JPH0125893B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an impeller that is attached to the lower end of a drive shaft rotatably supported within a vertical casing, and that The present invention relates to an improvement of a shaft sealing device for a hydraulic machine in which a bearing and a shaft sealing device using a magnetic fluid are arranged.

[Prior Art] For example, as a shaft sealing device for a conventional vertical hydraulic machine such as a vertical pump, a gland packing or a mechanical seal has been mainly used.

Figure 2 shows a cross-section of a conventional vertical pump that uses a gland packing as a shaft sealing device. Car 4 is attached. An elbow-shaped discharge port 2 is formed in the upper part of the casing 1, and the drive shaft 3 passes through the upper part of this elbow and is sealed with a shaft sealing device 10. This shaft sealing device 10 rotates the drive shaft 3, and when the impeller 1 pressurizes the liquid that has passed through the strainer 5 and discharges it from the discharge port 2, the liquid flows through the shaft 3 and the upper part of the discharge elbow. The shaft sealing device 10 is provided with a gland packing 6 between it and the drive shaft 3 to prevent leakage from the shaft. Although the clearance between the gland packing 6 and the drive shaft 3 is small and the shaft sealing effect is exhibited, it is necessary to inject clean liquid from the outside as a sealing liquid to also lubricate the sliding parts of the gland packing 6. be.

However, depending on where the pump is installed,
It may be impossible to obtain clean sealing liquid from outside the pump, or there may be a desire to eliminate the need to inject clean sealing liquid in order to save quality. In order to meet such demands, an apparatus using a magnetic fluid seal, which does not require sealing liquid, as shown in FIG. 3, has been proposed.

In FIG. 3, two yokes 7a and 7b are provided in the upper part of the pump casing 1 with a permanent magnet 8 in between, a sleeve 9 made of magnetic material is fitted around the outer periphery of the drive shaft 3, and a yoke Protrusions 9a and 9b are formed in the portions of the sleeve 9 that face the sleeves 7a and 7b, and these sleeves 7a and 7b, the permanent magnet 8, and the sleeve 9 form a magnetic circuit. Then, the yokes 7a, 7b and the protrusions 9a, 9b
Since the magnetic flux density is stronger between the yokes 7a and 7b and the protrusions 9a and 9b, when the magnetic fluid 11 is added there, the magnetic fluid 11 is concentrated in the clearance between the yokes 7a and 7b and the protrusions 9a and 9b, forming a magnetic fluid seal. .

However, since a submersible radial bearing (not shown) of a vertical pump generally has a large radial clearance, the radial vibration or runout of the drive shaft 3 is large. For this reason, the yokes 7a, 7b and the protrusion 9
The radial clearance with a and 9b must be made wider than the clearance of the radial bearing, and the drive shaft 3 swings and becomes eccentric, resulting in a disadvantage that the sealing performance of the magnetic fluid is significantly reduced.

[Object of the Invention] Therefore, an object of the present invention is to provide a shaft sealing device for a hydraulic machine using a magnetic fluid with improved sealing performance.

[Structure of the Invention] According to the present invention, an impeller is attached to the lower end of a drive shaft that is rotatably supported in a vertical casing, and a bearing and a magnetic fluid are used in the penetration part of the drive shaft in the upper part of the casing. In a shaft sealing device for a hydraulic machine in which a shaft sealing device is arranged, the casing of the shaft sealing device is formed separately, a ball bearing is interposed between the separate casing and the drive shaft, and the It is attached to the mold casing via a flexible member.

[Operations and Effects of the Invention] Therefore, the drive shaft and the shaft seal device are positioned in the radial direction by the ball bearing, and the deflection of the drive shaft is absorbed by the flexible member, thereby reducing the clearance of the shaft seal device. It can be made smaller than conventional devices and maintain its clearance. As a result, the sealing performance of the magnetic fluid can be significantly improved.

[Preferred Embodiment] When carrying out the present invention, it is preferable to use a soft rubber ring plate as the flexible member, and to sandwich and adhere the ring plate between the main body and the flange portion of the casing. In this way, the soft rubber ring plate can also serve as a seal.

[Examples] Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, a sleeve 15 made of a magnetic material is fitted around the outer periphery of the drive shaft 22. As shown in FIG.

On the other hand, the shaft sealing device, which is generally indicated by A, has yokes 13a, 13b and a ball located above and below, with a permanent magnet 12 in between, in a casing (hereinafter referred to as casing) 16 of the shaft sealing device that is formed separately from the pump casing 18. The bearings 14a and 14b are inserted, and the inner races of the ball bearings 14a and 14b are connected to the sleeve 15.
The outer race is fitted into the case 16. A projection 13 is provided on the radially inward side of the yokes 13a and 13b facing the sleeve 15.
a' and 13b' are formed. Therefore, this protrusion 1
The clearance between 3a', 13b' and the sleeve 15 is smaller than other parts, and the magnetic flux density formed by the permanent magnet 12 is larger in this clearance part than in other parts. Therefore, when the magnetic fluid 20 is added to this part, the magnetic fluid 20 will be applied to the protrusion 1.
3a', 13b' and the sleeve 15 form a magnetic fluid seal. Note 21
Reference numerals a and 21b are replenishment passages for replenishing the magnetic fluid that evaporates to some extent during pump operation.

The casing 16 consists of a main body 16a and a flange portion 16b, and a flexible member, for example, a ring plate 17 made of soft rubber, is provided between the two and adhered in a sandwich-like manner.
b is bolted to the pump casing 18.

Since the present invention is configured in this way, the clearance between the protrusions 13a', 13b' and the sleeve 15 is determined by the ball bearings 14a, 14b, and does not change due to the runout of the drive shaft 22. do not have. Therefore, it is not necessary to make the radial clearance wider than the radial clearance of the not-illustrated radial bearing of the conventional device, and on the contrary, it is possible to make the clearance optimally narrow. As a result, the sealing performance of the magnetic fluid 20 can be significantly improved. In addition, since the vibration of the drive shaft 22 is absorbed by the soft rubber ring plate 17 of the casing 16, the ball bearings 14a and 14b
An excessive radial load is not applied to the bearing, so a small and inexpensive bearing can be used, and the bearing life can be extended.

[Summary] As explained above, according to the present invention, the drive shaft and the shaft sealing device are positioned in the radial direction by the ball bearing, and the deflection of the drive shaft is absorbed by the flexible member, and the shaft The clearance of the sealing device can be set to an optimal value smaller than that of conventional devices, and the clearance can be maintained. As a result, the sealing performance of the magnetic fluid can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a side sectional view showing a conventional device using a gland packing, and FIG. 3 is a side sectional view showing a conventional device using a magnetic fluid. A... Shaft sealing device, 4... Impeller, 13a, 13b...
Yoke, 14a, 14b... Ball bearing, 15... Sleeve, 16... Casing, 17... Ring plate,
18...Pump casing, 22...Drive shaft.

Claims (1)

[Claims] 1 A hydraulic machine in which an impeller is attached to the lower end of a drive shaft rotatably supported in a vertical casing, and a bearing and a shaft sealing device using magnetic fluid are arranged in the penetration part of the drive shaft in the upper part of the casing. In the shaft sealing device, a casing of the shaft sealing device is formed separately, a ball bearing is interposed between the separate casing and the drive shaft, and a flexible member is inserted into the vertical casing. A shaft sealing device for a hydraulic machine using a magnetic fluid, characterized in that it is installed.