US2383194A - Pump - Google Patents

Description

. Patented Aug. 21,1 945 assale 1 PUMP Penrose 1t. Hoopcs, Philadelphia, Pa. Application July 19, 1941, Serial No. 403,141

4 Claims'. (Cl. 10S-R6) The present invention relates to pumps and more' particularly to pumps of the intermeshing gear type intended for high speed and high pressure operation.

An object of the present invention is to provide a gear pump of 'the abovef'indicated type which will secure and maintain a desired hydraulic eillciency; this being specifically accomplished by utilizing the developed pressure in cooperation with the pump parts to cause an automatic sealing upon the tendency of the liquid to back-flow from the high tothe low pressure side of the pump.

A still further object is `to provide a gear pump of the above-indicated type of high hydraulic efficiency capable of delivering iluid at high pressure without loss of emclency and which does 4not require a high degree of skill in its manufacture, but will. when constructed. operate mering or vibration. i

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

The invention accordingly consists in the fea,-

tures of construction, combination of elements,r and arrangement of 'parts which will be exempliiied in the construction hereafterset forth and the scope. of the application of whichV will be indicated in the appended claims.

In the accompanying drawing: I Figure 1 is a sectional Vview through .the pump without ham- Forconvenience in assembly. theshaft 26 of the gear 22 is journalled above the gearin'the header I2 and below the gear in the header I4; the lower portion of shaft 26 being of such length that it extends outwardly of the casing through a stuiling box 32 and carries on its outer end a driving pulley 34. In like manner, the shaft 28 of the gear 24 is journalled above and below the gear in the headers lf2 and I4.. y r

With this arrangement. when the gears are in place within the chamber 2li, the latter is divided into a low pressure or inlet side 3 6 and a high pressure or discharge side 38. To admit uid to the low pressure. side, there is provided a vertical inlet 4|!v in the header l2 leading directly to the low pressure chamber 3i and a second inlet 42 leading into the inlet 4I).J Either one of these inlets may be used-and the otherblanked off'. depending up'orithe manner in which the seen in F18. 2), the gear 24 will he simultaneoushousing showing the driving and driven gears constituting the pumping elements with the gears -shown in cross section to illustrate the details of construction thereof; and

Fig. 2 is a plan view with the pump casing partly broken away and partly in section to illustrate details of construction.

Referring tothe drawing, the pump is shown I as including a casing I0 comprising generally top and bottom header members I2 and I4 and a central gear chamber I6. More particularly, the gear chamber I6 is in the form of a ring to provide a chamber 20 having cut from its inner sur-v face dametrically opposite semi-cylindrical seg-v ments to denne. wall surfaces I8 and I9 which cooperate with the teeth of a. pair of gears 22 and 24 to trap and deliver` liquid from one side of the pump to the other. To obtain this cooperation, the gears 22 and 24 are lrespectively mounted on shafts 2B and 28.; the latter Ibeing so located that the wall surfaces I8 and I9 are concentric therewith, and the gears are of such size that substantially half of each gear iits within theconcentricsegment with the two gears intermeshing centrally of the chamber.

ly rotated in a counterclockwise direction, whereby as the teeth enter Vthe concentric segments theycooperate with the casing walls I8 and I9 to trap a portion of liquid and carry it from the low pressure side 36 into the high pressure side 38.

As is well known with this type or pump. upon` the trapping Vof the liquid in the low pressure side and carrying it towards the high pressure side; this increase in pressure tending to force the liquid back to the low pressure side. 4In accordance with the .present invention, this increase in pressure is utilized in cooperation with the pump structure to create an automatic seal and prevent the forcing of liquid back to the low pressure side. vMore specifically. this is accomplished in the present instance by so constructing the gears that upon increase of pressure they will Vcooperate with one another and with the surfaces of the' casing to form a seal and prevent a reverse flow of theliquid.-

To accomplish the foregoing,'the gears'are of a metal-plastic construction having outer sury faces which are suiiciently resilient to yield and distort under increasing pressure to close any clearances and form a positive 'trapr for the liquid carriedfrom the low to the high pressure side. In addition. the intermeshing teeth will form a positive seal to prevent the return `oi! liquid at that point. As best seen in Figs. 1

and 2, each gear consists of a plurality of spaced metal plates 50 completely embedded within a body 48 of suitable plastic such as natural or 'synthetic rubber. The plates 50 are preferably vspaced apart a distance less than their thickness to provide in effect alternate laminations of plastic and metal, but as the metal plates are completely embedded. the entire outerl surface of the gear is of plastic. Inasmuch as the metal plates 50y are provided with teeth 52, that portion. of the plastic which overlies the teeth is suiciently thin to permit it to yield together with the plastic laminations between the teeth o`f the plates when the gear is subjected to pressure. In this way, a sufficient distortion is obtained to seal any gap between the casing wall I8 and the teeth, which seals continuously move from the low to the high pressureside, positively trapping the liquid therebetween and preventing any back-ow from the high to the low pressure side. In like manner, at the point of intermeshing of the gear teeth the-yieldability of the plastic automatically seals and compensates for the varying volume of the clearance therebetween by allowing the volume of the fluid trapped between the teeth to adjust itself by leakage past the low pressure face of the tooth.

In this manner, the trapped uld passes out of the space as the latter 4decreases in volume and is drawn in as the space increases. By providing this automatic sealing action, there will be no drop in emciency as the speed of the pump increases with a consequent increase of pressureV on the high pressure side.

Another advantage of a pump here disclosed is that it can readily handle fluid containing particles of sand, grit, or other solid material as the resilient faces of the gears will permit auch solid particles to pass without the destruction of the sealing surfaces. In operation, the solid particles merely sink into the sealing surfaces, are carried through, and are then forced out by the spring-back of the plastic material as Athe particles reach the high pressure side of the gears.

In order to'give the gears greater strength, the metal plates may also be provided with openings 54-(see Fig. 2) whereby each lamination of plastic is secured to the next lamination.

v Likewise, for greaterstrength the metal plates andplasticbodymaybesecuredtoacentral v core 56, which provided on its outer surface with a plurality of recesses E8 for receiving for example, as laminated synthetic plastic, hard rubber, or fiber. d

With the gear so constructed, it will he seen that the essential characteristic is that it has a sti and strong core and body to resist major Theinterlorofthecore.

silient Aouter surface is integral with the plastic which forms the body portion of the gear. andthus upon any deformation occurring it will be absorbed vthroughout the plastic. thus eliminating the possibility of rapid wear and tear of the `light outer surface. It will also be seen that by constructing a pump in the manner heretofore described high standards of workmanship are not required. lThis is due to the fact that the sft surface of the gears will compensate for any variations in clearances, while still retaining a perfect sealing. Because of this, the pump will operate without hammering or vibration and is thus capable of high speed operation without the loss of eillclency which has heretofore resulted in pumps of this kind.

VAs many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that allv matter contained in the above description or shown ln the accompanying drawing shall be interpreted `as illustrative and not in a limiting It is also to be understood that the/languagel used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention: l

1. In a liquid gearv pump of the character described, a casing having a chamber ltherein, a pair of mating gears having intermeshingtceth -and mounted in said chamber and dividing said chamber into a. low pressure and a high pressure side, said low pressure side being providedwith an inlet port and said high pressure side with an outlet port, the interior wall of said chamber including wall portions concentric with a portion of each of said gears, each of said gears including a rigid core and a. plurality of alternate laminations of metal provided with radially extending teeth on their peripheries and plastic nonrotatably secured to said core, and an outer face of resilient plastic completely' covering the teeth of the gear and contacting the concentric wall portions of the casing, said .central core and metal laminations resisting major deformations of the gear, and said plastic' laminations and face allowing small distortions of the gear to maintain positive contact with the casing wall deformations with a comparatively soft resilient surface of wear-resisting material capable of undergoingsmallelastic deformations. Likewise to provide a seal trapping the liquid between the gear and the casing wall. l

2. For use in a gear pump, a gear having a plurality of radially extending teeth disposed about its periphery and comprising a relatively heavy central core, a plurality lof* metal plates secured to said core and spaced apart from one another at lesser distances than the thicknesses of the plates, said plates having'av plurality of aligned.

-ladially extending teeth disposed about their peripheries. and a molded resilient plastic interposed andvforming thin partitions between said metallic plates and having peripheral teeth enclosing and covering the teeth of said metallic Plates.

3. For use in a gear pump, an essentially metal- .l

spaced teeth on the edges thereof with angledv corners between the bases of the teeth and the 4same material integral with the teeth covering of the plate teeth.

4. A gear according to claim 3 in combination with a. part-cylindrical pump chamberwwall of a circumferential length to simultaneously receiveV numeral teeth of the plates and partitions. said partitions being in one homogeneous integral molded mass with said teeth and teeth coverings.

, PENROSE R. HOOPES.

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