US2059675A - Pump - Google Patents

Description

Nov. 3, A1936. G. H, wooDARD PUMP Filed March 20, 1955 INVENTOR. H11/00d @liti H115 ATTORNEY Patented Nov. 3, 1936 PATENT OFFICE PUMPb George H. Woodard, Phillipsburg, N. J., assignor to Ingersoll-Rand Company, Jersey City, N. J., a corporation of New Jersey lApplication March 20, 1935, Serial No. 11,971

2 Claims.

My invention relates to improvements in pumps, and particularly to means for controlling a pump when coupled to a closed vessel in which a vacuum is being created.

An object ofqthe invention is to provide a selfcontained .unit which can be operated Without the expenditure of an unduly largequantity of power at the beginning of the evacuating operaion.

This invention vbelongs to the same class as that set forth in my prior patent No. 2,044,867 of June 23, 1936, entitled a Regulating device for vacuum pumps, but differs therefrom in that the pump itself is so constructedthat it contains all the elements necessary to yield the desired result and no accessories or externalgoverning devices are required. When a pumpis used to establish a vacuum in a closed vessel containing a fluid medium, such as air, which is to be drawn out so as .l

to establisha vacuum therein, the pump must ordinarily do much more work at the start than later, when thevacuum has'been created and needs only t'o be maintained. The cause of this is the fact that at the outset the intake pressure ishigh and agreater mass ofv air must pass through thel pump and be compressed. The power required to compress the greater mass of air at high intake pressure is obviously greater than that required for a lesser mass at lower in- ,takev pressure.

In this invention the pump comprises a movable member, disposed in the preferred construction to revolve in a casing the intake. of which can be connected to the vessel to be evacuated and the outlet of which-opens to the atmosphere. The pump contains suitable passages controlled by valves, preferably in the movable member,

and opening to a second atmospheric outlet whenever the medium taken into the pump is compressed above a predetermined pressure;

taken with the Adrawing and the novel features are vpointed out in the appended claimsjThevr disclosure, however, is illustrative only andvariations may be made that are embraced within the broad and general meanings of the terms in which the claims are expressed.

On the drawing, Figure 1 shows a transverse sectional view of one embodiment of a pump according to this invention, 5

Figure 2 is a longitudinal view through a part of the pump showing one of the outlets, and

Figure 3 is a cross-section showing a modification.

The numeral I indicates the casing or cylinder l of the pump which comprises also a cylindrical rotor 2, the central axis of which is eccentric with respect to the casing I. As shown this rotor carries radial vanes 3. These vanes are mounted in-slots 4 and may be normally pushed outward l5 as by springs 5 at the inner end of these slots, as well as by centrifugal force when the rotor is turning. The rotor is driven, for example, by a shaft 6 extending into, one end of the cylinder I and the intake of the cylinder is shown at 1. The working space 8 on the inside of the pump between the rotor -and the casing is crescentshaped, so that the medium entering first expands and is then compressed before it is dischargedfrom the cylinder I. This design of pump if it has only the usual -outlet at 23 on the side of the cylinder remote stantially constant. Hence, when the evacuating operation is commenced and the pressure of the contents of the vessel, such as a condenser, which is to be evacuated so that steam or water vapor can be liquefied therein, is about atmospheric, the pump would compress the' contents of said vessel as they are withdrawn to a figure much above atmospheric, say thirty to sixty pounds 40 per square inch when the pressure is `about atmospheric at the inlet 1. As the contents of the vessel are progressively exhausted by the pump the discharge pressure would, of course, fall, but the ratio between the suction pressure and the 45 discharge pressure would be the same, regardless of the vacuum. l Therefore, as explained in my said prior application, much power is needed when the pump begins to work to withdraw the contents of the condenser or other vessel being exhausted, and later as the vacuum is established relatively little power is required to continue it. v My invention eliminates the large power required at the start and producesthe vacuum by the balls outward to close the ports I3.

v in the wall of the casing I. Y

The. rotor of the pump has a central bore 9 into The por-- which the operating shaft 6 extends. tions or sections of the rotor between the vanes 3 contain ducts I0 which extend from the periphery of therotor inward to the bore 9; Inthe form shown in Figure 1 the ducts I0 may be so arranged that one or more are between each pair of vanes 3 and they have enlargements at the outer ends as indicated at II. These ends receive plugs I2 having bores or 'ports I3 and atthe inner ends lof these plugs are valves, such as ball valves I4 engaged by springs I5 seating at the inner ends of these enlargements I I to force When the rotor turns, the valves will be shut partly by the force of the springs I5 and partly by the centrifugal force of the valve itself.

The shaft 6 turns in a ball-bearing I6 carried Over this ball-bearing is a cover I'| through which the shaft 6 passes, and which is counterbored to receive packing rings I8 held by a gland I9 in this cover, around the shaft 6.

In' operation when the rotor revolves the air will be drawn in through intake l connected to the condenser or other vessel to be evacuated, and compressed in the space 8. At first the suction pressure will be relatively high, but asvsoon as theV pressure in the space 8 between any two vanes reaches the predetermined maximum pressure, the valve or valves I4 of that section will be forcedopen and part of the air will be discharged into the bore 9. This bore is connected to the outer air by a passage 20 and a port 2| in the shaft 6. As the evacuation proceeds and the pressure drops at the intake of the pump, the air in the pump will bel compressed relatively higher and higher before the valves I4'0pen.

Hence, vthough the compression ratio now increases, the pump now discharges a lessening `mass of air and the differencein power needed atthe start and after the start is not very great.

No heavy consumption of power when the pumping operation commences takes place, and the 55' pump runs in a most efllcient and economical manner.

The shaft or trunnion 6 shown in Figure 2 will o f course be matched by a similar trunnion at the opposite end of the rotor 2. Power may be exerted at either end of the rotor and either or both shafts or trunnions may have passages Y 20 and ports 2| therein.

In Figure 3 the ball valves I4 are arranged in the bore 9 at the inner ends of the ducts I0 and '-l Of course several passages Il) may be" located side by side between each pair of vanes 4, in a row extending axially or otherwise of the rotor 2.

It will be seen that, with the rotor turning anticlockwise in Figure 1, the part of the crescent-shaped space `8 between each pair of vanes after leaving intake 1 constitutes a compression chamber from which most of the air is expelled as the valve I4 thereof opens. The air which remains after the pressure in Athe chamber has been lowered to the predetermined maximum isyof course discharged through Ithe outlet 23 at whatever nal pumping pressure may exist. These compression chambers, of course, revolve with the rotor 2 and the point at which the exhaust begins of course varies as the Work of evacuating the vessel connected to the intake 1 proceeds. At the beginning the contents of each chamber may be compressed to a sufliciently high point to enable the discharge into the atmosphere to begin just as the particular compression chamber passes through the lowest part of its cir'cular path of travel and starts upward at the right side of the pump casing I. As the air or other gaseous Amedium in the intake be comes less dense and lower` in pressure, the contents of each of these chambers must be com-z pressed to a greater extent and the valve thereof will therefore not open until the chamber has been carried farther up at the right with reference to Figure 1. The point in the circle of revolution of these chambers at which the exhaust commences therefore shifts as vacuum is being created.

While the pump is shown with a rotor I may also construct the pump so that the movable member does not necessarily rotate, but may move in some other manner. Also whether this member rotates, or moves in a different way, the location of the valves can of course be changed without departing from the spirit of this invention. v

The purpose of the invention is thus attained Without waste of power and withoutI any ex' ternal regulating devices being needed to work in connection with the pump. The construction of the pump is simple and in addition to the usual vanes 3 all that is needed are the passages I0,

' the valves I4 with their retainers to hold vthem normally in closed position, and the passages 9' and 20 and outlet port 2| 'I'he presence of the conventional discharge porty 23, in the pump casing l, leading to the discharge connection 24 enables the air to be .expelled efficiently` after the vacuum has been established. At full vacuum in the condenser or other enclosed space connected to the intake 'I there might be too much friction loss in the passages 9 and 2|. The outlet 23 avoids this loss and in no way interferes with the function of thevalves I4.

The air which remains in each compression chamber when the pressure has been lowered to the predetermined maximum value is of course discharged through the outlet 23, to prevent continuous expansion and compression ofA this left over air. Hence the outlet 23 isin continuous use and may serve as a source for low pressure air if desired.

I claim: l

1. A pump comprising a casing having a chamber and a movable pumping member therein, the casing having an inlet and an outlet port for fluid, the member having a discharge passage and a4 plurality of ducts leading from the pump chamber t0 the Passage. and valves controlling the ducts, 732

the valves being arranged to open at a predetermined pressure of the uid in the pump chamber to enable a part of the iluid to discharge from the pump through the ducts and passage, and the said outlet being dissociated from said passage and arranged to discharge the remaining fluid from the pump at the nal pumping pressure.

2. A pump comprising a casing having an inlet and outlet port for uid, a movable pumping member in the casing having means forming a plurality of pumping chambers in the pump, the

member containing a. dischargepassage and a `puulplng pressure.

plurality of ducts leading from the chambers to the passage, valves controlling the ducts, and spring members controlling the valves, the valves being arranged to open at apredetermined pressure of the fluid in the pump to enable part of the uid to discharge from the chambers through the ducts and passage, and the said outlet port being dissociated from said passage and arranged to communicate with each chamber to discharge the remaining uid from the GEORGE Hgwoonann.

pump at the final l0

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