JPS6329912Y2 - - Google Patents

Description

[Detailed description of the invention] (1) Industrial application field This invention relates to a shaft sealing device for a centrifugal pump, and particularly to a shaft sealing device for a centrifugal pump used for dredging.

(2) Conventional technology Conventionally, this type of centrifugal pump has a stuffing box 3 on the rear surface of the casing 2, as shown in Fig. 1.
An impeller shaft 5 having an impeller boss 4 attached to its tip is disposed passing through the stuffing box 3. As a shaft sealing device, a gland packing 7 is interposed between a sleeve 6 fitted to the impeller shaft 5 and the stuffing box 3.
The water pressure inside the pump chamber 8 is higher than the water pressure inside the pump chamber 8 to prevent muddy water mixed with earth and sand from entering from inside the pump chamber 8.
Sealing water is supplied from an inlet 9. 10 and 11 are a suction port and a discharge port, respectively, and 12 is an impeller.

(3) Problems to be solved by the invention By the way, clean water is preferable as the above-mentioned sealing water. However, when using a centrifugal pump for dredging, it may be necessary to use muddy water near the dredging site as sealing water instead of fresh water. The gland packing 7 and sleeve 6 are worn out by foreign substances such as earth and sand, which not only shortens their lifespan, but also makes it impossible to maintain the seal of the shaft seal, causing muddy water in the pump chamber 8 to leak. As a result, there was a problem that the pump efficiency decreased.

Therefore, the technical problem of this invention is to prevent water such as mud from the pump chamber from entering the shaft seal as much as possible without using sealing water.

(4) Means for Solving the Problems In order to solve the above technical problems, this invention provides a centrifugal auxiliary impeller and a spacer ring to the impeller shaft in the auxiliary pump chamber formed in the stuffing box, and the spacer ring to the impeller boss. A plurality of first oil seals are fitted in parallel so that they are on the side of the stuffing box, and have lip portions between the spacer ring and the impeller boss portion, and the lip portions are connected to the spacer ring and the impeller boss portion. placed in surface contact with the
A plurality of second oil seals having lip portions are disposed between the impeller shaft and the stuffing box on the rear end side of the auxiliary pump chamber, with the lip portions in surface contact with the impeller shaft. shall be.

(5) Function The intrusion of water such as muddy water from the pump chamber is successively prevented by the first oil seal, the action of the centrifugal auxiliary impeller that rotates to reverse the direction of water inflow, and the second oil seal. , three-step sealing is possible. Therefore, almost no water intrudes into the shaft seal. Moreover, it does not use any sealing water, so there is no need for water intake and injection equipment, making it particularly convenient for dredging.

(6) Embodiment FIG. 2 shows a shaft sealing device 1 for a dredging centrifugal pump. In FIG. 2, portions that are the same as those of the conventional device are given the same reference numerals as in FIG. 1, and their explanation will be omitted, and the explanation will mainly be given to the different portions.

Auxiliary pump chamber 1 is located inside stuffing box 3.
5 is formed. A centrifugal auxiliary impeller 1 is mounted on the impeller shaft 5 in the auxiliary pump chamber 15.
3 and a spacer ring 14 are fitted in parallel so that the spacer ring 14 is on the impeller boss portion 4 side. Between the spacer ring 14 and the rear end of the impeller boss portion 4 protruding into the stuffing box 3, there is provided an oil tube having a substantially U-shaped cross section and made of an elastic member such as rubber with a lip. There are multiple seals 16 (two in the drawing), and the lip portion is attached to the spacer ring 1.
4 and the impeller boss portion 4 in surface contact with each other. The oil seal 16 is positioned so that its open end faces the pump chamber 8 side, and a collar ring 1 for positioning and holding is provided between both oil seals 16.
7 is placed. Furthermore, a plurality of oil seals 18 (five in the drawing) having the same material and shape as the oil seal 16 are arranged between the sleeve 6 and the stuff-in box 3, with their lip portions in surface contact with the sleeve 6. ing. This oil seal 18 is also positioned so that its open end faces the pump chamber 8 side, and a collar ring 18 and a lantern ring 20 for positioning and holding are arranged between the oil seals 18. A hole 21 is provided in the peripheral wall of the lantern ring 20, and a grease inlet 22 communicating with the hole 21 is provided in the stuff-in box 3, so that the grease injected from the inlet 22 flows through the hole 21 of the lantern ring 20. The material is then supplied between the stuffing box 3 and the sleeve 6. In FIG. 2, reference numeral 23 indicates a cover fixed to the rear end of the stuffing box 3 and provided with a grease inlet 22', and 25 indicates a gasket.

FIG. 3 shows a diagram of the grease supply system. A pipe 27 from the grease pump 26 is connected to a distribution valve 28, and a branch pipe 29 branched off at the distribution valve 28 is connected to injection ports 22, 22'. The device based on this supply system is small enough to be installed near the shaft seal of a centrifugal pump.

In the shaft sealing device 1 for a centrifugal pump as described above, when the impeller shaft 5 is rotated and the pump is operated, muddy water in the pump chamber 8 flows into the gap between the back liner 2' of the casing and the impeller boss 4. After that, the oil tries to enter the shaft seal portion in the stuffing box 3 where a plurality of oil seals 18 are arranged. However, as the first step is the oil seal 16, this prevents muddy water from entering. Further, as the impeller shaft 5 rotates, the auxiliary impeller 13 rotates, and the rotation of the auxiliary impeller 13 changes the flow of muddy water in the opposite direction to the inflow direction, and also lowers the pressure in the auxiliary pump chamber 15 from the pressure in the shaft seal. This also prevents muddy water from entering as a second step. Furthermore, as a third stage, a plurality of oil seals 1 are installed in the shaft seal part.
8, this prevents muddy water from entering.

(7) Effects of the device This device is as described above, and uses three stages of the first oil seal, the action of the centrifugal auxiliary impeller, and the second oil seal to prevent water such as muddy water from entering from the pump chamber. Since this prevents the shaft seal from wearing out, its lifespan is extended, and the sealing effect of the shaft seal is much greater than that of conventional gland packing.
This prevents a decrease in pump efficiency. In addition, if there is no spacer ring, in order to prevent even the slightest amount of water from entering the auxiliary pump chamber, if the lip of the first oil seal is brought into strong contact with the impeller boss, the first oil seal, which is the contact sliding surface, will inevitably come into contact with the impeller boss. The seal and impeller boss part become severely worn, and when replacing the first oil seal, the sealing effect cannot be maintained again unless the impeller itself, including the impeller boss part, is replaced.In the case of this design, however, there is a spacer ring. Therefore, by leaving the impeller as it is and replacing the worn spacer ring and the first oil seal that contacts it with new ones, the sealing effect can be easily maintained again. Furthermore, since there is no need to use sealing water in the shaft seal as in the conventional case, there are excellent effects such as no need to provide water intake equipment for sealing water.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional shaft sealing device for a centrifugal pump, and FIG. 2 is a sectional view showing an embodiment of this invention.
FIG. 3 is a diagram showing a grease supply system. 1...Shaft sealing device, 2...Casing, 2'...
Back liner, 3...stuffing box,
4... Impeller boss section, 5... Impeller shaft, 6... Sleeve, 8... Pump chamber, 13...
Auxiliary impeller, 14...Spacer ring, 16,
18...Oil seal, 15...Auxiliary pump chamber.

Claims (1)

[Scope of utility model registration request] A stuffing box is provided on the rear surface of a casing forming a pump chamber, an impeller shaft with an impeller boss attached to its tip is arranged to pass through the stuffing box, and an auxiliary pump chamber is formed within the stuffing box. In the pump, a centrifugal auxiliary impeller and a spacer ring are fitted in parallel to the impeller shaft in the auxiliary pump chamber so that the spacer ring is on the impeller boss side, and a space between the spacer ring, the impeller boss, and the stuffing box is fitted. A plurality of first oil seals each having a lip portion are arranged such that the lip portions are in surface contact with the spacer ring and the impeller boss portion, and the impeller shaft and the stuffing box on the rear end side of the auxiliary pump chamber are connected to each other. a plurality of second parts with a lip part therebetween;
1. A shaft sealing device for a centrifugal pump, characterized in that an oil seal is disposed with its lip portion in surface contact with an impeller shaft.