US2464144A - Pumping mechanism - Google Patents

Description

March 8, 1949.

J. W. M CONAGHY PUMPING MECHANISM Filed April 2, 1945 \NVENTOR meslflifcflmqyb BY I Hi5 ATTORNEY- Patented Mar. 8, 1949 2,484,144 PUMPING MECHANISM James W. McConaghy, Phillipsburg, N. J., as-

signor to Ingersoll-Rand Company, New York N. Y., a corporation of New Jersey Application April 2, 1945, Serial No. 586,159

3 Claims. 1

This invention relates to pumps, and more particularly to pumping mechanism including a centrifugal pump and a vacuum pump for effooting the priming of the centrifugal pump.

One object of the invention is to obviate the necessity of driving the vacuum pump throughout the entire operating period of the centrifugal pump.

A more specific object is to disengage the driving connection between the centrifugal pump and the vacuum pump after the centrifugal pump has been primed.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings accompanying this specification and in which similar reference numerals refer to similar parts,

Figure 1 is a plan view of a pumping mechanism constructed and arranged in accordance with the practice of the invention, and

Figure 2 is a transverse view taken through Figure 1 on the line 22.

Referring more particularly to the drawings, 29 designates, in general, the pumping mechanisrn, 2| a centrifugal pump, 22 a vacuum pump for effecting the priming of the centrifugal pump, and 23 a motor for driving the pumps. Only a portion of the motor is shown in Figure 1 at an end of a distance piece 24 interposed between the motor and the pump 2|.

Each pump has its own. casing, that of the centrifugal pump 2| is designated 25 and is recessed to form an impeller chamber 26 and an inlet chamber 21 that opens axially into one side of the impeller chamber. The liquid to be pumped is conveyed to the inlet chamber by a suitable conduit 28, and the impeller chamber has a d scharge port 29 that opens into a discharge line 30.

The chamber 26 contains an impeller 3| keyed to a shaft 32 extending through the distance piece 24 for connection with-the shaft of the motor 23. The end 33 of the shaft 32 projects from the hub 34 of the impeller and is threaded for cooperation with the internal threads 35 of an extension 36 that bears against the hub 34 for pressing it against a sleeve 31 encircling the portion of the shaft 32 lying within the distance piece 24. The extension 36 extends through the inlet chamber 21 and through the end wall 38 of said chamber and is journaled in a bearing bushing 39 in the wall 38.

On the outer surface of the end wall 38 is an extension 40 having an external flange 4| to which is secured. as by bolts 42, the vacuum pump 22. The pump 22 may be of a well known type, the pumping chamber 43 of which is of elliptical shape and the impeller 4-4 is in hydraulic balance and has large radial clearances in the chamber 43 which is filled with liquid. The liquid is turned in the form of a belt along the elliptical surface of the chamber 43 by the impeller and alternately advances from and recedes toward the impeller to draw air into and expel it from the chamber. Such air enters and leaves the chamber 43 through ports 45 in an end wall 48 of the impeller.

During the rotation of the impeller 44 the ports 45 register alternately with inlet ports 4'! and exhaust ports 48 in a head 49 lying between the impeller and the extension 40. The ports 48, only one of which is indicated, open into a passage 50 in the head 49, and a conduit 5| connected to the head 49 affords communication between the passage 50 and a priming liquidsupply chamber 52 in a base member 53 supporting the pumping mechanism.

The ports 41 open into a passage 5-4 which is also located in the head 49 and communicates with the inlet chamber 21 of the centrifugal pump through a conduit 55 having interposed therein a suitable check valve 56 that permits flow-of air only from the centrifugal pump to the vacuum pump.

The shaft 51 for the impeller 44 is journaled in the head 49. It is keyed to the impeller which is held against endwise movement by a nut 59 on the adjacent end of the shaft. The opposite end of the shaft 51 extends exteriorly of the head 49 into a chamber 59 in the extension 40 and carries a clutch member 60 to cooperate with a clutch member Bl on the end of the shaft extension 36 for transmitting rotary movement from the shaft of the centrifugal pump to the rotor of the vacuum pump.

The clutch member 6| is shown as being an integral part of the shaft extension 39 but may, if desired, consist of a separate part and be suitably connected to the extension 36. The clutch member 60, on the other hand, is slidable endwise of the shaft 51 and is held against rotation member 60 confronting the clutch member 8|. Such liquid is conveyed to the chamber 59 by a conduit 68 opening at its other end into the discharge line 30. The inlet opening 81 of the conduit 86 is controlled by a flow-responsive valve 68 slidable endwise in the discharge line. This valve is of the sleeve type through which the discharge output of the centrifugal pump passes and has an introverted flange 69 providing a pressure surface III against which the liquid acts for lifting the valve.

The valve 68 is reciprocable in a cage H in-- terposed in the discharge line 30 and its endwise movement is limited by shoulders 12 and I3 lying respectively above and below the valve and being end surfaces of adjacent portions of the discharge line 80. The shoulders I2 and 13 are so positioned with respect to the inlet opening 61 that when the valve rests upon the shoulder 13 the opening 61 will be blanked-off, and when the valve bears against the shoulder 12 the inlet opening 61 will be fully uncovered to admit liquid into the chamber 59.

To the end that the pressure of the liquid acting against the pressure surface 65 may be quickly relieved whenever the source of liquid supply is cut-off by the valve 68, as when the centrifugal pump loses prime and in which case it is essential that the driving connection between the vacuum and centrifugal pumps be quickly effected, a slight clearance 14 is provided between the periphery of the clutch member 80 and the wall of the chamber 59. The liquid that flows through this clearance will pass from the chamber 59 to the chamber 52 through a conduit I! connected to the extension 40 and the base member 53.

In order to prevent a too free flow of liquid past the clutch member 60 while in the declutched position, a sleeve 16 is disposed in the chamber 59 to seat at one end against the head 49 and cooperate at its other end 11 with the adjacent end surface 18 of the clutch member 60 to restrain the too free flow of liquid through the clearance 14. A port 19 in the sleeve 16 affords communication between the conduit 75 and the chamber 58.

As will be readily seen, the liquid passing from the chamber 59 adds constantly to the supply in the chamber 52 required for use in the vacuum pump, and flowing thereto through a conduit 80 opening into the conduit 55, and necessitates the occasional removal of liquid from the chamber 52 in order that suflicient space may exist therein for the liquid trickling from the chamber 59. The removal of such liquid is effected by the centrifugal pump, and communication between said pump and the chamber 52 is controlled by suitable valve mechanism 8| comprising a casing 82 that is attached to an end of a conduit 83 the opposite end of which is connected to the centrifugal pump to communicate with the chamber 21. In the bottom of the casing 82 is a port 84 to admit liquid from the chamber 52 into the casing 82, and a valve 85 controls the port 84 and is connected operatively to a float 86 that rests in the liquid to rise and fall with the level thereof.

The operation of the pumping mechanism is as follows. Let it be assumed that the chamber 43 of the vacuum pump contains the amount of liquid necessary to efiect the drawing in and the discharge of air through the ports 45 and that the clutch members are in driving engagement with each other so that the impellers of the pumps 2| and 22 will turn in unison. The valve 68 will then also blank-oi! the inlet opening 51 to exclude liquid from the chamber 59. With the parts in these positions the vacuum pump will draw the air from the inlet chamber 21 through the conduit 55 and associated passages and ports into the chamber 43. Upon being compressed in the chamber 43 the air is expelled through the ports 45 and 48, the passage 50 and the conduit 5| into the priming liquid supply chamber 52. When the chambers and associated channels of the centrifugal pump have been thus evacuated the liquid will flow readily thereinto from supply and prime said pump whiclu may then operate at normal capacity.

When the centrifugal pump has been primed and operates at a normal rate the pressure of the liquid discharged thereby and acting against the surface I0 of the valve 68 will move the valve upwardly against the shoulder 12. The inlet opening 61 will then be uncovered and liquid will flow from the discharge line 30 through the conduit 65 against the pressure surface 65 and move the clutch member 60 out of engagement with the clutch member GI and against the surface 11.-

The vacuum pump will then be disconnected from the rotor of the centrifugal pump and will remain idle as long as the pressure in the discharge line 30 is of sufficient value to support the valve 83 in a position to uncover the inlet opening 61. However, when such pressure drops to a value that may be overcome by the weight of the valve 68, said valve will descend and cutoff communication between the inlet opening 61 and the discharge line 30, and after the pressure of the liquid acting against the pressure surface 65 has been sufficiently reduced through leakage past the surfaces 11 and 18 the spring 63 will move the clutch member 60 into engagement with the clutch member 6|. The vacuum pump will then again operate to evacuate the air from the centrifugal pump for primin it.

Whenever the liquid in the chamber 52 rises to a certain predetermined level, the float 86 will open the valve and liquid will then be lifted through the casing 82 and the conduit 83 into the inlet chamber 21 until the level in the chamber 52 is lowered sufliciently to,permit the float 86 to again return the valve 85 to its seat.

From the foregoing description it will be readily apparent that the vacuum pump operates only when necessary to effect the priming of the centrifugal pump. It is, therefore, subjected only to the wear occasioned by these comparatively brief periods of operation, and the cost of operating it is considerably lower than if the pump were required to operate throughout the entire operating period of the pumping unit.

I claim:

1. Pumping mechanism, comprising a centrifugal pump, a vacuum pump for effecting the priming of the centrifugal pump, shafts for the pumps. clutch means for connecting and disconnecting one shaft to the other, a pressure surface on the clutch means, conduit means for conveying liquid discharged by the centrifugal pump to the pressure surface for imparting disconnecting move ment to the clutch means, and a valve actuated by the liquid discharged by the centrifugal pump for controlling the flow of liquid into the conduit means.

2. Pumping mechanism, comprising a centrifugal pump, a vacuum pump for effecting the priming of the centrifugal pump, shafts for the pumps, spring-pressed shiftable clutch means for connecting the shafts together and being disconnected by liquid discharged by the centrifugal pump, and a valve having a pressure surface subjected to the pressure in the discharge stream of the centrifugal pump and moving respon-sively thereto for valving liquid to the clutch means.

3. Pumping mechanism, comprising a centrifugal pump, a vacuum pump for efiecting the priming of the centrifugal pump, shafts for the pumps, clutch members on the shafts for connecting and disconnecting one shaft to and from the other, one of said clutch members having a pressure surface and being movable axially of the other clutch member, a spring constantly tending to press said one clutch member into engagement with the other clutch member, conduit means for conveying-liquid from the centrifugal pump to the pressure surface for imparting disconnecting movement to the said one clutch member, and a float valve in the discharge stream of the centrifugal pump for controlling the flow of liquid from the discharge stream through the conduit means to the pressure surface for moving said one clutch member out of engagement with the other clutch member.

JAMES W. McCONAGI-IY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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