JP2001173794A - Shaft seal device for pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sealing fluid in a sealing chamber from being replaced by fluid to be sent even when pressure fluctuation of the fluid to be sent is large, and to improve durability of a shaft seal device. SOLUTION: In this shaft seal device, the sealing chamber 3 is formed between a rotary shaft 1 of a volute pump and a stuffing box 2, and multiple elastic seals 4A, 4B, 4C, 4D and a mechanical seal 6 are provided on the F-side of fluid to be sent and an atmospheric air side of the sealing chamber 3, respectively, to pressurize and supply grease G into the sealing chamber 3. Among the multiple elastic seals 4A, 4B, 4C, 4D, the elastic seals 4A, 4B on the fluid F-side on the interior side are mounted to a direction to seal against the fluid F-side, and the elastic seals 4C, 4D on the mechanical seal 6 side are mounted to a direction to seal against the mechanical seal 6 side. A supplying hole 8 for the grease G is provided between the elastic seals 4B, 4C opposite in direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device for a pump such as a slurry pump or a sand pump for transporting a fluid containing solid particles such as fine suspended particles, earth and sand, sand and pebbles.
The present invention relates to a shaft seal device for a pump used in a series operation or under a condition where pressure fluctuation is large due to a change in a state of a fluid to be transmitted, where it is difficult to inject fresh water from the outside.

[0002]

2. Description of the Related Art Conventionally, a gland packing, a mechanical seal, an oil seal sealed with a lip portion, and the like have been used for a shaft sealing device of a pump. In these shaft seal devices, it is necessary to supply another type of washing water in order to avoid the influence of the abrasive fluid to be transferred containing solid particles on the shaft seal portion.

On the other hand, in a pump for transporting a high-pressure and high-concentration slurry used for excavation of a large depth and a long distance where it is difficult to inject fresh water from the outside, an elastic fluid is applied to the seal chamber on the side of the fluid to be transmitted. A shaft seal device is used in which a mechanical seal is provided on the seal and the atmosphere side, and a sealing fluid is supplied under pressure from the mechanical seal side to prevent a fluid to be transmitted from entering the shaft seal portion.

In this shaft sealing device, as shown in FIG. 3, a seal chamber 3 is formed between a rotary shaft 1 of a centrifugal pump and a stuffing box 2, and the seal chamber 3 adjacent to a casing 9 is fed. A plurality of elastic seals 4 are mounted on the fluid F side so that the lip slides on the sleeve 5 of the rotating shaft 1, and the seal chamber 3
A mechanical seal 6 is provided on the atmosphere side and is covered with a seal cover 7.

At a position facing the mechanical seal of the stuffing box 2, a supply hole 8 for supplying a pressurized sealing fluid S into the seal chamber 3 is provided. In this shaft sealing device, the elastic seal 4 is mounted in a direction to seal against the fluid F to be transmitted, that is, with the lip facing the fluid F to be transmitted, and when the fluid F is at a high pressure. Demonstrate a sufficient sealing effect. However, the transmitted fluid F
When the pressure on the pressure side becomes negative pressure, as shown in FIG. 4, the sealing fluid S supplied into the seal chamber 3 is sucked into the fluid to be transmitted F side, and a vacuum portion V is generated in the seal chamber 3, and the fluid to be transmitted F side is formed. When the high pressure and the negative pressure are repeatedly generated, the sealing fluid S in the sealing chamber 3 is replaced with the fluid F to be transmitted.

For this reason, the mechanical seal 6 rotates in the wearable fluid F containing the replaced solid particles, so that the sliding surface wears out early and secures a stable seal life. It was difficult.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem in the shaft sealing device of a pump. Even when the pressure of the fluid to be transmitted fluctuates greatly, the sealing fluid in the sealing chamber is not sealed. It is an object of the present invention to provide a shaft seal device for a pump that can prevent the mechanical seal from being worn and has excellent durability without being worn.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a seal chamber is formed between a rotary shaft of a centrifugal pump and a stuffing box, and a plurality of elastic chambers are provided on a fluid-receiving side of the seal chamber. A seal, a mechanical seal is provided on the atmosphere side, and in a shaft seal device of a pump for supplying a sealing fluid into the seal chamber under pressure, the elastic seal on the fluid-to-be-transferred side of the plurality of elastic seals is arranged with respect to the fluid-to-be-transferred The elastic seal on the mechanical seal side is mounted so as to seal with respect to the mechanical seal side, and a sealing fluid supply hole is provided between the elastic seals having different directions.

When the pressure of the fluid to be transmitted is high, the elastic seal on the fluid to be transmitted side and the sealing fluid supplied under pressure prevent the fluid to be transmitted from entering the seal chamber. When the pressure of the fluid to be transmitted becomes negative, the elastic seal on the mechanical seal side prevents the sealing fluid from being sucked into the fluid to be transmitted. Therefore, even under the condition that high pressure and negative pressure are repeatedly generated on the fluid to be transmitted side, the sealing fluid in the sealing chamber is not replaced with the fluid to be transmitted, and the sliding surface of the mechanical seal contains solid particles. Since there is no direct contact with the abrasive fluid to be transferred, a stable seal life can be ensured.

When a pressure detector for detecting the pressure in the seal chamber and a seal fluid supply device for replenishing the seal fluid into the seal chamber when the pressure detected by the pressure detector falls below a predetermined pressure are provided, Even if the sealing fluid is slightly sucked in when the pressure on the side becomes negative, a slight amount of the sealing fluid equivalent to the sucked amount is immediately supplied into the sealing chamber, so that the sealing effect is further ensured.

[0011]

FIG. 1 is a longitudinal sectional view showing the structure of a shaft sealing device of a pump according to an embodiment of the present invention, and FIG. 2 is an explanatory view of the operation of the shaft sealing device. In this shaft sealing device, a seal chamber 3 is formed between a rotary shaft 1 of a centrifugal pump and a stuffing box 2, and a plurality of elastic seals 4 </ b> A are disposed on a fluid F side of the seal chamber 3 adjacent to a casing 9. 4B, 4
C and 4D are mounted so that the lip slides on the sleeve 5 of the rotating shaft 1, and a mechanical seal 6 is provided on the atmosphere side of the seal chamber 3 and is covered with a seal cover 7.

A plurality of elastic seals 4A, 4B, 4C, 4D
The elastic seals 4A and 4B on the side of the fluid F to be transmitted
And the elastic seals 4C and 4D on the mechanical seal 6 side are sealed with respect to the mechanical seal 6 side, that is, the lip is Is attached to the mechanical seal 6 side.

A sealing ring 10 is provided between the elastic seals 4B and 4C having different directions, and a supply hole 8 for a sealing fluid is opened in the sealing ring 10. Grease G is supplied under pressure from the fluid supply device 11 as a sealing fluid. The grease G may be continuously supplied under pressure in a small amount, may be supplied under pressure intermittently, or an appropriate supply method may be selected depending on operating conditions.

The shaft sealing device is provided with a pressure detector 12 for detecting the pressure in the seal chamber 3. When the pressure detected by the pressure detector 12 drops below a predetermined pressure, a sealing fluid is provided. The supply device 11 supplies grease G into the seal chamber 3. When the pressure of the fluid F is high, the grease G supplied from the sealing fluid supply device 11 into the sealing chamber 3 is pressurized.
Is partly pushed out to the fluid F side through the sliding contact surface between the lips of the elastic seals 4A and 4B and the sleeve 5 on the fluid F side, and the fluid is The solid particles in F are prevented from entering the sealing chamber 3.

When the pressure of the fluid F is reduced to a negative pressure, as shown in FIG.
Is sucked into the fluid to be transmitted F side, but the grease G on the mechanical seal 6 side from the water sealing ring 10 is blocked by the elastic seals 4C and 4D on the mechanical seal 6 side. There is no. In the case where a vacuum portion V is generated near the water sealing ring 10,
The pressure detector 12 detects a decrease in pressure, and the grease G is supplied from the sealing fluid supply device 11 into the sealing chamber 3. However, the amount of the grease G sucked into the fluid F to be transmitted is small. Since the amount of grease G supplied from the sealing fluid supply device 11 may be small, the vacuum portion V is quickly eliminated.

Therefore, even if the pressure of the fluid F is changed to a high pressure after a negative pressure, the grease G in the seal chamber 3 is not replaced with the fluid F, and the mechanical seal 6 is formed of solid particles. Therefore, there is no occurrence of a situation in which abrasion is caused by direct contact with the wearable fluid F containing abrasion. Therefore, a good sealing effect and a stable sealing life can be secured.

[0017]

As described above, the shaft sealing device of the pump according to the present invention can be used even when the pressure fluctuation of the fluid to be transmitted is large.
Since the fluid for sealing in the seal chamber can be prevented from being replaced with the fluid to be transmitted, the mechanical seal is not worn and has excellent durability. Further, when a pressure detector for detecting the pressure in the seal chamber and a sealing fluid supply device for replenishing the seal fluid into the seal chamber when the pressure detected by the pressure detector falls below a predetermined pressure are provided, the fluid to be transmitted is provided. Even if the sealing fluid is slightly sucked in the case of the negative pressure, the sealing fluid is immediately supplied into the sealing chamber, so that the sealing effect is further ensured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a shaft sealing device of a pump according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation of a shaft sealing device of a pump.

FIG. 3 is a longitudinal sectional view showing a configuration of a conventional shaft sealing device for a pump.

FIG. 4 is an explanatory view of an operation of a conventional shaft sealing device for a pump.

[Explanation of symbols]

 Reference Signs List 1 rotating shaft 2 stuffing box 3 sealing chamber 4A, 4B, 4C, 4D elastic seal 5 sleeve 6 mechanical seal 7 seal cover 8 supply hole 9 casing 10 sealing ring 11 sealing fluid supply device 12 pressure detector F fluid to be sent G Grease V Vacuum section

Claims (2)

[Claims] 1. A seal chamber is formed between a rotary shaft of a centrifugal pump and a stuffing box, a plurality of elastic seals are provided on a fluid-to-be-transmitted side of the seal chamber, and a mechanical seal is provided on an atmosphere side. A shaft seal device for a pump for supplying a fluid under pressure, wherein the elastic seal on the fluid-to-be-transmitted side of the plurality of elastic seals is mounted in a direction to seal against the fluid-to-be-transferred, and the elastic seal on the mechanical seal side is provided. A shaft seal device for a pump, wherein a seal fluid supply hole is provided between elastic seals of different directions, which are mounted in a sealing direction with respect to a mechanical seal side. A pressure detector for detecting a pressure in the seal chamber; and a seal fluid supply device for replenishing the seal chamber with a seal fluid when a pressure detected by the pressure detector falls below a predetermined pressure. The pump shaft sealing device according to claim 1, wherein: