JPH0596492U - Centrifugal pump shaft seal device - Google Patents

Abstract

(57) [Summary] [Purpose] To extend the service life of the shaft seal device for centrifugal pumps that handle muddy water. [Structure] Backliner 11 of pump chamber 2, stuffing box 12, intermediate material connecting both, and impeller 3
The auxiliary pump chamber 4 surrounded by the shroud rear surface 32 is formed. Back screw 41 that rotates together with the impeller
And an auxiliary impeller 42 that rotates together with the impeller is attached. A plurality of first seals 4 whose tips press mutually surfaces between the auxiliary impeller and the stuffing box.
A second seal 44 is provided between the impeller shaft 31 and the stuffing box 3A, 43B. [Effect] Since the action of pushing the intruding muddy water back to the pump chamber side occurs in the auxiliary pump chamber, the pressure of the muddy water is reduced and the seal member is less likely to be worn.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 TECHNICAL FIELD The present invention relates to a centrifugal pump, and more particularly to a shaft sealing device for a spiral pump for dredging, which is used for sucking up sediment such as seabed or riverbed.

[0002]

[Prior Art]

 As a shaft seal for a centrifugal pump, generally, a gland packing is sandwiched between the impeller shaft and the stuffing box, and a stuffing box in front of the gland packing (pump chamber side) prevents water from the pump room from entering the gap. In many cases, sealing water with a pressure higher than the water pressure in the pump chamber is supplied from the outside. If it is a fresh water pump, this method will not cause any serious problems, but if the water to be handled is to be used for dredging, which contains a large amount of earth and sand, then fresh water for this sealing must be prepared separately, and it is a good source of water. If you do not have it, you may have no choice but to apply the sucked mud. However, in such a shaft seal configuration, the hard solid matter in the muddy water rubs directly against the packing, damaging the extremely soft material, and the wear rapidly progresses within a short time, and the shaft seal action immediately decreases. There was a problem called.

FIG. 3 shows one of the conventional techniques proposed to solve this problem. In the figure, a stuffing box 12a is provided on the rear surface of the casing forming the pump chamber, and the impeller shaft 31a of the impeller 3a penetrates the stuffing box. The feature of this technique is to form an auxiliary pump chamber 4a surrounded by the inner peripheral surface and the inner side surface of the stuffing box 12a and the spacer ring 101, and in this auxiliary pump chamber 4a, the auxiliary impeller 42a fixed to the impeller shaft 31a is impeller 42a. It rotates with 3a. As the shaft seal, the first seal 43a is attached from the contact surface between the backliner 11a and the stuffing box to the inner peripheral surface of the stuffing box, and the sleeve 34a fitted on the outer periphery of the impeller shaft 31a and the inner peripheral surface of the stuffing box. The second seal 44a is attached between the and. By adopting such a configuration, the intrusion of muddy water from the pump chamber is prevented by the action of the auxiliary impeller 42a that rotates together with the first seal and the impeller to push out the water flow in the direction opposite to the intrusion direction, and finally. As the third step, it is said that the second seal completely stopped the muddy water and the shaft sealing effect could be improved much more than before.

[0004]

[Problems to be solved by the device]

 However, in the conventional technique cited in FIG. 3, the first encounter with the muddy water entering from the pump chamber is the first seal 43a made of a soft elastic material such as rubber. Therefore, the pressure of the pump chamber is directly applied to the first seal, and the elastic material is worn without resistance due to the hard solid matter contained in the muddy water, that is, the earth and sand. There is a problem that it is easy to reach. In this respect, although there is a backflow action of muddy water by the auxiliary impeller 42a in the auxiliary pump chamber 4a, it is unavoidable from the viewpoint of maintaining the shaft sealing effect.

In order to solve the above-described problems, the present invention aims to provide a device that further rationalizes the combination of the members constituting the shaft sealing device and further enhances the shaft sealing effect and sustains it. And

[0006]

[Means for Solving the Problems]

 The shaft sealing device for a centrifugal pump according to the present invention includes an inner peripheral surface of a back liner 11 of a casing 1, an inner surface of a stuffing box 12 that axially supports an impeller shaft 31, and an inner peripheral surface or an inner surface of an intermediate material that connects the two. An auxiliary pump chamber 4 surrounded by a side surface and a shroud rear surface 32 of the impeller 3 is formed, and a back screw 41 co-rotating with the impeller 1 in the auxiliary pump chamber 4 and an auxiliary impeller 42 co-rotating with the impeller are provided side by side. A plurality of first seals 43A and 43B, which are in pressure contact with the mating surface, are annularly attached to the auxiliary impeller 42 and the inner surface of the stuffing box facing the auxiliary impeller 42, and the impeller shaft 31 is also attached to the inner peripheral surface of the stuffing box 12. The above-mentioned problem was solved by fitting the second seal 44 which is in pressure contact with the outer peripheral surface of the. More specifically, the auxiliary back liner 13 is attached to the inner surface of the stuffing box 12, and the auxiliary pump chamber is interposed with the auxiliary impeller liner 14 as an intermediate material for connecting the back liner 11 and the stuffing box 12. 4 is preferable.

[0007]

[Action]

 The muddy water entering from the pump chamber is first pushed by the rotating back screw 41 and pushed back in the opposite direction. The pressure of the muddy water is greatly reduced here, and the energy to enter the muddy water is greatly reduced. Be reduced. Similarly, the auxiliary impeller 42 that rotates in parallel in the auxiliary pump chamber 4 also synergistically adds the effect of reducing the pressure of the muddy water by the action of the back blades, and most of the muddy water is prevented from entering here. After the pressure has dropped, the muddy water projects annularly toward the other side of the surface of the auxiliary impeller 42 and the side surface of the stuffing box or the member attached thereto, and comes into pressure contact with the surface. It reaches the seal, but at this time it has already lost strong pressure, so it is easily prevented from progressing, and there is no surplus power left to abrade the seal material. Even if some muddy water further intrudes from the auxiliary pump chamber 4, the muddy water having a slight pressure can be easily stopped by the second seal, and the complete water shutoff action can be maintained for a long time.

[0008]

【Example】

 FIG. 1 is a vertical sectional front view showing an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part thereof. In each drawing, a front flange 15 is provided on the front surface of a casing 1, a back liner 11 is provided on the rear surface thereof, and a pump chamber 2 having an opening 16 at the center opening of the front flange is formed. Behind the backliner is provided a stuffing box 12 for axially supporting an impeller shaft 31 of the impeller 3 together with a sleeve 34, and an auxiliary backliner 13 and an auxiliary impeller liner 14 as intermediate members between the backliner and the stuffing box. The back liner 11, the back cover 17, and the stuffing box 12 are fastened together to form the auxiliary pump chamber 4 around the impeller shaft. Needless to say, not all of these members are required, and even if all of them are integrally manufactured, the function and effect of the present invention will not be changed. The assembly method was merely adopted with priority given to the advantages of casting and the convenience of replacement after wear.

The impeller 3 rotating in the casing projects the blades 35 from the shroud front surface 36 toward the suction port side at an equal angle around the impeller boss 33, and the impeller shaft 31 penetrates the stuffing box 12 toward the rear part. It extends and its tip is connected to the rotary shaft of a drive source (not shown). The shroud rear surface 32 faces the front surface of the backliner 11 with a slight gap, and an auxiliary pump chamber 4 is formed from the rear part of the impeller boss 33 to the front part of the impeller shaft 31. , The auxiliary impeller 42 attached to the impeller shaft rotates together with the impeller. The back screw 41 is engraved on the outer peripheral surface with a male screw that feeds water in a direction opposite to the water feeding direction of the impeller 3, and the auxiliary impeller 42 also has a shroud-vane relationship opposite to that of the impeller 3 (front and back). Therefore, when it rotates together with the impeller 3, the action of sending back the muddy water in the opposite direction is synergistically exerted.

The first seal 43 includes a soft rubber annular body 43A which is an elastic material attached near the base of the rear surface of the shroud of the auxiliary impeller 42, and a soft rubber attached to the front surface of the auxiliary back liner 13 facing this surface. Each of the free ends (lips) presses against the surface of the other side and acts to prevent the muddy water from advancing in the axial direction during this period. The second seal 44 is a so-called dust seal and has a shape in which a plurality of annular bodies made of soft rubber and having an L-shaped cross section are fitted side by side on the inner peripheral surface of the stuffing box. The free end (lip) of the second seal 44 is the impeller shaft. The sleeve 34 around the outer circumference 31 is pressed. As shown in detail in FIG. 2, a backup ring 45 and a lantern ring 46 are used for this attachment. Further, the gland packing 47 is always fitted loosely in the sleeve 34, and when the first and second seals are worn and leakage occurs, the packing retainer 48 tightens the gland packing 47 to prevent leakage. Occurs.

[0011]

[Effect of the device]

 According to the present invention, as described above, when the muddy water reaches the first seal, the pressure of the muddy water is greatly reduced, the energy for invading the inside is lost, and the progress of the seal wear is extremely suppressed. It In addition, the muddy water that invades the second seal is almost prevented by this, and the wear of this part is also greatly suppressed, and in the end, the service life of the shaft seal part is greatly extended, and the continuous use of the pump for a long period of time is prolonged. It will be possible and will greatly contribute to the improvement of work efficiency such as dredging.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the same example.

FIG. 3 is a vertical sectional front view showing one of the conventional techniques.

[Explanation of symbols]

 1 Casing 2 Pump Chamber 3 Impeller 4 Auxiliary Pump Chamber 11 Backliner 12 Stuffing Box 13 Auxiliary Backliner 14 Auxiliary Impeller Liner 31 Impeller Shaft 32 Rear Shroud 33 Impeller Boss 34 Sleeve 41 Back Screw 42 Auxiliary Impeller 43 First Seal 44 Second Seal

Claims (2)

[Scope of utility model registration request] 1. A shaft seal device for sealing a leak from an impeller shaft 31 of an impeller 3 rotating in a pump chamber 2 of a centrifugal pump, wherein a backliner 11 of a casing 1 is provided.
Inner peripheral surface of the impeller shaft 31, the inner side surface of the stuffing box 12 that pivotally supports the impeller shaft 31, and the inner peripheral surface or the inner side surface of the intermediate material that connects the two and the shroud rear surface 3 of the impeller 3.
An auxiliary pump chamber 4 surrounded by 2 is formed, and a back screw 41 co-rotating with the impeller 1 in the auxiliary pump chamber 4 and an auxiliary impeller 42 co-rotating with the impeller are provided side by side, and the auxiliary impeller 42 and the opposing impeller 42 face each other. A plurality of first seals 43A and 43B, which are in pressure contact with each other on the inner surface of the stuffing box, are annularly attached to each other, and the impeller shaft 31 or the sleeve 34 for crowning the impeller shaft 31 is also attached to the inner peripheral surface of the stuffing box 12. A shaft seal device for a centrifugal pump, characterized in that a second seal 44, which is in pressure contact with the outer peripheral surface of, is fitted. 2. An auxiliary back liner 13 is attached to an inner surface of a stuffing box 12, and an auxiliary impeller liner 14 is interposed to form an auxiliary pump chamber 4 as an intermediate material for connecting the back liner 11 and the stuffing box 12 together. A shaft seal device for a centrifugal pump, which is characterized in that