the motor case 2, a stretch tube 6, a secondary seal 7, a motor section 8,
The motor section consists of a cylinder 9, a bolt 10, and an auxiliary cover 11. The motor section 8 has a structure that allows it to be taken in and out from under the motor case 2, and when removing or installing the motor section 8 from the motor case 2, the flange 4a near the upper end of the shaft 4 and a specially finished strainer are used. The upper end surface 6a of the tube 6 contacts to form a primary seal, and the secondary seal 7 is activated by pressure water from the outside to drain the reactor cooling water in the reactor pressure vessel 1. Now I can get the job done without any hassle.

Conventionally, the structure of this secondary seal was as shown in FIGS. 2 and 3. Secondary seal box 12
A circular sealing member having a trapezoidal cross section, for example, a sealing rubber 14, is housed in 13 and 13.
The seal rubber 14 is sealed by pressure water injected from the chamber.
was transformed from the standby state shown in FIG. 2 to the operating state shown in FIG. 3 to prevent reactor cooling water that had leaked through the primary seal and flowed into chamber B from flowing into chamber C. When the pressure water from the outside is released, the seal rubber 14 deforms by its own elastic deformation force.
The operating state shown in the figure returns to the standby state shown in FIG. 2.

[Problem to be solved by the invention]

However, with the structure of the seal rubber 14 of the secondary seal according to the prior art, especially when the secondary seal is in an operating state for a long time, as shown in FIG.
A protrusion 14c is formed on the seal rubber 14,
Therefore, even if the pressure water from the outside is released, the seal rubber 14 may not return from the operating state shown in FIG. 4 to the standby state shown in FIG. 2, which is a serious drawback. In order to increase the force for returning from the operating state to the standby state, the larger the inclination angle θ of both side surfaces of the seal rubber 14, the more easily the protrusion 14c will form, and even if the return force increases, the protrusion 14c However, the seal rubber did not return to its standby state and was insufficient as a secondary seal device for an internal pump that required high reliability.

Further, as an improvement on the above-mentioned conventional technique, there is also one described in Japanese Patent Application Laid-Open No. 55-27586.
Even with this prior art, in order to increase the return force of the seal rubber, the angle of inclination of the conical groove must be increased, and if the angle of inclination is increased, sufficient pressing force of the seal rubber against the shaft cannot be obtained. For this reason, the angle of inclination cannot be made large, and a secondary sealing device capable of obtaining a sufficient return force of the seal rubber cannot be realized.

An object of the present invention is to provide a secondary sealing device for an internal pump that reliably returns from an operating state to a standby state when pressure water from the outside is released.

[Means to solve the problem]

In order to achieve the above object, the present invention has a motor case provided at the bottom of a nuclear reactor pressure vessel, and a motor section and shaft provided within the motor case, and the motor case and shaft are connected by pressurized water from the outside. In the internal pump, the secondary seal is provided in a seal box provided on the inner surface of the motor case and a seal chamber configured by the seal box. and a sealing member having a radial direction, and the sealing chamber is formed to have a curved wall that gradually expands from the shaft side toward the outside in the radial direction of the shaft,
Both side surfaces of the sealing member have a portion formed perpendicular to the shaft on the shaft side, and a curved surface conforming to the shape of the end surface that contacts the sealing member of the sealing box toward the outside in the radial direction of the shaft. It is characterized by having a part.

[Effect]

According to the present invention, the angle of inclination of the curved wall of the seal chamber and the seal member increases as the radially outer side of the shaft (the outer circumferential side of the seal member) increases, so that a sufficient return force can be obtained on the outer circumferential side of the seal member. Further, since the seal member is configured to deform more greatly toward the outer circumference where the width thereof is larger, the seal member can be easily deformed, and the pressing force of the seal member against the shaft can be sufficiently large. Since the inner circumferential side (shaft side) of the seal member is perpendicular to the shaft, it does not deform and no protrusions occur as in the conventional case.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 5 to 8. The seal chamber constituted by the seal boxes 12 and 13 has a curved wall that gradually expands from the inner circumferential surface (on the shaft side) facing the shaft (not shown) toward the outer circumferential surface (radially outward of the shaft). have. Further, the sealing member, for example, the sealing rubber 14 that is loosely fitted into the sealing chamber, has both side surfaces formed perpendicularly to the shaft.
a, and a portion 14b having a curved surface matching the shape of the end surface that contacts the sealing members of the sealing boxes 12 and 13. The vertical portion 14a is formed on the shaft side, and the curved portion 14b is formed on the outside in the radial direction of the shaft. With this configuration, as shown in FIG.
Since the inclination angle θ becomes larger closer to the outer circumference of the seal box 4, the component of the reaction force F from the seal box 12 or 13, that is, the return force _F1 becomes larger. In addition, the seal rubber 14
The restoring force is only the deformation force of the portion 14b whose side surfaces are curved, and the portion 14a formed perpendicular to the shaft is not deformed, so the protrusion 14c as shown in FIG. 4 does not occur. do not have.

In this embodiment, a spring iron plate 15 as shown in FIG. 7 or 8 is provided in a portion 14b of the seal rubber 14 where both side surfaces are curved.
A garter spring 16 for holding it is installed outside the spring iron plate 15. This results in
It is possible to further increase the force for returning the seal rubber 14 from the operating state to the standby state.
It is preferable that the spring iron plate 15 and the garter spring 16 be installed, but they do not need to be installed.

〔Effect of the invention〕

According to the present invention, the force with which the sealing member of the secondary sealing device returns from the operating state to the standby state is large;
Furthermore, no protrusions are formed on the sealing member that would pose an obstacle upon return. Therefore, there is an effect that a secondary sealing device for an internal pump can be obtained that can reliably return the sealing member from an operating state to a standby state by releasing pressure water from the outside.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of the internal pump, Figure 2
The figure is a vertical cross-sectional view of the secondary seal standby state in a conventional device, FIG. 3 is a vertical cross-sectional view of the secondary seal operating state in the conventional device, FIG. Figure 5 is an explanatory longitudinal cross-sectional view showing one embodiment of the device of the present invention (secondary seal operating state), Figure 6 is an explanatory diagram of the return force of the seal member, and Figures 7 and 8 are examples of a spring iron plate, respectively. FIG. 1...Reactor pressure vessel, 2...Motor case,
3... impeller, 4... shaft, 5... differential user, 7... secondary seal, 12, 13... seal box, 14... seal rubber, 15... spring iron plate,
16...Gata Spring.

Claims (1)

[Claims] 1. It has a motor case provided at the bottom of the reactor pressure vessel, and a motor part and shaft provided within the motor case, and the space between the motor case and the shaft is sealed by pressurized water from the outside. In the internal pump equipped with a secondary seal, the secondary seal includes a seal box provided on the inner surface of the motor case, and a seal member provided in a seal chamber configured by the seal box. , the seal chamber is formed to have a curved wall that gradually expands from the shaft side toward the outside in the radial direction of the shaft, and both side surfaces of the seal member are formed with the shaft side being perpendicular to the shaft. and a portion having a curved surface matching the shape of the end surface that comes into contact with the sealing member of the sealing box toward the outside in the radial direction of the shaft.