US2669938A - Impeller and shaft construction - Google Patents

Description

Feb. 23, 1954 E, LA S R I 2,669,938

IMPELLER AND SHAFT CONSTRUCTION Filed Feb. 19, 1953 INVENTOR.

Patented Feb. 23, 1954 IMPELLER AND SHAFT CONSTRUCTION Harry E. La Bour, Elkhart, Ind., assignor to The La Bour Company, Inc., Elkhart, Ind., a corporation of Indiana Application February 19, 1953, Serial No. 337,750

1 Claim. (Cl. 103-115) The present invention relates to the construction of an impeller and its drive shaft, particularly for use in pumps handling corrosive liquids. While the present construction constitutes the solution of a problem in impellers for pumps employed in handling corrosive liquids or so called acid service, it is applicable to pumps handling liquids which are not corrosive. Fur thermore, it solves, in addition to the main problem, subsidiary problems, as will be apparent from the following specification.

A pump for acid service requires an impeller made of corrosion resistant metal and a connected supporting and driving shaft, a section of which must also be made of corrosion resistant metal. A common practice is to cast the corrosion resistant section of the impeller shaft integral with the body of the impeller, and then to machine both parts to the required dimensions.

Aside from the difiiculties which are encountered in casting integral an impeller shaft section and an impeller body, there is the requirement for a wide range in the dimensions and characteristics of the impellers, and a variation in the desired dimensions of the supporting shafts. The casting of an impeller and shaft section of corrosion resistant metals is difficult because of the relatively thin section involved, and the extent of the same. have a high degree of shrinkage and it is difficult to keep the mould filled.

It is old to make a shaft independently of the impeller body, particularly in metals which are not corrosion resistant, and to join the two together by projecting the end of the shaft through the hub of the impeller and threading the end of the shaft to receive a clamping nut which .holds the impeller against a radial shoulder on the shaft, as shown, for example, in Figure 2 of my Patent No. 2,286,425, of January 16, 1942. .I have found that under the effects of chemical attack and the mechanical action of stopping and starting, the nut on the threaded stud will sometimes become loose and permit loosening of the impeller on the shaft. V

A further difficulty which the aforesaid construction involves is the relatively small radial extent of the shoulder against which the impeller is drawn, with consequent likelihood of misalignment of the impeller with the shaft.

I have discovered that it is possible to overcome the aforesaid difficulties by the construction which constitutes the present invention, and which involvesdisposing a separate shaft section in a counterbore in the impeller which coun- Such metals usually 2 terbore provides a radial shoulder near the front end of the impeller hub, and the employment of a headed screw which extends from theintake side of the hub telescopically inside the end of the propeller shaft. The head of the screw closes the outer end of the bore and counterbore, and it is locked against rotationby deformation of a circular wall of the impeller hub surrounding the periphery of the screw head and fitting into a recess in the same. The results flowing from this construction are surprisingly advantageous. Aside from the advantages of separate manufacture of the impeller and of the shaft, the specific mode of attachment permits the shaft to retain its full diameter in the counteroore, whereby a larger area of guidance of "the shaft in the counterbore is provided. A greater radial depth of the interfitting shoulders of the hub and of the shaft is thereby obtained; and amuch longer hold of the screw on the shaft is secured by the telescopic arrangement of the parts. 'The circular head of the screw closes off any pos-. sible opening between the front of the impeller hub and the back of the same, particularlyalong the keyway, and loosening of the screw in the shaft is obviated by the radial indentation or plastic displacement of the metal at the pe riphery of the screw head. Now in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention, I shall describe, in connection with the accompanying drawings, a specific embodiment of thesame. In the drawings: 1 Figure 1 is afront end view of an impeller embodying my invention; and

Figure 2 is a side elevational View of the same, partly in section, to show the details of the connection between the shaft and the impeller hub. While the present invention is particularly suitable for open type impellers, it may be used as well in semi-open or closed impellers. The open type impeller is more generally used in selfpriming pumps of the type covered by my Patent No. 1,578,236, and involving peripheral. re-entry of priming liquid, and where acid service is encountered.

peller which I have shown herein employs curved blades, but the particular form of the blades is optional. The space in the pump casing occupied by the impeller here shown is generally cylindrical. The impeller l herein shown is of the type which substantially fills the casing with only the usual running clearance, although this also is optional. The blades may run in the channel or outside it. The edges 3 of the blades 1 are disposed in a generally conical surface, the axis of the cone being coaxial with the impeller and the shaft H. 7 center on the inlet side, which is on the left of Figure 2, a recess 4, which opens intotheintake passageway of the pump casing not shown. The edges of the blades 3 on the shaft side lie in a plane at right angles to theaxisqftl e Smith! The hub 5 has an axial bore 6 and a counterbore separated by a radial shoulder 8. The ,end face of the round shaft M is squared off at right angles to the ax-isof theshaft and fits closely in the counter-bore 7 with the saidsquared 0&- end engaging the radial shoulder .8 in theim-. peller hub. A keyway l2 ,iscutinithe hub radial lyof the-counterboreand of thebore 6, and a key (.3 set in the shaft ll projects into thekeye way- [land keys the sha-ftand the hubi together.

The end of theshaft H, which extends .into the counterbore isaxially bored and threaded to provide the threaded socket IQ. for receiving the threads of thecircularheaded. screw L5. The screw l5 hasa head,.theeperiphery of. which is substantiallycylindrical, and adapted to .fit fairly closely in the cylindrical recess [6 in the .hub 53,. The periphery of the head hasone or 1110 5616- cesses [.lintowhich themetal 0f the hubziS deformed, as by a prick punch or other tool .fOlf battering .over the. metal vof the. surroundi rim of the. hub to prevent turning of the screw leacent under force great enough to. displace the battered-over metalabovedescribed. Th inner face of the head of the screw is preferably radial, that. is, lies in a plane substantially at rightangles to the axis of the. shank Qith .SCIBW, and it extends a slight distance bey nd the outer edge of thekeyway l2, so that when the screw I5 is threadedtightlyv into the socket .4,. h6'he ld of the screw will close off communication between the intake side and the shaft side of the impeller. The head of the screw l5 axially beyond the cylindrical portion H5 is generally conical, with th outer end terminating in a n a ly radial surface with a non-circular (in this case square) socket for receiving a wrench whereby the screw may be turned on its threads.

The relatively long guiding surface 1 which the hub provides for the shaft H, the long eneasement of thescrew l5 and the shaft ll,1 and the substantial radial depth of the shoulder 8, permit the shaft H and the impeller 'Hl-tobe brought into and maintained in accurate .-align-. ment. The screw extends telescopically of the end of the shaft, and hence the length of threads which may be employed is. independen ei the projection of the ,head ..of the screw into the streambf liquid passing through the impeller. The flat underside of the head of thezscrew i5 bears against the flat face of the seat on the front'face of the hub, and theflat-end faeeof the shaftis pulled against theflat radial shoulder fl-inside the hubwith the benefit of .the relatively long and large diameter bearing oflthe sha'nk of thescrew in the socket L4 in the shaft. This holds the impeller accurately and strongly in placein a plane at right angles to the longitudinal The impeller has. at; t

axis of the shaft. Also because of such concealed thread, and the greater length of thread, the action of a corrosive liquid upon the cooperating threads is much less pronounced. In other words, the structure has longer useful life. This form of impeller and shaft construction makes it unnecessary to cast the impeller and shaft in one ,piece, as' has been g ierallyfpund nie'cessary for acid service. Where a shaft and impeller are cast as one piece, a defect in either the shaft or in a blade will require repairing which is expensive, and sometimes unsatisfactory, or rejection of the casting, which is more likely. According'tothepresent construction, the separate formation of-the impeller and the shaft section provides a combined shaft and impeller which from a, practi al. standpoint is substantially as good as the integral construction, and offers the -very'pronounced advantage of greater flexibility of production. Various lengths of shaft and diameterof shaftmay be provided on various diameters ofrblade and curvatures... and shame of blades by assembling suitable components.- This requires. a much lower-inven ory of steak tomeet the requirementscf the tra e The re:- newal of impellers. and connected haftseetigins in acid service is an m or ant. se vice ifi illimd of a manufacturer- Th constru ti n fulfills. the requirements- 0);- interchangea ility integral mpellers. which are in xis in pumns-s that he pr sent can: strueticnm ybe asat sf ch0 air part Th impeller and shaft. section m e-beeor esi n-ree sistant for acid service, The-parts", -.t: bencae pable. of accurate assembly w tb t es-te t care or difficulty. The shaft ar 1d.z ..ne .er must. be p tively tight against. reverse operation rerun-A screwing-under-rany conditions. of operatian. The attachment of the shaft to the impeller must avoidprojecting or irregular. parts WhiGheWOllld produce inefficiency in: the operation,ofathepumm Also, the attaching means should avoidnleak-i. age axially of the .joint between the, twoiparts. A11 of these requirements are fulfilled by the above described construction.

Thethread between the screw and theeshaf't: is preferably so related .to the. direction of -.rota-.. tion,.which in Figure Iris counterclockwise, that the threads would tighten. on- .the application; of: motor torque to the. shaft member! L The shaft section II which iserequiredto; be corrosion re: sistant for acid service must belong enoughto extend through thepacking gland .onshaft-seal which is-providedto keep a tight joint between the casing and the rotatable shaft. The con; nectionof the shaft section l I to the; motor shaft in a direct drivepump maybe made asxpentli'e a ran ement shown i m Paten ii 2 599, 33; or it may be mad oth rwise. i w

I claim:

An impeller having a shaft, side and an inlet side, a d a n a c ntra hub port ol'n with". peller' blades extending outwardly j ueae tilly in a plane at right anglesto theaiiis or 1th "5 porti said hu p rt on hav nea bore e i s ax y thr u th a a ha n acylindrical counterbore which extends through t he main part of the axial length of the huband provides a cylindrical guiding surface for a driv ing shaft, said hub having atthe junction of 'said bore and said counterbore an-annularradially extending shoulder disposed substantially in we plane at right anglesto theaxis of. the hub, said hub having a keyway whiehextends alongsthe length oftheinsidesurtace ofthehub; said hub having on its inlet side an annular seat disposed substantially in a plane parallel to the plane of said annular shoulder and recessed into the face of the hub, a driving shaft received into said counterbore and guided on said cylindrical surface, said shaft having a key recessed into the same, said key projecting into said keyway, the end surface of the shaft being disposed substantially in a plane at right angles to the longitudinal axis of the shaft and engaging on its full diameter endwise against said annular shoulder, said shaft having an axial socket screw threaded to receive a fastening screw, and a fastening screw having a threaded shank threaded into said socket and having a head provided with a sub- 1 stantially flat annular clamping face of greater References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,743,348 Hollander Jan. 14, 1930 2,166,436 Harlow July 18, 1939 2,331,310 Damonte Oct. 12, 1943 2,613,609 Buchi Oct. 14, 1952 2,635,548 Brawley Apr. 21, 1953

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