US2748896A - Mechanism for controlling the rotation of a pump shaft - Google Patents

Description

June 5, 1956 D. R. RANKIN 2,743,896

MECHANISM FOR CONTROLLING THE ROTATION OF A PUMP SHAFT Filed April 17, 1952 2 Sheets-Sheet l INVENTOR DAN R. RANKIN ATTORNEY D. R. RANKIN MECHANISM FOR CONTROLLING THE ROTATION OF A PUMP SHAFT June 5, 1956 2 Sheets-Sheet 2 Filed April 17, 1952 RN m A E R mR N A D ATTORNEY United States Patent" MECHANISM FOR CGNTROLLING THE ROTATION OF A PUMP SHAFT Dan R. Rankin, Altadena, Calif., asssignor to Food Machinery and Chemical Corporation, San .lose, Calif., a corporation of Delaware Application April 17, 1952, Serial No. 282,879

7 Claims. (Cl. 188-825) Patented June 5, 1956 Fig. 3 is a fragmentary perspective illustration of a portion of the structure shown in Figs. 1 and 2, as viewed in the direction of the arrow 3 in Fig. 2.

With particular reference to Fig. 1, the numeral 4 designates the upper portion of the vertical shaft of a deep-Well turbine pump which shaft passes axially through the rotor 5 of an electric motor 6 and extends downwardly into a well casing to mount a pump impeller (not shown) at its lower end. The motor 6 is arranged, as will become apparent hereinafter, to drive the pump shaft 4 and cause the impeller to force liquid upwardly through the well casing to and through a suitable discharge outlet, all in a well known manner.

The rotor 5 of the drive motor is supported from below by an anti-thrust bearing (not shown) which is in turn supported by the stationary housing 7 of the motor 6. A substantially tubular casting 8 is secured by bolts and essentially comprise a pump impeller situated at the desired depth in a well casing and connected by a long vertically-extending drive shaft to a motor, engine or other source of rotary power located at the surface of the ground. When the drive to such a pump is terminated, the liquid column within the well casing recedes downwardly and as the liquid passes through the impeller, a reverse rotation of the impeller, the shaft and the rotor of the power unit is produced. As a consequence of the depth of the wells, the receding liquid reaches high velocities and high reverse speeds of the rotary elements are thus produced. Excessive reverse rotation is generally undesirable and additionally, in those many instances where the liquid being pumped provides the lubricant for the upper shaft bearings, no lubrication is administered to said bearings when the liquid recedes, and their frequent replacement is necessitated.

To avoid the difficulties resulting from the described reverse rotation of the pump elements, ratchet mechanisms are frequently associated with the shafts of such deep-well turbine pumps to permit driving rotation but preclude reverse rotation thereof.

Such ratchet mechanisms have proved very successful in installations where the pump'impeller is set as deep as 400 feet but at deeper settings, actual compressive failure of the ratchet elements has resulted from the great torque exerted on the drive shaft by the rapid descent of the liquid through the pump impeller, immediately subsequent to the termination of a pumping op eration.

Accordingly, it is an object of the present invention to provide an improved ratchet arrangement for controlling the rotation of the drive shaft of a deep-well pump of the type described so as to avoid excessive reverse rotation of the rotary elements of the pump, but at the same time prevent damage to the ratchet elements under the hereinabove mentioned condition of high torque exerted on the pump shaft.

More particularly, an object of the invention is to provide, in deep-well pumps of the type referred to, a novel arrangement for connecting the ratchet device to the pump drive shaft so as to permit relative movement therebetween under predetermined conditions of torque on said shaft.

These and other objects will become apparent from the following description of the accompanying drawings wherein:

Fig. l is a central vertical section of the upper portion of a drive mechanism for a deep-well turbine pump, a structural embodiment of the present invention being therein illustrated.

Fig. 2 is a sectional view taken along line 22 of Fig. l.

9 to the upper side of the rotor 5 in co-axial relation thereto so that the bore 10 of said casting receives the vertical pump shaft 4. A key 11, which is inserted in a keyway 4a in the shaft 4 and in the keyway 8a in the casting 8, connects the shaft 4 and the tubular casting 8 and consequently establishes a rototary driving connection between the shaft 4 and the rotor 5 of the electric motor.

Said tubular casting 8 is arranged to support the pump drive shaft 4 at its upper end through an interposed element 12 which has substantially the configuration of a ring and is arranged to rotate in only the direction of pump-driving rotation.

In accordance with the present invention, a frictional connection is established between the casting 8 and the element 12 on the one side and the element 12 and the shaft 4 on the other side so that under predetermined conditions, to be specified hereinafter, the casting 8 and the shaft 4, which as previously mentioned are keyed together, may rotate relative to said element 12 reversely of the direction of pump-driving rotation; although said element is held against such rotary movement. To provide for such frictional connection, the ring-like element 12 is arranged to telescope over the upper portion of the tubular casting 8 to rest upon an annular friction disc 14 riveted to the top of a plate 15 which in turn is secured by pins 16 to a horizontal circular flange 17 formed integrally at an intermediate level on the casting. A cylind'rical bearing 18 may be inserted between the element 12 and the tubular exterior of the casting 8 to permit their relative rotation. An inturned lip 19 at the top of the ring-like element 12 supports a friction washer 20 which is keyed to the pump shaft 4, for rotation therewith, by a gib key 20a which is inserted in the keyway 4a in the shaft 4 and in a keyway Zilb in the washer 20. The washer '20 supports a large nut 21 threadedly affixed to the upper extremity of said shaft.

The described friction disc 14 and the friction washer 20 are preferably composed of an oilite bronze or a similar self-lubricating material. When the friction members 14 and 20 are mounted as described, the permissible relative rotation between said members and the interposed element 12 is determined by the force of engagement therebetween. Since the pump shaft 4 is supported by the large nut 21 directly on the friction washer 20, this force of engagement will be equal to the weight of the pump shaft 4 plus any downward thrust exerted by the liquid against the pump impeller. The force will be of large magnitude because the weight of the shaft of a deep-well pump is great and the downward thrust of the liquid column on the impeller of such a pump is also considerable. As a result, the frictional resistance to relative motion between the element 12 and the shaft 4 on one side and tubular casting 8 on the other side which respectively mount the friction members 14 and 29, will be substantial.

To limit the rotation of the element 12 to the direction of pump-driving rotation, said element forms part of a ratchet or brake mechanism 13. As shown, the ring-like element 12 may be provided with a circular channel or trough 21 to receive a cylindrical flange 22 which depends from :1 spoke wheel 23 secured at its rim to the stationary housing 7 of the motor by a plurality of bolts 24. A predetermined number of ratchet teeth 25 (Fig. 2) are formed integrally on the exterior of the dependent flange 22 and balls 26, one less in number than the teeth 25, are carried in pockets 27 formed in the outer upwardly directed rim 12a of the ring-shaped element 12. As shown clearly in Fig. 3, these pockets 27 extend outwardly and upwardly from the circular trough 21 in the ring-shaped element 12 so that the balls 26 are urged by gravity into engagement with the exterior surface of the flange 22 on which the ratchet teeth 25 are formed. Additionally, the pockets 27 are arranged to recede rearwardly into the rim 12a relative to the single direction of permissive rotation of the ratchet element 12. A can plate 28 is secured on the upper edge of the rim 12a to retain the balls 26 within the pockets 27.

With particular reference to Fig. 2, the ratchet mechanism 13 is arranged to permit rotation of the ring-shaped element 12 in a counterclockwise direction. As the ratchet element 12 moves in such direction, the gradually-sloped backs 25a of the ratchet teeth 25 engage the balls 26 carried at the entrance end of the pockets 27 and cam said balls deeper into said pockets. After a certain speed is attained, centrifugal force maintains the balls 26 fully inserted within the pockets 27 and entirely out of engagement with the ratchet teeth 25.

When, to the contrary, an attempt is made to move the ratchet element 12 in a clockwise direction, however, one of the balls 26, as shown in the three ocloek position in Fig. 2, is almost immediately wedged between the steep face 25b of a ratchet tooth 25 and the side of the adjacent pocket 27 and thus precludes continued clockwise movement of ring-shaped element 12. Due to the numerical difference between the number of balls 26 and the number of ratchet teeth 25, the permissible clockwise movement of the ratchet element 12 prior to the engagement of one ball with a tooth is never greater than a small fraction of the distance between the faces 25b of consecutive ratchet teeth. In this manner, shock on the parts of the ratchet mechanism 13 is substantially reduced.

Operation Power is supplied to the electric motor 6 so that the rotor thereof will rotate in a counterclockwise direction. as viewed from above. Such rotation is transmitted through the tubular casting 8 to the pump drive shaft 4 and thence to the pump impeller. As the pump impeller rotates in a counterclockwise direction, liquid is forced upwardly through the well casing and discharged through the outlet to the point of consumption or use. Since the balls 26 of the ratchet mechanism 13 move outwardly and deeper into the pockets 27 during this counterclockwise rotation, the drive to the pump impeller is not impeded.

Since a certain resilience is inherent in the elongated pump shaft, said shaft becomes somewhat twisted during the pumping operation. Specifically, since the rotation of the impeller is opposed by the liquid being pumped, the lower end of the pump shaft is rotatively displaced in a clockwise direction relative to the upper end of the shaft in an amount dependent upon the height to which the liquid must be raised and this condition of torsional inequilibrium exists at the moment that pumping action ceases. Consequently, at this moment, the lower end of the shaft tends to rotate in a counterclockwise direction and the upper end in a clockwise direction so that a state of equilibrium will be regained.

However, a column of liquid remains in the well casing at the moment of cessation of the drive to the pump.

lmmediately thereafter this liquid will descend by gravity in the casing to engage and urge the pump impeller in a clockwise direction and thus oppose the natural tendency of the lower end of the pump shaft to rotate in a counterclockwise direction resultant from its state of inequilibrium, as explained above. The tendency of the upper end of the shaft to rotate in a clockwise direction is not opposed by the descending liquid, however, and such rotation occurs immediately and with considerable torsional force as determined by the amount of twist in the pump shaft which amount is, in turn, dependent upon the height of the liquid column in the well casing, as previously indicated.

The clockwise or reverse rotation of the upper end of the pump shaft is limited by the ratchet mechanism 13 in the following manner. Upon cessation of the pumping action, the balls 26 roll back to the entrance end of the pockets 27 and after the ring-shaped ratchet element 12, frictionally connected to the pump shaft 4, has ro tated the limited clockwise amount required to wedge one of the balls 26 between the wall of a pocket 27 and the face 25b of a ratchet tooth 25, said ring-shaped ratchet element is positively blocked from further clockwise movement. In this position, it may also prevent further clockwise movement of the pump shaft 4 provided the torsional force applied thereto is not of an amount such as to subject the ratchet elements to excessive compressive stress. The frictional coupling established in accordance with the invention between the ratchet element 12 and the pump shaft 4 through the friction members 14 and 20 is so chosen that it will be overcome by an amount of torsional force that might result in damage or failure of any of the ratchet elements so that the shaft will be permitted to turn a limited number of revolutions until the torsional force applied to the shaft has been spent to an extent where it can no longer damage the ratchet elements. Such rotation of the shaft is limited to several turns by described design and composition of the friction disc 14 and washer 20 to preclude overheating of the parts.

It will, of course, be understood that the power source may comprise an engine rather than a motor, that the ratchet mechanism 13 may be changed or modified in its details and that many other variations may be made from the particular embodiment herein disclosed without departing from the spirit and scope of the present invention as set forth in the appended claims.

I claim:

1. Arrangement for controlling the rotation of the shaft of a deep-well turbine pump or the like comprising a brake mechanism including an element rotatable in only one direction, means supporting the pump shaft in frictional connection with said element for rotation in said one direction therewith and for restrained rotation in the opposite direction relative to said element upon the application of a predetermined amount of torque to said pump shaft in said opposite direction, said means including a first friction member operatively connected to the pump shaft for rotation therewith and supporting said element from below, and a second friction member and secured to the pump shaft and arranged to frictionally engage the top of said element to support the pump shaft thereon.

2. Drive mechanism for the shaft of a deep-well turbine pump or the like comprising a drive rotor operatively connected to the shaft, a brake mechanism including an element rotatable in one direction only, means providing for rotation of the pump shaft and said rotor with said element in said one direction and for restrained ro' tation of said shaft and rotor relative to said element in the opposite direction including a first member supporting and frictionally connecting said element to said rotor, and a second member frictionally engaging said element and secured to the pump shaft so as to support said shaft on said element.

3. In combination, a pump shaft journallcd for rotation about a vertical axis, drive means for rotating said shaft in a first rotary direction, an overrunning brake having a stationary element and a rotatable mem ber arranged to overrun said stationary element when rotated in said first rotary direction, said brake further having means for engaging said rotatable member to prevent rotation in an opposite rotary direction, a friction member keyed to said shaft and supported on said rotatable brake member, means on said shaft disposed on said friction member and arranged to transmit the load on said shaft to said rotatable brake member through said friction member, the weight of said shaft being effective to press said friction member into frictional gripping engagement with said rotatable brake member, the coeflicient of friction of the engaging surfaces of said friction member and said rotatable brake member being coordinated with the load on said shaft to develop a frictional force sufiicient to hold said shaft to said rotatable brake member to prevent reverse rotation of said shaft when said shaft is subjected to torsional loads below a predetermined value tending to rotate the shaft in a reverse direction, and said frictional force being proportioned to yield under reverse torsional loads in excess of said predetermined value.

4. In combination, a pump shaft journalled for rotation about a vertical axis, power means for driving said shaft in a first rotary direction, a brake disposed around said shaft having a stationary member and a rotatable annular member arranged to overrun said stationary member when rotated in said first direction and arranged to engage said stationary member and be detained thereby when rotated in a reverse direction, a friction ring keyed to said shaft having a lower surface in frictional engagement with the overrunning member of said brake, and a member secured to said shaft and overlying said friction ring and arranged to transmit the gravity and pressure loads on said shaft to said overrunning member through said friction ring and to provide a frictional gripping force between said friction ring and said overrunning member of a magnitude suflicient to hold said shaft to said overrunning member to prevent reverse rotation of the shaft when a reverse torsion load below a predetermined value is applied to the shaft, said frictional force being yieldable to permit reverse rotation of said shaft under a reverse torsion load in excess of said predetermined value.

5. In combination, a pump shaft journalled for rotation about a vertical axis, an electric motor having a rotor disposed around the upper end portion of said pump shaft, a hollow tube drive shaft connected between said rotor and said pump shaft and arranged to rotate said pump shaft in a first rotary direction when said motor is energized, an annular flange projecting laterally from said tubular drive shaft providing a flat support surface, a first friction ring disposed on the upper surface of said flange, an overrunning brake disposed around said pump shaft having a stationary member and a rotatable annular member, said rotatable annular member being supported on said friction ring and arranged to overrun said stationary member when rotated in said first rotary direction, a second friction ring keyed to said pump shaft and disposed in frictional engagement with said rotatable annular brake member, and means for applying a predetermined pressure to said second friction ring to press it into frictional engagement with said rotatable brake member and press said rotatable brake member against said first friction ring.

6. A drive mechanism for the vertical drive shaft of a deep-well turbine pump or the like comprising rotary power means disposed around said shaft and splined thereto, means providing an annular support surface on said rotary power means, brake means in frictional engagement with said annular surface and supported thereon and including rotary means movable in one direction of rotation only, and means transmitting the load on the vertical drive shaft to said one-direction rotary means.

7. A drive mechanism for the vertical drive shaft of a deep-well turbine pump or the like comprising an electric motor having a rotor disposed around the shaft and splined thereto, means providing an annular support on said rotor, said support having an upper flat friction surface, brake means disposed around said shaft and having a rotary member mounted for unlimited rotation in one rotary direction only, said one-way rotary member being disposed in frictional driven relation with said upper fiat frictional support surface, and means on the upper end of the shaft overlying said rotary member in frictional driven relation therewith and arranged to transmit the load on the shaft through said rotary member to said annular support surface.

References Cited in the file of this patent UNITED STATES PATENTS 565,474 Leyner Aug. 11, 1896 979,530 McKee Dec. 27, 1910 1,403,018 Walters et a1 Jan. 10, 1922 1,499,923 Hall July 1, 1924 1,820,151 Mullen Aug. 25, 1931 2,518,701 Luenberger Aug. 15, 1950

Claims (1)

1. ARRANGEMENT FOR CONTROLLING THE ROTATION OF THE SHAFT OF A DEEP-WELL TURBINE PUMP OR THE LIKE COMPRISING A BRAKE MECHANISM INCLUDING AN ELEMENT ROTATABLE IN ONLY ONE DIRECTION, MEANS SUPPORTING THE PUMP SHAFT IN FRICTIONAL CONNECTION WITH SAID ELEMENT FOR ROTATION IN SAID ONE DIRECTION THEREWITH AND FOR RESTRAINED ROTATION IN THE OPPOSITE DIRECTION RELATIVE TO SAID ELEMENT UPON THE APPLICATION OF A PREDETERMINED AMOUNT OF TORQUE TO SAID PUMP SHAFT IN SAID OPPOSITE DIRECTION, SAID MEANS INCLUDING A FIRST FRICTION MEMBER OPERATIVELY CONNECTED TO THE PUMP SHAFT FOR ROTATION THEREWITH AND SUPPORTING SAID ELEMENT FROM BELOW, AND A SECOND FRICTION MEMBER AND SECURED TO THE PUMP SHAFT AND ARRANGED TO FRICTIONALLY ENGAGE THE TOP OF SAID ELEMENT TO SUPPORT THE PUMP SHAFT THEREON.

Images