JP2003343482A - Immersion pump shaft sealing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the frequency of component replacement by suppressing wear of a shaft sealing device, and to facilitate maintenance and management of a submersible pump. A casing (22) is provided in a portion of a casing (5) through which a motor rotating shaft (3) penetrates.
Is rotatably inserted, and the cylindrical body 22 is freely movable in the radial direction of the motor rotation shaft 5 by the casing 5, and is held in a liquid-tight manner via the O-ring 23. By rotating the motor rotating shaft 3 as close as possible to non-contact with the cylindrical body 22 and moving the cylindrical body 22 following the shaft run-out of the motor rotating shaft 3, the cylindrical body 22 is extremely worn. This reduces the need for wear and replacement of shaft seal device parts, and facilitates maintenance of the immersion pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submersible pump used as a coolant pump for machine tools, and more particularly to a shaft sealing device for sealing liquid leakage from a rotary shaft penetrating portion.

[0002]

2. Description of the Related Art FIG. 3 is a side view showing a cross section of a main part of a conventional immersion pump. The illustrated pump is a multi-stage high-pressure pump, which is composed of a motor unit 1 composed of a three-phase induction motor and a pump unit 2 composed of a centrifugal pump, and a motor rotating shaft 3 and a pump rotating shaft 4 are directly connected. The pump unit 2 has impellers 6 in multiple stages inside a casing 5, and the casing 5 includes a discharge-side casing 7 that also serves as a drive-side bearing bracket of the motor unit 1, and a suction-side casing 8 below the discharge-side casing 7. It consists of The discharge-side casing 7 is an iron casting, and has a cylindrical main body portion 7a that is continuous with the frame of the motor unit 1 and a discharge portion 7 that projects laterally from the main body portion 7a.
It has an overall shape of b and is connected to the motor frame by screws.

In the main body portion 7a of the discharge side casing 7, there are double walls 7c, 7 of a motor side wall 7c and a pump side wall 7d.
d, the walls 7c, 7d are separated by a space 9 having a fan-shaped cross section. The bearing 10 is provided on the motor wall 7c.
Is held and the drive side end of the motor rotating shaft 3 supported by the bearing 10 penetrates the walls 7c and 7d and projects into the pump portion 2, and the pump rotating shaft 4 is fixed to the shaft end by welding. There is. Although not described in detail, the impeller 6 is mounted in multiple stages (6 stages in the drawing) on the pump rotating shaft 4 composed of a spline shaft via a spacing pipe 11, and is fixed by a nut 12 at the shaft end. Further, the suction side casing 8 paired with each impeller 6
Is press-molded from a stainless plate and is stacked in multiple stages around the impeller 6 at the lower end of the discharge-side casing 7. At the end, an annular suction chamber 13 and a strainer 14 composed of a perforated plate are stacked. Above, the upper end is hoisted and held at three locations on the outer periphery by a key-shaped hoisting belt 15 whose upper end is fixed to the discharge side casing 7 with screws.

Such a submersible pump is mounted upright on a top surface of a coolant tank 16 for a machine tool, for example, by a bolt (not shown) via a mounting flange 7e provided on the discharge side casing 7, and the pump portion 2 is attached. It is immersed in the liquid (coolant) 17 stored in the tank 16. When the motor unit 1 is energized and the pump unit 2 is rotationally driven in this state, the pressure of the liquid 17 sucked through the strainer 14 is gradually increased while being sent through the pump along the path indicated by the arrow, and the liquid 17 is discharged from the discharge unit 7b. It is supplied to the machine tool through a pipe (not shown). In that case, the high-pressure liquid 17 in the pump portion 2 tends to leak to the outside from the portion 18 of the discharge side casing 7 through which the motor rotating shaft 3 penetrates.
Therefore, a shaft sealing device 19 is provided in the penetrating portion 18.

FIG. 4 is an enlarged view of the shaft seal portion of FIG. Conventionally, a mechanical seal as shown in FIG. 4 is generally used as the shaft sealing device 19. Although the mechanical seal 19 is well known, the illustrated example will be described below. That is, in FIG. 4, the mechanical seal 19 has a fixed ring 50 fixed to the discharge side casing 7 and a rotary ring 51 fixed to the motor rotation shaft 3 side, and the fixed ring 50 and the rotary ring 51 slide on each other. The surface 52 seals the liquid. The fixed ring 50 is press-fitted into the spot facing surface of the penetrating portion in a liquid-tight manner via a rubber sheet 53. The rotary ring 50 is pressed against the fixed ring 50 by a compression spring 55 via a spring receiving member 54 divided into upper and lower parts.

The upper half of the spring bearing 54 is the rotary ring 5.
1 and the lower half of the spring catch 54 is a dish-shaped washer 5
A bellows 58 having a duck-shaped cross section is inserted between the metal ring 57 supported by the washer 56 and the washer 56 and the rotary ring 51, and the motor rotary shaft 3 and the rotary ring 51 are inserted.
Is sealed liquid-tight. The washer 56 is positioned at the end face of the motor rotating shaft 3 that is the coupling surface between the motor rotating shaft 3 and the pump rotating shaft 4, and the nut 12 (see FIG. 4) is inserted through the spacing pipe 11 that fixes the impeller 6. It is fixed by tightening.

[0007]

As described above, the conventional shaft sealing device 19 uses a mechanical seal. However, this mechanical seal has a fixed ring 50 and a rotary ring 5.
Since 1 and 1 are in sliding contact while being pressed by the compression spring 55, wear is likely to occur on the sliding surface 52, and it is necessary to frequently replace these worn parts as consumable parts, which makes maintenance of the immersion pump troublesome. . In addition, the timing of parts replacement is
It is determined based on the presence or absence of leakage of liquid into the space 9 of the discharge side casing 7.

Therefore, an object of the present invention is to suppress the wear of the shaft sealing device, reduce the frequency of parts replacement, and reduce the maintenance load of the immersion pump.

[0009]

In order to solve the above-mentioned problems, according to the present invention, a rotary shaft for rotating an impeller immersed in a liquid in a tank is installed at a portion penetrating a casing covering the impeller. In the shaft sealing device of the submersible pump that seals the penetrating portion in a liquid-tight manner, a cylinder is provided in a portion of the casing where the rotary shaft penetrates, and the rotary shaft is rotatably inserted into the cylinder. The cylindrical body is held by the casing so as to be movable in the radial direction of the rotary shaft and liquid-tight with respect to the casing (claim 1).

According to the present invention described above, the rotary shaft is simply inserted into the liquid-tight cylinder provided in the rotary shaft penetrating portion of the casing, and the rotary shaft as the rotary side member and the cylinder body as the fixed side member are provided. The liquid is sealed without applying a pressing force between them. The rotating shaft rotates within the cylinder through a gap, but by minimizing this gap, leakage from the surface of the rotating shaft can be almost completely sealed, and at the same time, the cylinder can be closed through a minute gap. By placing it in a state that is as close to non-contact as possible, it is possible to prevent wear of the cylinder body from occurring. In addition, a certain amount of shaft runout is usually unavoidable on the rotary shaft, but by holding the tubular body so that it can move freely in the radial direction of the rotary shaft and making the tubular body follow the axial runout of the rotary shaft, This avoids damage, wear and vibration on the contact surface due to collision with the cylinder.

According to a first aspect of the present invention, the cylindrical body is loosely housed in a hole of the casing through which the rotary shaft penetrates, and an annular elastic seal material is inserted between the outer periphery of the cylindrical body and the casing. It is possible (claim 2). In that case, an O-ring can be used as the sealing material (claim 3). Further, in claim 2, it is preferable that the cylindrical body is loosely locked against the casing (claim 4).

In the present invention, if a liquid draining ring is attached to the outer side portion of the casing of the rotary shaft adjacent to the cylindrical body and the liquid leaked from the cylindrical body is shaken off by a centrifugal force, it is provisional. Even if the liquid leaks from the cylindrical body, it can be shaken off by the centrifugal force to prevent the leakage of the liquid on the side of the motor (claim 5). In that case, if the casing is provided with a drain passage for returning the leaked liquid shaken off by the liquid cutting ring to the tank, the periphery of the pump can be kept clean and the consumption of the liquid can be reduced (claim 6). .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, based on FIG. 1 and FIG.
An embodiment in which the present invention is applied to the immersion pump shown in FIG. 3 shown as a conventional example will be described. Here, FIG. 1 is a side view of the submersible pump in which a main part is shown in a vertical cross section, and FIG. The same reference numerals are used for the parts corresponding to the conventional example, and the description of the same components will be omitted. First, in FIG. 1, the discharge side casing 7
Is provided with double walls 7d and 7f on the pump side.
f is separated from the wall 7d by a space 20 having a U-shaped cross section. A boss 7g is formed integrally with the motor rotation shaft penetrating portion 18 of the pump wall 7f, and a shaft sealing device 19 is provided in this portion 18. Next, the shaft sealing device 19 will be described with reference to FIG.

In FIG. 2, a stepped hole 21 is formed in the boss 7g, leaving a flange 7h at the upper end, and a cylindrical body 22 is housed in the hole 21. The tubular body 22 is a hollow cylindrical body made of gun metal, has a large-diameter portion 22a with a brim at the lower end, and a peripheral groove 22b is provided on the outer peripheral portion thereof. Also, the cylindrical body 2
Plate-shaped ear pieces 22c protruding in the radial direction are provided on the upper end portion of 2 at two locations opposite to each other. This cylinder 2
No. 2 is inserted into the hole 21 after the O-ring 23 as an elastic sealing material is fitted into the groove 22b.
c is loosely fitted in a vertical groove (not shown) of the flange 7g to prevent rotation. In addition, the cylindrical body 2 housed in the hole 21
2 is prevented from coming off by a C-shaped retaining ring 24 fitted in a circumferential groove inside the boss 7g. Here, the tubular body 22 is appropriately movable between the large-diameter portion 22a and the inner wall of the hole 21 or between the ear piece 22c and the vertical groove of the flange 7g so that the tubular body 22 can freely move in the radial direction in the hole 21 to some extent. There is play. However, the O-ring 23 is press-fitted into the hole 21 with a predetermined compression margin so as to liquid-tightly seal between the cylindrical body 22 and the discharge side casing 7.

Reference numeral 25 denotes a liquid draining ring having an annular projection 25a on the outer periphery thereof, which is made of, for example, nitrile rubber, is fitted into the motor rotating shaft 3 from the shaft end, and has a large diameter adjacent to the bearing portion of the motor rotating shaft 3. It is positioned by contacting the end face of the portion 3a. In the assembled state of FIG. 2, the liquid draining ring 25 is exposed to the external space 20 of the discharge side casing 7 and is adjacent to the tubular body 22. The washer 56 that comes into contact with the shaft end of the motor rotating shaft 3 is a conventional one, but is mounted in the opposite direction to the conventional one, and receives only the spacing pipe 11 that fixes the impeller 6. Further, the large diameter portion 3a of the motor rotating shaft 3 exposed in the space 9 has two outer peripheral surfaces opposite to each other flatly removed, and a tool is attached to the flat portion when the nut 12 (see FIG. 1) is tightened. Hang the motor rotation shaft 3
Can be locked.

The gap between the motor rotary shaft 3 and the cylinder 22 is minimized to the extent that the motor rotary shaft 3 can rotate. For example, the shaft diameter of the relevant portion of the motor rotating shaft 3 is 13 m.
In the case of m, the gap is 0.05 mm or less in diameter, preferably
It is set to about 0.01 to 0.03 mm. On the other hand, as described above, the movable range in the radial direction of the cylindrical body 22 movably held in the discharge side casing 7 is the above-described motor rotation shaft 3 and cylindrical body 2.
It is set larger than the gap with 2.

When the submersible pump equipped with such a shaft sealing device 19 is operated, high-pressure liquid acts on the shaft sealing device 19, but an O-ring 23 is provided between the cylindrical body 22 and the discharge side casing 7. The motor rotary shaft 3 and the cylindrical body 22 are sealed with a minute gap. On the other hand, the motor rotation shaft 3 always has a constant shaft runout, but when this shaft runout exceeds the minute gap between the motor rotation shaft 3 and the tubular body 22 described above, the tubular body 22 is radiused by the motor rotation shaft 3. Shaken in the direction. However, due to the above-mentioned play, the cylindrical body 22 floats in the hole 21 following the shaft run-out of the motor rotating shaft 3, so that no unreasonable force is generated in the cylindrical body 22.

In the illustrated embodiment, the motor rotating shaft 3
Rotates in the cylindrical body 22 in a state of almost non-contact via a minute gap, and the cylindrical body 22 floats following the runout of the motor rotating shaft 3, so that the cylindrical body 22 receives the spring pressure. Wear is much less than mechanical seals that make sliding contact with each other. Further, since the gap between the motor rotating shaft 3 and the cylindrical body 22 can be suppressed to an extremely small amount, liquid leakage from this gap is extremely small, and a shaft sealing function comparable to that of the mechanical seal can be obtained. The clearance between the motor rotating shaft 3 and the cylindrical body 22 can of course be precisely machined to determine an appropriate value in advance, but as a means for minimizing this clearance, the fitting is tight to some extent, For example, a method of assembling a pump with a so-called tom fit and rotating the pump as it is, for example, with no load so that the cylindrical body 22 fits into the motor rotating shaft 3 is also effective.

Further, in the illustrated embodiment, a liquid draining ring 25 is attached to the outer portion of the casing of the motor rotating shaft 3 adjacent to the cylindrical body 22. This draining ring 25
If liquid should leak from the cylindrical body 22, the liquid is blocked and shaken off by the centrifugal force from the annular projection 25a. This prevents the leaked liquid from entering the motor side. In addition, the liquid shaken off by the liquid cutting ring 25 is in the space 2
Then, the space 20 is returned to the inside of the tank 16 as indicated by an arrow in FIG.

In the illustrated embodiment, the cylindrical body is loosely movable in the radial direction and is watertightly held, and the cylindrical body is loosely housed in the hole of the casing (discharging side casing), and the outer periphery of the cylindrical body and the casing are An example is shown in which an O-ring is inserted as an annular elastic seal material between the two. However, the cylindrical body may be held in a watertight manner with respect to the casing so as to be free to move in the radial direction following the axial runout of the rotating shaft, and for example, the cylindrical body may be supported by an elastic member such as a coil spring or a leaf spring. Various modes are possible, such as gripping in the casing and sealing the gap between the cylinder and the casing with a bellows. In addition, although the example in which the motor rotation shaft is inserted into the cylinder is shown, when the pump rotation shaft penetrates the casing, the pump rotation shaft is inserted into the cylinder. It does not distinguish from the axis.

[0021]

As described above, according to the present invention, the rotary shaft is simply inserted into the casing-side cylinder, and the rotary shaft is rotated in a state of being almost in non-contact with the cylinder, and
By allowing the tubular body to follow the shaft runout of the rotary shaft and move, the wear of the tubular body is extremely small, and the wear exchange of the shaft sealing device parts is almost unnecessary, and the maintenance of the submersible pump is facilitated.

[Brief description of drawings]

FIG. 1 is a side view showing a longitudinal section of a main part of a pump showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a shaft sealing device portion in FIG.

FIG. 3 is a side view showing a vertical section of a main part of a conventional immersion pump.

FIG. 4 is an enlarged view of a shaft sealing device portion in FIG.

[Explanation of symbols]

1 Motor part 2 pump parts 3 motor rotation axis 4 pump rotation axis 5 casing 6 impeller 7 Discharge side casing 8 Suction side casing 16 Coolant tank 19 Shaft seal device 22 cylinder 23 O-ring 25 draining ring

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3H022 AA01 BA06 CA04 CA28 DA13                       DA16                 3J043 AA16 BA08 CA01 DA09

Claims (6)

[Claims] 1. A shaft seal of a submersible pump, wherein a rotary shaft for rotating an impeller immersed in a liquid in a tank is installed at a portion penetrating a casing covering the impeller, and the penetrating portion is liquid-tightly sealed. In the device, a tubular body is provided in a portion of the casing through which the rotary shaft penetrates, and the rotary shaft is rotatably inserted in the tubular body, and the tubular body is moved by the casing in a radial direction of the rotary shaft. A shaft sealing device for a submersible pump, characterized in that it is held liquid-tightly with respect to the casing. 2. The cylindrical body is loosely housed in a hole of the casing through which the rotary shaft penetrates, and an annular elastic seal member is inserted between the outer periphery of the cylindrical body and the casing. The submerged pump shaft sealing device according to 1. 3. The shaft sealing device for a submersible pump according to claim 2, wherein an O-ring is used as the sealing material. 4. The shaft seal device for a submersible pump according to claim 2, wherein the cylindrical body is loosely stopped from the casing. 5. A liquid draining ring is attached to an outer portion of the casing of the rotary shaft adjacent to the cylindrical body, and the liquid leaked from the cylindrical body is shaken off by a centrifugal force. Item 1. A shaft sealing device for a submersible pump according to item 1. 6. The shaft sealing device for a submersible pump according to claim 5, wherein the casing is provided with a drain passage for returning the leaked liquid shaken off by the liquid cutting ring to the tank.