US2858151A - Impeller fastening means with j-shaped keyway - Google Patents

Description

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0d, 28,, 1958 E. G. SEARING IMPELLER FASTENING MEANS WITH J-SHAPED KEYWAY Filed Dec 2, 1954 we/Ma ay IMPELLER FASTENING MEANS WITH J-SHAPED KEYWAY Elmer G. Searing, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application December 2, 1954, Serial No. 472,721 2 Claims. (Cl. 287--52.05)

This invention relates generally to centrifugal pumps. More specifically this invention relates to means for locking the impeller of a centrifugal pump to the shaft driving the impeller.

The hydraulic thrust generated in a centrifugal pump by the action of the fluid on the blades of the pumps impeller acts on the impeller and tends to cause an undesired axial movement of the impeller in the direction of the unbalanced hydraulic thrust. Impeller locking devices are used in centrifugal pumps to check or eliminate this undesired axial movement of the impellers. Certain of the centrifugal pump impeller locking devices used in the art today employ split retaining rings disposed in and extending out of annular grooves cut into the shaft of the centrifugal pump. These split retaining rings form a shoulder which abuts the impeller to limit the axial movement of the impeller in the direction of the unbalanced hydraulic thrust.

The assembly of impeller on the shaft of a centrifugal pump using the split retaining ring type of impeller locking device is a long and cumbersome procedure requiring two men and the use of a special tool. The impeller is heated and then moved axially along the shaft past the annular grooves by one man. The split retaining ring is placed in the annular groove and held in place by another man using a special tool, while the first man moves the impeller back over the ring so that a shoulder in the hub of the impeller abuts the split retaining ring. Another disadvantage of the split retaining ring type of impeller locking device is that the annular grooves in the shaft tend to weaken the shaft.

The impeller locking device of this invention makes the assembly of the impeller on the shaft of a centrifugal pump much easier and quicker by utilizing a torque transmitting key disposed in a shaft keyway and extending into the closed portion of a J-shaped keyway in the bore of the impeller, rather than annular grooves in the shaft and costly split retaining ring, to lock the impeller against axial movement relative to the shaft in the direction of the unbalanced hydraulic thrust generated in the centrifugal pump and acting on the impeller. A centrifugal pump using the impeller locking device of this invention is simpler, easier to manufacture and more economical than a centrifugal pump using the split retaining ring type of impeller locking device because the key and the shaft keyway are essential parts of a centrifugal pump regardless of the type of impeller locking device used in the pump while the annular grooves and split retaining rings are not essential parts of the pump. Furthermore, a centrifugal pump using the locking device of this invention has a shaft that has no annular grooves and is therefore much stronger.

Therefore it is the object of this invention to provide an impeller locking device which makes the assembly of an impeller on the drive shaft of a centrifugal pump easier and quicker than the assembly of an impeller on the shaft of a centrifugal pump using an impeller locking device of a type that is currently in use.

Another object of this invention is to make an impeller locking device that is more economical and easier to manufacture than impeller locking devices used in the art today. v

Another object of this invention is to make an impeller locking device that will not require the use of special tools in the assembly ofthe impeller and the locking device.

Another object of this invention is to make an peller locking device that will 'not require the use of annular grooves in the shaft.

Another object of this invention is to make an impeller locking device that will not require the use of costly split retaining rings.

Another object of this invention is to build an impeller locking device that uses a torque transmitting key to lock the impeller against axial movement in one direction.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a section through a portion of a centrifugal pump showing the impeller locking device of this invention;

Fig. 2 is a section taken along line IIII of Fig. 1; Fig. 3 is a section through a portion of the hub of the impeller of Fig. 2 at an intermediate state of being.

mounted on the shaft; and

Fig. 4 is a section of the portion of the hub of the.

impeller of Fig. 3 operably mounted on the shaft.

As shown in the drawings, the invention is embodied in a centrifugal pump 11. The pump 11 comprises a fluid containing casing 12, a rotatable shaft 13 mounted in the casing 12 and an impeller 14 mounted on and rotatable with the shaft 13. The impeller 14 has a series of circumferentially spaced blades 16 for applying pressure, when rotated, to the fluid contained in the casing. A J-shaped keyway 17 is cut in the wall of the bore 18 of the impeller 14. The shaft 13 has an axially extending keyway 19. A key 21 fits into the shaft keyway 19 and extends into the J-shaped keyway 17. The key may be made integral with the shaft forming a projection on the shaft; but preferably as shown, the key 21 is a separate piece inserted in the shaft keyway.

When assembling the centrifugal pump 11 the key 21 is placed in the shaft keyway 19 and the impeller 14 is mounted on the shaft 13 by moving the impeller 14 axially along the shaft 13 until the long leg 22 of the J-shaped keyway 17 has been moved completely over the key 21 extending out of the shaft keyway 19. The impeller is then turned in the direction opposite to the direction of the shaft rotation. As the impeller 14 is rotated on the shaft 13 the key passes from the long leg 22 of the J-shaped keyway 17 through. the circumferentially extending slot 23 to the complementary part of the short leg 24. The impeller 14 is then moved axially back along the shaft 13 until the key 21 is resting in the part of the short leg 24 nearest the face 26 of the impeller upon which the J-shaped keyway 17 opens. In this final assembled position the key 21 abuts the closed end of short leg 24 of the J-shaped keyway 17.

While the centrifugal pump is being operated there is a pressure applied to the fluid contained in the casing 12 by the impeller blades 11. This hydraulic pressure acts on the axial faces 26 and 26a of the impeller causing a thrust on both faces. The area of these faces 26 and 26a of the impeller 14 subjected to this fluid pressure are made unequal, so that there is a major and a minor hydraulic thrust generated by the action of the fluid on the faces 26 and 26a of the impeller 14 resulting in an unbalanced hydraulic thrust on the impeller 14. This unbalanced hydraulic thrust acts in the same direction Patented Oct. '28, 1958 that the major hydraulic thrust acts on the impeller 14 and tends to move the impeller 14 axially in that direction. However, the impeller locking device of this invention utilizing the driving key 21 and the keyways 17, 19 in the shaft 13 and. the impeller-14opposes this thrust on the impeller 14 and resists the axial motion of the impeller 14 relative to'the shaft 13 in1the, direction of the unbalanced thrust.

The drawings show the J-shaped keyway 17 positioned to-engage the key 21 disposed in the shaft keyway 19 in such away as to oppose the axial movement of the impeller 14 due to the unbalanced hydraulic thrust acting toward the intake side of the impeller 14. However the faces of the impeller can bfedesigned solthat the unbalanced hydraulic thrust can act on the impeller to produce movement of the impeller in either of the two axial directions. Therefore-,the; J -shap ed keyway in the bore of the impeller is alway positioned in such a way that when the impeller is mounted-on the shaft of the centrifugal pump the open end of the long leg of the J-shaped keyway is facing in the direction opposite to the direction of the unbalanced hydraulic thrust.

Although but one embodiment has been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. A centrifugal pump comprising a fluid containing casing, a rotatable shaft mounted in said casing, an impeller provided with a bore for receiving said shaft, said impeller being removably mounted on said shaft and within said casing, and being subjected to an unbalanced hydraulicthrust caused by said fluid exerting a major and a minor hydraulic thrust on faces of said impeller tending to move said impeller axially in one direction when said pump is operating, said bore of said impeller being provided with a J-shaped keyway adjacent to said shaft, said J-shaped keyway comprising a long leg closed at one end and extending axially to the face of said impeller to which said major hydraulic thrust is applied, a short leg axially closed at both ends and circnmferentially spaced from said long leg, a circnmferentially extending slot connecting said legs at their corresponding axially closed ends, said shaft having an axially extending keyway being complementary to the portion of said short leg of said J-shaped keyway closest to said face of said impeller; and a key disposed in said keyway of said shaft and extending into said. portion of said short leg so as to transmit torque from said shaft to said impeller and to secure said impeller against axial movement in the direction of said unbalanced hydraulic thrust.

2. A centrifugal pump comprising a fluid containing casing, a rotatable shaftmounted in said casing, an impeller provided with a bore for receiving said shaft, said impeller being removably mounted on said shaft and within said casing, and being subjected to an unbalanced hydraulic thrust caused by-said fluid exerting a major and a minor hydraulic thrust on the faces of said impeller tending to move said impeller axially in one direction when said pump is operating, said shaft having a keyway, said keyway having axially extending parallel edges and semicircular ends, a key. positioned in and extending out of said keyway, said bore of said impeller being provided with atJ-shaped keyway adjacent to said shaft, said J-shaped keyway comprising a long leg axially closed at one end and axially. extending to,the face of said impeller subjected to said major hydraulic thrust for initially receiving said key while said impelleris being mounted on:

said shaft, a short leg axially closed at both ends circnmferentially spaced from said long leg and cut to accommodate said key, and a circnmferentially extending slot connecting said legs at their corresponding axially closed ends and enabling said shaft and said key to rotate relatively to said impeller-to shift said key from said,

long leg to saidshort leg, whereby said impeller may be shifted axially in said-direction relatively to said shaft to position said key in theportion of said short leg closest to said face of said impeller to transmit torque from said,

shaft to said impeller and to locksaidimpeller against axial movement insaiddirection relatively to said shaft.

ReferencestCitedwin the file of this patent UNITED STATES PATENTS Sinclair Dec. 5, 1939

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